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Hajiagha MN, Kafil HS. Efflux pumps and microbial biofilm formation. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2023:105459. [PMID: 37271271 DOI: 10.1016/j.meegid.2023.105459] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 05/25/2023] [Accepted: 05/27/2023] [Indexed: 06/06/2023]
Abstract
Biofilm-related infections are resistant forms of pathogens that are regarded as a medical problem, particularly due to the spread of multiple drug resistance. One of the factors associated with biofilm drug resistance is the presence of various types of efflux pumps in bacteria. Efflux pumps also play a role in biofilm formation by influencing Physical-chemical interactions, mobility, gene regulation, quorum sensing (QS), extracellular polymeric substances (EPS), and toxic compound extrusion. According to the findings of studies based on efflux pump expression analysis, their role in the anatomical position within the biofilm will differ depending on the biofilm formation stage, encoding gene expression level, the type and concentration of substrate. In some cases, the function of the efflux pumps can overlap with each other, so it seems necessary to accurate identify the efflux pumps of biofilm-forming bacteria along with their function in this process. Such studies will help to choose treatment strategy, at least in combination with antibiotics. Furthermore, if the goal of treatment is an efflux pump manipulation, we should not limit it to inhibition.
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Affiliation(s)
- Mahdyeh Neghabi Hajiagha
- Department of Microbiology, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Hossein Samadi Kafil
- Drug Applied Research Center, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran.
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2
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Alves D, Lopes H, Machado I, Pereira MO. Colistin conditioning surfaces combined with antimicrobial treatment to prevent ventilator-associated infections. BIOFOULING 2022; 38:547-557. [PMID: 35903005 DOI: 10.1080/08927014.2022.2088284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 06/02/2022] [Accepted: 06/06/2022] [Indexed: 06/15/2023]
Abstract
Biofilm formation on endotracheal tubes (ETT) is an important factor in the development of ventilator-associated pneumonia (VAP). This work aimed to investigate the effectiveness of colistin (COL) against the early stages of biofilm formation by Pseudomonas aeruginosa. Two strategies were used: pre-conditioning the adhesion surfaces with COL before biofilm formation and growing biofilms in its presence. The combined effect of treating P. aeruginosa 24-hours old biofilms with Ciprofloxacin (CIP) or colistin (COL) on clean and COL-conditioned surfaces was also assessed. Random deposition of COL residues altered the physico-chemical properties of the adhesion surfaces and impaired biofilm formation. Moreover, as a consequence of the reduced amount of biofilms attached to COL conditioned surfaces, adhered cells became more exposed to the subsequent action of CIP or COL, suggesting a combined outcome of prophylactic and therapeutic COL-based strategies. Results highlighted the promising use of COL to prevent the establishment of biofilms on ETT.
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Affiliation(s)
- Diana Alves
- CEB-Centre of Biological Engineering, University of Minho, Braga, Portugal
- LABBELS-Associate Laboratory, Braga/Guimarães, Portugal
| | - Hélder Lopes
- CEB-Centre of Biological Engineering, University of Minho, Braga, Portugal
| | - Idalina Machado
- CEB-Centre of Biological Engineering, University of Minho, Braga, Portugal
| | - Maria Olívia Pereira
- CEB-Centre of Biological Engineering, University of Minho, Braga, Portugal
- LABBELS-Associate Laboratory, Braga/Guimarães, Portugal
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3
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Mallick S, Mishra N, Barik BK, Negi VD. Salmonella Typhimurium fepB negatively regulates C. elegans behavioral plasticity. J Infect 2022; 84:518-530. [PMID: 34990707 DOI: 10.1016/j.jinf.2021.12.043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2021] [Revised: 12/27/2021] [Accepted: 12/29/2021] [Indexed: 10/19/2022]
Abstract
OBJECTIVES Dauer is an alternative developmental stage of Caenorhabditis elegans (C. elegans) that gives survival benefits under unfavorable environmental conditions. Our study aims to decipher C. elegans dauer larvae development upon Salmonella Typhimurium infection and how the bacterial gene regulating the worm's behavioural plasticity for better survival. METHODS Age-synchronized L4 C. elegans worms were infected with Salmonella Typhimurium 14028s (WT-STM) strain and mutant strains to check the dauer larvae development using 1% SDS. Besides, bacterial load in animals' gut, pharyngeal pumping rate and viability were checked. Worm's immune genes (e.g., ilys-3, lys-7, pmk-1, abf-2, clec-60) and dauer regulatory genes (e.g., daf-7, daf-11, daf-12, daf-16, daf-3) were checked by performing qRT-PCR under infection conditions. RESULTS We found that deletion of the fepB gene in S. Typhimurium strain became less pathogenic with reduced flagellar motility and biofilm-forming ability. Besides, there was decreased bacterial burden in the worm's gut with no damage to their pharynx. The fepB mutant strain was also able to enhance the immune responses for better survival of worms. Infection with mutant strain could activate dauer signaling via the TGF-β pathway leading to a significant increase in dauer formation than WT-STM infection. CONCLUSION Our study indicated that the bacteria act as a food source for the growth of C. elegans and development and can act as a signal that might be playing an essential role in regulating the host physiology for their survival. Such a study can help us in understanding the complex host-pathogen interaction benefiting pathogen in host dissemination.
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Affiliation(s)
- Swarupa Mallick
- Laboratory of Infection Immunology, Department of Life Science, National Institute of Technology, Rourkela 769008, Odisha, India.
| | - Neha Mishra
- Laboratory of Infection Immunology, Department of Life Science, National Institute of Technology, Rourkela 769008, Odisha, India.
| | - Bedanta Kumar Barik
- Laboratory of Infection Immunology, Department of Life Science, National Institute of Technology, Rourkela 769008, Odisha, India.
| | - Vidya Devi Negi
- Laboratory of Infection Immunology, Department of Life Science, National Institute of Technology, Rourkela 769008, Odisha, India.
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Strain-specific interspecies interactions between co-isolated pairs of Staphylococcus aureus and Pseudomonas aeruginosa from patients with tracheobronchitis or bronchial colonization. Sci Rep 2022; 12:3374. [PMID: 35233050 PMCID: PMC8888623 DOI: 10.1038/s41598-022-07018-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 02/09/2022] [Indexed: 01/20/2023] Open
Abstract
Dual species interactions in co-isolated pairs of Staphylococcus aureus and Pseudomonas aeruginosa from patients with tracheobronchitis or bronchial colonization were examined. The genetic and phenotypic diversity between the isolates was high making the interactions detected strain-specific. Despite this, and the clinical origin of the strains, some interactions were common between some co-isolated pairs. For most pairs, P. aeruginosa exoproducts affected biofilm formation and reduced growth in vitro in its S. aureus counterpart. Conversely, S. aureus did not impair biofilm formation and stimulated swarming motility in P. aeruginosa. Co-culture in a medium that mimics respiratory mucus promoted coexistence and favored mixed microcolony formation within biofilms. Under these conditions, key genes controlled by quorum sensing were differentially regulated in both species in an isolate-dependent manner. Finally, co-infection in the acute infection model in Galleria mellonella larvae showed an additive effect only in the co-isolated pair in which P. aeruginosa affected less S. aureus growth. This work contributes to understanding the complex interspecies interactions between P. aeruginosa and S. aureus by studying strains isolated during acute infection.
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Influence of the Alternative Sigma Factor RpoN on Global Gene Expression and Carbon Catabolism in Enterococcus faecalis V583. mBio 2021; 12:mBio.00380-21. [PMID: 34006651 PMCID: PMC8262876 DOI: 10.1128/mbio.00380-21] [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] [Indexed: 12/13/2022] Open
Abstract
The alternative sigma factor σ54 has been shown to regulate the expression of a wide array of virulence-associated genes, as well as central metabolism, in bacterial pathogens. In Gram-positive organisms, the σ54 is commonly associated with carbon metabolism. In this study, we show that the Enterococcus faecalis alternative sigma factor σ54 (RpoN) and its cognate enhancer binding protein MptR are essential for mannose utilization and are primary contributors to glucose uptake through the Mpt phosphotransferase system. To gain further insight into how RpoN contributes to global transcriptional changes, we performed microarray transcriptional analysis of strain V583 and an isogenic rpoN mutant grown in a chemically defined medium with glucose as the sole carbon source. Transcripts of 340 genes were differentially affected in the rpoN mutant; the predicted functions of these genes mainly related to nutrient acquisition. These differentially expressed genes included those with predicted catabolite-responsive element (cre) sites, consistent with loss of repression by the major carbon catabolite repressor CcpA. To determine if the inability to efficiently metabolize glucose/mannose affected infection outcome, we utilized two distinct infection models. We found that the rpoN mutant is significantly attenuated in both rabbit endocarditis and murine catheter-associated urinary tract infection (CAUTI). Here, we examined a ccpA mutant in the CAUTI model and showed that the absence of carbon catabolite control also significantly attenuates bacterial tissue burden in this model. Our data highlight the contribution of central carbon metabolism to growth of E. faecalis at various sites of infection.
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6
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Wang T, Sun W, Fan L, Hua C, Wu N, Fan S, Zhang J, Deng X, Yan J. An atlas of the binding specificities of transcription factors in Pseudomonas aeruginosa directs prediction of novel regulators in virulence. eLife 2021; 10:61885. [PMID: 33779544 PMCID: PMC8041468 DOI: 10.7554/elife.61885] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 03/26/2021] [Indexed: 12/14/2022] Open
Abstract
A high-throughput systematic evolution of ligands by exponential enrichment assay was applied to 371 putative TFs in Pseudomonas aeruginosa, which resulted in the robust enrichment of 199 unique sequence motifs describing the binding specificities of 182 TFs. By scanning the genome, we predicted in total 33,709 significant interactions between TFs and their target loci, which were more than 11-fold enriched in the intergenic regions but depleted in the gene body regions. To further explore and delineate the physiological and pathogenic roles of TFs in P. aeruginosa, we constructed regulatory networks for nine major virulence-associated pathways and found that 51 TFs were potentially significantly associated with these virulence pathways, 32 of which had not been characterized before, and some were even involved in multiple pathways. These results will significantly facilitate future studies on transcriptional regulation in P. aeruginosa and other relevant pathogens, and accelerate to discover effective treatment and prevention strategies for the associated infectious diseases.
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Affiliation(s)
- Tingting Wang
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China
| | - Wenju Sun
- School of Medicine, Northwest University, Xi'an, China
| | - Ligang Fan
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China.,School of Medicine, Northwest University, Xi'an, China
| | - Canfeng Hua
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China
| | - Nan Wu
- School of Medicine, Northwest University, Xi'an, China
| | - Shaorong Fan
- School of Medicine, Northwest University, Xi'an, China
| | - Jilin Zhang
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Solna, Sweden
| | - Xin Deng
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China
| | - Jian Yan
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China.,School of Medicine, Northwest University, Xi'an, China
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Proner MC, de Meneses AC, Veiga AA, Schlüter H, Oliveira DD, Luccio MD. Industrial Cooling Systems and Antibiofouling Strategies: A Comprehensive Review. Ind Eng Chem Res 2021. [DOI: 10.1021/acs.iecr.0c05985] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Mariane Carolina Proner
- Department of Chemical and Food Engineering, Federal University of Santa Catarina (UFSC), Florianópolis, Santa Catarina 88040-900, Brazil
| | - Alessandra Cristina de Meneses
- Department of Chemical and Food Engineering, Federal University of Santa Catarina (UFSC), Florianópolis, Santa Catarina 88040-900, Brazil
| | - Andrea Azevedo Veiga
- Petrobras R&D Center, CENPES, Av. Horácio Macedo, 950, Cidade Universitária, Ilha do Fundão, Rio de Janeiro, Rio de Janeiro 21941-915, Brazil
| | - Helga Schlüter
- Petrobras R&D Center, CENPES, Av. Horácio Macedo, 950, Cidade Universitária, Ilha do Fundão, Rio de Janeiro, Rio de Janeiro 21941-915, Brazil
| | - Débora de Oliveira
- Department of Chemical and Food Engineering, Federal University of Santa Catarina (UFSC), Florianópolis, Santa Catarina 88040-900, Brazil
| | - Marco Di Luccio
- Department of Chemical and Food Engineering, Federal University of Santa Catarina (UFSC), Florianópolis, Santa Catarina 88040-900, Brazil
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8
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Wang Y, Liu G, Zhang J, Gu D, Hu M, Zhang Y, Pan Z, Geng S, Jiao X. WbaP is required for swarm motility and intramacrophage multiplication of Salmonella Enteritidis spiC mutant by glucose use ability. Microbiol Res 2020; 245:126686. [PMID: 33429286 DOI: 10.1016/j.micres.2020.126686] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 12/10/2020] [Accepted: 12/18/2020] [Indexed: 11/18/2022]
Abstract
Salmonella spp. can survive and replicate in macrophage cells to cause persistent infection, SpiC is a necessary T3SS effector, but its pathogenic mechanism is still not known completely. In our study, Salmonella Enteritidis spiC mutant (SEΔspiC) was found to have stronger swarming motility and intramacrophage hyperproliferation which was closely related to glucose metabolism. SEΔspiC wbaP::Tn5 mutant was screened out by transposon mutagenesis, which had weaker swarming motility and intramacrophage replication ability than SEΔspiC in the presence of glucose. Bioinformatics displayed that undecaprenyl-phosphate galactose phosphotransferase (Wbap), encoded by wbaP gene, was a key enzyme for glucose metabolism and Lipopolysaccharide(LPS) synthesis, which confirmed our outcome that Wbap was involved in intramacrophage replication ability by glucose use in addition to swarming motility based on SEΔspiC. This discovery will further promote the understanding of the interaction between wbaP gene and spiC gene and the intracellular Salmonella replication mechanism.
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Affiliation(s)
- Yaonan Wang
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, Jiangsu, 225009, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, Jiangsu, 225009, China; Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of Agriculture of China, Yangzhou University, Yangzhou, Jiangsu, 225009, China; Joint International Research Laboratory of Agriculture and Agri-product Safety of the Ministry of Education, Yangzhou University, Yangzhou, Jiangsu, 225009, China
| | - Guifeng Liu
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, Jiangsu, 225009, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, Jiangsu, 225009, China; Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of Agriculture of China, Yangzhou University, Yangzhou, Jiangsu, 225009, China; Joint International Research Laboratory of Agriculture and Agri-product Safety of the Ministry of Education, Yangzhou University, Yangzhou, Jiangsu, 225009, China
| | - Jian Zhang
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, Jiangsu, 225009, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, Jiangsu, 225009, China; Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of Agriculture of China, Yangzhou University, Yangzhou, Jiangsu, 225009, China; Joint International Research Laboratory of Agriculture and Agri-product Safety of the Ministry of Education, Yangzhou University, Yangzhou, Jiangsu, 225009, China
| | - Dan Gu
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, Jiangsu, 225009, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, Jiangsu, 225009, China; Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of Agriculture of China, Yangzhou University, Yangzhou, Jiangsu, 225009, China; Joint International Research Laboratory of Agriculture and Agri-product Safety of the Ministry of Education, Yangzhou University, Yangzhou, Jiangsu, 225009, China
| | - Maozhi Hu
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, Jiangsu, 225009, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, Jiangsu, 225009, China; Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of Agriculture of China, Yangzhou University, Yangzhou, Jiangsu, 225009, China; Joint International Research Laboratory of Agriculture and Agri-product Safety of the Ministry of Education, Yangzhou University, Yangzhou, Jiangsu, 225009, China
| | - Yunzheng Zhang
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, Jiangsu, 225009, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, Jiangsu, 225009, China; Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of Agriculture of China, Yangzhou University, Yangzhou, Jiangsu, 225009, China; Joint International Research Laboratory of Agriculture and Agri-product Safety of the Ministry of Education, Yangzhou University, Yangzhou, Jiangsu, 225009, China
| | - Zhiming Pan
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, Jiangsu, 225009, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, Jiangsu, 225009, China; Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of Agriculture of China, Yangzhou University, Yangzhou, Jiangsu, 225009, China; Joint International Research Laboratory of Agriculture and Agri-product Safety of the Ministry of Education, Yangzhou University, Yangzhou, Jiangsu, 225009, China
| | - Shizhong Geng
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, Jiangsu, 225009, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, Jiangsu, 225009, China; Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of Agriculture of China, Yangzhou University, Yangzhou, Jiangsu, 225009, China; Joint International Research Laboratory of Agriculture and Agri-product Safety of the Ministry of Education, Yangzhou University, Yangzhou, Jiangsu, 225009, China.
| | - Xin'an Jiao
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, Jiangsu, 225009, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, Jiangsu, 225009, China; Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of Agriculture of China, Yangzhou University, Yangzhou, Jiangsu, 225009, China; Joint International Research Laboratory of Agriculture and Agri-product Safety of the Ministry of Education, Yangzhou University, Yangzhou, Jiangsu, 225009, China.
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9
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Material properties of interfacial films of mucoid and nonmucoid Pseudomonas aeruginosa isolates. Acta Biomater 2020; 118:129-140. [PMID: 33053427 DOI: 10.1016/j.actbio.2020.10.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 09/20/2020] [Accepted: 10/07/2020] [Indexed: 12/19/2022]
Abstract
Chronic lung infection with bacterial biofilms is a leading cause of death in cystic fibrosis (CF) patients. Pseudomonas aeruginosa, one of the many species colonizing the lung airways, can undergo pathoadaptation, leading to a mucoid phenotype with interesting material properties. We hypothesize that the surface properties and extracellular materials of mucoid P. aeruginosa cells greatly influence the mechanical behavior of their films at fluid interfaces. In this study, we investigate the interfacial properties of films formed by nonmucoid (PANT) and mucoid (PASL) strains of P. aeruginosa isolated from CF patients. We use pendant drop elastometry to analyze the interfacial response of the films formed by PANT and PASL at the hexadecane-water interface. The dynamic rheological analyses of the films highlight the distinctive signature of the mucoid strains at fluid interfaces. The mucoid films exhibit greater relaxation following a compressive strain than a tensile one, while a full hysteresis response is achieved by the nonmucoid films; this indicates that the material properties of the PANT films are conserved under both compression and tension. The wrinkling and shape analyses of the interfacial bacterial films elucidate that the mucoid strain exhibits remarkable viscoelastic properties, enabling the remodeling of the living films and dissipation of the compressive stress. The comparative analysis of the material properties of mucoid and nonmucoid P. aeruginosa cells indicates that mucoid switch can play an important role in protecting the bacteria from interfacial stresses. Further characterization of interfacial bacterial films will provide new insights into the development of methods for controlling interfacial films of bacteria.
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10
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Shao X, Xie Y, Zhang Y, Liu J, Ding Y, Wu M, Wang X, Deng X. Novel therapeutic strategies for treating Pseudomonas aeruginosa infection. Expert Opin Drug Discov 2020; 15:1403-1423. [PMID: 32880507 DOI: 10.1080/17460441.2020.1803274] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
INTRODUCTION Persistent infections caused by the superbug Pseudomonas aeruginosa and its resistance to multiple antimicrobial agents are huge threats to patients with cystic fibrosis as well as those with compromised immune systems. Multidrug-resistant P. aeruginosa has posed a major challenge to conventional antibiotics and therapeutic approaches, which show limited efficacy and cause serious side effects. The public demand for new antibiotics is enormous; yet, drug development pipelines have started to run dry with limited targets available for inventing new antibacterial drugs. Consequently, it is important to uncover potential therapeutic targets. AREAS COVERED The authors review the current state of drug development strategies that are promising in terms of the development of novel and potent drugs to treat P. aeruginosa infection. EXPERT OPINION The prevention of P. aeruginosa infection is increasingly challenging. Furthermore, targeting key virulence regulators has great potential for developing novel anti-P. aeruginosa drugs. Additional promising strategies include bacteriophage therapy, immunotherapies, and antimicrobial peptides. Additionally, the authors believe that in the coming years, the overall network of molecular regulatory mechanism of P. aeruginosa virulence will be fully elucidated, which will provide more novel and promising drug targets for treating P. aeruginosa infections.
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Affiliation(s)
- Xiaolong Shao
- Department of Biomedical Sciences, City University of Hong Kong , Hong Kong SAR, China
| | - Yingpeng Xie
- Department of Biomedical Sciences, City University of Hong Kong , Hong Kong SAR, China
| | - Yingchao Zhang
- Department of Biomedical Sciences, City University of Hong Kong , Hong Kong SAR, China
| | - Jingui Liu
- Department of Biomedical Sciences, City University of Hong Kong , Hong Kong SAR, China
| | - Yiqing Ding
- Department of Biomedical Sciences, City University of Hong Kong , Hong Kong SAR, China
| | - Min Wu
- Department of Biomedical Sciences, University of North Dakota , Grand Forks, North Dakota, USA
| | - Xin Wang
- Department of Biomedical Sciences, City University of Hong Kong , Hong Kong SAR, China
| | - Xin Deng
- Department of Biomedical Sciences, City University of Hong Kong , Hong Kong SAR, China.,Shenzhen Research Institute, City University of Hong Kong , Shenzhen, China
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11
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Mendez E, Walker DK, Vipham J, Trinetta V. The use of a CDC biofilm reactor to grow multi-strain Listeria monocytogenes biofilm. Food Microbiol 2020; 92:103592. [PMID: 32950174 DOI: 10.1016/j.fm.2020.103592] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 05/19/2020] [Accepted: 06/29/2020] [Indexed: 02/07/2023]
Abstract
Listeria monocytogenes is one of the most concerning pathogens for the food industry due to its ability to form biofilms, particularly in difficult-to-clean sites of processing facilities. There is a current industry-wide lack of data to refer to when selecting a strategy to control L. monocytogenes biofilms in the food premises. Many strategies have been developed to study biofilm formation of bacteria; however, few have targeted L. monocytogenes biofilms under dynamic conditions. This study addresses the biofilm formation ability of L. monocytogenes on stainless steel and polycarbonate under dynamic conditions using TSBYE or BHI as media culture at 30 °C or 37 °C. Higher cell counts were recovered at 30 °C in TSBYE on polycarbonate while lower counts were obtained at 37 °C in BHI on stainless steel (P < 0.05). Nonetheless, all factors (temperature, media and material) were statistically significant (P < 0.05) and an interaction between temperature and media was observed (P < 0.05). To our knowledge, this work represents an initial framework to develop L. monocytogenes biofilms under different dynamic conditions. The use of CDC Biofilm Reactor is not widely used yet in the food industry and represent a novel approach to help sanitary control strategies implementation.
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Affiliation(s)
- Ellen Mendez
- Food Science Institute, Kansas State University, 1530 Mid-Campus Drive North, Manhattan, KS, 66506, USA
| | - Diane K Walker
- Center for Biofilm Engineering, Montana State University, 366 Barnard Hall, Bozeman, MT, 59717, USA
| | - Jessie Vipham
- Dept. of Animal Sciences and Industry, Kansas State University, 1424 Clafin Road, Manhattan KS, 66506, USA
| | - Valentina Trinetta
- Food Science Institute, Kansas State University, 1530 Mid-Campus Drive North, Manhattan, KS, 66506, USA; Dept. of Animal Sciences and Industry, Kansas State University, 1424 Clafin Road, Manhattan KS, 66506, USA.
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12
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Badal D, Jayarani AV, Kollaran MA, Kumar A, Singh V. Pseudomonas aeruginosa biofilm formation on endotracheal tubes requires multiple two-component systems. J Med Microbiol 2020; 69:906-919. [PMID: 32459613 DOI: 10.1099/jmm.0.001199] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Introduction. Indwelling medical devices such as endotracheal tubes (ETTs), urinary catheters, vascular access devices, tracheostomies and feeding tubes are often associated with hospital-acquired infections. Bacterial biofilm formed on the ETTs in intubated patients is a significant risk factor associated with ventilator-associated pneumonia. Pseudomonas aeruginosa is one of the four frequently encountered bacteria responsible for causing pneumonia, and the biofilm formation on ETTs. However, understanding of biofilm formation on ETT and interventions to prevent biofilm remains lagging. The ability to sense and adapt to external cues contributes to their success. Thus, the biofilm formation is likely to be influenced by the two-component systems (TCSs) that are composed of a membrane-associated sensor kinase and an intracellular response regulator.Aim. This study aims to establish an in vitro method to analyse the P. aeruginosa biofilm formation on ETTs, and identify the TCSs that contribute to this process.Methodology. In total, 112 P. aeruginosa PA14 TCS mutants were tested for their ability to form biofilm on ETTs, their effect on quorum sensing (QS) and motility.Results. Out of 112 TCS mutants studied, 56 had altered biofilm biomass on ETTs. Although the biofilm formation on ETTs is QS-dependent, none of the 56 loci controlled quorum signal. Of these, 18 novel TCSs specific to ETT biofilm were identified, namely, AauS, AgtS, ColR, CopS, CprR, NasT, KdpD, ParS, PmrB, PprA, PvrS, RcsC, PA14_11120, PA14_32580, PA14_45880, PA14_49420, PA14_52240, PA14_70790. The set of 56 included the GacS network, TCS proteins involved in fimbriae synthesis, TCS proteins involved in antimicrobial peptide resistance, and surface-sensing. Additionally, several of the TCS-encoding genes involved in biofilm formation on ETTs were found to be linked to flagellum-dependent swimming motility.Conclusions. Our study established an in vitro method for studying P. aeruginosa biofilm formation on the ETT surfaces. We also identified novel ETT-specific TCSs that could serve as targets to prevent biofilm formation on indwelling devices frequently used in clinical settings.
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Affiliation(s)
- Divakar Badal
- Department of Biosystems Sciences and Engineering, Indian Institute of Science, Bangalore, Karnataka, INDIA
| | - Abhijith Vimal Jayarani
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, Karnataka, INDIA
| | - Mohammed Ameen Kollaran
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, Karnataka, INDIA
| | - Aloke Kumar
- Department of Mechanical Engineering, Indian Institute of Science, Bangalore, Karnataka, INDIA.,Department of Biosystems Sciences and Engineering, Indian Institute of Science, Bangalore, Karnataka, INDIA
| | - Varsha Singh
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, Karnataka, INDIA.,Department of Biosystems Sciences and Engineering, Indian Institute of Science, Bangalore, Karnataka, INDIA
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13
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Li C, Sun W, Lu Z, Ao X, Li S. Ceramic nanocomposite membranes and membrane fouling: A review. WATER RESEARCH 2020; 175:115674. [PMID: 32200336 DOI: 10.1016/j.watres.2020.115674] [Citation(s) in RCA: 102] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 02/10/2020] [Accepted: 02/27/2020] [Indexed: 05/26/2023]
Abstract
Membrane technologies have broad applications in the removal of contaminants from drinking water and wastewater. In recent decades, ceramic membrane has made rapid progress in industrial/municipal wastewater treatment and drinking water treatment owing to their advantageous properties over conventional polymeric membrane. The beneficial characteristics of ceramic membranes include fouling resistance, high permeability, good recoverability, chemical stability, and long life time, which have found applications with the recent innovations in both fabrication methods and nanotechnology. Therefore, ceramic membranes hold great promise for potential applications in water treatment. This paper mainly reviews the progress in the research and development of ceramic membranes, with key focus on porous ceramic membranes and nanomaterial-functionalized ceramic membranes for nanofiltration or catalysis. The current state of the available ceramic membranes in industry and academia, and their potential advantages, limitations and applications are reviewed. The last section of the review focuses on ceramic membrane fouling and the efforts towards ceramic membrane fouling mitigation. The advances in ceramic membrane technologies have rarely been widely reviewed before, therefore, this review could be served as a guide for the new entrants to the field, as well to the established researchers.
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Affiliation(s)
- Chen Li
- School of Environment, Tsinghua University, Beijing, 100084, China
| | - Wenjun Sun
- School of Environment, Tsinghua University, Beijing, 100084, China.
| | - Zedong Lu
- School of Environment, Tsinghua University, Beijing, 100084, China
| | - Xiuwei Ao
- School of Environment, Tsinghua University, Beijing, 100084, China
| | - Simiao Li
- School of Environment, Tsinghua University, Beijing, 100084, China
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14
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Di Somma A, Moretta A, Canè C, Cirillo A, Duilio A. Antimicrobial and Antibiofilm Peptides. Biomolecules 2020; 10:biom10040652. [PMID: 32340301 PMCID: PMC7226136 DOI: 10.3390/biom10040652] [Citation(s) in RCA: 116] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 04/17/2020] [Accepted: 04/21/2020] [Indexed: 12/11/2022] Open
Abstract
The increasing onset of multidrug-resistant bacteria has propelled microbiology research towards antimicrobial peptides as new possible antibiotics from natural sources. Antimicrobial peptides are short peptides endowed with a broad range of activity against both Gram-positive and Gram-negative bacteria and are less prone to trigger resistance. Besides their activity against planktonic bacteria, many antimicrobial peptides also show antibiofilm activity. Biofilms are ubiquitous in nature, having the ability to adhere to virtually any surface, either biotic or abiotic, including medical devices, causing chronic infections that are difficult to eradicate. The biofilm matrix protects bacteria from hostile environments, thus contributing to the bacterial resistance to antimicrobial agents. Biofilms are very difficult to treat, with options restricted to the use of large doses of antibiotics or the removal of the infected device. Antimicrobial peptides could represent good candidates to develop new antibiofilm drugs as they can act at different stages of biofilm formation, on disparate molecular targets and with various mechanisms of action. These include inhibition of biofilm formation and adhesion, downregulation of quorum sensing factors, and disruption of the pre-formed biofilm. This review focuses on the proprieties of antimicrobial and antibiofilm peptides, with a particular emphasis on their mechanism of action, reporting several examples of peptides that over time have been shown to have activity against biofilm.
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Affiliation(s)
- Angela Di Somma
- Dipartimento di Scienze Chimiche, Università Federico II, 80126 Naples, Italy; (A.D.S.); (C.C.)
- Istituto Nazionale Biostrutture e Biosistemi (INBB), 00136 Rome, Italy
| | - Antonio Moretta
- Dipartimento di Scienze, Università degli Studi della Basilicata, 85100 Potenza, Italy;
| | - Carolina Canè
- Dipartimento di Scienze Chimiche, Università Federico II, 80126 Naples, Italy; (A.D.S.); (C.C.)
| | | | - Angela Duilio
- Dipartimento di Scienze Chimiche, Università Federico II, 80126 Naples, Italy; (A.D.S.); (C.C.)
- Correspondence:
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15
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Chang Y, Wang PC, Ma HM, Chen SY, Fu YH, Liu YY, Wang X, Yu GC, Huang T, Hibbs DE, Zhou HB, Chen WM, Lin J, Wang C, Zheng JX, Sun PH. Design, synthesis and evaluation of halogenated furanone derivatives as quorum sensing inhibitors in Pseudomonas aeruginosa. Eur J Pharm Sci 2019; 140:105058. [DOI: 10.1016/j.ejps.2019.105058] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 08/23/2019] [Accepted: 08/26/2019] [Indexed: 01/23/2023]
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16
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Cameron LC, Bonis B, Phan CQ, Kent LA, Lee AK, Hunter RC. A putative enoyl-CoA hydratase contributes to biofilm formation and the antibiotic tolerance of Achromobacter xylosoxidans. NPJ Biofilms Microbiomes 2019; 5:20. [PMID: 31396394 PMCID: PMC6684605 DOI: 10.1038/s41522-019-0093-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Accepted: 07/17/2019] [Indexed: 02/07/2023] Open
Abstract
Achromobacter xylosoxidans has attracted increasing attention as an emerging pathogen in patients with cystic fibrosis. Intrinsic resistance to several classes of antimicrobials and the ability to form robust biofilms in vivo contribute to the clinical manifestations of persistent A. xylosoxidans infection. Still, much of A. xylosoxidans biofilm formation remains uncharacterized due to the scarcity of existing genetic tools. Here we demonstrate a promising genetic system for use in A. xylosoxidans; generating a transposon mutant library which was then used to identify genes involved in biofilm development in vitro. We further described the effects of one of the genes found in the mutagenesis screen, encoding a putative enoyl-CoA hydratase, on biofilm structure and tolerance to antimicrobials. Through additional analysis, we find that a fatty acid signaling compound is essential to A. xylosoxidans biofilm ultrastructure and maintenance. This work describes methods for the genetic manipulation of A. xylosoxidans and demonstrated their use to improve our understanding of A. xylosoxidans pathophysiology.
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Affiliation(s)
- Lydia C. Cameron
- Department of Microbiology & Immunology, University of Minnesota, 689 23rd Avenue SE, Minneapolis, MN 55455 USA
| | - Benjamin Bonis
- Department of Microbiology & Immunology, University of Minnesota, 689 23rd Avenue SE, Minneapolis, MN 55455 USA
| | - Chi Q. Phan
- Department of Microbiology & Immunology, University of Minnesota, 689 23rd Avenue SE, Minneapolis, MN 55455 USA
- Present Address: Department of Genome Sciences, University of Washington, 3720 15th Ave NE, Seattle, WA 98195 USA
| | - Leslie A. Kent
- Department of Microbiology & Immunology, University of Minnesota, 689 23rd Avenue SE, Minneapolis, MN 55455 USA
| | - Alysha K. Lee
- Department of Microbiology & Immunology, University of Minnesota, 689 23rd Avenue SE, Minneapolis, MN 55455 USA
- Present Address: Department of Earth System Science, Stanford University, Stanford, CA 94305 USA
| | - Ryan C. Hunter
- Department of Microbiology & Immunology, University of Minnesota, 689 23rd Avenue SE, Minneapolis, MN 55455 USA
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17
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Marine Bacteria, A Source for Alginolytic Enzyme to Disrupt Pseudomonas aeruginosa Biofilms. Mar Drugs 2019; 17:md17050307. [PMID: 31137680 PMCID: PMC6562671 DOI: 10.3390/md17050307] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 05/18/2019] [Accepted: 05/22/2019] [Indexed: 12/24/2022] Open
Abstract
Pseudomonas aeruginosa biofilms are typically associated with the chronic lung infection of cystic fibrosis (CF) patients and represent a major challenge for treatment. This opportunistic bacterial pathogen secretes alginate, a polysaccharide that is one of the main components of its biofilm. Targeting this major biofilm component has emerged as a tempting therapeutic strategy for tackling biofilm-associated bacterial infections. The enormous potential in genetic diversity of the marine microbial community make it a valuable resource for mining activities responsible for a broad range of metabolic processes, including the alginolytic activity responsible for degrading alginate. A collection of 36 bacterial isolates were purified from marine water based on their alginolytic activity. These isolates were identified based on their 16S rRNA gene sequences. Pseudoalteromonas sp. 1400 showed the highest alginolytic activity and was further confirmed to produce the enzyme alginate lyase. The purified alginate lyase (AlyP1400) produced by Pseudoalteromonas sp. 1400 showed a band of 23 KDa on a protein electrophoresis gel and exhibited a bifunctional lyase activity for both poly-mannuronic acid and poly-glucuronic acid degradation. A tryptic digestion of this gel band analyzed by liquid chromatography-tandem mass spectrometry confirmed high similarity to the alginate lyases in polysaccharide lyase family 18. The purified alginate lyase showed a maximum relative activity at 30 °C at a slightly acidic condition. It decreased the sodium alginate viscosity by over 90% and reduced the P. aeruginosa (strain PA14) biofilms by 69% after 24 h of incubation. The combined activity of AlyP1400 with carbenicillin or ciprofloxacin reduced the P. aeruginosa biofilm thickness, biovolume and surface area in a flow cell system. The present data revealed that AlyP1400 combined with conventional antibiotics helped to disrupt the biofilms produced by P. aeruginosa and can be used as a promising combinational therapeutic strategy.
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18
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Fluidic resistance control enables high-throughput establishment of mixed-species biofilms. Biotechniques 2019; 66:235-239. [DOI: 10.2144/btn-2018-0150] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Bacteria often live in communities of mixed species embedded in a self-produced extracellular matrix of polysaccharides, proteins and DNA, termed biofilms. The BioFlux microfluidic flow system is useful for studying biofilm formation in different media under flow. However, analyzing the architecture and maturation of biofilms under flow requires a proper seeding, which can prove difficult when working with bacteria of different sizes, motile bacteria or aiming for a high number of replicates. Here we developed an efficient protocol that exploits viscosity tuning and seeding indicator dyes to improve seeding and allow for high-throughput examination and visualization of consistent mono- and mixed-species biofilm developments under flow.
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19
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Yasir M, Willcox MDP, Dutta D. Action of Antimicrobial Peptides against Bacterial Biofilms. MATERIALS 2018; 11:ma11122468. [PMID: 30563067 PMCID: PMC6317029 DOI: 10.3390/ma11122468] [Citation(s) in RCA: 156] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2018] [Revised: 11/30/2018] [Accepted: 12/01/2018] [Indexed: 12/22/2022]
Abstract
Microbes are known to colonize surfaces and form biofilms. These biofilms are communities of microbes encased in a self-produced matrix that often contains polysaccharides, DNA and proteins. Antimicrobial peptides (AMPs) have been used to control the formation and to eradicate mature biofilms. Naturally occurring or synthetic antimicrobial peptides have been shown to prevent microbial colonization of surfaces, to kill bacteria in biofilms and to disrupt the biofilm structure. This review systemically analyzed published data since 1970 to summarize the possible anti-biofilm mechanisms of AMPs. One hundred and sixty-two published reports were initially selected for this review following searches using the criteria ‘antimicrobial peptide’ OR ‘peptide’ AND ‘mechanism of action’ AND ‘biofilm’ OR ‘antibiofilm’ in the databases PubMed; Scopus; Web of Science; MEDLINE; and Cochrane Library. Studies that investigated anti-biofilm activities without describing the possible mechanisms were removed from the analysis. A total of 17 original reports were included which have articulated the mechanism of antimicrobial action of AMPs against biofilms. The major anti-biofilm mechanisms of antimicrobial peptides are: (1) disruption or degradation of the membrane potential of biofilm embedded cells; (2) interruption of bacterial cell signaling systems; (3) degradation of the polysaccharide and biofilm matrix; (4) inhibition of the alarmone system to avoid the bacterial stringent response; (5) downregulation of genes responsible for biofilm formation and transportation of binding proteins.
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Affiliation(s)
- Muhammad Yasir
- School of Optometry and Vision Science, University of New South Wales, Sydney, NSW 2052, Australia.
| | | | - Debarun Dutta
- School of Optometry and Vision Science, University of New South Wales, Sydney, NSW 2052, Australia.
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20
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Recent developments in biofouling control in membrane bioreactors for domestic wastewater treatment. Sep Purif Technol 2018. [DOI: 10.1016/j.seppur.2018.06.004] [Citation(s) in RCA: 100] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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21
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Segev-Zarko LA, Kapach G, Josten M, Klug YA, Sahl HG, Shai Y. Deficient Lipid A Remodeling by the arnB Gene Promotes Biofilm Formation in Antimicrobial Peptide Susceptible Pseudomonas aeruginosa. Biochemistry 2018. [PMID: 29518324 DOI: 10.1021/acs.biochem.8b00149] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Multidrug resistant bacteria possess various mechanisms that can sense environmental stresses such as antibiotics and antimicrobial peptides and rapidly respond to defend themselves. Two known defense strategies are biofilm formation and lipopolysaccharide (LPS) modification. Though LPS modifications are observed in biofilm-embedded bacteria, their effect on biofilm formation is unknown. Using biochemical and biophysical methods coupled with confocal microscopy, atomic force microscopy, and transmission electron microscopy, we show that biofilm formation is promoted in a Pseudomonas aeruginosa PAO1 strain with a loss of function mutation in the arnB gene. This loss of function prevents the addition of the positively charged sugar 4-amino-4-deoxy-l-arabinose to lipid A of LPS under restrictive magnesium conditions. The data reveal that the arnB mutant, which is susceptible to antimicrobial peptides, forms a biofilm that is more robust than that of the wild type. This is in line with the observations that the arnB mutant exhibits outer surface properties such as hydrophobicity and net negative charge that promote the formation of biofilms. Moreover, when grown under Mg2+ limitation, both the wild type and the arnB mutant exhibited a reduction in the level of membrane-bound polysaccharides. The data suggest that the loss of polysaccharides exposes the membrane and alters its biophysical properties, which in turn leads to more biofilm formation. In summary, we show for the first time that blocking a specific lipid A modification promotes biofilm formation, suggesting a trade-off between LPS remodeling and resistance mechanisms of biofilm formation.
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Affiliation(s)
- Li-Av Segev-Zarko
- Department of Biomolecular Sciences , The Weizmann Institute of Science , Rehovot , Israel
| | - Gal Kapach
- Department of Biomolecular Sciences , The Weizmann Institute of Science , Rehovot , Israel
| | - Michaele Josten
- Institute of Medical Microbiology, Immunology and Parasitology , University of Bonn , Bonn , Germany
| | - Yoel Alexander Klug
- Department of Biomolecular Sciences , The Weizmann Institute of Science , Rehovot , Israel
| | - Hans-Georg Sahl
- Institute of Medical Microbiology, Immunology and Parasitology , University of Bonn , Bonn , Germany
| | - Yechiel Shai
- Department of Biomolecular Sciences , The Weizmann Institute of Science , Rehovot , Israel
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22
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Pu M, Sheng L, Song S, Gong T, Wood TK. Serine Hydroxymethyltransferase ShrA (PA2444) Controls Rugose Small-Colony Variant Formation in Pseudomonas aeruginosa. Front Microbiol 2018. [PMID: 29535691 PMCID: PMC5835335 DOI: 10.3389/fmicb.2018.00315] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Pseudomonas aeruginosa causes many biofilm infections, and the rugose small-colony variants (RSCVs) of this bacterium are important for infection. We found here that inactivation of PA2444, which we determined to be a serine hydroxymethyltransferase (SHMT), leads to the RSCV phenotype of P. aeruginosa PA14. In addition, loss of PA2444 increases biofilm formation by two orders of magnitude, increases exopolysaccharide by 45-fold, and abolishes swarming. The RSCV phenotype is related to higher cyclic diguanylate concentrations due to increased activity of the Wsp chemosensory system, including diguanylate cyclase WspR. By characterizing the PA2444 enzyme in vitro, we determined the physiological function of PA2444 protein by relating it to S-adenosylmethionine (SAM) concentrations and methylation of a membrane bound methyl-accepting chemotaxis protein WspA. A whole transcriptome analysis also revealed PA2444 is related to the redox state of the cells, and the altered redox state was demonstrated by an increase in the intracellular NADH/NAD+ ratio. Hence, we provide a mechanism for how an enzyme of central metabolism controls the community behavior of the bacterium, and suggest the PA2444 protein should be named ShrA for serine hydroxymethyltransferase related to rugose colony formation.
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Affiliation(s)
- Mingming Pu
- Department of Chemical Engineering, Pennsylvania State University, University Park, PA, United States
| | - Lili Sheng
- Department of Chemical Engineering, Pennsylvania State University, University Park, PA, United States
| | - Sooyeon Song
- Department of Chemical Engineering, Pennsylvania State University, University Park, PA, United States
| | - Ting Gong
- Department of Chemical Engineering, Pennsylvania State University, University Park, PA, United States
| | - Thomas K Wood
- Department of Chemical Engineering, Pennsylvania State University, University Park, PA, United States
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23
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Falcone M, Ferrara S, Rossi E, Johansen HK, Molin S, Bertoni G. The Small RNA ErsA of Pseudomonas aeruginosa Contributes to Biofilm Development and Motility through Post-transcriptional Modulation of AmrZ. Front Microbiol 2018; 9:238. [PMID: 29497413 PMCID: PMC5819304 DOI: 10.3389/fmicb.2018.00238] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 01/31/2018] [Indexed: 11/13/2022] Open
Abstract
The small RNA ErsA of Pseudomonas aeruginosa was previously suggested to be involved in biofilm formation via negative post-transcriptional regulation of the algC gene that encodes the virulence-associated enzyme AlgC, which provides sugar precursors for the synthesis of several polysaccharides. In this study, we show that a knock-out ersA mutant strain forms a flat and uniform biofilm, not characterized by mushroom-multicellular structures typical of a mature biofilm. Conversely, the knock-out mutant strain showed enhanced swarming and twitching motilities. To assess the influence of ErsA on the P. aeruginosa transcriptome, we performed RNA-seq experiments comparing the knock-out mutant with the wild-type. More than 160 genes were found differentially expressed in the knock-out mutant. Parts of these genes, important for biofilm formation and motility regulation, are known to belong also to the AmrZ transcriptional regulator regulon. Here, we show that ErsA binds in vitro and positively regulates amrZ mRNA at post-transcriptional level in vivo suggesting an interesting contribution of the ErsA-amrZ mRNA interaction in biofilm development at several regulatory levels.
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Affiliation(s)
- Marilena Falcone
- Dipartimento di Bioscienze, Università degli Studi di Milano, Milan, Italy
| | - Silvia Ferrara
- Dipartimento di Bioscienze, Università degli Studi di Milano, Milan, Italy
| | - Elio Rossi
- Department of Clinical Microbiology, Rigshospitalet, Copenhagen, Denmark
| | - Helle K Johansen
- Department of Clinical Microbiology, Rigshospitalet, Copenhagen, Denmark.,Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Søren Molin
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Giovanni Bertoni
- Dipartimento di Bioscienze, Università degli Studi di Milano, Milan, Italy
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Francis VI, Stevenson EC, Porter SL. Two-component systems required for virulence in Pseudomonas aeruginosa. FEMS Microbiol Lett 2018; 364:3828290. [PMID: 28510688 PMCID: PMC5812489 DOI: 10.1093/femsle/fnx104] [Citation(s) in RCA: 108] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Accepted: 05/15/2017] [Indexed: 11/13/2022] Open
Abstract
Pseudomonas aeruginosa is a versatile opportunistic pathogen capable of infecting a broad range of hosts, in addition to thriving in a broad range of environmental conditions outside of hosts. With this versatility comes the need to tightly regulate its genome to optimise its gene expression and behaviour to the prevailing conditions. Two-component systems (TCSs) comprising sensor kinases and response regulators play a major role in this regulation. This minireview discusses the growing number of TCSs that have been implicated in the virulence of P. aeruginosa, with a special focus on the emerging theme of multikinase networks, which are networks comprising multiple sensor kinases working together, sensing and integrating multiple signals to decide upon the best response. The networks covered in depth regulate processes such as the switch between acute and chronic virulence (GacS network), the Cup fimbriae (Roc network and Rcs/Pvr network), the aminoarabinose modification of lipopolysaccharide (a network involving the PhoQP and PmrBA TCSs), twitching motility and virulence (a network formed from the Chp chemosensory pathway and the FimS/AlgR TCS), and biofilm formation (Wsp chemosensory pathway). In addition, we highlight the important interfaces between these systems and secondary messenger signals such as cAMP and c-di-GMP.
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Affiliation(s)
- Vanessa I Francis
- Biosciences, Geoffrey Pope Building, College of Life and Environmental Sciences, University of Exeter, Exeter EX 4QD, UK
| | - Emma C Stevenson
- Biosciences, Geoffrey Pope Building, College of Life and Environmental Sciences, University of Exeter, Exeter EX 4QD, UK
| | - Steven L Porter
- Biosciences, Geoffrey Pope Building, College of Life and Environmental Sciences, University of Exeter, Exeter EX 4QD, UK
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25
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Phage Inhibit Pathogen Dissemination by Targeting Bacterial Migrants in a Chronic Infection Model. mBio 2017; 8:mBio.00240-17. [PMID: 28377527 PMCID: PMC5380840 DOI: 10.1128/mbio.00240-17] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The microbial communities inhabiting chronic infections are often composed of spatially organized micrometer-sized, highly dense aggregates. It has recently been hypothesized that aggregates are responsible for the high tolerance of chronic infections to host immune functions and antimicrobial therapies. Little is currently known regarding the mechanisms controlling aggregate formation and antimicrobial tolerance primarily because of the lack of robust, biologically relevant experimental systems that promote natural aggregate formation. Here, we developed an in vitro model based on chronic Pseudomonas aeruginosa infection of the cystic fibrosis (CF) lung. This model utilizes a synthetic sputum medium that readily promotes the formation of P. aeruginosa aggregates with sizes similar to those observed in human CF lung tissue. Using high-resolution imaging, we exploited this model to elucidate the life history of P. aeruginosa and the mechanisms that this bacterium utilizes to tolerate antimicrobials, specifically, bacteriophage. In the early stages of growth in synthetic sputum, planktonic cells form aggregates that increase in size over time by expansion. In later growth, migrant cells disperse from aggregates and colonize new areas, seeding new aggregates. When added simultaneously with phage, P. aeruginosa was readily killed and aggregates were unable to form. When added after initial aggregate formation, phage were unable to eliminate all of the aggregates because of exopolysaccharide production; however, seeding of new aggregates by dispersed migrants was inhibited. We propose a model in which aggregates provide a mechanism that allows P. aeruginosa to tolerate phage therapy during chronic infection without the need for genetic mutation.IMPORTANCE Bacteria in chronic infections often reside in communities composed of micrometer-sized, highly dense aggregates. A primary challenge for studying aggregates has been the lack of laboratory systems that promote natural aggregate formation in relevant environments. Here, we developed a growth medium that mimics chronic lung infection and promotes natural aggregate formation by the bacterium Pseudomonas aeruginosa High-resolution, single-cell microscopy allowed us to characterize P. aeruginosa's life history-seeding, aggregate formation, and dispersal-in this medium. Our results reveal that this bacterium readily forms aggregates that release migrants to colonize new areas. We also show that aggregates allow P. aeruginosa to tolerate therapeutic bacteriophage addition, although this treatment limits P. aeruginosa dissemination by targeting migrants.
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26
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Lim WS, Phang KKS, Tan AHM, Li SFY, Ow DSW. Small Colony Variants and Single Nucleotide Variations in Pf1 Region of PB1 Phage-Resistant Pseudomonas aeruginosa. Front Microbiol 2016; 7:282. [PMID: 27014207 PMCID: PMC4783410 DOI: 10.3389/fmicb.2016.00282] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 02/22/2016] [Indexed: 01/21/2023] Open
Abstract
Phage therapy involves the application of lytic bacteriophages for treatment of clinical infections but bacterial resistance may develop over time. Isolated from nosocomial infections, small colony variants (SCVs) are morphologically distinct, highly virulent bacterial strains that are resistant to conventional antibiotics. In this study, SCVs was derived from Pseudomonas aeruginosa exposed to the lytic bacteriophage PB1 and these cells were resistant to subsequent phage infection by PB1. To elucidate the mechanism of the SCV phage resistance, we performed phenotypic assays, DNA microarrays and whole-genome sequencing. Compared with wild-type P. aeruginosa, the SCV isolate showed impaired biofilm formation, decreased twitching motility, reduced elastase and pyocyanin production. The SCV is also more susceptible to the antibiotic ciprofloxacin and exhibited higher syrface hydrophobicity than the wild-type, indicative of changes to cell surface lipopolysaccharide (LPS) composition. Consistent with these results, transcriptomic studies of SCV revealed up-regulation of genes involved in O-specific antigen (OSA) biosynthesis, suggesting the regulation of surface moieties may account for phage resistance. Western blot analysis showed a difference in OSA distribution between the two strains. Simultaneously, genes involved in aromatic and branched chain amino acid catabolism were down-regulated. Whole genome sequencing of the SCV revealed multiple single nucleotide variations within the Pf1 prophage region, a genetic locus known to play a crucial role in biofilm formation and to provide survival advantage via gene transfer to a subpopulation of cells. Insights into phenotypic and genetic changes in SCV gained here should help direct future studies to elucidate mechanisms underpinning phage resistance, leading to novel counter resistance measures.
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Affiliation(s)
- Wee S Lim
- Agency for Science, Technology and Research, Bioprocessing Technology InstituteSingapore, Singapore; NUS Graduate School for Integrative Sciences and Engineering, National University of SingaporeSingapore, Singapore; NUS Environmental Research Institute, National University of SingaporeSingapore, Singapore
| | - Kevin K S Phang
- Agency for Science, Technology and Research, Bioprocessing Technology Institute Singapore, Singapore
| | - Andy H-M Tan
- Agency for Science, Technology and Research, Bioprocessing Technology InstituteSingapore, Singapore; Lee Kong Chian School of Medicine, Nanyang Technological UniversitySingapore, Singapore
| | - Sam F-Y Li
- NUS Graduate School for Integrative Sciences and Engineering, National University of SingaporeSingapore, Singapore; NUS Environmental Research Institute, National University of SingaporeSingapore, Singapore; Department of Chemistry, Faculty of Science, National University of SingaporeSingapore, Singapore
| | - Dave S-W Ow
- Agency for Science, Technology and Research, Bioprocessing Technology Institute Singapore, Singapore
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Song S, Du L, Yu J, Ai Q, Pan Y, Fu Y, Wang Z. Does Streptococcus mitis, a neonatal oropharyngeal bacterium, influence the pathogenicity of Pseudomonas aeruginosa? Microbes Infect 2015; 17:710-6. [DOI: 10.1016/j.micinf.2015.08.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 08/04/2015] [Accepted: 08/04/2015] [Indexed: 10/23/2022]
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Chua SL, Hultqvist LD, Yuan M, Rybtke M, Nielsen TE, Givskov M, Tolker-Nielsen T, Yang L. In vitro and in vivo generation and characterization of Pseudomonas aeruginosa biofilm-dispersed cells via c-di-GMP manipulation. Nat Protoc 2015; 10:1165-80. [PMID: 26158442 DOI: 10.1038/nprot.2015.067] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP) is a global secondary bacterial messenger that controls the formation of drug-resistant multicellular biofilms. Lowering the intracellular c-di-GMP content can disperse biofilms, and it is proposed as a biofilm eradication strategy. However, freshly dispersed biofilm cells exhibit a physiology distinct from biofilm and planktonic cells, and they might have a clinically relevant role in infections. Here we present in vitro and in vivo protocols for the generation and characterization of dispersed cells from Pseudomonas aeruginosa biofilms by reducing the intracellular c-di-GMP content through modulation of phosphodiesterases (PDEs). Unlike conventional protocols that demonstrate biofilm dispersal by biomass quantification, our protocols enable physiological characterization of the dispersed cells. Biomarkers of dispersed cells are identified and quantified, serving as potential targets for treating the dispersed cells. The in vitro protocol can be completed within 4 d, whereas the in vivo protocol requires 7 d.
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Affiliation(s)
- Song Lin Chua
- 1] Singapore Centre on Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Singapore. [2] National University of Singapore (NUS) Graduate School of Integrative Sciences and Engineering, National University of Singapore, Singapore
| | - Louise D Hultqvist
- Department of International Health, Immunology and Microbiology, Costerton Biofilm Center, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mingjun Yuan
- Singapore Centre on Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Singapore
| | - Morten Rybtke
- Department of International Health, Immunology and Microbiology, Costerton Biofilm Center, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Thomas E Nielsen
- Department of International Health, Immunology and Microbiology, Costerton Biofilm Center, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Michael Givskov
- 1] Singapore Centre on Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Singapore. [2] Department of International Health, Immunology and Microbiology, Costerton Biofilm Center, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Tim Tolker-Nielsen
- Department of International Health, Immunology and Microbiology, Costerton Biofilm Center, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Liang Yang
- 1] Singapore Centre on Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Singapore. [2] School of Biological Sciences, Nanyang Technological University, Singapore
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Laganà P, Caruso G, Mazzù F, Caruso G, Parisi S, Santi Delia A. Brief Notes About Biofilms. SPRINGERBRIEFS IN MOLECULAR SCIENCE 2015. [DOI: 10.1007/978-3-319-20559-5_3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Staudinger BJ, Muller JF, Halldórsson S, Boles B, Angermeyer A, Nguyen D, Rosen H, Baldursson O, Gottfreðsson M, Guðmundsson GH, Singh PK. Conditions associated with the cystic fibrosis defect promote chronic Pseudomonas aeruginosa infection. Am J Respir Crit Care Med 2014; 189:812-24. [PMID: 24467627 DOI: 10.1164/rccm.201312-2142oc] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
RATIONALE Progress has been made in understanding how the cystic fibrosis (CF) basic defect produces lung infection susceptibility. However, it remains unclear why CF exclusively leads to chronic infections that are noninvasive and highly resistant to eradication. Although biofilm formation has been suggested as a mechanism, recent work raises questions about the role of biofilms in CF. OBJECTIVES To learn how airway conditions attributed to CF transmembrane regulator dysfunction could lead to chronic infection, and to determine if biofilm-inhibiting genetic adaptations that are common in CF isolates affect the capacity of Pseudomonas aeruginosa to develop chronic infection phenotypes. METHODS We studied P. aeruginosa isolates grown in agar and mucus gels containing sputum from patients with CF and measured their susceptibility to killing by antibiotics and host defenses. We also measured the invasive virulence of P. aeruginosa grown in sputum gels using airway epithelial cells and a murine infection model. MEASUREMENTS AND MAIN RESULTS We found that conditions likely to result from increased mucus density, hyperinflammation, and defective bacterial killing could all cause P. aeruginosa to grow in bacterial aggregates. Aggregated growth markedly increased the resistance of bacteria to killing by host defenses and antibiotics, and reduced their invasiveness. In addition, we found that biofilm-inhibiting mutations do not impede aggregate formation in gel growth environments. CONCLUSIONS Our findings suggest that conditions associated with several CF pathogenesis hypotheses could cause the noninvasive and resistant infection phenotype, independently of the bacterial functions needed for biofilm formation.
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Kalai Chelvam K, Chai LC, Thong KL. Variations in motility and biofilm formation of Salmonella enterica serovar Typhi. Gut Pathog 2014; 6:2. [PMID: 24499680 PMCID: PMC3922113 DOI: 10.1186/1757-4749-6-2] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2013] [Accepted: 01/28/2014] [Indexed: 01/02/2023] Open
Abstract
Background Salmonella enterica serovar Typhi (S. Typhi) exhibits unique characteristics as an intracellular human pathogen. It causes both acute and chronic infection with various disease manifestations in the human host only. The principal factors underlying the unique lifestyle of motility and biofilm forming ability of S. Typhi remain largely unknown. The main objective of this study was to explore and investigate the motility and biofilm forming behaviour among S. Typhi strains of diverse background. Results Swim and swarm motility tests were performed with 0.25% and 0.5% agar concentration, respectively; while biofilm formation was determined by growing the bacterial cultures for 48 hrs in 96-well microtitre plate. While all S. Typhi strains demonstrated swarming motility with smooth featureless morphology, 58 out of 60 strains demonstrated swimming motility with featureless or bull’s eye morphology. Interestingly, S. Typhi strains of blood-borne origin exhibited significantly higher swimming motility (P < 0.05) than stool-borne strains suggesting that swimming motility may play a role in the systemic invasion of S. Typhi in the human host. Also, stool-borne S. Typhi displayed a negative relationship between motility and biofilm forming behaviour, which was not observed in the blood-borne strains. Conclusion In summary, both swimming and swarming motility are conserved among S. Typhi strains but there was variation for biofilm forming ability. There was no difference observed in this phenotype for S. Typhi strains from diverse background. These findings serve as caveats for future studies to understand the lifestyle and transmission of this pathogen.
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Affiliation(s)
| | | | - Kwai Lin Thong
- Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia.
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Huse HK, Kwon T, Zlosnik JEA, Speert DP, Marcotte EM, Whiteley M. Pseudomonas aeruginosa enhances production of a non-alginate exopolysaccharide during long-term colonization of the cystic fibrosis lung. PLoS One 2013; 8:e82621. [PMID: 24324811 PMCID: PMC3855792 DOI: 10.1371/journal.pone.0082621] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Accepted: 10/25/2013] [Indexed: 01/31/2023] Open
Abstract
The gram-negative opportunistic pathogen Pseudomonas aeruginosa is the primary cause of chronic respiratory infections in individuals with the heritable disease cystic fibrosis (CF). These infections can last for decades, during which time P. aeruginosa has been proposed to acquire beneficial traits via adaptive evolution. Because CF lacks an animal model that can acquire chronic P. aeruginosa infections, identifying genes important for long-term in vivo fitness remains difficult. However, since clonal, chronological samples can be obtained from chronically infected individuals, traits undergoing adaptive evolution can be identified. Recently we identified 24 P. aeruginosa gene expression traits undergoing parallel evolution in vivo in multiple individuals, suggesting they are beneficial to the bacterium. The goal of this study was to determine if these genes impact P. aeruginosa phenotypes important for survival in the CF lung. By using a gain-of-function genetic screen, we found that 4 genes and 2 operons undergoing parallel evolution in vivo promote P. aeruginosa biofilm formation. These genes/operons promote biofilm formation by increasing levels of the non-alginate exopolysaccharide Psl. One of these genes, phaF, enhances Psl production via a post-transcriptional mechanism, while the other 5 genes/operons do not act on either psl transcription or translation. Together, these data demonstrate that P. aeruginosa has evolved at least two pathways to over-produce a non-alginate exopolysaccharide during long-term colonization of the CF lung. More broadly, this approach allowed us to attribute a biological significance to genes with unknown function, demonstrating the power of using evolution as a guide for targeted genetic studies.
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Affiliation(s)
- Holly K. Huse
- Section of Molecular Genetics and Microbiology, University of Texas at Austin, Austin, Texas, United States of America
- Institute of Cellular and Molecular Biology and Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, Texas, United States of America
| | - Taejoon Kwon
- Institute of Cellular and Molecular Biology and Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, Texas, United States of America
| | - James E. A. Zlosnik
- Department of Pediatrics and Center for Understanding and Preventing Infection in Children, The University of British Columbia, Vancouver, British Columbia, Canada
| | - David P. Speert
- Department of Pediatrics and Center for Understanding and Preventing Infection in Children, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Edward M. Marcotte
- Institute of Cellular and Molecular Biology and Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, Texas, United States of America
| | - Marvin Whiteley
- Section of Molecular Genetics and Microbiology, University of Texas at Austin, Austin, Texas, United States of America
- Institute of Cellular and Molecular Biology and Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, Texas, United States of America
- * E-mail:
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Beceiro A, Tomás M, Bou G. Antimicrobial resistance and virulence: a successful or deleterious association in the bacterial world? Clin Microbiol Rev 2013; 26:185-230. [PMID: 23554414 PMCID: PMC3623377 DOI: 10.1128/cmr.00059-12] [Citation(s) in RCA: 602] [Impact Index Per Article: 54.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Hosts and bacteria have coevolved over millions of years, during which pathogenic bacteria have modified their virulence mechanisms to adapt to host defense systems. Although the spread of pathogens has been hindered by the discovery and widespread use of antimicrobial agents, antimicrobial resistance has increased globally. The emergence of resistant bacteria has accelerated in recent years, mainly as a result of increased selective pressure. However, although antimicrobial resistance and bacterial virulence have developed on different timescales, they share some common characteristics. This review considers how bacterial virulence and fitness are affected by antibiotic resistance and also how the relationship between virulence and resistance is affected by different genetic mechanisms (e.g., coselection and compensatory mutations) and by the most prevalent global responses. The interplay between these factors and the associated biological costs depend on four main factors: the bacterial species involved, virulence and resistance mechanisms, the ecological niche, and the host. The development of new strategies involving new antimicrobials or nonantimicrobial compounds and of novel diagnostic methods that focus on high-risk clones and rapid tests to detect virulence markers may help to resolve the increasing problem of the association between virulence and resistance, which is becoming more beneficial for pathogenic bacteria.
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Machado I, Graça J, Lopes H, Lopes S, Pereira MO. Antimicrobial Pressure of Ciprofloxacin and Gentamicin on Biofilm Development by an Endoscope-Isolated Pseudomonas aeruginosa. ISRN BIOTECHNOLOGY 2012; 2013:178646. [PMID: 25969768 PMCID: PMC4403614 DOI: 10.5402/2013/178646] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Accepted: 06/21/2012] [Indexed: 12/02/2022]
Abstract
This work aims at characterizing endoscope biofilm-isolated (PAI) and reference strain P. aeruginosa (PA) adhesion, biofilm formation and sensitivity to antibiotics. The recovery ability of the biofilm-growing bacteria subjected to intermittent antibiotic pressure (ciprofloxacin (CIP) and gentamicin (GM)), as well as the development of resistance towards antibiotics and benzalkonium chloride (BC), were also determined. The capacity of both strains to develop biofilms was greatly impaired in the presence of CIP and GM. Sanitization was not complete allowing biofilm recovery after the intermittent cycles of antibiotic pressure. The environmental pressure exerted by CIP and GM did not develop P. aeruginosa resistance to antibiotics nor cross-resistance towards BC. However, data highlighted that none of the antimicrobials led to complete biofilm eradication, allowing the recovery of the remaining adhered population possibly due to the selection of persister cells. This feature may lead to biofilm recalcitrance, reinforcement of bacterial attachment, and recolonization of other sites.
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Affiliation(s)
- Idalina Machado
- Centre of Biological Engineering, Institute for Biotechnology and Bioengineering (IBB), University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
| | - Joana Graça
- Centre of Biological Engineering, Institute for Biotechnology and Bioengineering (IBB), University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
| | - Hélder Lopes
- Centre of Biological Engineering, Institute for Biotechnology and Bioengineering (IBB), University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
| | - Susana Lopes
- Centre of Biological Engineering, Institute for Biotechnology and Bioengineering (IBB), University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
| | - Maria O Pereira
- Centre of Biological Engineering, Institute for Biotechnology and Bioengineering (IBB), University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
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Miller DJ, Araújo PA, Correia PB, Ramsey MM, Kruithof JC, van Loosdrecht MCM, Freeman BD, Paul DR, Whiteley M, Vrouwenvelder JS. Short-term adhesion and long-term biofouling testing of polydopamine and poly(ethylene glycol) surface modifications of membranes and feed spacers for biofouling control. WATER RESEARCH 2012; 46:3737-53. [PMID: 22578432 DOI: 10.1016/j.watres.2012.03.058] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2012] [Revised: 03/23/2012] [Accepted: 03/24/2012] [Indexed: 05/16/2023]
Abstract
Ultrafiltration, nanofiltration membranes and feed spacers were hydrophilized with polydopamine and polydopamine-g-poly(ethylene glycol) surface coatings. The fouling propensity of modified and unmodified membranes was evaluated by short-term batch protein and bacterial adhesion tests. The fouling propensity of modified and unmodified membranes and spacers was evaluated by continuous biofouling experiments in a membrane fouling simulator. The goals of the study were: 1) to determine the effectiveness of polydopamine and polydopamine-g-poly(ethylene glycol) membrane coatings for biofouling control and 2) to compare techniques commonly used in assessment of membrane biofouling propensity with biofouling experiments under practical conditions. Short-term adhesion tests were carried out under static, no-flow conditions for 1 h using bovine serum albumin, a common model globular protein, and Pseudomonas aeruginosa, a common model Gram-negative bacterium. Biofouling tests were performed in a membrane fouling simulator (MFS) for several days under flow conditions similar to those encountered in industrial modules with the autochthonous drinking water population and acetate dosage as organic substrate. Polydopamine- and polydopamine-g-poly(ethylene glycol)-modified membranes showed significantly reduced adhesion of bovine serum albumin and P. aeruginosa in the short-term adhesion tests, but no reduction of biofouling was observed during longer biofouling experiments with modified membranes and spacers. These results demonstrate that short-term batch adhesion experiments using model proteins or bacteria under static conditions are not indicative of biofouling, while continuous biofouling experiments showed that membrane surface modification by polydopamine and polydopamine-g-poly(ethylene glycol) is not effective for biofouling control.
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Affiliation(s)
- Daniel J Miller
- Department of Chemical Engineering, The University of Texas at Austin, Center for Energy and Environmental Resources, 10100 Burnet Road, Austin, TX 78758, USA
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Olivares J, Alvarez-Ortega C, Linares JF, Rojo F, Köhler T, Martínez JL. Overproduction of the multidrug efflux pump MexEF-OprN does not impair Pseudomonas aeruginosa fitness in competition tests, but produces specific changes in bacterial regulatory networks. Environ Microbiol 2012; 14:1968-81. [PMID: 22417660 DOI: 10.1111/j.1462-2920.2012.02727.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
It is generally assumed that acquisition of antibiotic resistance leads to non-specific fitness costs. We have tested the alternative hypothesis that acquisition of antibiotic resistance may not always produce a general burden to the microorganisms, as measured in competition tests, but rather lead to specific changes in bacterial physiology. To this end we studied the effect of overproducing the multidrug efflux pump MexEF-OprN on Pseudomonas aeruginosa due to a constitutive activation of MexT, the transcriptional activator of the mexEF-oprN genes. We found that overexpression of MexEF-OprN does not cause a significant decrease in P.aeruginosa fitness in classical competition tests, indicating the absence of a large metabolic burden and that any possible negative effects might be observed only under specific conditions. Transcriptomic analyses revealed that overexpression of MexEF-OprN results in reduced expression of several quorum-sensing regulated genes. We traced back this phenotype to a delay in PQS production due to extrusion of kynurenine, a PQS precursor, through the efflux pump. Type VI secretion was also impaired. A Caenorhabditis elegans model demonstrated that overproduction of MexEF-OprN impairs virulence in P.aeruginosa. This effect was mainly due to the activity of the efflux pump, and not to MexT, despite the fact that the latter regulates Type III and Type VI secretion. Altogether, these data indicate that antibiotic resistance can produce modifications in the bacterial regulatory networks with relevant consequences for the bacterial behaviour in specific ecosystems, including the infected host.
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Affiliation(s)
- Jorge Olivares
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Darwin 3, Cantoblanco, 28049-Madrid, Spain
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Liu GY, Guo BQ, Chen WN, Cheng C, Zhang QL, Dai MB, Sun JR, Sun PH, Chen WM. Synthesis, Molecular Docking, and Biofilm Formation Inhibitory Activity of 5-Substituted 3,4-Dihalo-5H-furan-2-one Derivatives on Pseudomonas aeruginosa. Chem Biol Drug Des 2012; 79:628-38. [DOI: 10.1111/j.1747-0285.2012.01342.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Xia S, Zhou L, Zhang Z, Li J. Influence and mechanism of N-(3-oxooxtanoyl)-L-homoserine lactone (C8-oxo-HSL) on biofilm behaviors at early stage. J Environ Sci (China) 2012; 24:2035-40. [PMID: 23534198 DOI: 10.1016/s1001-0742(11)61060-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
N-acyl-homoserines quenching, enzymatic quenching of bacterial quorum sensing, has recently applied to mitigate biofilm in membrane bioreactor. However, the effect of AHLs on the behavior of biofilm formation is still sparse. In this study, Pseudomonas aeruginosa biofilm was formed on ultra-filtration membrane under a series of N-(3-oxooxtanoyl)-L-homoserine lactone (Cs-oxo-HSL) concentrations. Diffusing C8-oxo-HSL increased the growth rate of cells on biofilm where the concentration of C8-oxo-HSL was over 10(-7) g/L. The C8-oxo-HSL gradient had no observable influence on cell density and extracellular polymeric substances of biofilm with over 10(-7) g/L C8-oxo-HSL. Surprisingly, 10(-11)-10(-8) g/L of C8-oxo-HSL had no effect on cell growth in liquid culture. The cell analysis demonstrated that the quorum sensing system might enhance the growth of neighboring cells in contact with surfaces into biofilm and may influence the structure and organization of biofilm.
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Affiliation(s)
- Siqing Xia
- State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092, China.
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Lamarche MG, Déziel E. MexEF-OprN efflux pump exports the Pseudomonas quinolone signal (PQS) precursor HHQ (4-hydroxy-2-heptylquinoline). PLoS One 2011; 6:e24310. [PMID: 21957445 PMCID: PMC3177830 DOI: 10.1371/journal.pone.0024310] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Accepted: 08/08/2011] [Indexed: 11/19/2022] Open
Abstract
Bacterial cells have evolved the capacity to communicate between each other via small diffusible chemical signals termed autoinducers. Pseudomonas aeruginosa is an opportunistic pathogen involved, among others, in cystic fibrosis complications. Virulence of P. aeruginosa relies on its ability to produce a number of autoinducers, including 4-hydroxy-2-alkylquinolines (HAQ). In a cell density-dependent manner, accumulated signals induce the expression of multiple targets, especially virulence factors. This phenomenon, called quorum sensing, promotes bacterial capacity to cause disease. Furthermore, P. aeruginosa possesses many multidrug efflux pumps conferring adaptive resistance to antibiotics. Activity of some of these efflux pumps also influences quorum sensing. The present study demonstrates that the MexEF-OprN efflux pump modulates quorum sensing through secretion of a signalling molecule belonging to the HAQ family. Moreover, activation of MexEF-OprN reduces virulence factor expression and swarming motility. Since MexEF-OprN can be activated in infected hosts even in the absence of antibiotic selective pressure, it could promote establishment of chronic infections in the lungs of people suffering from cystic fibrosis, thus diminishing the immune response to virulence factors. Therapeutic drugs that affect multidrug efflux pumps and HAQ-mediated quorum sensing would be valuable tools to shut down bacterial virulence.
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Affiliation(s)
| | - Eric Déziel
- INRS-Institut Armand-Frappier, Laval, Québec, Canada
- * E-mail:
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Mulcahy H, Lewenza S. Magnesium limitation is an environmental trigger of the Pseudomonas aeruginosa biofilm lifestyle. PLoS One 2011; 6:e23307. [PMID: 21858064 PMCID: PMC3156716 DOI: 10.1371/journal.pone.0023307] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Accepted: 07/15/2011] [Indexed: 11/30/2022] Open
Abstract
Biofilm formation is a conserved strategy for long-term bacterial survival in nature and during infections. Biofilms are multicellular aggregates of cells enmeshed in an extracellular matrix. The RetS, GacS and LadS sensors control the switch from a planktonic to a biofilm mode of growth in Pseudomonas aeruginosa. Here we detail our approach to identify environmental triggers of biofilm formation by investigating environmental conditions that repress expression of the biofilm repressor RetS. Mg2+ limitation repressed the expression of retS leading to increased aggregation, exopolysaccharide (EPS) production and biofilm formation. Repression of retS expression under Mg2+ limitation corresponded with induced expression of the GacA-controlled small regulatory RNAs rsmZ and rsmY and the EPS biosynthesis operons pel and psl. We recently demonstrated that extracellular DNA sequesters Mg2+ cations and activates the cation-sensing PhoPQ two-component system, which leads to increased antimicrobial peptide resistance in biofilms. Here we show that exogenous DNA and EDTA, through their ability to chelate Mg2+, promoted biofilm formation. The repression of retS in low Mg2+ was directly controlled by PhoPQ. PhoP also directly controlled expression of rsmZ but not rsmY suggesting that PhoPQ controls the equilibrium of the small regulatory RNAs and thus fine-tunes the expression of genes in the RetS pathway. In summary, Mg2+ limitation is a biologically relevant environmental condition and the first bonafide environmental signal identified that results in transcriptional repression of retS and promotes P. aeruginosa biofilm formation.
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Affiliation(s)
- Heidi Mulcahy
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Canada
| | - Shawn Lewenza
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Canada
- * E-mail:
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Orgad O, Oren Y, Walker SL, Herzberg M. The role of alginate in Pseudomonas aeruginosa EPS adherence, viscoelastic properties and cell attachment. BIOFOULING 2011; 27:787-798. [PMID: 21797737 DOI: 10.1080/08927014.2011.603145] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Among various functions, extracellular polymeric substances (EPS) provide microbial biofilms with mechanical stability and affect initial cell attachment, the first stage in the biofilm formation process. The role of alginate, an abundant polysaccharide in Pseudomonas aeruginosa biofilms, in the viscoelastic properties and adhesion kinetics of EPS was analyzed using a quartz crystal microbalance with dissipation (QCM-D) monitoring technology. EPS was extracted from two P. aeruginosa biofilms, a wild type strain, PAO1, and a mucoid strain, PAOmucA22 that over-expresses alginate production. The higher alginate content in the EPS originating from the mucoid biofilms was clearly shown to increase both the rate and the extent of attachment of the EPS, as well as the layer's thickness. Also, the presence of calcium and elevated ionic strength increased the thickness of the EPS layer. Dynamic light scattering (DLS) showed that the presence of calcium and elevated ionic strength induced intermolecular attractive interactions in the mucoid EPS molecules. For the wild type EPS, in the presence of calcium, an elevated shift in the distribution of the diffusion coefficients was observed with DLS due to a more compacted conformation of the EPS molecules. Moreover, the alginate over-expression effect on EPS adherence was compared to the effect of alginate over-expression on P. aeruginosa cell attachment. In a parallel plate flow cell, under similar hydraulic and aquatic conditions as those applied for the EPS adsorption tests in the QCM-D flow cell, reduced adherence of the mucoid strain was clearly observed compared to the wild type isogenic bacteria. The results suggest that alginate contributes to steric hindrance and shielding of cell surface features and adhesins that are known to promote cell attachment.
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Affiliation(s)
- Oded Orgad
- Department of Desalination and Water Treatment, Zuckerberg Institute for Water Research, Ben-Gurion University of the Negev, Sede Boqer Campus 84990, Israel
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Bordi C, de Bentzmann S. Hacking into bacterial biofilms: a new therapeutic challenge. Ann Intensive Care 2011; 1:19. [PMID: 21906350 PMCID: PMC3224501 DOI: 10.1186/2110-5820-1-19] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Accepted: 06/13/2011] [Indexed: 02/07/2023] Open
Abstract
Microbiologists have extensively worked during the past decade on a particular phase of the bacterial cell cycle known as biofilm, in which single-celled individuals gather together to form a sedentary but dynamic community within a complex structure, displaying spatial and functional heterogeneity. In response to the perception of environmental signals by sensing systems, appropriate responses are triggered, leading to biofilm formation. This process involves various molecular systems that enable bacteria to identify appropriate surfaces on which to anchor themselves, to stick to those surfaces and to each other, to construct multicellular communities several hundreds of micrometers thick, and to detach from the community. The biofilm microbial community is a unique, highly competitive, and crowded environment facilitating microevolutionary processes and horizontal gene transfer between distantly related microorganisms. It is governed by social rules, based on the production and use of "public" goods, with actors and recipients. Biofilms constitute a unique shield against external aggressions, including drug treatment and immune reactions. Biofilm-associated infections in humans have therefore generated major problems for the diagnosis and treatment of diseases. Improvements in our understanding of biofilms have led to innovative research designed to interfere with this process.
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Affiliation(s)
- Christophe Bordi
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, UPR9027 CNRS - Aix Marseille Université, Institut de Microbiologie de la Méditerranée, 31 Chemin Joseph Aiguier, 13402 Marseille, France.
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Biosurfactant-producing Bacillus are present in produced brines from Oklahoma oil reservoirs with a wide range of salinities. Appl Microbiol Biotechnol 2011; 91:1083-93. [DOI: 10.1007/s00253-011-3326-z] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Revised: 04/07/2011] [Accepted: 04/07/2011] [Indexed: 11/26/2022]
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44
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Have flagella a preferred orientation during early stages of biofilm formation?: AFM study using patterned substrates. Colloids Surf B Biointerfaces 2011; 82:536-42. [DOI: 10.1016/j.colsurfb.2010.10.013] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2010] [Revised: 10/06/2010] [Accepted: 10/07/2010] [Indexed: 11/22/2022]
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45
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Lee W, Ahn CH, Hong S, Kim S, Lee S, Baek Y, Yoon J. Evaluation of surface properties of reverse osmosis membranes on the initial biofouling stages under no filtration condition. J Memb Sci 2010. [DOI: 10.1016/j.memsci.2010.01.035] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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46
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Tian ZX, Fargier E, Mac Aogáin M, Adams C, Wang YP, O'Gara F. Transcriptome profiling defines a novel regulon modulated by the LysR-type transcriptional regulator MexT in Pseudomonas aeruginosa. Nucleic Acids Res 2010; 37:7546-59. [PMID: 19846594 PMCID: PMC2794183 DOI: 10.1093/nar/gkp828] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The LysR-family regulator MexT modulates the expression of the MexEF-OprN efflux system in the human pathogen Pseudomonas aeruginosa. Recently, we demonstrated that MexT regulates certain virulence phenotypes, including the type-three secretion system and early attachment independent of its role in regulating MexEF-OprN. In this study, transcriptome profiling was utilized to investigate the global nature of MexT regulation in P. aeruginosa PAO1 and an isogenic mexEF mutant. Twelve genes of unknown function were highly induced by overexpressing MexT independent of MexEF-OprN. A well-conserved DNA motif was identified in the upstream regulatory region of nine of these genes and upstream of mexE. Reporter fusion analysis demonstrated that the expression of the genes was significantly induced by MexT in P. aeruginosa and a heterogenous Escherichia coli strain and that the conserved sequence was required for this induction. The conserved DNA motif was further characterized as the MexT binding site by site-directed mutagenesis and electrophoretic mobility shift assays. Genes containing this conserved regulatory sequence were identified across other Pseudomonas species, and their expression was activated by MexT. Thus, a novel regulon directly modulated by MexT, that includes but is independent of mexEF-oprN, has been identified.
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Affiliation(s)
- Zhe-Xian Tian
- BIOMERIT Research Centre, Department of Microbiology, University College Cork, Cork, Ireland
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Lakretz A, Ron EZ, Mamane H. Biofouling control in water by various UVC wavelengths and doses. BIOFOULING 2010; 26:257-267. [PMID: 20024789 DOI: 10.1080/08927010903484154] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
UV light irradiation is being increasingly applied as a primary process for water disinfection, effectively used for inactivation of suspended (planktonic) cells. In this study, the use of UV irradiation was evaluated as a pretreatment strategy to control biofouling. The objective of this research was to elucidate the relative effectiveness of various targeted UV wavelengths and a polychromatic spectrum on bacterial inactivation and biofilm control. In a model system using Pseudomonas aeruginosa, the inactivation spectra corresponded to the DNA absorption spectra for all wavelengths between 220 and 280 nm, while wavelengths between 254 nm and 270 nm were the most effective for bacterial inactivation. Similar wavelengths of 254-260-270 nm were also more effective for biofilm control in most cases than targeted 239 and 280 nm. In addition, the prevention of biofilm formation by P. aeruginosa with a full polychromatic lamp was UV dose-dependent. It appears that biofilm control is improved when larger UV doses are given, while higher levels of inactivation are obtained when using a full polychromatic MP lamp. However, no significant differences were found between biofilms produced by bacteria that survived UV irradiation and biofilms produced by control bacteria at the same microbial counts. Moreover, the experiments showed that biofilm prevention depends on the post-treatment incubation time and nutrient availability, in addition to targeted wavelengths, UV spectrum and UV dose.
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Affiliation(s)
- Anat Lakretz
- School of Mechanical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel
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Tian ZX, Mac Aogáin M, O'Connor HF, Fargier E, Mooij MJ, Adams C, Wang YP, O'Gara F. MexT modulates virulence determinants in Pseudomonas aeruginosa independent of the MexEF-OprN efflux pump. Microb Pathog 2009; 47:237-41. [PMID: 19683048 DOI: 10.1016/j.micpath.2009.08.003] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2009] [Revised: 07/27/2009] [Accepted: 08/03/2009] [Indexed: 11/19/2022]
Abstract
In the human pathogen Pseudomonas aeruginosa, the LysR-family regulator MexT modulates the induction of the tripartite MexEF-OprN resistance nodulation-division multi-drug efflux system resulting in increased resistance to diverse antibiotics. The MexEF-OprN system is normally quiescent in wild-type cells, but is highly induced in nfxC-type phenotypic mutants in a MexT dependent manner. In addition to antibiotic resistance, induction of mexEF-oprN in nfxC-type mutants has been linked to reduced levels of homoserine lactone-dependent virulence traits, including pyocyanin, elastase, rhamnolipids and PQS and to reduced expression of type three secretion effector proteins. In this study, MexT is overexpressed in wild-type PAO1 and an isogenic mexEF deletion mutant to determine if MexT regulates diverse virulence phenotypes dependent or independent of MexEF-OprN. It is shown that MexT regulates type three secretion, pyocyanin production and early surface attachment independent of MexEF-OprN. In contrast, MexT modulation of the expression of the virulence genes rhlA, lasB and hcnB is dependent on MexEF-OprN, which apparently mediates these effects via efflux of cell-signaling intermediates. The data presented demonstrates that MexT may play a more global role in modulating P. aeruginosa virulence than previously reported and suggests that MexT regulates diverse targets that mediate phenotypic alterations independent of MexEF-OprN.
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Affiliation(s)
- Zhe-Xian Tian
- BIOMERIT Research Centre, Department of Microbiology, University College Cork, Cork, Ireland
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Characterization of alanine catabolism in Pseudomonas aeruginosa and its importance for proliferation in vivo. J Bacteriol 2009; 191:6329-34. [PMID: 19666712 DOI: 10.1128/jb.00817-09] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The opportunistic pathogen Pseudomonas aeruginosa causes a variety of infections in immunocompromised individuals, including individuals with the heritable disease cystic fibrosis. Like the carbon sources metabolized by many disease-causing bacteria, the carbon sources metabolized by P. aeruginosa at the host infection site are unknown. We recently reported that l-alanine is a preferred carbon source for P. aeruginosa and that two genes potentially involved in alanine catabolism (dadA and dadX) are induced during in vivo growth in the rat peritoneum and during in vitro growth in sputum (mucus) collected from the lungs of individuals with cystic fibrosis. The goals of this study were to characterize factors required for alanine catabolism in P. aeruginosa and to assess the importance of these factors for in vivo growth. Our results reveal that dadA and dadX are arranged in an operon and are required for catabolism of l-alanine. The dad operon is inducible by l-alanine, d-alanine, and l-valine, and induction is dependent on the transcriptional regulator Lrp. Finally, we show that a mutant unable to catabolize dl-alanine displays decreased competitiveness in a rat lung model of infection.
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Ueda A, Wood TK. Connecting quorum sensing, c-di-GMP, pel polysaccharide, and biofilm formation in Pseudomonas aeruginosa through tyrosine phosphatase TpbA (PA3885). PLoS Pathog 2009; 5:e1000483. [PMID: 19543378 PMCID: PMC2691606 DOI: 10.1371/journal.ppat.1000483] [Citation(s) in RCA: 238] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2008] [Accepted: 05/22/2009] [Indexed: 11/19/2022] Open
Abstract
With the opportunistic pathogen Pseudomonas aeruginosa, quorum sensing based on homoserine lactones was found to influence biofilm formation. Here we discern a mechanism by which quorum sensing controls biofilm formation by screening 5850 transposon mutants of P. aeruginosa PA14 for altered biofilm formation. This screen identified the PA3885 mutant, which had 147-fold more biofilm than the wild-type strain. Loss of PA3885 decreased swimming, abolished swarming, and increased attachment, although this did not affect production of rhamnolipids. The PA3885 mutant also had a wrinkly colony phenotype, formed pronounced pellicles, had substantially more aggregation, and had 28-fold more exopolysaccharide production. Expression of PA3885 in trans reduced biofilm formation and abolished aggregation. Whole transcriptome analysis showed that loss of PA3885 activated expression of the pel locus, an operon that encodes for the synthesis of extracellular matrix polysaccharide. Genetic screening identified that loss of PelABDEG and the PA1120 protein (which contains a GGDEF-motif) suppressed the phenotypes of the PA3885 mutant, suggesting that the function of the PA3885 protein is to regulate 3,5-cyclic diguanylic acid (c-di-GMP) concentrations as a phosphatase since c-di-GMP enhances biofilm formation by activating PelD, and c-di-GMP inhibits swarming. Loss of PA3885 protein increased cellular c-di-GMP concentrations; hence, PA3885 protein is a negative regulator of c-di-GMP production. Purified PA3885 protein has phosphatase activity against phosphotyrosine peptides and is translocated to the periplasm. Las-mediated quorum sensing positively regulates expression of the PA3885 gene. These results show that the PA3885 protein responds to AHL signals and likely dephosphorylates PA1120, which leads to reduced c-di-GMP production. This inhibits matrix exopolysaccharide formation, which leads to reduced biofilm formation; hence, we provide a mechanism for quorum sensing control of biofilm formation through the pel locus and suggest PA3885 should be named TpbA for tyrosine phosphatase related to biofilm formation and PA1120 should be TpbB.
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Affiliation(s)
- Akihiro Ueda
- Artie McFerrin Department of Chemical Engineering, Texas A & M University, College Station, Texas, United States of America
| | - Thomas K. Wood
- Artie McFerrin Department of Chemical Engineering, Texas A & M University, College Station, Texas, United States of America
- Department of Biology, Texas A & M University, College Station, Texas, United States of America
- Zachry Department of Civil Engineering, Texas A & M University, College Station, Texas, United States of America
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