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Ren J, Wang M, Zhou W, Liu Z. Efflux pumps as potential targets for biofilm inhibition. Front Microbiol 2024; 15:1315238. [PMID: 38596384 PMCID: PMC11002903 DOI: 10.3389/fmicb.2024.1315238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 01/26/2024] [Indexed: 04/11/2024] Open
Abstract
Biofilms account for a great deal of infectious diseases and contribute significantly to antimicrobial resistance. Efflux pumps confer antimicrobial resistance to microorganisms and involve multiple processes of biofilm formation. Efflux pump inhibitors (EPIs) are attracting considerable attention as a biofilm inhibition strategy. The regulatory functions of efflux pumps in biofilm formation such as mediating adherence, quorum sensing (QS) systems, and the expression of biofilm-associated genes have been increasingly identified. The versatile properties confer efflux pumps both positive and negative effects on biofilm formation. Furthermore, the expression and function of efflux pumps in biofilm formation are species-specific. Therefore, this review aims to detail the double-edged sword role of efflux pumps in biofilm formation to provide potential inhibition targets and give an overview of the effects of EPIs on biofilm formation.
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Affiliation(s)
| | | | - Wenjuan Zhou
- Department of Implantology, Yantai Stomatological Hospital Affiliated to Binzhou Medical University, Yantai, China
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Fekri Kohan S, Nouhi Kararoudi A, Bazgosha M, Adelifar S, Hafezolghorani Esfahani A, Ghaderi Barmi F, Kouchakinejad R, Barzegari E, Shahriarinour M, Ranji N. Determining the potential targets of silybin by molecular docking and its antibacterial functions on efflux pumps and porins in uropathogenic E. coli. Int Microbiol 2024:10.1007/s10123-024-00488-9. [PMID: 38363383 DOI: 10.1007/s10123-024-00488-9] [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: 12/03/2023] [Revised: 01/11/2024] [Accepted: 01/29/2024] [Indexed: 02/17/2024]
Abstract
BACKGROUND One of the causes of antibiotic resistance is the reduced accumulation of antibiotics in bacterial cells through pumping out the drugs. Silybin, a key component of the Silybum marianum plant, exhibits various beneficial properties, including anti-bacterial, anti-inflammatory, antioxidant, and hepatoprotective effects. METHODS AND RESULTS Clinical isolates of E. coli were procured from 17 Shahrivar Children's Hospital in Rasht, Guilan, located in northern Iran. Their susceptibility to six antibiotics was assessed using disc diffusion and broth dilution (MIC) methods. The antibacterial effects of silybin-loaded polymersome nanoparticles (SPNs) were investigated with broth dilution (MIC) and biofilm assays. Molecular docking was utilized to evaluate silybin's (the antibacterial component) binding affinity to efflux pumps, porins, and their regulatory elements. Additionally, qRT-PCR analysis explored the expression patterns of acrA, acrB, tolC, ompC, and ompF genes in both SPNs (sub-MIC) and ciprofloxacin (sub-MIC)-treated and untreated E. coli isolates. The combined use of SPNs and ciprofloxacin exhibited a notable reduction in bacterial growth and biofilm formation, in ciprofloxacin-resistant isolates. The study identified eight overlapping binding sites of the AcrABZ-TolC efflux pump in association with silybin, demonstrating a binding affinity ranging from -7.688 to -10.33 Kcal/mol. Furthermore, the qRT-PCR analysis showed that silybin upregulated AcrAB-TolC efflux pump genes and downregulated ompC and ompF porin genes in combination with ciprofloxacin in transcriptional level in uropathogenic E. coli. CONCLUSIONS Silybin, a safe herbal compound, exhibits potential in inhibiting antibiotic resistance within bacterial isolates, potentially through the regulation of gene expression and plausible binding to target proteins.
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Affiliation(s)
- Shirin Fekri Kohan
- Department of Biology, Faculty of Sciences, Rasht Branch, Islamic Azad University, P.O. Box: 41335-3516, Rasht, Iran
| | - Alireza Nouhi Kararoudi
- Department of Biology, Faculty of Sciences, Lahijan Branch, Islamic Azad University, Rasht, Iran
| | - Maryam Bazgosha
- Department of Biology, Faculty of Sciences, Rasht Branch, Islamic Azad University, P.O. Box: 41335-3516, Rasht, Iran
| | - Somayeh Adelifar
- Department of Biology, Faculty of Sciences, Rasht Branch, Islamic Azad University, P.O. Box: 41335-3516, Rasht, Iran
| | - Arman Hafezolghorani Esfahani
- Department of Biology, Faculty of Sciences, Rasht Branch, Islamic Azad University, P.O. Box: 41335-3516, Rasht, Iran
| | - Fatemeh Ghaderi Barmi
- Sanford School of Medicine, University of South Dakota, Vermillion, South Dakota, USA
| | - Reyhaneh Kouchakinejad
- Department of Chemistry, Faculty of Sciences, Rasht Branch, Islamic Azad University, Rasht, Iran
| | - Ebrahim Barzegari
- Medical Biology Research Center, Health Technology Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Mahdi Shahriarinour
- Department of Biology, Faculty of Sciences, Rasht Branch, Islamic Azad University, P.O. Box: 41335-3516, Rasht, Iran.
| | - Najmeh Ranji
- Department of Biology, Faculty of Sciences, Rasht Branch, Islamic Azad University, P.O. Box: 41335-3516, Rasht, Iran.
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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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Qi P, Wang N, Zhang T, Feng Y, Zhou X, Zeng D, Meng J, Liu L, Jin L, Yang S. Anti-Virulence Strategy of Novel Dehydroabietic Acid Derivatives: Design, Synthesis, and Antibacterial Evaluation. Int J Mol Sci 2023; 24:2897. [PMID: 36769220 PMCID: PMC9917773 DOI: 10.3390/ijms24032897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 01/27/2023] [Accepted: 01/28/2023] [Indexed: 02/05/2023] Open
Abstract
Anti-virulence strategies are attractive and interesting strategies for controlling bacterial diseases because virulence factors are fundamental to the infection process of numerous serious phytopathogenics. To extend the novel anti-virulence agents, a series of dehydroabietic acid (DAA) derivatives decorated with amino alcohol unit were semi-synthesized based on structural modification of the renewable natural DAA and evaluated for their antibacterial activity against Xanthomonas oryzae pv. oryzae (Xoo), Xanthomonas axonopodis pv. citri (Xac), and Pseudomonas syringae pv. actinidiae (Psa). Compound 2b showed the most promising antibacterial activity against Xoo with an EC50 of 2.7 μg mL-1. Furthermore, compound 2b demonstrated remarkable control effectiveness against bacterial leaf blight (BLB) in rice, with values of 48.6% and 61.4% for curative and protective activities. In addition, antibacterial behavior suggested that compound 2b could suppress various virulence factors, including EPS, biofilm, swimming motility, and flagella. Therefore, the current study provided promising lead compounds for novel bactericides discovery by inhibiting bacterial virulence factors.
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Affiliation(s)
| | | | | | | | - Xiang Zhou
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyang 550025, China
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Hou B, Wang CY, Li SW, Zhou LJ, Che YL, Chen QY. Effects of Toxin-Antitoxin System HicAB on Biofilm Formation by Extraintestinal Pathogenic E. coli. Curr Microbiol 2022; 80:50. [PMID: 36542185 DOI: 10.1007/s00284-022-03138-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 12/01/2022] [Indexed: 12/24/2022]
Abstract
The type II toxin-antitoxin (T-A) HicAB system is abundant in several bacteria and archaea, such as Escherichia coli, Burkholderia Pseudomallei, Yersinia pestis, Pseudomonas aeruginosa, and Streptococcus pneumoniae. This system engages in stress response, virulence, and bacterial persistence. This study showed that the biofilm-forming ability of the hicAB deletion mutant was significantly decreased to moderate ability compared to the extra-intestinal pathogenic Escherichia coli (ExPEC) parent strain and the complemented strain, which are strong biofilm producers. Congo red assay showed that the hicAB mutant maintained the ability to form curli fimbriae. Using RNA-seq and comparative real-time quantitative RT-PCR, we observed the difference in gene expression between the hicAB mutant and the parent strain, which was associated with biofilm formation. Our data indicate that the HicAB type II T-A system has a key role in biofilm formation by ExPEC, which may be associated with outer membrane protein (OMP) gene expression. Collectively, our results indicate that the hicAB type II T-A system is involved in ExPEC biofilm formation.
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Affiliation(s)
- Bo Hou
- Institute of Animal Husbandry and Veterinary Medicine, Fujian Animal Disease Control Technology Development Center, Fujian Academy of Agricultural Sciences, No. 104 Xindian Town, Fuzhou, 350013, Fujian, China.
| | - Chen-Yan Wang
- Institute of Animal Husbandry and Veterinary Medicine, Fujian Animal Disease Control Technology Development Center, Fujian Academy of Agricultural Sciences, No. 104 Xindian Town, Fuzhou, 350013, Fujian, China
| | - Shao-Wen Li
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, Hubei, China
| | - Lun-Jiang Zhou
- Institute of Animal Husbandry and Veterinary Medicine, Fujian Animal Disease Control Technology Development Center, Fujian Academy of Agricultural Sciences, No. 104 Xindian Town, Fuzhou, 350013, Fujian, China.
| | - Yong-Liang Che
- Institute of Animal Husbandry and Veterinary Medicine, Fujian Animal Disease Control Technology Development Center, Fujian Academy of Agricultural Sciences, No. 104 Xindian Town, Fuzhou, 350013, Fujian, China
| | - Qiu-Yong Chen
- Institute of Animal Husbandry and Veterinary Medicine, Fujian Animal Disease Control Technology Development Center, Fujian Academy of Agricultural Sciences, No. 104 Xindian Town, Fuzhou, 350013, Fujian, China
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ompX contribute to biofilm formation, osmotic response and swimming motility in Citrobacter werkmanii. Gene X 2022; 851:147019. [DOI: 10.1016/j.gene.2022.147019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 10/12/2022] [Accepted: 10/25/2022] [Indexed: 11/04/2022] Open
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Glucose Reduces Norovirus Binding to Enterobacter cloacae and Alters Gene Expression of Bacterial Surface Structures in a Growth Phase Dependent Manner. Viruses 2022; 14:v14081596. [PMID: 35893662 PMCID: PMC9331879 DOI: 10.3390/v14081596] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 07/11/2022] [Accepted: 07/20/2022] [Indexed: 12/03/2022] Open
Abstract
Norovirus is the leading cause of acute viral gastroenteritis. Both human and murine noroviruses attach to commensal bacteria belonging to the mammalian gut flora, and binding levels are influenced by nutrients present in bacterial media. However, it is not known which nutrients are responsible for altering viral binding or why binding is altered. Gene expression of commensal bacteria can be changed by the external environment as well as by interaction with pathogens. For example, growth phase and incubation conditions impact expression levels of specific bacterial genes in Escherichia coli. We have previously shown that binding by both human and murine noroviruses to the commensal bacterium Enterobacter cloacae induces genome-wide changes in gene expression with a large number of differentially expressed genes associated with the surface structure of the bacterial cell. The current study evaluated norovirus binding under nutrient-limited conditions and assessed the expression of a select panel of these genes that are significantly altered by norovirus binding under these conditions. The goal of this work was to determine how norovirus attachment to Enterobacter cloacae affected the expression of these genes under varying nutrient and growth phase conditions. We found that the presence of glucose in minimal media reduced murine norovirus binding to E. cloacae and viral binding in the presence of glucose reduced gene expression for surface structures previously associated with norovirus attachment. Changes in viral binding and gene expression occurred in a growth phase-dependent manner. Collectively, these data demonstrate that both the growth phase and nutrient availability alter viral interactions with commensal bacteria and the subsequent changes in gene expression. Ultimately, this work advances our understanding of norovirus-bacterium interactions and provides a foundation for elucidating the conditions and surface structures that regulate norovirus attachment to bacteria.
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Extensively Drug-Resistant Klebsiella pneumoniae Counteracts Fitness and Virulence Costs That Accompanied Ceftazidime-Avibactam Resistance Acquisition. Microbiol Spectr 2022; 10:e0014822. [PMID: 35435751 PMCID: PMC9241641 DOI: 10.1128/spectrum.00148-22] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The ability of extensively drug-resistant (XDR) Klebsiella pneumoniae to rapidly acquire resistance to novel antibiotics is a global concern. Moreover, Klebsiella clonal lineages that successfully combine resistance and hypervirulence have increasingly occurred during the last years. However, the underlying mechanisms of counteracting fitness costs that accompany antibiotic resistance acquisition remain largely unexplored. Here, we investigated whether and how an XDR sequence type (ST)307 K. pneumoniae strain developed resistance against the novel drug combination ceftazidime-avibactam (CAZ-AVI) using experimental evolution. In addition, we performed in vitro and in vivo assays, molecular modeling, and bioinformatics to identify resistance-conferring processes and explore the resulting decrease in fitness and virulence. The subsequent amelioration of the initial costs was also addressed. We demonstrate that distinct mutations of the major nonselective porin OmpK36 caused CAZ-AVI resistance that persists even upon following a second experimental evolution without antibiotic selection pressure and that the Klebsiella strain compensates the resulting fitness and virulence costs. Furthermore, the genomic and transcriptomic analyses suggest the envelope stress response regulator rpoE and associated RpoE-regulated genes as drivers of this compensation. This study verifies the crucial role of OmpK36 in CAZ-AVI resistance and shows the rapid adaptation of a bacterial pathogen to compensate fitness- and virulence-associated resistance costs, which possibly contributes to the emergence of successful clonal lineages. IMPORTANCE Extensively drug-resistant Klebsiella pneumoniae causing major outbreaks and severe infections has become a significant challenge for health care systems worldwide. Rapid resistance development against last-resort therapeutics like ceftazidime-avibactam is a significant driver for the accelerated emergence of such pathogens. Therefore, it is crucial to understand what exactly mediates rapid resistance acquisition and how bacterial pathogens counteract accompanying fitness and virulence costs. By combining bioinformatics with in vitro and in vivo phenotypic approaches, this study revealed the critical role of mutations in a particular porin channel in ceftazidime-avibactam resistance development and a major metabolic regulator for ameliorating fitness and virulence costs. These results highlight underlying mechanisms and contribute to the understanding of factors important for the emergence of successful bacterial pathogens.
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9
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Briones AC, Lorca D, Cofre A, Cabezas CE, Krüger GI, Pardo-Esté C, Baquedano MS, Salinas CR, Espinoza M, Castro-Severyn J, Remonsellez F, Hidalgo AA, Morales EH, Saavedra CP. Genetic regulation of the ompX porin of Salmonella Typhimurium in response to hydrogen peroxide stress. Biol Res 2022; 55:8. [PMID: 35193678 PMCID: PMC8862304 DOI: 10.1186/s40659-022-00377-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 01/30/2022] [Indexed: 11/11/2022] Open
Abstract
Background Salmonella Typhimurium is a Gram-negative pathogen that causes a systemic disease in mice resembling typhoid fever. During its infective cycle, S. Typhimurium is phagocytized by macrophages and proliferates inside a Salmonella-containing vacuole where Salmonella is exposed and survives oxidative stress induced by H2O2 through modulation of gene expression. After exposure of Salmonella to H2O2, the expression of the porin-encoding gene ompX increases, as previously shown by microarray analysis. Expression of ompX mRNA is regulated at a post-transcriptional level by MicA and CyaR sRNAs in aerobiosis. In addition, sequence analysis predicts a site for OxyS sRNA in ompX mRNA. Results In this work we sought to evaluate the transcriptional and post-transcriptional regulation of ompX under H2O2 stress. We demonstrate that ompX expression is induced at the transcriptional level in S. Typhimurium under such conditions. Unexpectedly, an increase in ompX gene transcript and promoter activity after challenges with H2O2 does not translate into increased protein levels in the wild-type strain, suggesting that ompX mRNA is also regulated at a post-transcriptional level, at least under oxidative stress. In silico gene sequence analysis predicted that sRNAs CyaR, MicA, and OxyS could regulate ompX mRNA levels. Using rifampicin to inhibit mRNA expression, we show that the sRNAs (MicA, CyaR and OxyS) and the sRNA:mRNA chaperone Hfq positively modulate ompX mRNA levels under H2O2-induced stress in Salmonella during the exponential growth phase in Lennox broth. Conclusions Our results demonstrate that ompX mRNA is regulated in response to H2O2 by the sRNAs CyaR, MicA and OxyS is Salmonella Typhimurium. Supplementary Information The online version contains supplementary material available at 10.1186/s40659-022-00377-3.
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Affiliation(s)
- A C Briones
- Laboratorio de Microbiología Molecular, Departamento de Ciencias de La Vida, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - D Lorca
- Laboratorio de Microbiología Molecular, Departamento de Ciencias de La Vida, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - A Cofre
- Laboratorio de Microbiología Molecular, Departamento de Ciencias de La Vida, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - C E Cabezas
- Laboratorio de Microbiología Molecular, Departamento de Ciencias de La Vida, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - G I Krüger
- Laboratorio de Microbiología Molecular, Departamento de Ciencias de La Vida, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - C Pardo-Esté
- Laboratorio de Microbiología Molecular, Departamento de Ciencias de La Vida, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - M S Baquedano
- Laboratorio de Microbiología Molecular, Departamento de Ciencias de La Vida, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - C R Salinas
- Laboratorio de Microbiología Molecular, Departamento de Ciencias de La Vida, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - M Espinoza
- Laboratorio de Microbiología Molecular, Departamento de Ciencias de La Vida, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - J Castro-Severyn
- Laboratorio de Microbiología Aplicada Y Extremófilos, Facultad de Ingeniería Y Ciencias Geológicas, Universidad Católica 83 del Norte, Antofagasta, Chile
| | - F Remonsellez
- Laboratorio de Microbiología Aplicada Y Extremófilos, Facultad de Ingeniería Y Ciencias Geológicas, Universidad Católica 83 del Norte, Antofagasta, Chile.,Centro de Investigación Tecnológica del Agua en El Desierto (CEITSAZA), Universidad Católica del Norte, Antofagasta, Chile
| | - A A Hidalgo
- Laboratory of Molecular Pathogenesis and Antimicrobials, Escuela de Química Y Farmacia, Facultad de Medicina, Universidad Andres Bello, Santiago, Chile
| | - E H Morales
- Laboratorio de Microbiología Molecular, Departamento de Ciencias de La Vida, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - C P Saavedra
- Laboratorio de Microbiología Molecular, Departamento de Ciencias de La Vida, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile.
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Increased Production of Outer Membrane Vesicles by Salmonella Interferes with Complement-Mediated Innate Immune Attack. mBio 2021; 12:e0086921. [PMID: 34061589 PMCID: PMC8262969 DOI: 10.1128/mbio.00869-21] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacterial outer membrane vesicles (OMVs) enriched with bioactive proteins, toxins, and virulence factors play a critical role in host-pathogen and microbial interactions. The two-component system PhoP-PhoQ (PhoPQ) of Salmonella enterica orchestrates the remodeling of outer membrane lipopolysaccharide (LPS) molecules and concomitantly upregulates OMV production. In this study, we document a novel use of nanoparticle tracking analysis to determine bacterial OMV size and number. Among the PhoPQ-activated genes tested, pagC expression had the most significant effect on the upregulation of OMV production. We provide the first evidence that PhoPQ-mediated upregulation of OMV production contributes to bacterial survival by interfering with complement activation. OMVs protected bacteria in a dose-dependent manner, and bacteria were highly susceptible to complement-mediated killing in their absence. OMVs from bacteria expressing PagC bound to complement component C3b in a dose-dependent manner and inactivated it by recruiting complement inhibitor Factor H. As we also found that Factor H binds to PagC, we propose that PagC interferes with complement-mediated killing of Salmonella in the following two steps: first by engaging Factor H, and second, through the production of PagC-enriched OMVs that divert and inactivate the complement away from the bacteria. Since PhoPQ activation occurs intracellularly, the resultant increase in PagC expression and OMV production is suggested to contribute to the local and systemic spread of Salmonella released from dying host cells that supports the infection of new cells. IMPORTANCE Bacterial outer membrane vesicles (OMVs) mediate critical bacterium-bacterium and host-microbial interactions that influence pathogenesis through multiple mechanisms, including the elicitation of inflammatory responses, delivery of virulence factors, and enhancement of biofilm formation. As such, there is a growing interest in understanding the underlying mechanisms of OMV production. Recent studies have revealed that OMV biogenesis is a finely tuned physiological process that requires structural organization and selective sorting of outer membrane components into the vesicles. In Salmonella, outer membrane remodeling and OMV production are tightly regulated by its PhoPQ system. In this study, we demonstrate that PhoPQ-regulated OMV production plays a significant role in defense against host innate immune attack. PhoPQ-activated PagC expression recruits the complement inhibitor Factor H and degrades the active C3 component of complement. Our results provide valuable insight into the combination of tools and environmental signals that Salmonella employs to evade complement-mediated lysis, thereby suggesting a strong evolutionary adaptation of this facultative intracellular pathogen to protect itself during its extracellular stage in the host.
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Xu Z, Liu Z, Soteyome T, Hua J, Zhang L, Yuan L, Ye Y, Cai Z, Yang L, Chen L, Harro JM, Kjellerup BV, Liu J, Li Y. Impact of pmrA on Cronobacter sakazakii planktonic and biofilm cells: A comprehensive transcriptomic study. Food Microbiol 2021; 98:103785. [PMID: 33875213 DOI: 10.1016/j.fm.2021.103785] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 12/30/2020] [Accepted: 03/05/2021] [Indexed: 10/21/2022]
Abstract
Cronobacter sakazakii is an emerging opportunistic foodborne pathogen causing rare but severe infections in neonates. Furthermore, the formation of biofilm allows C. sakazakii to persist in different environments. We have demonstrated that the mutator phenotype ascribed to deficiency of the pmrA gene results in more biomass in the first 24 h but less during the post maturation stage (7-14 d) compared with BAA 894. The present study aimed to investigate the regulatory mechanism modulating biofilm formation due to pmrA mutation. The transcriptomic analyses of BAA 894 and s-3 were performed by RNA-sequencing on planktonic and biofilm cells collected at different time points. According to the results, when comparing biofilm to planktonic cells, expression of genes encoding outer membrane proteins, lysozyme, etc. were up-regulated, with LysR family transcriptional regulators, periplasmic proteins, etc. down-regulated. During biofilm formation, cellulose synthase operon genes, flagella-related genes, etc. played essential roles in different stages. Remarkably, pmrA varies the expression of a number of genes related to motility, biofilm formation, and antimicrobial resistance, including srfB, virK, mviM encoding virulence factor, flgF, fliN, etc. encoding flagellar assembly, and marA, ramA, etc. encoding AraC family transcriptional regulators in C. sakazakii. This study provides valuable insights into transcriptional regulation of C. sakazakii pmrA mutant during biofilm formation.
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Affiliation(s)
- Zhenbo Xu
- School of Food Science and Engineering, Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, South China University of Technology, Guangzhou, 510640, China; Department of Clinical Pharmacy and Translational Science, College of Pharmacy, University of Tennessee Health Science Center, Memphis, TN, 38103, USA; Home Economics Technology, Rajamangala University of Technology Phra Nakhon, Bangkok, Thailand; National Institute of Fundamental Studies, Hantana Road, Kandy, Sri Lanka; Overseas Expertise Introduction Center for Discipline Innovation of Food Nutrition and Human Health (111 Center), Guangzhou, 510640, China
| | - Ziqi Liu
- School of Food Science and Engineering, Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, South China University of Technology, Guangzhou, 510640, China
| | - Thanapop Soteyome
- National Institute of Fundamental Studies, Hantana Road, Kandy, Sri Lanka
| | - Jingjing Hua
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China
| | - Liang Zhang
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China.
| | - Lei Yuan
- College of Food Science and Engineering, Yangzhou University, Yangzhou, China
| | - Yanrui Ye
- School of Biological Science and Engineering, South China University of Technology, Guangzhou, 510640, China
| | - Zhao Cai
- School of Medicine, Southern University of Science and Technology, Shenzhen, 518055, Guangdong, China
| | - Liang Yang
- School of Medicine, Southern University of Science and Technology, Shenzhen, 518055, Guangdong, China
| | - Ling Chen
- School of Food Science and Engineering, Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, South China University of Technology, Guangzhou, 510640, China
| | - Janette M Harro
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, MD, 21201, USA
| | - Birthe Veno Kjellerup
- Department of Civil and Environmental Engineering, University of Maryland, College Park, MD, 20742, USA
| | - Junyan Liu
- Department of Civil and Environmental Engineering, University of Maryland, College Park, MD, 20742, USA
| | - Yanyan Li
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, 18 Shilongshan Road, Xihu District, Hangzhou, 310024, Zhejiang Province, China.
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Characterization and proteomic analysis of outer membrane vesicles from a commensal microbe, Enterobacter cloacae. J Proteomics 2021; 231:103994. [PMID: 33007464 DOI: 10.1016/j.jprot.2020.103994] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 09/22/2020] [Accepted: 09/25/2020] [Indexed: 12/16/2022]
Abstract
Outer membrane vesicles (OMVs) are membrane-enclosed spherical entities released by gram-negative bacteria and are important for bacterial survival under stress conditions. There have been numerous studies on OMVs released by gram-negative pathogenic bacteria, but an understanding of the functions and characteristics of the OMVs produced by commensal microbes is still lacking. Enterobacter cloacae is a gram-negative commensal bacterium present in the human gut microbiome, but this organism can also function as an opportunistic pathogen. Understanding the OMV-mediated communication route between bacteria-bacteria or bacteria-host is essential for the determination of the biological functions of the commensal bacterium in the gut and delineating between benign and virulent characteristics. In this study, we have described a proteome of E. cloacae OMVs, which are membrane vesicles in a size range of 20-300 nm. Proteomic analysis showed the presence of membrane-bound proteins, including transporters, receptors, signaling molecules, and protein channels. The physical and proteomic analyses also indicate this bacterium uses two mechanisms for OMV production. This study is one of the few existing descriptions of the proteomic profile of OMVs generated by a commensal Proteobacteria, and the first report of OMVs produced by E. cloacae. SIGNIFICANCE: This study prioritizes the importance of understanding the vesicular proteome of the human commensal bacterium, Enterobacter cloacae. We demonstrate for the first time that the gram-negative bacterium E. cloacae ATCC 13047 produces outer membrane vesicles (OMVs). The proteomic analysis showed enrichment of membrane-bound proteins in these vesicles. Understanding the cargo proteins of OMVs will help in exploring the physiological and functional role of these vesicles in the human microbiome and how they assist in the conversion of a bacterium from commensal to pathogen under certain conditions. While EM images reveal vesicles budding from the bacterial surface, the presence of cytoplasmic proteins and genomic DNA within the OMVs indicate that explosive cell lysis is an additional mechanism of biogenesis for these OMVs along with outer membrane blebbing. This research encourages future work on characterizing membrane vesicles produced by commensal bacterial and investigating their role in cell to cell communication.
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13
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Guo G, Qin S, Kong X, Wang Z, Shen Y, Huo X, Zhang W. Identification of novel fibronectin-binding proteins by 2D-far Western blot in atypical enteropathogenic Escherichia coli serotype O55:H7. Microb Pathog 2020; 150:104682. [PMID: 33296715 DOI: 10.1016/j.micpath.2020.104682] [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: 07/05/2020] [Revised: 12/03/2020] [Accepted: 12/03/2020] [Indexed: 10/22/2022]
Abstract
Atypical enteropathogenic Escherichia coli (aEPEC) is a subgroup of EPEC, which is one of the major pathogens responsible for fatal diarrhoea in children. Compared with typical EPEC (tEPEC), aEPEC lack an EAF (EPEC adherence factor) plasmid (pEAF), which encodes a series of virulence-associated genes. The extracellular matrix (ECM) component of human cells has been reported to be an important element in the interaction between host and bacterial pathogens. In this research, a 2D-Far Western blot method was performed to identifiy the bacterial proteins that could bind to fibronectin, one of the most common constituents of ECM. A total of 17 protein spots were identified, including 4 outer membrane proteins (OMPs), namely, OmpC, OmpD, OmpX and LamB. In vitro studies were used to determine whether these OMPs were involved in the adherence process. Through indirect immunofluorescence assays, four OMPs could be observed on the surfaces of host cells. After incubating the cells with the recombinant proteins, the adhesion rate of the O55:H7 isolate was decreased. Furthermore, the deletion of OmpX and LamB can also decrease the adhesion rate of WT. Taken together, a high-throughput screening method for host ECM-binding proteins based on 2D Far-Western blot was established, and four outer membrane proteins identified by this method were found to be involved in the adherence process.
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Affiliation(s)
- Genglin Guo
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China; Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing, 210095, China; OIE Reference Lab for Swine Streptococcosis, Nanjing, 210095, China.
| | - Si Qin
- Institute of Food Safety and Assessment, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, 210009, China.
| | - Xuewei Kong
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China; Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing, 210095, China; OIE Reference Lab for Swine Streptococcosis, Nanjing, 210095, China.
| | - Zhuohao Wang
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China; Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing, 210095, China; OIE Reference Lab for Swine Streptococcosis, Nanjing, 210095, China.
| | - Yun Shen
- Institute of Food Safety and Assessment, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, 210009, China.
| | - Xiang Huo
- Institute of Food Safety and Assessment, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, 210009, China.
| | - Wei Zhang
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China; Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing, 210095, China; OIE Reference Lab for Swine Streptococcosis, Nanjing, 210095, China.
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14
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Bhardwaj DK, Taneja NK, Dp S, Chakotiya A, Patel P, Taneja P, Sachdev D, Gupta S, Sanal MG. Phenotypic and genotypic characterization of biofilm forming, antimicrobial resistant, pathogenic Escherichia coli isolated from Indian dairy and meat products. Int J Food Microbiol 2020; 336:108899. [PMID: 33160121 DOI: 10.1016/j.ijfoodmicro.2020.108899] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Revised: 09/12/2020] [Accepted: 09/15/2020] [Indexed: 12/12/2022]
Abstract
Escherichia coli are commensal gastrointestinal microflora of humans, but few strains may cause food-borne diseases. Present study aimed to identify antimicrobial resistant (AMR), biofilm-forming E. coli from Indian dairy and meat products. A total of 32 E. coli isolates were identified and evaluated for biofilm-formation. EMC17, an E. coli isolate was established as a powerful biofilm-former that attained maximum biofilm-formation within 96 h on glass and stainless-steel surfaces. Presence and expression of virulence-associated genes (adhesins, invasins and polysaccharides) and ability to adhere and invade human liver carcinoma HepG2 cell lines implicates EMC17 to be pathotype belonging to Extra-intestinal Pathogenic E. coli (ExPEC). Antibiotic profiling of EMC17 identified it as multi-drug resistant (MDR) strain, possessing extended spectrum β-lactamases (ESBL's) and biofilm phenotype. Early production of quorum sensing molecules (AHLs) alongside EPS production facilitated early onset of biofilm formation by EMC17. Furthermore, the biofilm-forming genes of EMC17 were significantly upregulated 3-27 folds in the biofilm-state. This study showed prevalence of MDR, biofilm-forming, pathogenic E. coli in Indian dairy and meat products that potentially serve as reservoirs for transmission of antimicrobial-resistant (AMR) genes of bacteria from food to humans and pose serious food safety threat.
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Affiliation(s)
| | - Neetu Kumra Taneja
- Department of Basic and Applied Sciences, NIFTEM, Sonipat 131028, Haryana, India.
| | - Shivaprasad Dp
- Department of Basic and Applied Sciences, NIFTEM, Sonipat 131028, Haryana, India
| | - Ankita Chakotiya
- Department of Basic and Applied Sciences, NIFTEM, Sonipat 131028, Haryana, India
| | - Praveen Patel
- Department of Basic and Applied Sciences, NIFTEM, Sonipat 131028, Haryana, India
| | - Pankaj Taneja
- Department of Life Sciences, Sharda University, Greater Noida, Uttar Pradesh, India
| | - Divya Sachdev
- Department of Basic and Applied Sciences, NIFTEM, Sonipat 131028, Haryana, India
| | - Sarita Gupta
- Institute of Liver and Biliary Sciences, Vasant Kunj, New Delhi, India
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15
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Gangadharappa BS, Rajashekarappa S, Sathe G. Proteomic profiling of Serratia marcescens by high-resolution mass spectrometry. ACTA ACUST UNITED AC 2020; 10:123-135. [PMID: 32363156 PMCID: PMC7186543 DOI: 10.34172/bi.2020.15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 08/07/2019] [Accepted: 09/03/2019] [Indexed: 11/09/2022]
Abstract
Introduction: Serratia marcescens, an opportunistic human pathogen, is reported as an important cause of nosocomial infection and outbreaks. Although the genome of S. marcescens (ATCC 13880) was completely sequenced by 2014, there are no studies on the proteomic profile of the organism. The objective of the present study is to analyze the protein profile of S. marcescens (ATCC 13880) using a high resolution mass spectrometry (MS). Methods: Serratia marcescens ATCC 13880 strain was grown in Luria-Bertani broth and the protein extracted was subjected to trypsin digestion, followed by basic reverse phase liquid chromatography fractionation. The peptide fractions were then analysed using Orbitrap Fusion Mass Spectrometry and the raw MS data were processed in Proteome Discoverer software. Results: The proteomic analysis identified 15 009 unique peptides mapping to 2541 unique protein groups, which corresponds to approximately 54% of the computationally predicted protein-coding genes. Bioinformatic analysis of these identified proteins showed their involvement in biological processes such as cell wall organization, chaperone-mediated protein folding and ATP binding. Pathway analysis revealed that some of these proteins are associated with bacterial chemotaxis and beta-lactam resistance pathway. Conclusion: To the best of our knowledge, this is the first high-throughput proteomics study of S. marcescens (ATCC 13880). These novel observations provide a crucial baseline molecular profile of the S. marcescens proteome which will prove to be helpful for the future research in understanding the host-pathogen interactions during infection, elucidating the mechanism of multidrug resistance, and developing novel diagnostic markers or vaccine for the disease.
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Affiliation(s)
- Bhavya Somalapura Gangadharappa
- Department of Biotechnology, M.S. Ramaiah Institute of Technology, Bengaluru-560054, Karnataka, India.,Visvesvaraya Technological University, Belagavi-590018, Karnataka, India
| | | | - Gajanan Sathe
- Institute of Bioinformatics, International Technology Park, Bangalore-560066, Karnataka, India.,Center for Molecular Medicine, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore-560029, Karnataka, India
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16
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Li Q, Yin L, Xue M, Wang Z, Song X, Shao Y, Liu H, Tu J, Qi K. The transcriptional regulator PhoP mediates the tolC molecular mechanism on APEC biofilm formation and pathogenicity. Avian Pathol 2020; 49:211-220. [PMID: 31809574 DOI: 10.1080/03079457.2019.1701182] [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] [Indexed: 02/06/2023]
Abstract
As a transcriptional regulator of the classical binary regulatory system, PhoP plays an important role in the life activities of avian pathogenic Escherichia coli (APEC). In previous experiments, we found that the absence of phoP affects APEC biofilm formation and pathogenicity. To further explore the molecular mechanism of phoP regulation of these phenomena, the differentially expressed gene tolC was screened based on phoP-derived transcriptional data, and the specific sequence identity of the PhoP binding sequence was predicted by bioinformatics and verified by electrophoretic mobility shift assay (EMSA). The results showed that PhoP can directly bind to the tolC promoter. On this basis, tolC deletion and complementary strains were constructed. Biofilm formation was quantified by crystal violet staining and rdar morphology change was observed in these strains. Loss of tolC reduced biofilm formation. We also examined pathological changes in organ paraffin sections by challenging chicks with the strains. After loss of tolC, the clinical signs of pericarditis and liver and spleen enlargement in chicks were alleviated, and pathogenicity to the host cells was decreased. Additionally, quantitative real-time polymerase chain reaction (qRT-PCR) analysis revealed that tolC deletion downregulated secA/secB/secE/secY transcript levels, which are part of the type II secretion system secreting virulence effector element. These results indicate that tolC contributes to the phoP-mediated effect on APEC biofilm formation and pathogenicity.
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Affiliation(s)
- Qianwen Li
- Anhui Province Key Laboratory of Veterinary and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei, People's Republic of China
| | - Lei Yin
- Anhui Province Key Laboratory of Veterinary and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei, People's Republic of China
| | - Mei Xue
- Anhui Province Key Laboratory of Veterinary and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei, People's Republic of China
| | - Zeping Wang
- Anhui Province Key Laboratory of Veterinary and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei, People's Republic of China
| | - Xiangjun Song
- Anhui Province Key Laboratory of Veterinary and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei, People's Republic of China
| | - Yin Shao
- Anhui Province Key Laboratory of Veterinary and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei, People's Republic of China
| | - Hongmei Liu
- Anhui Province Key Laboratory of Veterinary and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei, People's Republic of China
| | - Jian Tu
- Anhui Province Key Laboratory of Veterinary and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei, People's Republic of China
| | - Kezong Qi
- Anhui Province Key Laboratory of Veterinary and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei, People's Republic of China
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Differential Gene Expression Patterns of Yersinia pestis and Yersinia pseudotuberculosis during Infection and Biofilm Formation in the Flea Digestive Tract. mSystems 2019; 4:mSystems00217-18. [PMID: 30801031 PMCID: PMC6381227 DOI: 10.1128/msystems.00217-18] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 01/27/2019] [Indexed: 01/01/2023] Open
Abstract
Yersinia pestis, the etiologic agent of plague, emerged as a fleaborne pathogen only within the last 6,000 years. Just five simple genetic changes in the Yersinia pseudotuberculosis progenitor, which served to eliminate toxicity to fleas and to enhance survival and biofilm formation in the flea digestive tract, were key to the transition to the arthropodborne transmission route. To gain a deeper understanding of the genetic basis for the development of a transmissible biofilm infection in the flea foregut, we evaluated additional gene differences and performed in vivo transcriptional profiling of Y. pestis, a Y. pseudotuberculosis wild-type strain (unable to form biofilm in the flea foregut), and a Y. pseudotuberculosis mutant strain (able to produce foregut-blocking biofilm in fleas) recovered from fleas 1 day and 14 days after an infectious blood meal. Surprisingly, the Y. pseudotuberculosis mutations that increased c-di-GMP levels and enabled biofilm development in the flea did not change the expression levels of the hms genes responsible for the synthesis and export of the extracellular polysaccharide matrix required for mature biofilm formation. The Y. pseudotuberculosis mutant uniquely expressed much higher levels of Yersinia type VI secretion system 4 (T6SS-4) in the flea, and this locus was required for flea blockage by Y. pseudotuberculosis but not for blockage by Y. pestis. Significant differences between the two species in expression of several metabolism genes, the Psa fimbrial genes, quorum sensing-related genes, transcription regulation genes, and stress response genes were evident during flea infection. IMPORTANCE Y. pestis emerged as a highly virulent, arthropod-transmitted pathogen on the basis of relatively few and discrete genetic changes from Y. pseudotuberculosis. Parallel comparisons of the in vitro and in vivo transcriptomes of Y. pestis and two Y. pseudotuberculosis variants that produce a nontransmissible infection and a transmissible infection of the flea vector, respectively, provided insights into how Y. pestis has adapted to life in its flea vector and point to evolutionary changes in the regulation of metabolic and biofilm development pathways in these two closely related species.
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18
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Role of Pseudomonas aeruginosa lipopolysaccharides in modulation of biofilm and virulence factors of Enterobacteriaceae. ANN MICROBIOL 2018. [DOI: 10.1007/s13213-018-1420-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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Cattò C, Secundo F, James G, Villa F, Cappitelli F. α-Chymotrypsin Immobilized on a Low-Density Polyethylene Surface Successfully Weakens Escherichia coli Biofilm Formation. Int J Mol Sci 2018; 19:E4003. [PMID: 30545074 PMCID: PMC6321288 DOI: 10.3390/ijms19124003] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 11/23/2018] [Accepted: 12/10/2018] [Indexed: 12/25/2022] Open
Abstract
The protease α-chymotrypsin (α-CT) was covalently immobilized on a low-density polyethylene (LDPE) surface, providing a new non-leaching material (LDPE-α-CT) able to preserve surfaces from biofilm growth over a long working timescale. The immobilized enzyme showed a transesterification activity of 1.24 nmol/h, confirming that the immobilization protocol did not negatively affect α-CT activity. Plate count viability assays, as well as confocal laser scanner microscopy (CLSM) analysis, showed that LDPE-α-CT significantly impacts Escherichia coli biofilm formation by (i) reducing the number of adhered cells (-70.7 ± 5.0%); (ii) significantly affecting biofilm thickness (-81.8 ± 16.7%), roughness (-13.8 ± 2.8%), substratum coverage (-63.1 ± 1.8%), and surface to bio-volume ratio (+7.1 ± 0.2-fold); and (iii) decreasing the matrix polysaccharide bio-volume (80.2 ± 23.2%). Additionally, CLSM images showed a destabilized biofilm with many cells dispersing from it. Notably, biofilm stained for live and dead cells confirmed that the reduction in the biomass was achieved by a mechanism that did not affect bacterial viability, reducing the chances for the evolution of resistant strains.
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Affiliation(s)
- Cristina Cattò
- Department of Food, Environmental and Nutritional Sciences, Università degli Studi di Milano, Milano 20133, Italy.
| | - Francesco Secundo
- Institute of Chemistry of Molecular Recognition, National Research Council, Milano 20131, Italy.
| | - Garth James
- Center for Biofilm Engineering, Montana State University, Bozeman, MT 59717, USA.
| | - Federica Villa
- Department of Food, Environmental and Nutritional Sciences, Università degli Studi di Milano, Milano 20133, Italy.
| | - Francesca Cappitelli
- Department of Food, Environmental and Nutritional Sciences, Università degli Studi di Milano, Milano 20133, Italy.
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