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Rima M, Villeneuve-Faure C, Soumbo M, El Garah F, Pilloux L, Roques C, Makasheva K. Towards a better understanding of the effect of protein conditioning layers on microbial adhesion: a focused investigation of fibronectin and bovine serum albumin layers on SiO 2 surfaces. Biomater Sci 2024; 12:3086-3099. [PMID: 38716803 DOI: 10.1039/d4bm00099d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2024]
Abstract
The interaction of foreign implants with their surrounding environment is significantly influenced by the adsorption of proteins on the biomaterial surfaces, playing a role in microbial adhesion. Therefore, understanding protein adsorption on solid surfaces and its effect on microbial adhesion is essential to assess the associated risk of infection. The aim of this study is to evaluate the effect of conditioning by fibronectin (Fn) or bovine serum albumin (BSA) protein layers of silica (SiO2) surfaces on the adhesion and detachment of two pathogenic microorganisms: Pseudomonas aeruginosa PAO1-Tn7-gfp and Candida albicans CIP 48.72. Experiments are conducted under both static and hydrodynamic conditions using a shear stress flow chamber. Through the use of very low wall shear stresses, the study brings the link between the static and dynamic conditions of microbial adhesion. The results reveal that the microbial adhesion critically depends on: (i) the presence of a protein layer conditioning the SiO2 surface, (ii) the type of protein and (iii) the protein conformation and organization in the conditioning layer. In addition, a very distinct adhesion behaviour of P. aeruginosa is observed towards the two tested proteins, Fn and BSA. This effect is reinforced by the amount of proteins adsorbed on the surface and their organization in the layer. The results are discussed in the light of atomic force microscopy analysis of the organization and conformation of proteins in the layers after adsorption on the SiO2 surface, as well as the specificity in bacterial behaviour when interacting with these protein layers. The study also demonstrates the very distinctive behaviours of the prokaryote P. aeruginosa PAO1-Tn7-gfp compared to the eukaryote C. albicans CIP 48.72. This underscores the importance of considering species-specific interactions between the protein conditioning layer and different pathogenic microorganisms, which appear crucial in designing tailored anti-adhesive surfaces.
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Affiliation(s)
- Maya Rima
- LGC, University of Toulouse, CNRS, UTIII, INPT, Toulouse, France.
| | | | - Marvine Soumbo
- LGC, University of Toulouse, CNRS, UTIII, INPT, Toulouse, France.
- LAPLACE, University of Toulouse, CNRS, UTIII, INPT, Toulouse, France.
| | - Fatima El Garah
- LGC, University of Toulouse, CNRS, UTIII, INPT, Toulouse, France.
| | - Ludovic Pilloux
- LGC, University of Toulouse, CNRS, UTIII, INPT, Toulouse, France.
| | - Christine Roques
- LGC, University of Toulouse, CNRS, UTIII, INPT, Toulouse, France.
| | - Kremena Makasheva
- LAPLACE, University of Toulouse, CNRS, UTIII, INPT, Toulouse, France.
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2
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Lutfi LL, Shaaban MI, Elshaer SL. Vitamin D and vitamin K1 as novel inhibitors of biofilm in Gram-negative bacteria. BMC Microbiol 2024; 24:173. [PMID: 38762474 PMCID: PMC11102130 DOI: 10.1186/s12866-024-03293-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 04/04/2024] [Indexed: 05/20/2024] Open
Abstract
BACKGROUND The persistent surge in antimicrobial resistance represents a global disaster. The initial attachment and maturation of microbial biofilms are intimately related to antimicrobial resistance, which in turn exacerbates the challenge of eradicating bacterial infections. Consequently, there is a pressing need for novel therapies to be employed either independently or as adjuvants to diminish bacterial virulence and pathogenicity. In this context, we propose a novel approach focusing on vitamin D and vitamin K1 as potential antibiofilm agents that target Gram-negative bacteria which are hazardous to human health. RESULTS Out of 130 Gram-negative bacterial isolates, 117 were confirmed to be A. baumannii (21 isolates, 17.9%), K. pneumoniae (40 isolates, 34.2%) and P. aeruginosa (56 isolates, 47.9%). The majority of the isolates were obtained from blood and wound specimens (27.4% each). Most of the isolates exhibited high resistance rates to β-lactams (60.7-100%), ciprofloxacin (62.5-100%), amikacin (53.6-76.2%) and gentamicin (65-71.4%). Approximately 93.2% of the isolates were biofilm producers, with 6.8% categorized as weak, 42.7% as moderate, and 50.4% as strong biofilm producers. The minimum inhibitory concentrations (MICs) of vitamin D and vitamin K1 were 625-1250 µg mL-1 and 2500-5000 µg mL-1, respectively, against A. baumannii (A5, A20 and A21), K. pneumoniae (K25, K27 and K28), and P. aeruginosa (P8, P16, P24 and P27) clinical isolates and standard strains A. baumannii (ATCC 19606 and ATCC 17978), K. pneumoniae (ATCC 51503) and P. aeruginosa PAO1 and PAO14. Both vitamins significantly decreased bacterial attachment and significantly eradicated mature biofilms developed by the selected standard and clinical Gram-negative isolates. The anti-biofilm effects of both supplements were confirmed by a notable decrease in the relative expression of the biofilm-encoding genes cusD, bssS and pelA in A. baumannii A5, K. pneumoniae K28 and P. aeruginosa P16, respectively. CONCLUSION This study highlights the anti-biofilm activity of vitamins D and K1 against the tested Gram-negative strains, which emphasizes the potential of these vitamins for use as adjuvant therapies to increase the efficacy of treatment for infections caused by multidrug-resistant (MDR) strains and biofilm-forming phenotypes. However, further validation through in vivo studies is needed to confirm these promising results.
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Affiliation(s)
- Lekaa L Lutfi
- Department of Microbiology and Immunology, Faculty of Pharmacy, Mansoura University, Mansoura, 35516, Egypt
| | - Mona I Shaaban
- Department of Microbiology and Immunology, Faculty of Pharmacy, Mansoura University, Mansoura, 35516, Egypt.
| | - Soha Lotfy Elshaer
- Department of Microbiology and Immunology, Faculty of Pharmacy, Mansoura University, Mansoura, 35516, Egypt
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Sun H, Zhou ZJ, Wen HQ, Chen FF, Pan Y, Tang Q, Yu HQ. Deciphering the Roles of Extracellular Polymeric Substances (EPS) in Shaping Disinfection Kinetics through Permanent Removal via Genetic Disruption. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:6552-6563. [PMID: 38571383 DOI: 10.1021/acs.est.4c01612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/05/2024]
Abstract
Extracellular polymeric substances (EPS) ubiquitously encapsulate microbes and play crucial roles in various environmental processes. However, understanding their complex interactions with dynamic bacterial behaviors, especially during the disinfection process, remains very limited. In this work, we investigated the impact of EPS on bacterial disinfection kinetics by developing a permanent EPS removal strategy. We genetically disrupted the synthesis of exopolysaccharides, the structural components of EPS, in Pseudomonas aeruginosa, a well-known EPS-producing opportunistic pathogen found in diverse environments, creating an EPS-deficient strain. This method ensured a lasting absence of EPS while maintaining bacterial integrity and viability, allowing for real-time in situ investigations of the roles of EPS in disinfection. Our findings indicate that removing EPS from bacteria substantially lowered their susceptibility threshold to disinfectants such as ozone, chloramine B, and free chlorine. This removal also substantially accelerated disinfection kinetics, shortened the resistance time, and increased disinfection efficiency, thereby enhancing the overall bactericidal effect. The absence of EPS was found to enhance bacterial motility and increase bacterial cell vulnerability to disinfectants, resulting in greater membrane damage and intensified reactive oxygen species (ROS) production upon exposure to disinfectants. These insights highlight the central role of EPS in bacterial defenses and offer promising implications for developing more effective disinfection strategies.
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4
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Tago H, Maeda Y, Tanaka Y, Kohketsu H, Lim TK, Harada M, Yoshino T, Matsunaga T, Tanaka T. Line image sensor-based colony fingerprinting system for rapid pathogenic bacteria identification. Biosens Bioelectron 2024; 249:116006. [PMID: 38199081 DOI: 10.1016/j.bios.2024.116006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 01/03/2024] [Accepted: 01/04/2024] [Indexed: 01/12/2024]
Abstract
The rapid identification of pathogenic bacteria is crucial across various industries, including food or beverage manufacturing. Bacterial microcolony image-based classification has emerged as a promising approach to expedite identification, automate inspections, and reduce costs. However, conventional imaging methods have significant practical limitations, namely low throughput caused by the limited imaging range and slow imaging speed. To address these challenges, we developed an imaging system based on a line image sensor for rapid and wide-field imaging compared to existing colony imaging methods. This system can image a standard Petri dish (92 mm in diameter) completely within 22 s, successfully acquiring bacterial microcolony images. This process yielded a set of discrimination parameters termed as colony fingerprints, which were employed for machine learning. We demonstrated the performance of our system by identifying Staphylococcus aureus in food products using a machine learning model trained on a colony fingerprint dataset of 15 species from 9 genera, including foodborne pathogens. While conventional mass spectrometry-based methods require 24 h of incubation, our colony fingerprinting approach achieved 96% accuracy in just 10 h of incubation. Line image sensor offer high imaging speeds and scalability, allowing for swift and straightforward microbiological testing, eliminating the need for specialized expertise and overcoming the limitations of conventional methods. This innovation marks a transformative shift in industrial applications.
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Affiliation(s)
- Hikaru Tago
- Division of Biotechnology and Life Science, Institute of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo, 184-8588, Japan
| | - Yoshiaki Maeda
- Division of Biotechnology and Life Science, Institute of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo, 184-8588, Japan; Institute of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki, 305-8572, Japan
| | - Yusuke Tanaka
- Division of Biotechnology and Life Science, Institute of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo, 184-8588, Japan
| | - Hiroya Kohketsu
- Division of Biotechnology and Life Science, Institute of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo, 184-8588, Japan
| | - Tae-Kyu Lim
- Malcom Co., Ltd., 4-15-10, Honmachi, Shibuya-ku, Tokyo, 151-0071, Japan
| | - Manabu Harada
- Malcom Co., Ltd., 4-15-10, Honmachi, Shibuya-ku, Tokyo, 151-0071, Japan
| | - Tomoko Yoshino
- Division of Biotechnology and Life Science, Institute of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo, 184-8588, Japan
| | - Tadashi Matsunaga
- Division of Biotechnology and Life Science, Institute of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo, 184-8588, Japan
| | - Tsuyoshi Tanaka
- Division of Biotechnology and Life Science, Institute of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo, 184-8588, Japan.
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Tang M, Yang R, Zhuang Z, Han S, Sun Y, Li P, Fan K, Cai Z, Yang Q, Yu Z, Yang L, Li S. Divergent molecular strategies drive evolutionary adaptation to competitive fitness in biofilm formation. THE ISME JOURNAL 2024; 18:wrae135. [PMID: 39052320 PMCID: PMC11307329 DOI: 10.1093/ismejo/wrae135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 05/09/2024] [Accepted: 07/24/2024] [Indexed: 07/27/2024]
Abstract
Biofilm is a group of heterogeneously structured and densely packed bacteria with limited access to nutrients and oxygen. These intrinsic features can allow a mono-species biofilm to diversify into polymorphic subpopulations, determining the overall community's adaptive capability to changing ecological niches. However, the specific biological functions underlying biofilm diversification and fitness adaptation are poorly demonstrated. Here, we launched and monitored the experimental evolution of Pseudomonas aeruginosa biofilms, finding that two divergent molecular trajectories were adopted for adaptation to higher competitive fitness in biofilm formation: one involved hijacking bacteriophage superinfection to aggressively inhibit kin competitors, whereas the other induced a subtle change in cyclic dimeric guanosine monophosphate signaling to gain a positional advantage via enhanced early biofilm adhesion. Bioinformatics analyses implicated that similar evolutionary strategies were prevalent among clinical P. aeruginosa strains, indicative of parallelism between natural and experimental evolution. Divergence in the molecular bases illustrated the adaptive values of genomic plasticity for gaining competitive fitness in biofilm formation. Finally, we demonstrated that these fitness-adaptive mutations reduced bacterial virulence. Our findings revealed how the mutations intrinsically generated from the biofilm environment influence the evolution of P. aeruginosa.
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Affiliation(s)
- Mingxing Tang
- Department of Otorhinolaryngology, Shenzhen Nanshan People’s Hospital, Shenzhen 518052, China
| | - Ruixue Yang
- Community Health Service Center of Southern University of Science and Technology, Nanshan Medical Group Headquarters, Shenzhen 518055, China
| | - Zilin Zhuang
- Department of Pharmacology, School of Medicine, Southern University of Science and Technology, Shenzhen 518055, China
| | - Shuhong Han
- Department of Pharmacology, School of Medicine, Southern University of Science and Technology, Shenzhen 518055, China
| | - Yunke Sun
- Department of Pharmacology, School of Medicine, Southern University of Science and Technology, Shenzhen 518055, China
| | - Peiyu Li
- Department of Infectious Diseases, Shenzhen Nanshan People’s Hospital, Shenzhen University School of Medicine, Shenzhen 518052, China
| | - Kewei Fan
- Department of Infectious Diseases, Shenzhen Nanshan People’s Hospital, Shenzhen University School of Medicine, Shenzhen 518052, China
| | - Zhao Cai
- Department of Research and Development, Shenzhen Mindray Bio-Medical Electronics Co, Ltd, Shenzhen 518057, China
| | - Qiong Yang
- Department of Otorhinolaryngology, Shenzhen Nanshan People’s Hospital, Shenzhen 518052, China
| | - Zhijian Yu
- Department of Infectious Diseases, Shenzhen Nanshan People’s Hospital, Shenzhen University School of Medicine, Shenzhen 518052, China
| | - Liang Yang
- Department of Pharmacology, School of Medicine, Southern University of Science and Technology, Shenzhen 518055, China
| | - Shuo Li
- Department of Otorhinolaryngology, Shenzhen Nanshan People’s Hospital, Shenzhen 518052, China
- Allergy Prevention and Control Center, Nanshan People’s Hospital, Shenzhen 518052, China
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6
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Rattray JB, Lowhorn RJ, Walden R, Márquez-Zacarías P, Molotkova E, Perron G, Solis-Lemus C, Pimentel Alarcon D, Brown SP. Machine learning identification of Pseudomonas aeruginosa strains from colony image data. PLoS Comput Biol 2023; 19:e1011699. [PMID: 38091365 PMCID: PMC10752536 DOI: 10.1371/journal.pcbi.1011699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 12/27/2023] [Accepted: 11/20/2023] [Indexed: 12/28/2023] Open
Abstract
When grown on agar surfaces, microbes can produce distinct multicellular spatial structures called colonies, which contain characteristic sizes, shapes, edges, textures, and degrees of opacity and color. For over one hundred years, researchers have used these morphology cues to classify bacteria and guide more targeted treatment of pathogens. Advances in genome sequencing technology have revolutionized our ability to classify bacterial isolates and while genomic methods are in the ascendancy, morphological characterization of bacterial species has made a resurgence due to increased computing capacities and widespread application of machine learning tools. In this paper, we revisit the topic of colony morphotype on the within-species scale and apply concepts from image processing, computer vision, and deep learning to a dataset of 69 environmental and clinical Pseudomonas aeruginosa strains. We find that colony morphology and complexity under common laboratory conditions is a robust, repeatable phenotype on the level of individual strains, and therefore forms a potential basis for strain classification. We then use a deep convolutional neural network approach with a combination of data augmentation and transfer learning to overcome the typical data starvation problem in biological applications of deep learning. Using a train/validation/test split, our results achieve an average validation accuracy of 92.9% and an average test accuracy of 90.7% for the classification of individual strains. These results indicate that bacterial strains have characteristic visual 'fingerprints' that can serve as the basis of classification on a sub-species level. Our work illustrates the potential of image-based classification of bacterial pathogens and highlights the potential to use similar approaches to predict medically relevant strain characteristics like antibiotic resistance and virulence from colony data.
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Affiliation(s)
- Jennifer B. Rattray
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, United States of America
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Ryan J. Lowhorn
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, United States of America
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Ryan Walden
- Department of Computer Science, Georgia State University, Atlanta, GA, United States of America
| | | | - Evgeniya Molotkova
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, United States of America
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Gabriel Perron
- Department of Biology, Bard College, Annandale-On-Hudson, New York, United States of America
- Center for Systems Biology and Genomics, New York University, New York, New York, United States of America
| | - Claudia Solis-Lemus
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Daniel Pimentel Alarcon
- Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Department of Biostatistics and Medical Informatics, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Sam P. Brown
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, United States of America
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, Georgia, United States of America
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7
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Ferguson DL, Gloag ES, Parsek MR, Wozniak DJ. Extracellular DNA enhances biofilm integrity and mechanical properties of mucoid Pseudomonas aeruginosa. J Bacteriol 2023; 205:e0023823. [PMID: 37791754 PMCID: PMC10601617 DOI: 10.1128/jb.00238-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 08/31/2023] [Indexed: 10/05/2023] Open
Abstract
Pseudomonas aeruginosa is one of the most common biofilm-forming pathogens responsible for lung infections of individuals with cystic fibrosis (CF). P. aeruginosa becomes tolerant to antimicrobials in the biofilm state and is difficult to treat. Production of extracellular polymeric substances (EPS), such as alginate and extracellular DNA (eDNA), can allow adherence to abiotic and biotic surfaces, antimicrobial evasion, and resilience to environmental pressures. Alginate-producing mucoid variants of P. aeruginosa are frequently isolated from CF airway samples and are associated with worsening patient outcomes. While eDNA is a major structural component of nonmucoid P. aeruginosa biofilms, the potential role of eDNA in mucoid biofilms is unclear. Here, we investigate how eDNA contributes to clinical mucoid biofilm physiology and integrity. We predicted that eDNA plays a structural and mechanical role in mucoid biofilms. To test this, we quantified biofilm eDNA in mucoid biofilms and used microscopy and rheology to visualize eDNA and detect changes in biofilm structure and mechanics upon DNaseI treatment. We showed that biofilm eDNA abundance is diverse across clinical mucoid strains and observed a temporal increase in foci of eDNA within intact mucoid biofilms. Increased cell dispersal and reduced biomass were also observed following DNaseI treatment of mucoid biofilms. Degradation of eDNA also impacted the mechanical integrity of mucoid biofilms by increasing the stiffness and decreasing the cohesion of the biofilm. These findings advance our understanding of clinical mucoid P. aeruginosa biofilms and facilitate the development of new approaches to target biofilms by exploiting the functions of EPS components. IMPORTANCE Understanding the role of eDNA in mucoid Pseudomonas aeruginosa biofilms will lead to therapeutic strategies that combat the biophysical and structural function of EPS for the eradication of bacteria in mucoid biofilms during chronic infections. This knowledge can be used to further identify unknown matrix component interactions within pathogenic biofilm-forming clinical isolates.
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Affiliation(s)
- Danielle L. Ferguson
- Department of Microbial Infection and Immunity, Microbiology, The Ohio State University, Columbus, Ohio, USA
| | - Erin S. Gloag
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia, USA
| | - Matthew R. Parsek
- Department of Microbiology, University of Washington, Seattle, Washington, USA
| | - Daniel J. Wozniak
- Department of Microbial Infection and Immunity, Microbiology, The Ohio State University, Columbus, Ohio, USA
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Melaugh G, Martinez VA, Baker P, Hill PJ, Howell PL, Wozniak DJ, Allen RJ. Distinct types of multicellular aggregates in Pseudomonas aeruginosa liquid cultures. NPJ Biofilms Microbiomes 2023; 9:52. [PMID: 37507436 PMCID: PMC10382557 DOI: 10.1038/s41522-023-00412-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 06/15/2023] [Indexed: 07/30/2023] Open
Abstract
Pseudomonas aeruginosa forms suspended multicellular aggregates when cultured in liquid media. These aggregates may be important in disease, and/or as a pathway to biofilm formation. The polysaccharide Psl and extracellular DNA (eDNA) have both been implicated in aggregation, but previous results depend strongly on the experimental conditions. Here we develop a quantitative microscopy-based method for assessing changes in the size distribution of suspended aggregates over time in growing cultures. For exponentially growing cultures of P. aeruginosa PAO1, we find that aggregation is mediated by cell-associated Psl, rather than by either eDNA or secreted Psl. These aggregates arise de novo within the culture via a growth process that involves both collisions and clonal growth, and Psl non-producing cells do not aggregate with producers. In contrast, we find that stationary phase (overnight) cultures contain a different type of multicellular aggregate, in which both eDNA and Psl mediate cohesion. Our findings suggest that the physical and biological properties of multicellular aggregates may be very different in early-stage vs late-stage bacterial cultures.
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Affiliation(s)
- Gavin Melaugh
- SUPA, School of Physics and Astronomy, University of Edinburgh, Edinburgh, EH9 3FD, UK.
- School of Engineering, University of Edinburgh, Edinburgh, EH9 3JL, UK.
| | - Vincent A Martinez
- SUPA, School of Physics and Astronomy, University of Edinburgh, Edinburgh, EH9 3FD, UK
| | - Perrin Baker
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, M5G 0A4, ON, Canada
| | - Preston J Hill
- Departments of Microbial Infection and Immunity, Microbiology, Infectious Diseases Institute, Ohio State University, Columbus, OH, 43210, USA
| | - P Lynne Howell
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, M5G 0A4, ON, Canada
- Department of Biochemistry, University of Toronto, Toronto, M5S 1A8, ON, Canada
| | - Daniel J Wozniak
- Departments of Microbial Infection and Immunity, Microbiology, Infectious Diseases Institute, Ohio State University, Columbus, OH, 43210, USA
| | - Rosalind J Allen
- SUPA, School of Physics and Astronomy, University of Edinburgh, Edinburgh, EH9 3FD, UK
- Theoretical Microbial Ecology, Institute of Microbiology, Faculty of Biological Sciences, Friedrich Schiller University, Jena, 07745, Germany
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Emergence of Small Colony Variants Is an Adaptive Strategy Used by Pseudomonas aeruginosa to Mitigate the Effects of Redox Imbalance. mSphere 2023; 8:e0005723. [PMID: 36853007 PMCID: PMC10117050 DOI: 10.1128/msphere.00057-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023] Open
Abstract
The ability to generate a subpopulation of small colony variants (SCVs) is a conserved feature of Pseudomonas aeruginosa and could represent a key adaptive strategy to colonize and persist in multiple niches. However, very little is known about the role of the SCV phenotype, the conditions that promote its emergence, and its possible involvement in an adaptive strategy. In the present work, we investigated the in vitro selective conditions promoting the emergence of SCVs from the prototypical strain PA14, which readily forms SCVs in nonagitated standing cultures. We found that O2 limitation, which causes a redox imbalance, is the main factor selecting for the SCV phenotype, which promotes survival of the population via formation of a biofilm at the air-liquid interface to access the electron acceptor. When this selective pressure is relieved by aeration or supplementation of an alternative electron acceptor, SCVs are barely detectable. We also observed that SCV emergence contributes to redox rebalancing, suggesting that it is involved in an adaptive strategy. We conclude that selection for the SCV phenotype is an adaptive solution adopted by P. aeruginosa to access poorly available O2. IMPORTANCE The bacterium Pseudomonas aeruginosa is an opportunistic pathogen that thrives in many environments. It poses a significant health concern, notably because it is a causative agent of nosocomial infections and the most prevalent pathogen found in the lungs of people with cystic fibrosis. In infected hosts, its persistence is often related to the emergence of an alternative phenotype known as small colony variant (SCV). Identification of conditions selecting for the SCV phenotype contributes to knowledge regarding adaptive mechanisms exploited by P. aeruginosa to survive in multiple niches and persist during infections. Hindering this adaptation strategy could help control persistent P. aeruginosa infections.
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Grossich R, Lemos Vilches M, Costa CS, Pezzoni M. Role of Pel and Psl polysaccharides in the response of Pseudomonas aeruginosa to environmental challenges: oxidative stress agents (UVA, H 2O 2, sodium hypochlorite) and its competitor Staphylococcus aureus. MICROBIOLOGY (READING, ENGLAND) 2023; 169. [PMID: 36757866 DOI: 10.1099/mic.0.001301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Pseudomonas aeruginosa is a versatile bacterium capable of adapting to a wide range of stress factors, including solar UVA radiation (400-315 nm). High UVA doses produce lethal effects due to the action of reactive oxygen species. Sublethal UVA doses also induces oxidative damage, but, in addition, it triggers a variety of adaptive responses, including the overexpression of pelA and pslA genes in P. aeruginosa. These genes encode the synthesis of Pel and Psl, which are essential polysaccharides in biofilm formation. The present study analysed the role of Pel and Psl in the adaptive responses generated by exposure to low UVA doses, and their importance in the response to lethal doses of UVA, hydrogen peroxide (H2O2), and sodium hypochlorite, in both planktonic cells and submerged and air-liquid interface (ALI) biofilms. It also studied the roles of Pel and Psl in P. aeruginosa-Staphylococcus aureus interaction. The results demonstrate that the capacity of sublethal UVA exposure to increase cell hydrophobicity and cell attachment and generate cross-protection phenomena in P. aeruginosa depends on the presence of Pel and Psl. The study also shows that Pel and Psl have a key role in the tolerance to lethal doses of UVA radiation, sodium hypochlorite and H2O2, in both biofilms and planktonic cells. Finally, co-culture assays showed total inhibition of S. aureus growth in presence of P. aeruginosa. This phenomenon depends, at least in part, on the simultaneous presence of Pel and Psl in planktonic cells and biofilms, suggesting a relevant role of these polysaccharides in the interaction between these species.
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Affiliation(s)
- Romina Grossich
- Departamento de Radiobiología, Comision Nacional de Energía Atómica, San Martín, Buenos Aires, Argentina
| | - Martín Lemos Vilches
- Departamento de Radiobiología, Comision Nacional de Energía Atómica, San Martín, Buenos Aires, Argentina
| | - Cristina S Costa
- Departamento de Radiobiología, Comision Nacional de Energía Atómica, San Martín, Buenos Aires, Argentina
| | - Magdalena Pezzoni
- Departamento de Radiobiología, Comision Nacional de Energía Atómica, San Martín, Buenos Aires, Argentina
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11
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Distinct Long- and Short-Term Adaptive Mechanisms in Pseudomonas aeruginosa. Microbiol Spectr 2022; 10:e0304322. [PMID: 36374016 PMCID: PMC9769816 DOI: 10.1128/spectrum.03043-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Heterogeneous environments such as the chronically infected cystic fibrosis lung drive the diversification of Pseudomonas aeruginosa populations into, e.g., mucoid, alginate-overproducing isolates or small-colony variants (SCVs). In this study, we performed extensive genome and transcriptome profiling on a clinical SCV isolate that exhibited high cyclic diguanylate (c-di-GMP) levels and a mucoid phenotype. We observed a delayed, stepwise decrease of the high levels of c-di-GMP as well as alginate gene expression upon passaging the SCV under noninducing, rich medium growth conditions over 7 days. Upon prolonged passaging, this lagging reduction of the high c-di-GMP levels under noninducing planktonic conditions (reminiscent of a hysteretic response) was followed by a phenotypic switch to a large-colony morphology, which could be linked to mutations in the Gac/Rsm signaling pathway. Complementation of the Gac/Rsm signaling-negative large-colony variants with a functional GacSA system restored the SCV colony morphotype but was not able to restore the high c-di-GMP levels of the SCV. Our data thus suggest that expression of the SCV colony morphotype and modulation of c-di-GMP levels are genetically separable and follow different evolutionary paths. The delayed switching of c-di-GMP levels in response to fluctuating environmental conditions might provide a unique opportunity to include a time dimension to close the gap between short-term phenotypic and long-term genetic adaptation to biofilm-associated growth conditions. IMPORTANCE Extreme environments, such as those encountered during an infection process in the human host, make effective bacterial adaptation inevitable. While bacteria adapt individually by activating stress responses, long-term adaptation of bacterial communities to challenging conditions can be achieved via genetic fixation of favorable traits. In this study, we describe a two-pronged bacterial stress resistance strategy in the opportunistic pathogen Pseudomonas aeruginosa. We show that the production of adjusted elevated c-di-GMP levels, which drive protected biofilm-associated phenotypes in vivo, resembles a stable hysteretic response which prevents unwanted frequent switching. Cellular hysteresis might provide a link between individual adaptability and evolutionary adaptation to ensure the evolutionary persistence of host-adapted stress response strategies.
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12
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Wang X, Blumenfeld R, Feng XQ, Weitz DA. 'Phase transitions' in bacteria - From structural transitions in free living bacteria to phenotypic transitions in bacteria within biofilms. Phys Life Rev 2022; 43:98-138. [PMID: 36252408 DOI: 10.1016/j.plrev.2022.09.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 09/30/2022] [Indexed: 12/05/2022]
Abstract
Phase transitions are common in inanimate systems and have been studied extensively in natural sciences. Less explored are the rich transitions that take place at the micro- and nano-scales in biological systems. In conventional phase transitions, large-scale properties of the media change discontinuously in response to continuous changes in external conditions. Such changes play a significant role in the dynamic behaviours of organisms. In this review, we focus on some transitions in both free-living and biofilms of bacteria. Particular attention is paid to the transitions in the flagellar motors and filaments of free-living bacteria, in cellular gene expression during the biofilm growth, in the biofilm morphology transitions during biofilm expansion, and in the cell motion pattern transitions during the biofilm formation. We analyse the dynamic characteristics and biophysical mechanisms of these phase transition phenomena and point out the parallels between these transitions and conventional phase transitions. We also discuss the applications of some theoretical and numerical methods, established for conventional phase transitions in inanimate systems, in bacterial biofilms.
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Affiliation(s)
- Xiaoling Wang
- School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083, China; John A. Paulson School of Engineering and Applied Sciences, Harvard University, 9 Oxford St, Cambridge, MA, 02138, USA.
| | - Raphael Blumenfeld
- Gonville & Caius College, University of Cambridge, Trinity St., Cambridge CB2 1TA, UK
| | - Xi-Qiao Feng
- Institute of Biomechanics and Medical Engineering, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China
| | - David A Weitz
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, 9 Oxford St, Cambridge, MA, 02138, USA; Department of Physics, Harvard University, 9 Oxford St, Cambridge, MA, 02138, USA
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13
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Lv F, Zhan Y, Lu W, Ke X, Shao Y, Ma Y, Zheng J, Yang Z, Jiang S, Shang L, Ma Y, Cheng L, Elmerich C, Yan Y, Lin M. Regulation of hierarchical carbon substrate utilization, nitrogen fixation, and root colonization by the Hfq/Crc/CrcZY genes in Pseudomonas stutzeri. iScience 2022; 25:105663. [PMID: 36505936 PMCID: PMC9730152 DOI: 10.1016/j.isci.2022.105663] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 09/08/2022] [Accepted: 11/18/2022] [Indexed: 11/24/2022] Open
Abstract
Bacteria of the genus Pseudomonas consume preferred carbon substrates in nearly reverse order to that of enterobacteria, and this process is controlled by RNA-binding translational repressors and regulatory ncRNA antagonists. However, their roles in microbe-plant interactions and the underlying mechanisms remain uncertain. Here we show that root-associated diazotrophic Pseudomonas stutzeri A1501 preferentially catabolizes succinate, followed by the less favorable substrate citrate, and ultimately glucose. Furthermore, the Hfq/Crc/CrcZY regulatory system orchestrates this preference and contributes to optimal nitrogenase activity and efficient root colonization. Hfq has a central role in this regulatory network through different mechanisms of action, including repressing the translation of substrate-specific catabolic genes, activating the nitrogenase gene nifH posttranscriptionally, and exerting a positive effect on the transcription of an exopolysaccharide gene cluster. Our results illustrate an Hfq-mediated mechanism linking carbon metabolism to nitrogen fixation and root colonization, which may confer rhizobacteria competitive advantages in rhizosphere environments.
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Affiliation(s)
- Fanyang Lv
- Biotechnology Research Institute/Key Laboratory of Agricultural Microbiome (MARA), Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yuhua Zhan
- Biotechnology Research Institute/Key Laboratory of Agricultural Microbiome (MARA), Chinese Academy of Agricultural Sciences, Beijing, China
| | - Wei Lu
- Biotechnology Research Institute/Key Laboratory of Agricultural Microbiome (MARA), Chinese Academy of Agricultural Sciences, Beijing, China
| | - Xiubin Ke
- Biotechnology Research Institute/Key Laboratory of Agricultural Microbiome (MARA), Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yahui Shao
- Biotechnology Research Institute/Key Laboratory of Agricultural Microbiome (MARA), Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yiyuan Ma
- Biotechnology Research Institute/Key Laboratory of Agricultural Microbiome (MARA), Chinese Academy of Agricultural Sciences, Beijing, China
| | - Juan Zheng
- Biotechnology Research Institute/Key Laboratory of Agricultural Microbiome (MARA), Chinese Academy of Agricultural Sciences, Beijing, China
| | - Zhimin Yang
- Biotechnology Research Institute/Key Laboratory of Agricultural Microbiome (MARA), Chinese Academy of Agricultural Sciences, Beijing, China
| | - Shanshan Jiang
- Biotechnology Research Institute/Key Laboratory of Agricultural Microbiome (MARA), Chinese Academy of Agricultural Sciences, Beijing, China
| | - Liguo Shang
- Biotechnology Research Institute/Key Laboratory of Agricultural Microbiome (MARA), Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yao Ma
- Biotechnology Research Institute/Key Laboratory of Agricultural Microbiome (MARA), Chinese Academy of Agricultural Sciences, Beijing, China
| | - Lei Cheng
- Key Laboratory of Development and Application of Rural Renewable Energy, Biogas Institute of Ministry of Agriculture and Rural Affairs, Chengdu, China
| | | | - Yongliang Yan
- Biotechnology Research Institute/Key Laboratory of Agricultural Microbiome (MARA), Chinese Academy of Agricultural Sciences, Beijing, China,Corresponding author
| | - Min Lin
- Biotechnology Research Institute/Key Laboratory of Agricultural Microbiome (MARA), Chinese Academy of Agricultural Sciences, Beijing, China,Key Laboratory of Development and Application of Rural Renewable Energy, Biogas Institute of Ministry of Agriculture and Rural Affairs, Chengdu, China,Corresponding author
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14
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Pseudomonas aeruginosa Strains from Both Clinical and Environmental Origins Readily Adopt a Stable Small-Colony-Variant Phenotype Resulting from Single Mutations in c-di-GMP Pathways. J Bacteriol 2022; 204:e0018522. [PMID: 36102640 PMCID: PMC9578426 DOI: 10.1128/jb.00185-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A subpopulation of small-colony variants (SCVs) is a frequently observed feature of Pseudomonas aeruginosa isolates obtained from colonized cystic fibrosis lungs. Since most SCVs have until now been isolated from clinical samples, it remains unclear how widespread the ability of P. aeruginosa strains to develop this phenotype is and what the genetic mechanism(s) behind the emergence of SCVs are according to the origin of the isolate. In the present work, we investigated the ability of 22 P. aeruginosa isolates from various environmental origins to spontaneously adopt an SCV-like smaller alternative morphotype distinguishable from that of the ancestral parent strain under laboratory culture conditions. We found that all the P. aeruginosa strains tested could adopt an SCV phenotype, regardless of their origin. Whole-genome sequencing of SCVs obtained from clinical and environmental sources revealed single mutations exclusively in two distinct c-di-GMP signaling pathways, the Wsp and YfiBNR pathways. We conclude that the ability to switch to an SCV phenotype is a conserved feature of P. aeruginosa and results from the acquisition of a stable genetic mutation, regardless of the origin of the strain. IMPORTANCE P. aeruginosa is an opportunistic pathogen that thrives in many environments. It poses a significant health concern, notably because this bacterium is the most prevalent pathogen found in the lungs of people with cystic fibrosis. In infected hosts, its persistence is considered related to the emergence of an alternative small-colony-variant (SCV) phenotype. By reporting the distribution of P. aeruginosa SCVs in various nonclinical environments and the involvement of c-di-GMP in SCV emergence from both clinical and environmental strains, this work contributes to understanding a conserved adaptation mechanism used by P. aeruginosa to adapt readily in all environments. Hindering this adaptation strategy could help control persistent infection by P. aeruginosa.
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15
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Rahman MU, Fleming DF, Wang L, Rumbaugh KP, Gordon VD, Christopher GF. Microrheology of Pseudomonas aeruginosa biofilms grown in wound beds. NPJ Biofilms Microbiomes 2022; 8:49. [PMID: 35705574 PMCID: PMC9200728 DOI: 10.1038/s41522-022-00311-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 05/13/2022] [Indexed: 11/13/2022] Open
Abstract
A new technique was used to measure the viscoelasticity of in vivo Pseudomonas aeruginosa biofilms. This was done through ex vivo microrheology measurements of in vivo biofilms excised from mouse wound beds. To our knowledge, this is the first time that the mechanics of in vivo biofilms have been measured. In vivo results are then compared to typical in vitro measurements. Biofilms grown in vivo are more relatively elastic than those grown in a wound-like medium in vitro but exhibited similar compliance. Using various genetically mutated P. aeruginosa strains, it is observed that the contributions of the exopolysaccharides Pel, Psl, and alginate to biofilm viscoelasticity were different for the biofilms grown in vitro and in vivo. In vitro experiments with collagen containing medium suggest this likely arises from the incorporation of host material, most notably collagen, into the matrix of the biofilm when it is grown in vivo. Taken together with earlier studies that examined the in vitro effects of collagen on mechanical properties, we conclude that collagen may, in some cases, be the dominant contributor to biofilm viscoelasticity in vivo.
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Affiliation(s)
- Minhaz Ur Rahman
- Department of Mechanical Engineering, Whitacre College of Engineering, Texas Tech University, Lubbock, TX, USA
| | - Derek F Fleming
- Department of Surgery, Texas Tech University Health Sciences, Lubbock, TX, USA
| | - Liyun Wang
- Department of Physics, Center for Nonlinear Dynamics, Interdisciplinary Life Sciences Graduate Programs, LaMontagne Center for Infectious Disease, The University of Texas at Austin, Austin, TX, USA
| | - Kendra P Rumbaugh
- Department of Surgery, Texas Tech University Health Sciences, Lubbock, TX, USA
| | - Vernita D Gordon
- Department of Physics, Center for Nonlinear Dynamics, Interdisciplinary Life Sciences Graduate Programs, LaMontagne Center for Infectious Disease, The University of Texas at Austin, Austin, TX, USA
| | - Gordon F Christopher
- Department of Mechanical Engineering, Whitacre College of Engineering, Texas Tech University, Lubbock, TX, USA.
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16
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Liverpool Epidemic Strain Isolates of Pseudomonas aeruginosa Display High Levels of Antimicrobial Resistance during Both Planktonic and Biofilm Growth. Microbiol Spectr 2022; 10:e0102422. [PMID: 35658710 PMCID: PMC9241699 DOI: 10.1128/spectrum.01024-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Eight isolates of the Liverpool epidemic strain (LES) of Pseudomonas aeruginosa have previously been characterized using comparative genomics and preliminary phenotypic assays. Here, we extend the characterization of these clinically relevant P. aeruginosa isolates with planktonic and biofilm growth assays and analysis of antibiotic susceptibility for both planktonic and biofilm cultures. Laboratory strains PAO1 and PA14 were included as comparator strains. Antibiotic susceptibility to eight classes of antibiotics was determined. MICs were determined to measure susceptibility of planktonic cultures, and minimum biofilm eradication concentration (MBEC) assays were used to estimate levels of resistance during the production of biofilm. LES isolates had high levels of resistance compared with laboratory reference strains when grown planktonically (up to nine 2-fold dilutions higher), and resistance was increased in the biofilm mode of growth. Measurements of biofilm biomass in the MBEC assays showed that certain isolates often show increased biofilm biomass in the presence of antibiotics. IMPORTANCEPseudomonas aeruginosa is an opportunistic pathogen with high intrinsic antibiotic resistance. This resistance is typically increased in clinical isolates through adaptations to the host and production of small-colony variants (SCVs) and when P. aeruginosa forms biofilms, which are surface-attached communities that are protected by a self-produced matrix. Understanding the combination of SCVs, biofilm production, and the diversity of drug resistance phenotypes in clinical isolates can lead to improved treatments for P. aeruginosa infections.
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17
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Liu Y, Gloag ES, Hill PJ, Parsek MR, Wozniak DJ. Interbacterial Antagonism Mediated by a Released Polysaccharide. J Bacteriol 2022; 204:e0007622. [PMID: 35446119 PMCID: PMC9112932 DOI: 10.1128/jb.00076-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 04/06/2022] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas aeruginosa and Staphylococcus aureus are two common pathogens causing chronic infections in the lungs of people with cystic fibrosis (CF) and in wounds, suggesting that these two organisms coexist in vivo. However, P. aeruginosa utilizes various mechanisms to antagonize S. aureus when these organisms are grown together in vitro. Here, we suggest a novel role for Psl in antagonizing S. aureus growth. Psl is an exopolysaccharide that exists in both cell-associated and cell-free forms and is important for biofilm formation in P. aeruginosa. When grown in planktonic coculture with a P. aeruginosa psl mutant, S. aureus had increased survival compared to when it was grown with wild-type P. aeruginosa. We found that cell-free Psl was critical for the killing, as purified cell-free Psl was sufficient to kill S. aureus. Transmission electron microscopy of S. aureus treated with Psl revealed disrupted cell envelopes, suggesting that Psl causes S. aureus cell lysis. This was independent of known mechanisms used by P. aeruginosa to antagonize S. aureus. Cell-free Psl could also promote S. aureus killing during growth in in vivo-like conditions. We also found that Psl production in P. aeruginosa CF clinical isolates positively correlated with the ability to kill S. aureus. This could be a result of P. aeruginosa coevolution with S. aureus in CF lungs. In conclusion, this study defines a novel role for P. aeruginosa Psl in killing S. aureus, potentially impacting the coexistence of these two opportunistic pathogens in vivo. IMPORTANCE Pseudomonas aeruginosa and Staphylococcus aureus are two important opportunistic human pathogens commonly coisolated from clinical samples. However, P. aeruginosa can utilize various mechanisms to antagonize S. aureus in vitro. Here, we investigated the interactions between these two organisms and report a novel role for P. aeruginosa exopolysaccharide Psl in killing S. aureus. We found that cell-free Psl could kill S. aureus in vitro, possibly by inducing cell lysis. This was also observed in conditions reflective of in vivo scenarios. In accord with this, Psl production in P. aeruginosa clinical isolates positively correlated with their ability to kill S. aureus. Together, our data suggest a role for Psl in affecting the coexistence of P. aeruginosa and S. aureus in vivo.
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Affiliation(s)
- Yiwei Liu
- Department of Microbiology, Ohio State University, Columbus, Ohio, USA
- Department of Microbial Infection and Immunity, Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Erin S. Gloag
- Department of Microbial Infection and Immunity, Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Preston J. Hill
- Department of Microbial Infection and Immunity, Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Matthew R. Parsek
- Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA
| | - Daniel J. Wozniak
- Department of Microbiology, Ohio State University, Columbus, Ohio, USA
- Department of Microbial Infection and Immunity, Ohio State University College of Medicine, Columbus, Ohio, USA
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18
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Fleming D, Niese B, Redman W, Vanderpool E, Gordon V, Rumbaugh KP. Contribution of Pseudomonas aeruginosa Exopolysaccharides Pel and Psl to Wound Infections. Front Cell Infect Microbiol 2022; 12:835754. [PMID: 35463635 PMCID: PMC9021892 DOI: 10.3389/fcimb.2022.835754] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 03/01/2022] [Indexed: 11/24/2022] Open
Abstract
Biofilms are the cause of most chronic bacterial infections. Living within the biofilm matrix, which is made of extracellular substances, including polysaccharides, proteins, eDNA, lipids and other molecules, provides microorganisms protection from antimicrobials and the host immune response. Exopolysaccharides are major structural components of bacterial biofilms and are thought to be vital to numerous aspects of biofilm formation and persistence, including adherence to surfaces, coherence with other biofilm-associated cells, mechanical stability, protection against desiccation, binding of enzymes, and nutrient acquisition and storage, as well as protection against antimicrobials, host immune cells and molecules, and environmental stressors. However, the contribution of specific exopolysaccharide types to the pathogenesis of biofilm infection is not well understood. In this study we examined whether the absence of the two main exopolysaccharides produced by the biofilm former Pseudomonas aeruginosa would affect wound infection in a mouse model. Using P. aeruginosa mutants that do not produce the exopolysaccharides Pel and/or Psl we observed that the severity of wound infections was not grossly affected; both the bacterial load in the wounds and the wound closure rates were unchanged. However, the size and spatial distribution of biofilm aggregates in the wound tissue were significantly different when Pel and Psl were not produced, and the ability of the mutants to survive antibiotic treatment was also impaired. Taken together, our data suggest that while the production of Pel and Psl do not appear to affect P. aeruginosa pathogenesis in mouse wound infections, they may have an important implication for bacterial persistence in vivo.
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Affiliation(s)
- Derek Fleming
- Department of Surgery, Texas Tech University Health Sciences, Lubbock, TX, United States
| | - Brandon Niese
- Department of Physics, Center for Nonlinear Dynamics, The University of Texas at Austin, Austin TX, United States
| | - Whitni Redman
- Department of Surgery, Texas Tech University Health Sciences, Lubbock, TX, United States
| | - Emily Vanderpool
- Department of Surgery, Texas Tech University Health Sciences, Lubbock, TX, United States
| | - Vernita Gordon
- Department of Physics, Center for Nonlinear Dynamics, The University of Texas at Austin, Austin TX, United States
- Interdisciplinary Life Sciences Graduate Programs, LaMontagne Center for Infectious Disease, The University of Texas at Austin, Austin, TX, United States
| | - Kendra P. Rumbaugh
- Department of Surgery, Texas Tech University Health Sciences, Lubbock, TX, United States
- Burn Center for Research Excellence, Texas Tech University Health Sciences, Lubbock, TX, United States
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19
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Lakshmi SA, Alexpandi R, Shafreen RMB, Tamilmuhilan K, Srivathsan A, Kasthuri T, Ravi AV, Shiburaj S, Pandian SK. Evaluation of antibiofilm potential of four-domain α-amylase from Streptomyces griseus against exopolysaccharides (EPS) of bacterial pathogens using Danio rerio. Arch Microbiol 2022; 204:243. [PMID: 35381886 DOI: 10.1007/s00203-022-02847-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Revised: 02/27/2022] [Accepted: 03/14/2022] [Indexed: 12/19/2022]
Abstract
Biofilm formation is a major issue in healthcare settings as 75% of nosocomial infection arises due to biofilm residing bacteria. Exopolysaccharides (EPS), a key component of the biofilm matrix, contribute to the persistence of cells in a complex milieu and defends greatly from exogenous stress and demolition. It has been shown to be vital for biofilm scaffold and pathogenic features. The present study was aimed to investigate the effectiveness of four domain-containing α-amylase from Streptomyces griseus (SGAmy) in disrupting the EPS of multidrug-resistant bacteria, especially methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa. In vitro analysis of preformed biofilm unveiled the antibiofilm efficacy of SGAmy against MRSA (85%, p < 0.05) and P. aeruginosa (82%, p < 0.05). The total carbohydrate content in the EPS matrix of MRSA and P. aeruginosa was significantly reduced to 71.75% (p < 0.01) and 74.09% (p < 0.01), respectively. The findings inferred from in vitro analysis were further corroborated through in vivo studies using an experimental model organism, Danio rerio. Remarkably, the survival rate was extended to 88.8% (p < 0.05) and 74.2% (p < 0.05) in MRSA and P. aeruginosa infected fishes, respectively. An examination of gills, kidneys, and intestines of D. rerio organs depicted the reduced level of microbial colonization in SGAmy-treated cohorts and these findings were congruent with bacterial enumeration results.
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Affiliation(s)
- Selvaraj Alagu Lakshmi
- Department of Biotechnology, Alagappa University, Tamil Nadu, Science Campus, Karaikudi, 630003, India
| | - Rajaiah Alexpandi
- Department of Biotechnology, Alagappa University, Tamil Nadu, Science Campus, Karaikudi, 630003, India
| | | | - Kannapiran Tamilmuhilan
- Department of Biotechnology, Alagappa University, Tamil Nadu, Science Campus, Karaikudi, 630003, India
| | - Adimoolam Srivathsan
- Department of Biotechnology, Alagappa University, Tamil Nadu, Science Campus, Karaikudi, 630003, India
| | - Thirupathi Kasthuri
- Department of Biotechnology, Alagappa University, Tamil Nadu, Science Campus, Karaikudi, 630003, India
| | - Arumugam Veera Ravi
- Department of Biotechnology, Alagappa University, Tamil Nadu, Science Campus, Karaikudi, 630003, India
| | - Sugathan Shiburaj
- Division of Microbiology, Jawaharlal Nehru Tropical Botanic Garden and Research Institute, Palode, Thiruvananthapuram, Kerala, 695562, India.,Department of Botany, University of Kerala, Kariavattom, Thiruvananthapuram, Kerala, 695581, India
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20
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Agarwal S, Kallmyer NE, Vang DX, Ramirez AV, Islam MM, Hillier AC, Halverson L, Reuel NF. Single-Walled Carbon Nanotube Probes for the Characterization of Biofilm-Degrading Enzymes Demonstrated against Pseudomonas aeruginosa Extracellular Matrices. Anal Chem 2022; 94:856-865. [PMID: 34939783 PMCID: PMC9150823 DOI: 10.1021/acs.analchem.1c03633] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Hydrolase co-therapies that degrade biofilm extracellular polymeric substances (EPS) allow for a better diffusion of antibiotics and more effective treatment; current methods for quantitatively measuring the enzymatic degradation of EPS are not amendable to high-throughput screening. Herein, we present biofilm EPS-functionalized single-walled carbon nanotube (SWCNT) probes for rapid screening of hydrolytic enzyme selectivity and activity on EPS. The extent of biofilm EPS degradation is quantified by monitoring the quenching of the SWCNT fluorescence. We used this platform to screen 16 hydrolases with varying bond breaking selectivity against a panel of wild-type Pseudomonas aeruginosa and mutants deficient or altered in one or more EPS. Next, we performed concentration-dependent studies of six enzymes on two common strains found in cystic fibrosis (CF) environments and, for each enzyme, extracted three first-order rate constants and their relative contributions by fitting a parallel, multi-site degradation model, with a good model fit (R2 from 0.65 to 0.97). Reaction rates (turnover rates) are dependent on the enzyme concentration and range from 6.67 × 10-11 to 2.80 × 10-3 *s-1 per mg/mL of enzymes. Lastly, we confirmed findings from this new assay using an established crystal-violet staining assay for a subset of hydrolase panels. In summary, our work shows that this modular sensor is amendable to the high-throughput screening of EPS degradation, thereby improving the rate of discovery and development of novel hydrolases.
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Affiliation(s)
- Sparsh Agarwal
- Department of Chemical and Biological Engineering, Iowa State University, Ames, Iowa, 50011, United States
| | - Nathaniel E Kallmyer
- Department of Chemical and Biological Engineering, Iowa State University, Ames, Iowa, 50011, United States
| | - Dua X Vang
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, Iowa, 50011, United States,Interdepartmental Microbiology Graduate Program, Iowa State University, Ames, Iowa 50011, United States
| | - Alma V Ramirez
- Department of Chemical and Biological Engineering, Iowa State University, Ames, Iowa, 50011, United States
| | - Md Monirul Islam
- Department of Chemical and Biological Engineering, Iowa State University, Ames, Iowa, 50011, United States
| | - Andrew C Hillier
- Department of Chemical and Biological Engineering, Iowa State University, Ames, Iowa, 50011, United States
| | - Larry Halverson
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, Iowa, 50011, United States,Interdepartmental Microbiology Graduate Program, Iowa State University, Ames, Iowa 50011, United States
| | - Nigel F Reuel
- Department of Chemical and Biological Engineering, Iowa State University, Ames, Iowa, 50011, United States,Interdepartmental Microbiology Graduate Program, Iowa State University, Ames, Iowa 50011, United States,Corresponding Author: Prof. Nigel F Reuel, 2114 Sweeney Hall, 618 Bissell Rd, Iowa State University, Ames, IA, 50011, United States, , Ph: 515-294-4592
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21
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Sindeldecker D, Stoodley P. The many antibiotic resistance and tolerance strategies of Pseudomonas aeruginosa. Biofilm 2021; 3:100056. [PMID: 34471871 PMCID: PMC8387898 DOI: 10.1016/j.bioflm.2021.100056] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 08/17/2021] [Accepted: 08/18/2021] [Indexed: 12/15/2022] Open
Abstract
Pseudomonas aeruginosa is a bacterial pathogen associated with a wide range of infections and utilizes several strategies to establish and maintain infection including biofilm production, multidrug resistance, and antibiotic tolerance. Multidrug resistance in P. aeruginosa, as well as in all other bacterial pathogens, is a growing concern. Aminoglycoside resistance, in particular, is a major concern in P. aeruginosa infections and must be better understood in order to maintain effective clinical treatment. In this review, the various antibiotic resistance and tolerance mechanisms of Pseudomonas are explored including: classic mutation driven resistance, adaptive resistance, persister cells, small colony variants, phoenix colonies, and biofilms. It is important to further characterize each of these phenotypes and continue to evaluate antibiotic surviving isolates for novel driving mechanisms, so that we are better prepared to combat the rising number of recurrent and recalcitrant infections.
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Affiliation(s)
- Devin Sindeldecker
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, USA
- Biomedical Sciences Graduate Program, The Ohio State University, Columbus, OH, USA
| | - Paul Stoodley
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, USA
- Department of Orthopaedics, The Ohio State University, Columbus, OH, USA
- National Center for Advanced Tribology at Southampton (nCATS), Mechanical Engineering, University of Southampton, Southampton, UK
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22
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Putrescine and its metabolic precursor arginine promote biofilm and c-di-GMP synthesis in Pseudomonas aeruginosa. J Bacteriol 2021; 204:e0029721. [PMID: 34723645 DOI: 10.1128/jb.00297-21] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas aeruginosa, an opportunistic bacterial pathogen can synthesize and catabolize a number of small cationic molecules known as polyamines. In several clades of bacteria polyamines regulate biofilm formation, a lifestyle-switching process that confers resistance to environmental stress. The polyamine putrescine and its biosynthetic precursors, L-arginine and agmatine, promote biofilm formation in Pseudomonas spp. However, it remains unclear whether the effect is a direct effect of polyamines or through a metabolic derivative. Here we used a genetic approach to demonstrate that putrescine accumulation, either through disruption of the spermidine biosynthesis pathway or the catabolic putrescine aminotransferase pathway, promoted biofilm formation in P. aeruginosa. Consistent with this observation, exogenous putrescine robustly induced biofilm formation in P. aeruginosa that was dependent on putrescine uptake and biosynthesis pathways. Additionally, we show that L-arginine, the biosynthetic precursor of putrescine, also promoted biofilm formation, but via a mechanism independent of putrescine or agmatine conversion. We found that both putrescine and L-arginine induced a significant increase in the intracellular level of bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP) (c-di-GMP), a bacterial second messenger widely found in Proteobacteria that upregulates biofilm formation. Collectively these data show that putrescine and its metabolic precursor arginine promote biofilm and c-di-GMP synthesis in P. aeruginosa. Importance: Biofilm formation allows bacteria to physically attach to a surface, confers tolerance to antimicrobial agents, and promotes resistance to host immune responses. As a result, regulation of biofilm is often crucial for bacterial pathogens to establish chronic infections. A primary mechanism of biofilm promotion in bacteria is the molecule c-di-GMP, which promotes biofilm formation. The level of c-di-GMP is tightly regulated by bacterial enzymes. In this study, we found that putrescine, a small molecule ubiquitously found in eukaryotic cells, robustly enhances P. aeruginosa biofilm and c-di-GMP. We propose that P. aeruginosa may sense putrescine as a host-associated signal that triggers a lifestyle switching that favors chronic infection.
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23
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İnat G, Sırıken B, Başkan C, Erol İ, Yıldırım T, Çiftci A. Quorum sensing systems and related virulence factors in Pseudomonas aeruginosa isolated from chicken meat and ground beef. Sci Rep 2021; 11:15639. [PMID: 34341384 PMCID: PMC8329004 DOI: 10.1038/s41598-021-94906-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 07/05/2021] [Indexed: 11/09/2022] Open
Abstract
The objective of this study was to evaluate 50 [chicken meat (n = 45) and ground beef (n = 5)] Pseudomonas aeruginosa isolates to determine the expression of the lasI and rhl QS systems, related virulence factors, and the presence of N-3-oxo-dodecanoyl homoserine lactone (AHL: 3-O-C12-HSL). For the isolation and identification of P. aeruginosa, conventional culture and oprL gene-based molecular techniques were used. In relation to QS systems, eight genes consisting of four intact and four internal (lasI/R, rhlI/R) genes were analyzed with PCR assay. The two QS systems genes in P. aeruginosa isolates from ground beef (80.00%) and chicken meat (76.00%) were present at quite high levels. The 3-O-C12-HSL was detected in 14.00% of the isolates. Both biofilm formation and motility were detected in 98.00% of the isolates. Protease activity was determined in 54.00% of the isolates. Pyocyanin production was detected in 48.00% of the isolates. The las system scores strongly and positively correlated with the rhl system (p ˂ .01). PYA moderately and positively correlated with protease (p ˂ .05). In addition, there was statistically significance between lasI and protease activity (p < .10), and rhlI and twitching motility (p < .10). In conclusion, the high number of isolates having QS systems and related virulence factors are critical for public health. Pyocyanin, protease, and biofilm formation can cause spoilage and play essential role in food spoilage and food safety.
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Affiliation(s)
- Gökhan İnat
- Department of Food Hygiene and Technology, Faculty of Veterinary Medicine, Ondokuz Mayıs University, Samsun, Turkey
| | - Belgin Sırıken
- Department of Aquatic Animal Diseases, Faculty of Veterinary Medicine, Ondokuz Mayıs University, Samsun, Turkey.
| | - Ceren Başkan
- Department of Physical Therapy and Rehabilitation, Sabuncuoğlu Şerefeddin Health Services Vocational School, Amasya University, Amasya, Turkey
| | - İrfan Erol
- Faculty of Health Sciences, Eastern Mediterranean University, Gazimagusa TRNC Via Mersin, Turkey
| | - Tuba Yıldırım
- Department of Biology, Faculty of Arts and Sciences, Amasya University, Amasya, Turkey
| | - Alper Çiftci
- Department of Microbiology, Faculty of Veterinary Medicine, Ondokuz Mayıs University, Samsun, Turkey
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24
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Trebino MA, Shingare RD, MacMillan JB, Yildiz FH. Strategies and Approaches for Discovery of Small Molecule Disruptors of Biofilm Physiology. Molecules 2021; 26:molecules26154582. [PMID: 34361735 PMCID: PMC8348372 DOI: 10.3390/molecules26154582] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 07/24/2021] [Accepted: 07/26/2021] [Indexed: 12/02/2022] Open
Abstract
Biofilms, the predominant growth mode of microorganisms, pose a significant risk to human health. The protective biofilm matrix, typically composed of exopolysaccharides, proteins, nucleic acids, and lipids, combined with biofilm-grown bacteria’s heterogenous physiology, leads to enhanced fitness and tolerance to traditional methods for treatment. There is a need to identify biofilm inhibitors using diverse approaches and targeting different stages of biofilm formation. This review discusses discovery strategies that successfully identified a wide range of inhibitors and the processes used to characterize their inhibition mechanism and further improvement. Additionally, we examine the structure–activity relationship (SAR) for some of these inhibitors to optimize inhibitor activity.
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Affiliation(s)
- Michael A. Trebino
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, CA 95064, USA;
| | - Rahul D. Shingare
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA;
| | - John B. MacMillan
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA;
- Correspondence: (J.B.M.); (F.H.Y.)
| | - Fitnat H. Yildiz
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, CA 95064, USA;
- Correspondence: (J.B.M.); (F.H.Y.)
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25
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Xuan TF, Wang ZQ, Liu J, Yu HT, Lin QW, Chen WM, Lin J. Design and Synthesis of Novel c-di-GMP G-Quadruplex Inducers as Bacterial Biofilm Inhibitors. J Med Chem 2021; 64:11074-11089. [PMID: 34323486 DOI: 10.1021/acs.jmedchem.1c00465] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The formation of biofilms by clinical pathogens typically leads to chronic and recurring antibiotic-resistant infections. High cellular levels of cyclic diguanylate (c-di-GMP), a ubiquitous secondary messenger of bacteria, have been proven to be associated with a sessile biofilm lifestyle of pathogens. A promising antibiofilm strategy involving the induction of c-di-GMP to form dysfunctional G-quadruplexes, thereby blocking the c-di-GMP-mediated biofilm regulatory pathway, was proposed in this study. In this new strategy, a series of novel c-di-GMP G-quadruplex inducers were designed and synthesized for development of therapeutic biofilm inhibitors. Compound 5h exhibited favorable c-di-GMP G-quadruplex-inducing activity and 62.18 ± 6.76% biofilm inhibitory activity at 1.25 μM without any DNA intercalation effect. Moreover, the favorable performance of 5h in interfering with c-di-GMP-related biological functions, including bacterial motility and bacterial extracellular polysaccharide secretion, combined with the reporter strain and transcriptome analysis results confirmed the c-di-GMP signaling-related action mechanism of 5h.
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Affiliation(s)
- Teng-Fei Xuan
- College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China
| | - Zi-Qiang Wang
- College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China
| | - Jun Liu
- College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China
| | - Hai-Tao Yu
- College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China
| | - Qian-Wen Lin
- College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China
| | - Wei-Min Chen
- College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China
| | - Jing Lin
- College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China
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26
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Effects of the Quinone Oxidoreductase WrbA on Escherichia coli Biofilm Formation and Oxidative Stress. Antioxidants (Basel) 2021; 10:antiox10060919. [PMID: 34204135 PMCID: PMC8229589 DOI: 10.3390/antiox10060919] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 05/30/2021] [Accepted: 06/02/2021] [Indexed: 12/31/2022] Open
Abstract
The effects of natural compounds on biofilm formation have been extensively studied, with the goal of identifying biofilm formation antagonists at sub-lethal concentrations. Salicylic and cinnamic acids are some examples of these compounds that interact with the quinone oxidoreductase WrbA, a potential biofilm modulator and an antibiofilm compound biomarker. However, WrbA’s role in biofilm development is still poorly understood. To investigate the key roles of WrbA in biofilm maturation and oxidative stress, Escherichia coli wild-type and ∆wrbA mutant strains were used. Furthermore, we reported the functional validation of WrbA as a molecular target of salicylic and cinnamic acids. The lack of WrbA did not impair planktonic growth, but rather affected the biofilm formation through a mechanism that depends on reactive oxygen species (ROS). The loss of WrbA function resulted in an ROS-sensitive phenotype that showed reductions in biofilm-dwelling cells, biofilm thickness, matrix polysaccharide content, and H2O2 tolerance. Endogenous oxidative events in the mutant strain generated a stressful condition to which the bacterium responded by increasing the catalase activity to compensate for the lack of WrbA. Cinnamic and salicylic acids inhibited the quinone oxidoreductase activity of purified recombinant WrbA. The effects of these antibiofilm molecules on WrbA function was proven for the first time.
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27
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Bacterial cyclic diguanylate signaling networks sense temperature. Nat Commun 2021; 12:1986. [PMID: 33790266 PMCID: PMC8012707 DOI: 10.1038/s41467-021-22176-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 02/17/2021] [Indexed: 02/01/2023] Open
Abstract
Many bacteria use the second messenger cyclic diguanylate (c-di-GMP) to control motility, biofilm production and virulence. Here, we identify a thermosensory diguanylate cyclase (TdcA) that modulates temperature-dependent motility, biofilm development and virulence in the opportunistic pathogen Pseudomonas aeruginosa. TdcA synthesizes c-di-GMP with catalytic rates that increase more than a hundred-fold over a ten-degree Celsius change. Analyses using protein chimeras indicate that heat-sensing is mediated by a thermosensitive Per-Arnt-SIM (PAS) domain. TdcA homologs are widespread in sequence databases, and a distantly related, heterologously expressed homolog from the Betaproteobacteria order Gallionellales also displayed thermosensitive diguanylate cyclase activity. We propose, therefore, that thermotransduction is a conserved function of c-di-GMP signaling networks, and that thermosensitive catalysis of a second messenger constitutes a mechanism for thermal sensing in bacteria.
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28
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Thi MTT, Wibowo D, Rehm BH. Pseudomonas aeruginosa Biofilms. Int J Mol Sci 2020; 21:ijms21228671. [PMID: 33212950 PMCID: PMC7698413 DOI: 10.3390/ijms21228671] [Citation(s) in RCA: 322] [Impact Index Per Article: 80.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 11/09/2020] [Accepted: 11/13/2020] [Indexed: 12/17/2022] Open
Abstract
Pseudomonas aeruginosa is an opportunistic human pathogen causing devastating acute and chronic infections in individuals with compromised immune systems. Its highly notorious persistence in clinical settings is attributed to its ability to form antibiotic-resistant biofilms. Biofilm is an architecture built mostly by autogenic extracellular polymeric substances which function as a scaffold to encase the bacteria together on surfaces, and to protect them from environmental stresses, impedes phagocytosis and thereby conferring the capacity for colonization and long-term persistence. Here we review the current knowledge on P. aeruginosa biofilms, its development stages, and molecular mechanisms of invasion and persistence conferred by biofilms. Explosive cell lysis within bacterial biofilm to produce essential communal materials, and interspecies biofilms of P. aeruginosa and commensal Streptococcus which impedes P. aeruginosa virulence and possibly improves disease conditions will also be discussed. Recent research on diagnostics of P. aeruginosa infections will be investigated. Finally, therapeutic strategies for the treatment of P. aeruginosa biofilms along with their advantages and limitations will be compiled.
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29
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Carruthers NJ, McClellan SA, Somayajulu M, Pitchaikannu A, Bessert D, Peng X, Huitsing K, Stemmer PM, Hazlett LD. Effects of Glycyrrhizin on Multi-Drug Resistant Pseudomonas aeruginosa. Pathogens 2020; 9:pathogens9090766. [PMID: 32962036 PMCID: PMC7557769 DOI: 10.3390/pathogens9090766] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 09/16/2020] [Indexed: 02/06/2023] Open
Abstract
The effects of glycyrrhizin (GLY) on multi-drug resistant (MDR) systemic (MDR9) vs. ocular (B1045) Pseudomonas aeruginosa clinical isolates were determined. Proteomes of each isolate with/without GLY treatment were profiled using liquid chromatography mass spectrometry (LC-MS/MS). The effect of GLY on adherence of MDR isolates to immortalized human (HCET) and mouse (MCEC) corneal epithelial cells, and biofilm and dispersal was tested. Both isolates were treated with GLY (0.25 minimum inhibitory concentration (MIC), 10 mg/mL for MDR9 and 3.75 mg/mL for B1045) and subjected to proteomic analysis. MDR9 had a greater response to GLY (51% of identified proteins affected vs. <1% in B1045). In MDR9 vs. controls, GLY decreased the abundance of proteins for: antibiotic resistance, biofilm formation, and type III secretion. Further, antibiotic resistance and type III secretion proteins had higher control abundances in MDR9 vs. B1045. GLY (5 and 10 mg/mL) significantly reduced binding of both isolates to MCEC, and B1045 to HCET. MDR9 binding to HCET was only reduced at 10 mg/mL GLY. GLY (5 and 10 mg/mL) enhanced dispersal for both isolates, at early (6.5 h) but not later times (24–72 h). This study provides evidence that GLY has a greater effect on the proteome of MDR9 vs. B1045, yet it was equally effective at disrupting adherence and early biofilm dispersal.
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Affiliation(s)
- Nicholas J. Carruthers
- Institute of Environmental Health Sciences, Wayne State University School of Medicine, 540 E. Canfield Avenue, Detroit, MI 48201, USA; (N.J.C.); (P.M.S.)
| | - Sharon A. McClellan
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University, School of Medicine, Detroit, MI 48201, USA; (S.A.M.); (M.S.); (A.P.); (D.B.); (K.H.)
| | - Mallika Somayajulu
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University, School of Medicine, Detroit, MI 48201, USA; (S.A.M.); (M.S.); (A.P.); (D.B.); (K.H.)
| | - Ahalya Pitchaikannu
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University, School of Medicine, Detroit, MI 48201, USA; (S.A.M.); (M.S.); (A.P.); (D.B.); (K.H.)
| | - Denise Bessert
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University, School of Medicine, Detroit, MI 48201, USA; (S.A.M.); (M.S.); (A.P.); (D.B.); (K.H.)
| | - Xudong Peng
- Department of Ophthalmology, The Affiliated Hospital of Qingdao University, Qingdao 266071, China;
| | - Kylie Huitsing
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University, School of Medicine, Detroit, MI 48201, USA; (S.A.M.); (M.S.); (A.P.); (D.B.); (K.H.)
| | - Paul M. Stemmer
- Institute of Environmental Health Sciences, Wayne State University School of Medicine, 540 E. Canfield Avenue, Detroit, MI 48201, USA; (N.J.C.); (P.M.S.)
| | - Linda D. Hazlett
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University, School of Medicine, Detroit, MI 48201, USA; (S.A.M.); (M.S.); (A.P.); (D.B.); (K.H.)
- Correspondence: ; Tel.: +1-313-577-1079; Fax: +1-313-577-3125
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30
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Chaves S, Longo M, Gómez López A, Del V Loto F, Mechetti M, Romero CM. Control of microbial biofilm formation as an approach for biomaterials synthesis. Colloids Surf B Biointerfaces 2020; 194:111201. [PMID: 32615520 DOI: 10.1016/j.colsurfb.2020.111201] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 06/13/2020] [Accepted: 06/15/2020] [Indexed: 11/26/2022]
Abstract
The search for new biomaterials with superior mechanical properties is the focus in the area of materials science. A promising pathway is drawing inspiration from nature to design and develop materials with enhanced properties. In this work, a novel strategy to produce functionalized supramolecular bionanomaterials from the microbial biofilm is reported. Tuneable biofilms with specific characteristics were obtained by controlling the culture condition of the microorganism. When the exopolysaccharide (EPS) production was desired the tryptone was the best nutritional component for the EPS production into the biofilm. However, for the expression of a high amount of amyloid protein the combination of peptone and glucose was the best nutritional choice. Each biofilm obtained showed its owner rheology properties. These properties were altered by the addition of extracellular DNA, which increased the viscosity of the biofilm and induced a viscoelastic hydrogel behavior. Besides, as a proof of concept of bionanomaterial, a novel supramolecular polymeric hybrid EPS-Amyloid protein (EPAP) was obtained from the biofilm and it was tested as a new natural functionalized support for enzyme immobilization. The results suggest that this technology could be used as a new concept to obtain biomaterials from biofilms by controlling the nutritional conditions of a microorganism. Understanding environmental factors affecting biofilm formation will help the development of methods for controlling biofilm production and therefore obtaining new biomaterials.
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Affiliation(s)
- Silvina Chaves
- Instituto de Medicina Molecular y Celular Aplicada (IMMCA), CONICET-UNT-SIPROSA, Pje. Dorrego 1080, San Miguel de Tucumán, Argentina
| | - Marianella Longo
- Planta Piloto de Procesos Industriales Microbiológicos (PROIMI), CONICET, Av. Belgrano y Pasaje Caseros, T4001 MVB, Tucumán Fac. Bioq., Qca. y Farmacia (UNT), Ayacucho 471, 4000, Tucumán, Argentina
| | - Azucena Gómez López
- Laboratorio de Física de Fluidos y Electrorreología, Instituto de Física del Noroeste Argentino-INFINOA (CONICET-UNT), Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán, Av. Independencia 1800, San Miguel de Tucumán, 4000, Argentina
| | - Flavia Del V Loto
- Planta Piloto de Procesos Industriales Microbiológicos (PROIMI), CONICET, Av. Belgrano y Pasaje Caseros, T4001 MVB, Tucumán Fac. Bioq., Qca. y Farmacia (UNT), Ayacucho 471, 4000, Tucumán, Argentina
| | - Magdalena Mechetti
- Laboratorio de Física de Fluidos y Electrorreología, Instituto de Física del Noroeste Argentino-INFINOA (CONICET-UNT), Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán, Av. Independencia 1800, San Miguel de Tucumán, 4000, Argentina
| | - Cintia M Romero
- Planta Piloto de Procesos Industriales Microbiológicos (PROIMI), CONICET, Av. Belgrano y Pasaje Caseros, T4001 MVB, Tucumán Fac. Bioq., Qca. y Farmacia (UNT), Ayacucho 471, 4000, Tucumán, Argentina.
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31
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Bridier A, Piard JC, Briandet R, Bouchez T. Emergence of a Synergistic Diversity as a Response to Competition in Pseudomonas putida Biofilms. MICROBIAL ECOLOGY 2020; 80:47-59. [PMID: 31844910 DOI: 10.1007/s00248-019-01470-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 12/01/2019] [Indexed: 06/10/2023]
Abstract
Genetic diversification through the emergence of variants is one of the known mechanisms enabling the adaptation of bacterial communities. We focused in this work on the adaptation of the model strain Pseudomonas putida KT2440 in association with another P. putida strain (PCL1480) recently isolated from soil to investigate the potential role of bacterial interactions in the diversification process. On the basis of colony morphology, three variants of P. putida KT2440 were obtained from co-culture after 168 h of growth whereas no variant was identified from the axenic KT2440 biofilm. The variants exhibited distinct phenotypes and produced biofilms with specific architecture in comparison with the ancestor. The variants better competed with the P. putida PCL1480 strain in the dual-strain biofilms after 24 h of co-culture in comparison with the ancestor. Moreover, the synergistic interaction of KT2440 ancestor and the variants led to an improved biofilm production and to higher competitive ability versus the PCL1480 strain, highlighting the key role of diversification in the adaptation of P. putida KT2440 in the mixed community. Whole genome sequencing revealed mutations in polysaccharides biosynthesis protein, membrane transporter, or lipoprotein signal peptidase genes in variants.
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Affiliation(s)
- Arnaud Bridier
- ANSES, Fougères Laboratory, AB2R, 10B rue Claude Bourgelat, 35300, Fougères, France.
- IRSTEA, UR PROSE, 1 rue Pierre-Gilles de Gennes, 92761, Antony Cedex, France.
| | - J C Piard
- Institut Micalis, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | - R Briandet
- Institut Micalis, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | - T Bouchez
- IRSTEA, UR PROSE, 1 rue Pierre-Gilles de Gennes, 92761, Antony Cedex, France
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32
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Harrison JJ, Almblad H, Irie Y, Wolter DJ, Eggleston HC, Randall TE, Kitzman JO, Stackhouse B, Emerson JC, Mcnamara S, Larsen TJ, Shendure J, Hoffman LR, Wozniak DJ, Parsek MR. Elevated exopolysaccharide levels in Pseudomonas aeruginosa flagellar mutants have implications for biofilm growth and chronic infections. PLoS Genet 2020; 16:e1008848. [PMID: 32530919 PMCID: PMC7314104 DOI: 10.1371/journal.pgen.1008848] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 06/24/2020] [Accepted: 05/11/2020] [Indexed: 01/08/2023] Open
Abstract
Pseudomonas aeruginosa colonizes the airways of cystic fibrosis (CF) patients, causing infections that can last for decades. During the course of these infections, P. aeruginosa undergoes a number of genetic adaptations. One such adaptation is the loss of swimming motility functions. Another involves the formation of the rugose small colony variant (RSCV) phenotype, which is characterized by overproduction of the exopolysaccharides Pel and Psl. Here, we provide evidence that the two adaptations are linked. Using random transposon mutagenesis, we discovered that flagellar mutations are linked to the RSCV phenotype. We found that flagellar mutants overexpressed Pel and Psl in a surface-contact dependent manner. Genetic analyses revealed that flagellar mutants were selected for at high frequencies in biofilms, and that Pel and Psl expression provided the primary fitness benefit in this environment. Suppressor mutagenesis of flagellar RSCVs indicated that Psl overexpression required the mot genes, suggesting that the flagellum stator proteins function in a surface-dependent regulatory pathway for exopolysaccharide biosynthesis. Finally, we identified flagellar mutant RSCVs among CF isolates. The CF environment has long been known to select for flagellar mutants, with the classic interpretation being that the fitness benefit gained relates to an impairment of the host immune system to target a bacterium lacking a flagellum. Our new findings lead us to propose that exopolysaccharide production is a key gain-of-function phenotype that offers a new way to interpret the fitness benefits of these mutations. Microbiologists have known for decades that Pseudomonas aeruginosa mutates during chronic respiratory infection of cystic fibrosis (CF) patients. One of the most reported functions lost during these infections is flagellar motility. A long-standing interpretation of this observation is that the flagellum is disadvantageous for the bacterium in the CF environment. We report the surprising finding that mutation of a wide range of flagellar genes results in the overproduction of the biofilm matrix polysaccharides Psl and Pel. We propose, therefore, that flagellar mutations represent a gain-of-function that would help the bacterium to form biofilms and persist in the CF airways.
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Affiliation(s)
- Joe J Harrison
- Department of Biological Sciences, University of Calgary, University Drive NW, Calgary, AB, Canada
| | - Henrik Almblad
- Department of Biological Sciences, University of Calgary, University Drive NW, Calgary, AB, Canada
| | - Yasuhiko Irie
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
| | - Daniel J Wolter
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America.,Department of Pediatrics, University of Washington, Seattle, Washington, United States of America
| | - Heather C Eggleston
- Department of Microbial Infection and Immunity, Department of Microbiology, Center for Microbial Interface Biology, The Ohio State University, Columbus, Ohio, United States of America
| | - Trevor E Randall
- Department of Biological Sciences, University of Calgary, University Drive NW, Calgary, AB, Canada
| | - Jacob O Kitzman
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Bethany Stackhouse
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Julia C Emerson
- Center for Clinical and Translational Research, Seattle Children's Hospital, Seattle, Washington, United States of America
| | - Sharon Mcnamara
- Center for Clinical and Translational Research, Seattle Children's Hospital, Seattle, Washington, United States of America
| | - Tyler J Larsen
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
| | - Jay Shendure
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Lucas R Hoffman
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America.,Department of Pediatrics, University of Washington, Seattle, Washington, United States of America
| | - Daniel J Wozniak
- Department of Microbial Infection and Immunity, Department of Microbiology, Center for Microbial Interface Biology, The Ohio State University, Columbus, Ohio, United States of America
| | - Matthew R Parsek
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
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33
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Tavares TD, Antunes JC, Padrão J, Ribeiro AI, Zille A, Amorim MTP, Ferreira F, Felgueiras HP. Activity of Specialized Biomolecules against Gram-Positive and Gram-Negative Bacteria. Antibiotics (Basel) 2020; 9:E314. [PMID: 32526972 PMCID: PMC7344598 DOI: 10.3390/antibiotics9060314] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 06/01/2020] [Accepted: 06/08/2020] [Indexed: 11/24/2022] Open
Abstract
The increased resistance of bacteria against conventional pharmaceutical solutions, the antibiotics, has raised serious health concerns. This has stimulated interest in the development of bio-based therapeutics with limited resistance, namely, essential oils (EOs) or antimicrobial peptides (AMPs). This study envisaged the evaluation of the antimicrobial efficacy of selected biomolecules, namely LL37, pexiganan, tea tree oil (TTO), cinnamon leaf oil (CLO) and niaouli oil (NO), against four bacteria commonly associated to nosocomial infections: Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli and Pseudomonas aeruginosa. The antibiotic vancomycin and silver nanoparticles (AgNPs) were used as control compounds for comparison purposes. The biomolecules were initially screened for their antibacterial efficacy using the agar-diffusion test, followed by the determination of minimal inhibitory concentrations (MICs), kill-time kinetics and the evaluation of the cell morphology upon 24 h exposure. All agents were effective against the selected bacteria. Interestingly, the AgNPs required a higher concentration (4000-1250 µg/mL) to induce the same effects as the AMPs (500-7.8 µg/mL) or EOs (365.2-19.7 µg/mL). Pexiganan and CLO were the most effective biomolecules, requiring lower concentrations to kill both Gram-positive and Gram-negative bacteria (62.5-7.8 µg/mL and 39.3-19.7 µg/mL, respectively), within a short period of time (averaging 2 h 15 min for all bacteria). Most biomolecules apparently disrupted the bacteria membrane stability due to the observed cell morphology deformation and by effecting on the intracellular space. AMPs were observed to induce morphological deformations and cellular content release, while EOs were seen to split and completely envelope bacteria. Data unraveled more of the potential of these new biomolecules as replacements for the conventional antibiotics and allowed us to take a step forward in the understanding of their mechanisms of action against infection-related bacteria.
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Affiliation(s)
| | | | | | | | | | | | | | - Helena P. Felgueiras
- Centre for Textile Science and Technology (2C2T), Department of Textile Engineering, University of Minho, Campus of Azurém, 4800-058 Guimarães, Portugal; (T.D.T.); (J.C.A.); (J.P.); (A.I.R.); (A.Z.); (M.T.P.A.); (F.F.)
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Pezzoni M, Pizarro RA, Costa CS. Role of quorum sensing in UVA-induced biofilm formation in Pseudomonas aeruginosa. MICROBIOLOGY-SGM 2020; 166:735-750. [PMID: 32496187 DOI: 10.1099/mic.0.000932] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Pseudomonas aeruginosa, a versatile bacterium present in terrestrial and aquatic environments and a relevant opportunistic human pathogen, is largely known for the production of robust biofilms. The unique properties of these structures complicate biofilm eradication, because they make the biofilms very resistant to diverse antibacterial agents. Biofilm development and establishment is a complex process regulated by multiple regulatory genetic systems, among them is quorum sensing (QS), a mechanism employed by bacteria to regulate gene transcription in response to population density. In addition, environmental factors such as UVA radiation (400-315 nm) have been linked to biofilm formation. In this work, we further investigate the mechanism underlying the induction of biofilm formation by UVA, analysing the role of QS in this phenomenon. We demonstrate that UVA induces key genes of the Las and Rhl QS systems at the transcriptional level. We also report that pelA and pslA genes, which are essential for biofilm formation and whose transcription depends in part on QS, are significantly induced under UVA exposure. Finally, the results demonstrate that in a relA strain (impaired for ppGpp production), the UVA treatment does not induce biofilm formation or QS genes, suggesting that the increase of biofilm formation due to exposure to UVA in P. aeruginosa could rely on a ppGpp-dependent QS induction.
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Affiliation(s)
- Magdalena Pezzoni
- Departamento de Radiobiología, Comisión Nacional de Energía Atómica, General San Martín, Argentina
| | - Ramón A Pizarro
- Departamento de Radiobiología, Comisión Nacional de Energía Atómica, General San Martín, Argentina
| | - Cristina S Costa
- Departamento de Radiobiología, Comisión Nacional de Energía Atómica, General San Martín, Argentina
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Raio A, Brilli F, Baraldi R, Neri L, Puopolo G. Impact of spontaneous mutations on physiological traits and biocontrol activity of Pseudomonas chlororaphis M71. Microbiol Res 2020; 239:126517. [PMID: 32535393 DOI: 10.1016/j.micres.2020.126517] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 05/06/2020] [Accepted: 05/13/2020] [Indexed: 10/24/2022]
Abstract
Three morphological mutants (M71a, M71b, M71c) of the antagonist Pseudomonas chlororaphis M71, naturally arose during a biocontrol trial against the phytopathogenic fungus Fusarium oxysporum f.sp. radicis-lycopersisci. In this study, the three mutants were investigated to elucidate their role in the biocontrol of plant pathogens. M71a and M71b phenotypes were generated by a mutation in the two-component system GacS/GacA. The mutation determined an increase in siderophore production and an impaired ability to release proteases, to swarm, to produce phenazine and AHLs and to colonize tomato roots. In vitro antagonistic activity against different plant pathogens was partially reduced in M71a, while M71b resulted effective only against Pythium ultimum. Biocontrol efficacy against Fusarium oxysporum f.sp. radicis-lycopersisci, was partially reduced in M71a and completely lost in M71b. M71c phenotype was impaired in swarming motility, did not produce biofilms and its antagonistic activity was similar to the parental M71 strain. M71c showed an enhanced ability to colonize tomato roots, on which its progeny in part reverted to the M71 parental phenotype. Volatile organic compounds (VOCs) emitted by all four strains, inhibited the growth of Clavibacter michiganensis subsp. michiganensis and Seiridium cardinale in vitro. Real-time screening of VOCs by PTR-MS combined with GC-MS analysis, showed that methanethiol was the main component of the blend produced by all four M71 strains. However, the emissions of hydrogen cyanide, dimethyl disulfide, 1,3-butadiene and acetone were significantly affected by the three different mutations. These findings highlight that the simultaneous presence of different M71 phenotypes may improve, through the integration of different mechanisms, the ecological fitness and biocontrol efficacy of P. chlororaphis M71.
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Affiliation(s)
- Aida Raio
- Institute for Sustainable Plant Protection, National Research Council, Via Madonna del Piano 10, 50019, Sesto Fiorentino, FI, Italy.
| | - Federico Brilli
- Institute for Sustainable Plant Protection, National Research Council, Via Madonna del Piano 10, 50019, Sesto Fiorentino, FI, Italy
| | - Rita Baraldi
- Institute of BioEconomy, National Research Council, Bologna, Italy
| | - Luisa Neri
- Center Agriculture Food Environment (C3A), University of Trento, via E. Mach 1, San Michele all'Adige, 38010, Italy
| | - Gerardo Puopolo
- Department of Sustainable Agro-ecosystems and Bioresources, Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach 1, San Michele all'Adige, 38010, Italy
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36
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Azimi S, Roberts AEL, Peng S, Weitz JS, McNally A, Brown SP, Diggle SP. Allelic polymorphism shapes community function in evolving Pseudomonas aeruginosa populations. ISME JOURNAL 2020; 14:1929-1942. [PMID: 32341475 DOI: 10.1038/s41396-020-0652-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 03/23/2020] [Accepted: 03/31/2020] [Indexed: 12/31/2022]
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that chronically infects the lungs of individuals with cystic fibrosis (CF) by forming antibiotic-resistant biofilms. Emergence of phenotypically diverse isolates within CF P. aeruginosa populations has previously been reported; however, the impact of heterogeneity on social behaviors and community function is poorly understood. Here we describe how this heterogeneity impacts on behavioral traits by evolving the strain PAO1 in biofilms grown in a synthetic sputum medium for 50 days. We measured social trait production and antibiotic tolerance, and used a metagenomic approach to analyze and assess genomic changes over the duration of the evolution experiment. We found that (i) evolutionary trajectories were reproducible in independently evolving populations; (ii) over 60% of genomic diversity occurred within the first 10 days of selection. We then focused on quorum sensing (QS), a well-studied P. aeruginosa trait that is commonly mutated in strains isolated from CF lungs. We found that at the population level, (i) evolution in sputum medium selected for decreased the production of QS and QS-dependent traits; (ii) there was a significant correlation between lasR mutant frequency, the loss of protease, and the 3O-C12-HSL signal, and an increase in resistance to clinically relevant β-lactam antibiotics, despite no previous antibiotic exposure. Overall, our findings provide insights into the effect of allelic polymorphism on community functions in diverse P. aeruginosa populations. Further, we demonstrate that P. aeruginosa population and evolutionary dynamics can impact on traits important for virulence and can lead to increased tolerance to β-lactam antibiotics.
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Affiliation(s)
- Sheyda Azimi
- Center for Microbial Dynamics & Infection, Georgia Institute of Technology, Atlanta, GA, USA.,School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - Aled E L Roberts
- Microbiology & Infectious Diseases Group, Institute of Life Science, Swansea University Medical School, Swansea, UK
| | - Shengyun Peng
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - Joshua S Weitz
- Center for Microbial Dynamics & Infection, Georgia Institute of Technology, Atlanta, GA, USA.,School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA.,School of Physics, Georgia Institute of Technology, Atlanta, GA, USA
| | - Alan McNally
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Samuel P Brown
- Center for Microbial Dynamics & Infection, Georgia Institute of Technology, Atlanta, GA, USA.,School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - Stephen P Diggle
- Center for Microbial Dynamics & Infection, Georgia Institute of Technology, Atlanta, GA, USA. .,School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA.
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37
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Isolation and Characterization of Bacteria from Refinery Effluent for Degradation of Petroleum Crude Oil in Seawater. JOURNAL OF PURE AND APPLIED MICROBIOLOGY 2020. [DOI: 10.22207/jpam.14.1.49] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
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38
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Activity of Antibiotics against Pseudomonas aeruginosa in an In Vitro Model of Biofilms in the Context of Cystic Fibrosis: Influence of the Culture Medium. Antimicrob Agents Chemother 2020; 64:AAC.02204-19. [PMID: 32015047 DOI: 10.1128/aac.02204-19] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Accepted: 01/24/2020] [Indexed: 12/28/2022] Open
Abstract
Pseudomonas aeruginosa is a major cause of respiratory biofilm-related infections in patients with cystic fibrosis. We developed an in vitro pharmacodynamic model to study the activity of antipseudomonal antibiotics against PAO1 biofilms grown in artificial sputum medium with agar [ASM(+)] versus that against biofilms grown in Trypticase soy broth supplemented with glucose and NaCl (TGN). We measured bacterial counts, metabolic activity (fluorescein diacetate [FDA] hydrolysis), and biomass (crystal violet absorbance). Biofilms grew slower in ASM(+) than in TGN but reached the same CFU counts and metabolic activity in both media and a slightly higher biomass after 48 h in ASM(+) than in TGN. The concentration-response curves of the antibiotics after 24 h of incubation with mature biofilms showed maximal effects ranging from a 3 (ciprofloxacin)- to a 1.5 (ceftazidime, meropenem)-log10-CFU decrease, with tobramycin and colistin showing intermediate values. These maximal reductions in the numbers of CFU were similar in both media for ciprofloxacin and β-lactams but lower in ASM(+) than in TGN for tobramycin and colistin; they were reached at concentrations lower than the human maximum concentration in plasma for ciprofloxacin and β-lactams only. The reductions in metabolic activity and in biomass were low in both media. Small-colony variants were selected by tobramycin in ASM(+) and by ciprofloxacin in both media. The model was then successfully applied to 4 isolates from patients with cystic fibrosis. These biofilms showed CFU counts similar to those of PAO1 biofilms in ASM(+) but a higher biomass than PAO1 biofilms in ASM(+) and moderate differences in their susceptibility to antibiotics from that of PAO1 biofilms grown in this medium. This model proved useful to establish the pharmacodynamic profile of drugs against P. aeruginosa biofilms in the context of cystic fibrosis.
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39
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Nonuniform growth and surface friction determine bacterial biofilm morphology on soft substrates. Proc Natl Acad Sci U S A 2020; 117:7622-7632. [PMID: 32193350 DOI: 10.1073/pnas.1919607117] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
During development, organisms acquire three-dimensional (3D) shapes with important physiological consequences. While basic mechanisms underlying morphogenesis are known in eukaryotes, it is often difficult to manipulate them in vivo. To circumvent this issue, here we present a study of developing Vibrio cholerae biofilms grown on agar substrates in which the spatiotemporal morphological patterns were altered by varying the agar concentration. Expanding biofilms are initially flat but later undergo a mechanical instability and become wrinkled. To gain mechanistic insights into this dynamic pattern-formation process, we developed a model that considers diffusion of nutrients and their uptake by bacteria, bacterial growth/biofilm matrix production, mechanical deformation of both the biofilm and the substrate, and the friction between them. Our model shows quantitative agreement with experimental measurements of biofilm expansion dynamics, and it accurately predicts two distinct spatiotemporal patterns observed in the experiments-the wrinkles initially appear either in the peripheral region and propagate inward (soft substrate/low friction) or in the central region and propagate outward (stiff substrate/high friction). Our results, which establish that nonuniform growth and friction are fundamental determinants of stress anisotropy and hence biofilm morphology, are broadly applicable to bacterial biofilms with similar morphologies and also provide insight into how other bacterial biofilms form distinct wrinkle patterns. We discuss the implications of forming undulated biofilm morphologies, which may enhance the availability of nutrients and signaling molecules and serve as a "bet hedging" strategy.
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40
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Kovach KN, Fleming D, Wells MJ, Rumbaugh KP, Gordon VD. Specific Disruption of Established Pseudomonas aeruginosa Biofilms Using Polymer-Attacking Enzymes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:1585-1595. [PMID: 31990563 PMCID: PMC7063831 DOI: 10.1021/acs.langmuir.9b02188] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Biofilms are communities of bacteria embedded in a polymeric matrix which are found in infections and in environments outside the body. Breaking down the matrix renders biofilms more susceptible to physical disruption and to treatments such as antibiotics. Different species of bacteria, and different strains within the same species, produce different types of matrix polymers. This suggests that targeting specific polymers for disruption may be more effective than nonspecific approaches to disrupting biofilm matrixes. In this study, we treated Pseudomonas aeruginosa biofilms with enzymes that are specific to different matrix polymers. We measured the resulting alteration in biofilm mechanics using bulk rheology and changes in structure using electron microscopy. We find that, for biofilms grown in vitro, the effect of enzymatic treatment is greatest when the enzyme is specific to a dominant matrix polymer. Specifically matched enzymatic treatment tends to reduce yield strain and yield stress and increase the rate of biofilm drying, due to increased diffusivity as a result of network compromise. Electron micrographs qualitatively suggest that well-matched enzymatic treatments reduce long-range structure and shorten connecting network fibers. Previous work has shown that generic glycoside hydrolases can cause dispersal of bacteria from in vivo and ex vivo biofilms into a free-swimming state, and thereby make antibiotic treatment more effective. For biofilms grown in wounded mice, we find that well-matched treatments that result in the greatest mechanical compromise in vitro induce the least dispersal ex vivo. Moreover, we find that generic glycoside hydrolases have no measurable effect on the mechanics of biofilms grown in vitro, while previous work has shown them to be highly effective at inducing dispersal in vivo and ex vivo. This highlights the possibility that effective approaches to eradicating biofilms may depend strongly on the growth environment.
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Affiliation(s)
- Kristin N Kovach
- Department of Physics and Center for Nonlinear Dynamics , The University of Texas at Austin , Austin , Texas 78712 , United States
| | - Derek Fleming
- Department of Surgery , Texas Tech University Health Sciences Center , Lubbock , Texas 79430 , United States
| | - Marilyn J Wells
- Department of Physics and Center for Nonlinear Dynamics , The University of Texas at Austin , Austin , Texas 78712 , United States
| | - Kendra P Rumbaugh
- Department of Surgery , Texas Tech University Health Sciences Center , Lubbock , Texas 79430 , United States
| | - Vernita Diane Gordon
- Department of Physics and Center for Nonlinear Dynamics , The University of Texas at Austin , Austin , Texas 78712 , United States
- Institute for Cellular and Molecular Biology , The University of Texas at Austin , Austin , Texas 78712 , United States
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41
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Sankaran J, Tan NJHJ, But KP, Cohen Y, Rice SA, Wohland T. Single microcolony diffusion analysis in Pseudomonas aeruginosa biofilms. NPJ Biofilms Microbiomes 2019; 5:35. [PMID: 31728202 PMCID: PMC6841743 DOI: 10.1038/s41522-019-0107-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 10/04/2019] [Indexed: 01/25/2023] Open
Abstract
The influence of the biofilm matrix on molecular diffusion is commonly hypothesized to be responsible for emergent characteristics of biofilms such as nutrient trapping, signal accumulation and antibiotic tolerance. Hence quantifying the molecular diffusion coefficient is important to determine whether there is an influence of biofilm microenvironment on the mobility of molecules. Here, we use single plane illumination microscopy fluorescence correlation spectroscopy (SPIM-FCS) to obtain 3D diffusion coefficient maps with micrometre spatial and millisecond temporal resolution of entire Pseudomonas aeruginosa microcolonies. We probed how molecular properties such as size and charge as well as biofilm properties such as microcolony size and depth influence diffusion of fluorescently labelled dextrans inside biofilms. The 2 MDa dextran showed uneven penetration and a reduction in diffusion coefficient suggesting that the biofilm acts as a molecular sieve. Its diffusion coefficient was negatively correlated with the size of the microcolony. Positively charged dextran molecules and positively charged antibiotic tobramycin preferentially partitioned into the biofilm and remained mobile inside the microcolony, albeit with a reduced diffusion coefficient. Lastly, we measured changes of diffusion upon induction of dispersal and detected an increase in diffusion coefficient inside the biofilm before any loss of biomass. Thus, the change in diffusion is a proxy to detect early stages of dispersal. Our work shows that 3D diffusion maps are very sensitive to physiological changes in biofilms, viz. dispersal. However, this study also shows that diffusion, as mediated by the biofilm matrix, does not account for the high level of antibiotic tolerance associated with biofilms.
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Affiliation(s)
- Jagadish Sankaran
- 1Department of Biological Sciences, National University of Singapore, 117558 Singapore, Singapore.,2Centre for BioImaging Sciences, National University of Singapore, 117557 Singapore, Singapore
| | - Nicholas J H J Tan
- 3Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, 637551 Singapore, Singapore.,4School of Biological Sciences, Nanyang Technological University, 637551 Singapore, Singapore
| | - Ka Pui But
- 2Centre for BioImaging Sciences, National University of Singapore, 117557 Singapore, Singapore.,5Department of Chemistry, National University of Singapore, 117543 Singapore, Singapore
| | - Yehuda Cohen
- 3Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, 637551 Singapore, Singapore.,4School of Biological Sciences, Nanyang Technological University, 637551 Singapore, Singapore
| | - Scott A Rice
- 3Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, 637551 Singapore, Singapore.,4School of Biological Sciences, Nanyang Technological University, 637551 Singapore, Singapore.,6ithree Institute, University of Technology Sydney, Sydney, Australia
| | - Thorsten Wohland
- 1Department of Biological Sciences, National University of Singapore, 117558 Singapore, Singapore.,2Centre for BioImaging Sciences, National University of Singapore, 117557 Singapore, Singapore.,5Department of Chemistry, National University of Singapore, 117543 Singapore, Singapore
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42
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Soares A, Caron F, Etienne M. Commentary: Tolerance and Resistance of Pseudomonas aeruginosa Biofilms to Antimicrobial Agents-How P. aeruginosa Can Escape Antibiotics. Front Microbiol 2019; 10:2164. [PMID: 31620114 PMCID: PMC6759825 DOI: 10.3389/fmicb.2019.02164] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 09/03/2019] [Indexed: 01/13/2023] Open
Affiliation(s)
- Anaïs Soares
- GRAM 2.0, EA 2656, Normandie Univ, UNIROUEN, Rouen, France.,Microbiology Department, Rouen University Hospital, Rouen, France
| | - François Caron
- GRAM 2.0, EA 2656, Normandie Univ, UNIROUEN, Rouen, France.,Infectious Diseases Department, Rouen University Hospital, Rouen, France
| | - Manuel Etienne
- GRAM 2.0, EA 2656, Normandie Univ, UNIROUEN, Rouen, France.,Infectious Diseases Department, Rouen University Hospital, Rouen, France
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43
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Hou L, Debru A, Chen Q, Bao Q, Li K. AmrZ Regulates Swarming Motility Through Cyclic di-GMP-Dependent Motility Inhibition and Controlling Pel Polysaccharide Production in Pseudomonas aeruginosa PA14. Front Microbiol 2019; 10:1847. [PMID: 31474950 PMCID: PMC6707383 DOI: 10.3389/fmicb.2019.01847] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2019] [Accepted: 07/26/2019] [Indexed: 11/16/2022] Open
Abstract
Swarming is a surface-associated motile behavior that plays an important role in the rapid spread, colonization, and subsequent establishment of bacterial communities. In Pseudomonas aeruginosa, swarming is dependent upon a functional flagella and aided by the production of biosurfactants. AmrZ, a conserved transcription factor across pseudomonads, has been shown to be a global regulator of multiple genes important for virulence and ecological fitness. In this study, we expand this concept of global control to swarming motility by showing that deletion of amrZ results in a severe defect in swarming, while multicopy expression of this gene stimulates swarming of P. aeruginosa. Mechanistic studies showed that the swarming defect of an amrZ mutant does not involve changes of biosurfactant production but is associated with flagellar malfunction. The ∆amrZ mutant exhibits increased levels of the second messenger cyclic di-GMP (c-di-GMP) compared to the wild-type strain, under swarming conditions. We found that the diguanylate cyclase GcbA was the main contributor to the increased accumulation of c-di-GMP observed in the ∆amrZ mutant and was a strong inhibitor of flagellar-dependent motility. Our results revealed that the GcbA-dependent inhibition of motility required the presence of two c-di-GMP receptors containing a PilZ domain: FlgZ and PA14_56180. Furthermore, the ∆amrZ mutant exhibits enhanced production of Pel polysaccharide. Epistasis analysis revealed that GcbA and the Pel polysaccharide act independently to limit swarming in ΔamrZ. Our results support a role for AmrZ in controlling swarming motility, yet another social behavior besides biofilm formation that is crucial for the ability of P. aeruginosa to colonize a variety of surfaces. The central role of AmrZ in controlling these behaviors makes it a good target for the development of treatments directed to combat P. aeruginosa infections.
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Affiliation(s)
- Lingli Hou
- Department of Microbiology and Immunology, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China.,Scientific Research Center of Wenzhou Medical University, Wenzhou, China
| | - Alexander Debru
- Department of Microbiology and Immunology, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China
| | - Qianqian Chen
- Department of Microbiology and Immunology, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China
| | - Qiyu Bao
- Department of Microbiology and Immunology, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China
| | - Kewei Li
- Department of Microbiology and Immunology, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China
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Gloag ES, Marshall CW, Snyder D, Lewin GR, Harris JS, Santos-Lopez A, Chaney SB, Whiteley M, Cooper VS, Wozniak DJ. Pseudomonas aeruginosa Interstrain Dynamics and Selection of Hyperbiofilm Mutants during a Chronic Infection. mBio 2019; 10:e01698-19. [PMID: 31409682 PMCID: PMC6692513 DOI: 10.1128/mbio.01698-19] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 07/10/2019] [Indexed: 12/14/2022] Open
Abstract
Opportunistic pathogens establishing new infections experience strong selection to adapt, often favoring mutants that persist. Capturing this initial dynamic is critical for identifying the first adaptations that drive pathogenesis. Here we used a porcine full-thickness burn wound model of chronic infection to study the evolutionary dynamics of diverse Pseudomonas aeruginosa infections. Wounds were infected with a mixed community of six P. aeruginosa strains, including the model PA14 strain (PA14-1), and biopsies taken at 3, 14, and 28 days postinfection. Hyperbiofilm-forming rugose small-colony variants (RSCVs) were the earliest and predominant phenotypic variant. These variants were detected on day 3 and persisted, with the majority evolved from PA14-1. Whole-genome sequencing of PA14-1 RSCV isolates revealed driver mutations exclusively in the wsp pathway, conferring hyperbiofilm phenotypes. Several of the wsp mutant RSCVs also acquired CRISPR-Cas adaptive immunity to prophages isolated from the P. aeruginosa wound isolate (B23-2) that was also present in the inoculum. These observations emphasize the importance of interstrain dynamics and the role of lysogenic phages in the survival of an invading pathogen. Rather than being a side effect of chronicity, the rapid rise of RSCVs in wounds is evidence of positive selection on the Wsp chemosensory system to produce mutants with elevated biofilm formation capacity. We predict that RSCVs provide a level of phenotypic diversity to the infecting bacterial community and are common, early adaptations during infections. This would likely have significant consequences for clinical outcomes.IMPORTANCE Bacteria adapt to infections by evolving variants that are more fit and persistent. These recalcitrant variants are typically observed in chronic infections. However, it is unclear when and why these variants evolve. To address these questions, we used a porcine chronic wound model to study the evolutionary dynamics of Pseudomonas aeruginosa in a mixed-strain infection. We isolated hyperbiofilm variants that persisted early in the infection. Interstrain interactions were also observed, where adapted variants acquired CRISPR-mediated immunity to phages. We show that when initiating infection, P. aeruginosa experiences strong positive selection for hyperbiofilm phenotypes produced by mutants of a single chemosensory system, the Wsp pathway. We predict that hyperbiofilm variants are early adaptations to infection and that interstrain interactions may influence bacterial burden and infection outcomes.
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Affiliation(s)
- Erin S Gloag
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, Ohio, USA
| | - Christopher W Marshall
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Center for Evolutionary Biology and Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Daniel Snyder
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Center for Evolutionary Biology and Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Gina R Lewin
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
- Emory-Children's Cystic Fibrosis Center, Atlanta, Georgia, USA
| | - Jacob S Harris
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, Ohio, USA
| | - Alfonso Santos-Lopez
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Center for Evolutionary Biology and Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Sarah B Chaney
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, Ohio, USA
| | - Marvin Whiteley
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
- Emory-Children's Cystic Fibrosis Center, Atlanta, Georgia, USA
| | - Vaughn S Cooper
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Center for Evolutionary Biology and Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Daniel J Wozniak
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, Ohio, USA
- Department of Microbiology, The Ohio State University, Columbus, Ohio, USA
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Guła G, Dorotkiewicz-Jach A, Korzekwa K, Valvano MA, Drulis-Kawa Z. Complex Signaling Networks Controlling Dynamic Molecular Changes in Pseudomonas aeruginosa Biofilm. Curr Med Chem 2019; 26:1979-1993. [PMID: 30207213 DOI: 10.2174/0929867325666180912110151] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 07/11/2018] [Accepted: 08/31/2018] [Indexed: 02/06/2023]
Abstract
The environment exerts strong influence on microbes. Adaptation of microbes to changing conditions is a dynamic process regulated by complex networks. Pseudomonas aeruginosa is a life-threating, versatile opportunistic and multi drug resistant pathogen that provides a model to investigate adaptation mechanisms to environmental changes. The ability of P. aeruginosa to form biofilms and to modify virulence in response to environmental changes is coordinated by various mechanisms including two-component systems (TCS), and secondary messengers involved in quorum sensing (QS) and c-di-GMP networks (diguanylate cyclase systems, DGC). In this review, we focus on the role of c-di-GMP during biofilm formation. We describe TCS and QS signal cascades regulated by c-di-GMP in response to changes in the external environment. We present a complex signaling network dynamically changing during the transition of P. aeruginosa from the free-living to sessile mode of growth.
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Affiliation(s)
- Grzegorz Guła
- Department of Pathogen Biology and Immunology, Institute of Genetics and Microbiology, University of Wroclaw, Przybyszewskiego 63/77, 51-148 Wroclaw, Poland
| | - Agata Dorotkiewicz-Jach
- Department of Pathogen Biology and Immunology, Institute of Genetics and Microbiology, University of Wroclaw, Przybyszewskiego 63/77, 51-148 Wroclaw, Poland
| | - Kamila Korzekwa
- Department of Microbiology, Institute of Genetics and Microbiology, University of Wroclaw, Przybyszewskiego 63/77, 51-148 Wroclaw, Poland
| | - Miguel A Valvano
- Wellcome- Wolfson Institute for Experimental Medicine, Queen's University Belfast, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, United Kingdom
| | - Zuzanna Drulis-Kawa
- Department of Pathogen Biology and Immunology, Institute of Genetics and Microbiology, University of Wroclaw, Przybyszewskiego 63/77, 51-148 Wroclaw, Poland
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Malhotra S, Hayes D, Wozniak DJ. Cystic Fibrosis and Pseudomonas aeruginosa: the Host-Microbe Interface. Clin Microbiol Rev 2019; 32:e00138-18. [PMID: 31142499 PMCID: PMC6589863 DOI: 10.1128/cmr.00138-18] [Citation(s) in RCA: 258] [Impact Index Per Article: 51.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
In human pathophysiology, the clash between microbial infection and host immunity contributes to multiple diseases. Cystic fibrosis (CF) is a classical example of this phenomenon, wherein a dysfunctional, hyperinflammatory immune response combined with chronic pulmonary infections wreak havoc upon the airway, leading to a disease course of substantial morbidity and shortened life span. Pseudomonas aeruginosa is an opportunistic pathogen that commonly infects the CF lung, promoting an accelerated decline of pulmonary function. Importantly, P. aeruginosa exhibits significant resistance to innate immune effectors and to antibiotics, in part, by expressing specific virulence factors (e.g., antioxidants and exopolysaccharides) and by acquiring adaptive mutations during chronic infection. In an effort to review our current understanding of the host-pathogen interface driving CF pulmonary disease, we discuss (i) the progression of disease within the primitive CF lung, specifically focusing on the role of host versus bacterial factors; (ii) critical, neutrophil-derived innate immune effectors that are implicated in CF pulmonary disease, including reactive oxygen species (ROS) and antimicrobial peptides (e.g., LL-37); (iii) P. aeruginosa virulence factors and adaptive mutations that enable evasion of the host response; and (iv) ongoing work examining the distribution and colocalization of host and bacterial factors within distinct anatomical niches of the CF lung.
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Affiliation(s)
- Sankalp Malhotra
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, Ohio, USA
- The Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Don Hayes
- The Ohio State University College of Medicine, Columbus, Ohio, USA
- Department of Pediatrics, The Ohio State University, Columbus, Ohio, USA
- Section of Pulmonary Medicine, Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Daniel J Wozniak
- The Ohio State University College of Medicine, Columbus, Ohio, USA
- Section of Pulmonary Medicine, Nationwide Children's Hospital, Columbus, Ohio, USA
- Department of Microbiology, The Ohio State University, Columbus, Ohio, USA
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Gordon V, Bakhtiari L, Kovach K. From molecules to multispecies ecosystems: the roles of structure in bacterial biofilms. Phys Biol 2019; 16:041001. [PMID: 30913545 DOI: 10.1088/1478-3975/ab1384] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Biofilms are communities of sessile microbes that are bound to each other by a matrix made of biopolymers and proteins. Spatial structure is present in biofilms on many lengthscales. These range from the nanometer scale of molecular motifs to the hundred-micron scale of multicellular aggregates. Spatial structure is a physical property that impacts the biology of biofilms in many ways. The molecular structure of matrix components controls their interaction with each other (thereby impacting biofilm mechanics) and with diffusing molecules such as antibiotics and immune factors (thereby impacting antibiotic tolerance and evasion of the immune system). The size and structure of multicellular aggregates, combined with microbial consumption of growth substrate, give rise to differentiated microenvironments with different patterns of metabolism and gene expression. Spatial association of more than one species can benefit one or both species, while distances between species can both determine and result from the transport of diffusible factors between species. Thus, a widespread theme in the biological importance of spatial structure in biofilms is the effect of structure on transport. We survey what is known about this and other effects of spatial structure in biofilms, from molecules up to multispecies ecosystems. We conclude with an overview of what experimental approaches have been developed to control spatial structure in biofilms and how these and other experiments can be complemented with computational work.
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Affiliation(s)
- Vernita Gordon
- Department of Physics, University of Texas at Austin, Austin TX 78712, United States of America. Center for Nonlinear Dynamics, University of Texas at Austin, Austin TX 78712, United States of America. Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin TX 78712, United States of America. Author to whom any correspondence should be addressed
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Bruguera-Àvila N, Garcia-Olive I, Marin A, Prat C, Lacoma A, Gil M, Abad Capa J. Microbiological Progress in Patients with Bronchial Infection with <b><i>Pseudomonas aeruginosa</i></b> Treated with Nebulised Colistin. Respiration 2019; 97:501-507. [DOI: 10.1159/000495069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 11/01/2018] [Indexed: 11/19/2022] Open
Abstract
<b><i>Background:</i></b> Inhaled antibiotics allow the delivery of higher drug concentrations at the site of infection without the systemic adverse effects observed with the use of parenteral or oral antibiotics. These antibiotics have shown to decrease the number of exacerbations, reduce bacterial load or improve pulmonary function in several chronic respiratory conditions. <b><i>Objectives:</i></b> The aim of this study was to describe changes in the bacteriology of sputum in patients with chronic bronchial infection with <i>Pseudomonas aeruginosa</i> treated with nebulised colistin. <b><i>Material and Methods:</i></b> All patients with chronical infection with <i>P. aeruginosa</i> treated with nebulised colistin attending a day care unit during a 5-year (January 2010 to December 2014) period were included. Repeated-measures <i>t</i> tests were used to assess whether the introduction of colistin was associated with changes in the number of exacerbations or the length of the hospitalisations. <b><i>Results:</i></b> Treatment with colistin was associated with a decrease in the number of ambulatory exacerbations (1.87–1.1, <i>p</i> = 0.007), of hospital exacerbations (1.3–0.7, <i>p</i> = 0.010) and of length of stay (15.7–8.6 days, <i>p</i> = 0.005). There was no linear trend in the proportion of isolate Enterobacteriaceae, gram-positive cocci, <i>Haemophilus influenzae</i> or fungi. Isolation of Enterobacteriaceae within 1 year after the beginning of the treatment with nebulised colistin was associated with an increase in the number of ambulatory exacerbations (incidence rate ratio 1.99, 95% CI 1.05–3.79). <b><i>Conclusions:</i></b> Nebulised colistin was effective in the treatment of chronic infection with <i>P. aeruginosa,</i> and no significant changes in the microbiological evolution were observed. Isolation of Enterobacteriaceae within 1 year after the beginning of the treatment with nebulised colistin was associated with an increase in the number of exacerbations.
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Majzoub ME, McElroy K, Maczka M, Thomas T, Egan S. Causes and Consequences of a Variant Strain of Phaeobacter inhibens With Reduced Competition. Front Microbiol 2018; 9:2601. [PMID: 30450086 PMCID: PMC6224355 DOI: 10.3389/fmicb.2018.02601] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 10/11/2018] [Indexed: 11/13/2022] Open
Abstract
Phaeobacter inhibens 2.10 is an effective biofilm former and colonizer of marine surfaces and has the ability to outcompete other microbiota. During biofilm dispersal P. inhibens 2.10 produces heritable phenotypic variants, including those that have a reduced ability to inhibit the co-occurring bacterium Pseudoalteromonas tunicata. However, the genetic changes that underpin the phenotypic variation and what the ecological consequences are for variants within the population are unclear. To answer these questions we sequenced the genomes of strain NCV12a1, a biofilm variant of P. inhibens 2.10 with reduced inhibitory activity and the P. inhibens 2.10 WT parental strain. Genome wide analysis revealed point mutations in genes involved in synthesis of the antibacterial compound tropodithietic acid (TDA) and indirectly in extracellular polymeric substances (EPS) production. However, confocal laser scanning microscopy analyses found little differences in biofilm growth between P. inhibens 2.10 WT (parental) and NCV12a1. P. inhibens NCV12a1 was also not outcompeted in co-cultured biofilms with P. tunicata, despite its reduced inhibitory activity, rather these biofilms were thicker than those produced when the WT strain was co-cultured with P. tunicata. Notably, dispersal populations from biofilms of P. inhibens NCV12a1 had a higher proportion of WT-like morphotypes when co-cultured with P. tunicata. These observations may explain why the otherwise non-inhibiting variant persists in the presence of a natural competitor, adding to our understanding of the relative importance of genetic diversification in microbial biofilms.
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Affiliation(s)
- Marwan E Majzoub
- Centre for Marine Bio-Innovation, School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, Australia
| | - Kerensa McElroy
- Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation, Canberra, ACT, Australia
| | - Michael Maczka
- Institute of Organic Chemistry, Technische Universität Braunschweig, Braunschweig, Germany
| | - Torsten Thomas
- Centre for Marine Bio-Innovation, School of Biological, Earth and Environmental Sciences, The University of New South Wales, Sydney, NSW, Australia
| | - Suhelen Egan
- Centre for Marine Bio-Innovation, School of Biological, Earth and Environmental Sciences, The University of New South Wales, Sydney, NSW, Australia
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Sousa AM, Monteiro R, Pereira MO. Unveiling the early events of Pseudomonas aeruginosa adaptation in cystic fibrosis airway environment using a long-term in vitro maintenance. Int J Med Microbiol 2018; 308:1053-1064. [PMID: 30377031 DOI: 10.1016/j.ijmm.2018.10.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 09/16/2018] [Accepted: 10/10/2018] [Indexed: 01/22/2023] Open
Abstract
Pseudomonas aeruginosa chronic infections are the major cause of high morbidity and mortality in cystic fibrosis (CF) patients due to the use of sophisticated mechanisms of adaptation, including clonal diversification into specialized CF-adapted phenotypes. In contrast to chronic infections, very little is known about what occurs after CF lungs colonization and at early infection stages. This study aims to investigate the early events of P. aeruginosa adaptation to CF environment, in particular, to inspect the occurrence of clonal diversification at early stages of infection development and its impact on antibiotherapy effectiveness. To mimic CF early infections, three P. aeruginosa strains were long-term grown in artificial sputum (ASM) over 10 days and phenotypic diversity verified through colony morphology characterization. Biofilm sub- and inhibitory concentrations of ciprofloxacin were applied to non- and diversified populations to evaluate antibiotic effectiveness on P. aeruginosa eradication. Our results demonstrated that clonal diversification might occur after ASM colonization and growth. However, this phenotypic diversification did not compromise ciprofloxacin efficacy in P. aeruginosa eradication since a biofilm minimal inhibitory dosage would be applied. The expected absence of mutators in P. aeruginosa populations led us to speculate that clonal diversification in the absence of ciprofloxacin treatments could be driven by niche specialization. Yet, biofilm sub-inhibitory concentrations of ciprofloxacin seemed to overlap niche specialization as "fitter" variants emerged, such as mucoid, small colony and pinpoint variants, known to be highly resistant to antibiotics. The pathogenic potential of all emergent colony morphotypes-associated bacteria, distinct from the wild-morphotypes, revealed that P. aeruginosa evolved to a non-swimming phenotype. Impaired swimming motility seemed to be one of the first evolutionary steps of P. aeruginosa in CF lungs that could pave the way for further adaptation steps including biofilm formation and progress to chronic infection. Based on our findings, impaired swimming motility seemed to be a candidate to disease marker of P. aeruginosa infection development. Despite our in vitro CF model represents a step forward towards in vivo scenario simulation and provided valuable insights about the early events, more and distinct P. aeruginosa strains should be studied to strengthen our results.
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Affiliation(s)
- Ana Margarida Sousa
- CEB - Centre of Biological Engineering, LIBRO - Laboratório de Investigação em Biofilmes Rosário Oliveira, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
| | - Rosana Monteiro
- CEB - Centre of Biological Engineering, LIBRO - Laboratório de Investigação em Biofilmes Rosário Oliveira, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
| | - Maria Olívia Pereira
- CEB - Centre of Biological Engineering, LIBRO - Laboratório de Investigação em Biofilmes Rosário Oliveira, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
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