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Bacterial Responses to Environmental Stress and Their Specific Contribution to Escherichia coli and Vibrio spp. Survival and Virulence

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A special issue of Microorganisms (ISSN 2076-2607). This special issue belongs to the section "Molecular Microbiology and Immunology".

Deadline for manuscript submissions: closed (31 January 2021) | Viewed by 38005

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Special Issue Editors

Prof. Dr. Ines Arana

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Guest Editor

Department of Immunology, Universidad del Pais Vasco, Leioa, Spain
Interests: stress-resistance and persistence of microbe; vbnc state
Special Issues, Collections and Topics in MDPI journals

Prof. Dr. Vladimir R. Kaberdin

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Guest Editor

1. Department of Immunology, Microbiology and Parasitology, Faculty of Science and Technology, University of the Basque Country UPV/EHU, 48340 Leioa, Spain
2. IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain
Interests: Escherichia coli and vibrio; molecular microbiology
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleague,

Escherichia coli and Vibrio species are common model organisms widely used to study adaptation, survival, and pathogenicity of enterobacteria and their counterparts present in natural aquatic systems. While often striving in continuously changing environments, these microorganisms are able to trigger a large number of adaptation mechanisms that ensure cell fitness and proliferation in their natural habitats under a wide range of adverse conditions.

Since some E. coli and Vibrio spp. are pathogenic to humans and marine organisms essential for sea food industry (e.g., shrimps, mussels and fish), their increasing antibiotic resistance, appearance of new multidrug-resistant strains, and fast adaptation to climate change and polluted environments increase public awareness and concern. Given the above trends, further characterization of bacterial stress responses essential for cell adaptation and host–pathogen interactions could help to identify new drug targets and develop efficient tools to control the presence and virulence of these pathogens in natural and artificial settings.

The purpose of this Special Issue is to attract new research articles that address the key mechanisms and strategy adopted by E. coli and Vibrio spp. to cope with single and multiple stresses that affect their capacity to survive and elicit infections.

Prof. Ines Arana
Prof. Vladimir R. Kaberdin
Guest Editors

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Keywords

bacterial stress responses
host–pathogen interactions
climate change
adaptation mechanisms

Published Papers (13 papers)

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Research

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15 pages, 1640 KiB

Open AccessArticle

The Effect of Visible Light on Cell Envelope Subproteome during Vibrio harveyi Survival at 20 °C in Seawater

by Maite Orruño, Claudia Parada, Vladimir R. Kaberdin and Inés Arana

Microorganisms 2021, 9(3), 594; https://doi.org/10.3390/microorganisms9030594 - 13 Mar 2021

Cited by 2 | Viewed by 2243

Abstract

A number of Vibrio spp. belong to the well-studied model organisms used to understand the strategies developed by marine bacteria to cope with adverse conditions (starvation, suboptimal temperature, solar radiation, etc.) in their natural environments. Temperature and nutrient availability are considered to be the key factors that influence Vibrio harveyi physiology, morphology, and persistence in aquatic systems. In contrast to the well-studied effects of temperature and starvation on Vibrio survival, little is known about the impact of visible light able to cause photooxidative stress. Here we employ V. harveyi ATCC 14126^T as a model organism to analyze and compare the survival patterns and changes in the protein composition of its cell envelope during the long-term permanence of this bacterium in seawater microcosm at 20 °C in the presence and absence of illumination with visible light. We found that V. harveyi exposure to visible light reduces cell culturability likely inducing the entry into the Viable but Non Culturable state (VBNC), whereas populations maintained in darkness remained culturable for at least 21 days. Despite these differences, the starved cells in both populations underwent morphological changes by reducing their size. Moreover, further proteomic analysis revealed a number of changes in the composition of cell envelope potentially accountable for the different adaptation pattern manifested in the absence and presence of visible light. Full article

(This article belongs to the Special Issue Bacterial Responses to Environmental Stress and Their Specific Contribution to Escherichia coli and Vibrio spp. Survival and Virulence)

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14 pages, 2393 KiB

Open AccessArticle

L-Alanine Prototrophic Suppressors Emerge from L-Alanine Auxotroph through Stress-Induced Mutagenesis in Escherichia coli

by Harutaka Mishima, Hirokazu Watanabe, Kei Uchigasaki, So Shimoda, Shota Seki, Toshitaka Kumagai, Tomonori Nochi, Tasuke Ando and Hiroshi Yoneyama

Microorganisms 2021, 9(3), 472; https://doi.org/10.3390/microorganisms9030472 - 25 Feb 2021

Cited by 2 | Viewed by 2153

Abstract

In Escherichia coli, L-alanine is synthesized by three isozymes: YfbQ, YfdZ, and AvtA. When an E. coli L-alanine auxotrophic isogenic mutant lacking the three isozymes was grown on L-alanine-deficient minimal agar medium, L-alanine prototrophic mutants emerged considerably more frequently than by spontaneous mutation; the emergence frequency increased over time, and, in an L-alanine-supplemented minimal medium, correlated inversely with L-alanine concentration, indicating that the mutants were derived through stress-induced mutagenesis. Whole-genome analysis of 40 independent L-alanine prototrophic mutants identified 16 and 18 clones harboring point mutation(s) in pyruvate dehydrogenase complex and phosphotransacetylase-acetate kinase pathway, which respectively produce acetyl coenzyme A and acetate from pyruvate. When two point mutations identified in L-alanine prototrophic mutants, in pta (D656A) and aceE (G147D), were individually introduced into the original L-alanine auxotroph, the isogenic mutants exhibited almost identical growth recovery as the respective cognate mutants. Each original- and isogenic-clone pair carrying the pta or aceE mutation showed extremely low phosphotransacetylase or pyruvate dehydrogenase activity, respectively. Lastly, extracellularly-added pyruvate, which dose-dependently supported L-alanine auxotroph growth, relieved the L-alanine starvation stress, preventing the emergence of L-alanine prototrophic mutants. Thus, L-alanine starvation-provoked stress-induced mutagenesis in the L-alanine auxotroph could lead to intracellular pyruvate increase, which eventually induces L-alanine prototrophy. Full article

(This article belongs to the Special Issue Bacterial Responses to Environmental Stress and Their Specific Contribution to Escherichia coli and Vibrio spp. Survival and Virulence)

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13 pages, 1877 KiB

Open AccessArticle

Phenotypic and Genetic Determination of Biofilm Formation in Heat Resistant Escherichia coli Possessing the Locus of Heat Resistance

by Angela Ma, Norman Neumann and Linda Chui

Microorganisms 2021, 9(2), 403; https://doi.org/10.3390/microorganisms9020403 - 15 Feb 2021

Cited by 7 | Viewed by 2592

Abstract

Despite the effectiveness of thermal inactivation processes, Escherichiacoli biofilms continue to be a persistent source of contamination in food processing environments. E. coli strains possessing the locus of heat resistance are a novel food safety threat and raises the question of whether these strains can also form biofilms. The objectives of this study were to determine biofilm formation in heat resistant E. coli isolates from clinical and environmental origins using an in-house, two-component apparatus and to characterize biofilm formation-associated genes in the isolates using whole genome sequencing. Optimal conditions for biofilm formation in each of the heat resistant isolates were determined by manipulating inoculum size, nutrient concentration, and temperature conditions. Biofilm formation in the heat resistant isolates was detected at temperatures of 24 °C and 37 °C but not at 4 °C. Furthermore, biofilm formation was observed in all environmental isolates but only one clinical isolate despite shared profiles in biofilm formation-associated genes encoded by the isolates from both sources. The circulation of heat resistant E. coli isolates with multi-stress tolerance capabilities in environments related to food processing signify that such strains may be a serious food safety and public health risk. Full article

(This article belongs to the Special Issue Bacterial Responses to Environmental Stress and Their Specific Contribution to Escherichia coli and Vibrio spp. Survival and Virulence)

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12 pages, 666 KiB

Open AccessArticle

Asymptomatic Bacteriuria (ABU) in Elderly: Prevalence, Virulence, Phylogeny, Antibiotic Resistance and Complement C3 in Urine

by Rikke Fleron Leihof, Karen Leth Nielsen and Niels Frimodt-Møller

Microorganisms 2021, 9(2), 390; https://doi.org/10.3390/microorganisms9020390 - 14 Feb 2021

Cited by 11 | Viewed by 2422

Abstract

Background: The incidence of asymptomatic bacteriuria (ABU) increases with age and is most common for persons 80 years of age and above and in elderly living in nursing homes. The distinction between ABU and urinary tract infection (UTI) is often difficult, especially in individuals, who are unable to communicate their symptoms, and there is a lack of objective methods to distinguish between the two entities. This can lead to overuse of antibiotics, which results in the selection and dissemination of antibiotic resistant isolates. Materials and methods: From voided midstream urine samples of 211 participants ≥60 years old from nursing homes, an activity center and a general practitioners clinic, we collected 19 ABU, 16 UTI and 22 control urine samples and compared them with respect to levels of complement component C3 in urine as determined by an ELISA assay relative to creatinine levels in the same urine samples, as measured by a creatinine assay. Further, we studied all Escherichia coli isolates for selected virulence genes by multiplex PCR, and by whole-genome sequencing (WGS) for genotypes and phylogenetic clustering. Antibiotic susceptibility was determined by microtiter broth dilution. Results: We identified a prevalence of ABU of 18.9% in nursing home residents, whereas ABU was only found in 4% of elderly living in the community (p < 0.001). E. coli from ABU patients were significantly more antibiotic resistant than E. coli from UTIs (p = 0.01). Prevalence of classical virulence genes, detected by multiplex PCR, was similar in E. coli isolates from ABU and UTI patients. Whole-genome sequencing of the E. coli isolates showed no specific clustering of ABU isolates compared to UTI isolates. Three isolates from three different individuals from one of the nursing homes showed signs of transmission. We demonstrated a significantly increased level of C3/creatinine ratio in ABU and UTI samples compared to healthy controls; however, there was no significant difference between the ABU and UTI group with respect to C3 level, or virulence factor genes. Conclusion: ABU was significantly more prevalent in the elderly residing in nursing homes than in the elderly living at home. Antibiotic resistance was more prevalent in E. coli from nursing homes than in UTI isolates, but there was no difference in prevalence of virulence associated genes between the two groups and no phylogenetic clustering, as determined by WGS relative to the two types of E. coli bacteriuria. The similar complement C3 response in ABU and UTI patients may indicate that ABU should be reconsidered as an infection albeit without symptoms. Full article

(This article belongs to the Special Issue Bacterial Responses to Environmental Stress and Their Specific Contribution to Escherichia coli and Vibrio spp. Survival and Virulence)

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17 pages, 2226 KiB

Open AccessArticle

Escherichia coli Isolated from Diabetic Foot Osteomyelitis: Clonal Diversity, Resistance Profile, Virulence Potential, and Genome Adaptation

by Alexi Lienard, Michel Hosny, Joanne Jneid, Sophie Schuldiner, Nicolas Cellier, Albert Sotto, Bernard La Scola, Jean-Philippe Lavigne and Alix Pantel

Microorganisms 2021, 9(2), 380; https://doi.org/10.3390/microorganisms9020380 - 13 Feb 2021

Cited by 9 | Viewed by 2530

Abstract

This study assessed the clonal diversity, the resistance profile and the virulence potential of Escherichia coli strains isolated from diabetic foot infection (DFI) and diabetic foot osteomyelitis (DFOM). A retrospective single-centre study was conducted on patients diagnosed with E. coli isolated from deep DFI and DFOM at Clinique du Pied Diabétique Gard-Occitanie (France) over a two-year period. Phylogenetic backgrounds, virulence factors (VFs) and antibiotic resistance profiles were determined. Whole-genome analysis of E. coli strains isolated from same patients at different periods were performed. From the two-years study period, 35 E. coli strains isolated from 33 patients were analysed; 73% were isolated from DFOM. The majority of the strains belonged to the virulent B2 and D phylogenetic groups (82%). These isolates exhibited a significant higher average of VFs number than strains belonging to other groups (p < 0.001). papG2 gene was significantly more detected in strains belonging to B2 phylogroup isolated from DFI compared to DFOM (p = 0.003). The most prevalent antibiotic resistance pattern was observed for ampicillin (82%), cotrimoxazole (45%), and ciprofloxacin (33%). The genome analysis of strains isolated at two periods in DFOM showed a decrease of the genome size, and this decrease was more important for the strain isolated at nine months (vs. four months). A shared mutation on the putative acyl-CoA dehydrogenase-encoding gene aidB was observed on both strains. E. coli isolates from DFOM were highly genetically diverse with different pathogenicity traits. Their adaptation in the bone structure could require genome reduction and some important modifications in the balance virulence/resistance of the bacteria. Full article

(This article belongs to the Special Issue Bacterial Responses to Environmental Stress and Their Specific Contribution to Escherichia coli and Vibrio spp. Survival and Virulence)

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7 pages, 2372 KiB

Open AccessCommunication

Escherichia coli HS and Enterotoxigenic Escherichia coli Hinder Stress Granule Assembly

by Felipe Velásquez, Josefina Marín-Rojas, Ricardo Soto-Rifo, Alexia Torres, Felipe Del Canto and Fernando Valiente-Echeverría

Microorganisms 2021, 9(1), 17; https://doi.org/10.3390/microorganisms9010017 - 23 Dec 2020

Cited by 2 | Viewed by 2701

Abstract

Escherichia coli, one of the most abundant bacterial species in the human gut microbiota, has developed a mutualistic relationship with its host, regulating immunological responses. In contrast, enterotoxigenic E. coli (ETEC), one of the main etiologic agents of diarrheal morbidity and mortality in children under the age of five in developing countries, has developed mechanisms to reduce the immune-activator effect to carry out a successful infection. Following infection, the host cell initiates the shutting-off of protein synthesis and stress granule (SG) assembly. This is mostly mediated by the phosphorylation of translation initiator factor 2α (eIF2α). We therefore evaluated the ability of a non-pathogenic E. coli strain (E. coli HS) and an ETEC strain (ETEC 1766a) to induce stress granule assembly, even in response to exogenous stresses. In this work, we found that infection with E. coli HS or ETEC 1766a prevents SG assembly in Caco-2 cells treated with sodium arsenite (Ars) after infection. We also show that this effect occurs through an eIF2α phosphorylation (eIF2α-P)-dependent mechanism. Understanding how bacteria counters host stress responses will lay the groundwork for new therapeutic strategies to bolster host cell immune defenses against these pathogens. Full article

(This article belongs to the Special Issue Bacterial Responses to Environmental Stress and Their Specific Contribution to Escherichia coli and Vibrio spp. Survival and Virulence)

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10 pages, 5575 KiB

Open AccessCommunication

Transcriptomic Analysis of Shiga Toxin-Producing Escherichia coli during Initial Contact with Cattle Colonic Explants

by Zachary R. Stromberg, Rick E. Masonbrink and Melha Mellata

Microorganisms 2020, 8(11), 1662; https://doi.org/10.3390/microorganisms8111662 - 27 Oct 2020

Cited by 6 | Viewed by 2042

Abstract

Foodborne pathogens are a public health threat globally. Shiga toxin-producing Escherichia coli (STEC), particularly O26, O111, and O157 STEC, are often associated with foodborne illness in humans. To create effective preharvest interventions, it is critical to understand which factors STEC strains use to colonize the gastrointestinal tract of cattle, which serves as the reservoir for these pathogens. Several colonization factors are known, but little is understood about initial STEC colonization factors. Our objective was to identify these factors via contrasting gene expression between nonpathogenic E. coli and STEC. Colonic explants were inoculated with nonpathogenic E. coli strain MG1655 or STEC strains (O26, O111, or O157), bacterial colonization levels were determined, and RNA was isolated and sequenced. STEC strains adhered to colonic explants at numerically but not significantly higher levels compared to MG1655. After incubation with colonic explants, flagellin (fliC) was upregulated (log₂ fold-change = 4.0, p < 0.0001) in O157 STEC, and collectively, Lon protease (lon) was upregulated (log₂ fold-change = 3.6, p = 0.0009) in STEC strains compared to MG1655. These results demonstrate that H7 flagellum and Lon protease may play roles in early colonization and could be potential targets to reduce colonization in cattle. Full article

(This article belongs to the Special Issue Bacterial Responses to Environmental Stress and Their Specific Contribution to Escherichia coli and Vibrio spp. Survival and Virulence)

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13 pages, 2061 KiB

Open AccessArticle

Crucial Role of the C-Terminal Domain of Hfq Protein in Genomic Instability

by Virali J. Parekh, Frank Wien, Wilfried Grange, Thomas A. De Long, Véronique Arluison and Richard R. Sinden

Microorganisms 2020, 8(10), 1598; https://doi.org/10.3390/microorganisms8101598 - 17 Oct 2020

Cited by 10 | Viewed by 3995

Abstract

G-rich DNA repeats that can form G-quadruplex structures are prevalent in bacterial genomes and are frequently associated with regulatory regions of genes involved in virulence, antigenic variation, and antibiotic resistance. These sequences are also inherently mutagenic and can lead to changes affecting cell survival and adaptation. Transcription of the G-quadruplex-forming repeat (G₃T)_n in E. coli, when mRNA comprised the G-rich strand, promotes G-quadruplex formation in DNA and increases rates of deletion of G-quadruplex-forming sequences. The genomic instability of G-quadruplex repeats may be a source of genetic variability that can influence alterations and evolution of bacteria. The DNA chaperone Hfq is involved in the genetic instability of these G-quadruplex sequences. Inactivation of the hfq gene decreases the genetic instability of G-quadruplex, demonstrating that the genomic instability of this regulatory element can be influenced by the E. coli highly pleiotropic Hfq protein, which is involved in small noncoding RNA regulation pathways, and DNA organization and packaging. We have shown previously that the protein binds to and stabilizes these sequences, increasing rates of their genomic instability. Here, we extend this analysis to characterize the role of the C-terminal domain of Hfq protein in interaction with G-quadruplex structures. This allows to better understand the function of this specific region of the Hfq protein in genomic instability. Full article

(This article belongs to the Special Issue Bacterial Responses to Environmental Stress and Their Specific Contribution to Escherichia coli and Vibrio spp. Survival and Virulence)

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13 pages, 1618 KiB

Open AccessArticle

Regulation of Chitin-Dependent Growth and Natural Competence in Vibrio parahaemolyticus

by Anusuya Debnath, Tamaki Mizuno and Shin-ichi Miyoshi

Microorganisms 2020, 8(9), 1303; https://doi.org/10.3390/microorganisms8091303 - 26 Aug 2020

Cited by 10 | Viewed by 3009

Abstract

Vibrios can degrade chitin surfaces to soluble N-acetyl glucosamine oligosaccharides (GlcNAc_n) that can be utilized as a carbon source and also induce a state of natural genetic competence. In this study, we characterized chitin-dependent growth and natural competence in Vibrio parahaemolyticus and its regulation. We found that growth on chitin was regulated through chitin sensors ChiS (sensor histidine kinase) and TfoS (transmembrane transcriptional regulator) by predominantly controlling the expression of chitinase VPA0055 (ChiA2) in a TfoX-dependent manner. The reduced growth of ΔchiA2, ΔchiS and ΔtfoS mutants highlighted the critical role played by ChiA2 in chitin breakdown. This growth defect of ΔchiA2 mutant could be recovered when chitin oligosaccharides GlcNAc₂ or GlcNAc₆ were supplied instead of chitin. The ΔtfoS mutant was also able to grow on GlcNAc₂ but the ΔchiS mutant could not, which indicates that GlcNAc₂ catabolic operon is dependent on ChiS and independent of TfoS. However, the ΔtfoS mutant was unable to utilize GlcNAc₆ because the periplasmic enzymes required for the breakdown of GlcNAc₆ were found to be downregulated at the mRNA level. We also showed that natural competence can be induced only by GlcNAc₆, not GlcNAc₂, because the expression of competence genes was significantly higher in the presence of GlcNAc₆ compared to GlcNAc₂. Moreover, this might be an indication that GlcNAc₂ and GlcNAc₆ were detected by different receptors. Therefore, we speculate that GlcNAc₂-dependent activation of ChiS and GlcNAc₆-dependent activation of TfoS might be crucial for the induction of natural competence in V. parahaemolyticus through the upregulation of the master competence regulator TfoX. Full article

(This article belongs to the Special Issue Bacterial Responses to Environmental Stress and Their Specific Contribution to Escherichia coli and Vibrio spp. Survival and Virulence)

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9 pages, 1090 KiB

Open AccessCommunication

Genomic Insight of VIM-harboring IncA Plasmid from a Clinical ST69 Escherichia coli Strain in Italy

by Vittoria Mattioni Marchetti, Ibrahim Bitar, Aurora Piazza, Alessandra Mercato, Elena Fogato, Jaroslav Hrabak and Roberta Migliavacca

Microorganisms 2020, 8(8), 1232; https://doi.org/10.3390/microorganisms8081232 - 12 Aug 2020

Cited by 5 | Viewed by 2894

Abstract

Background: VIM (Verona Integron-encoded Metallo-beta-lactamase) is a member of the Metallo-Beta-Lactamases (MBLs), and is able to hydrolyze all beta-lactams antibiotics, except for monobactams, and including carbapenems. Here we characterize a VIM-producing IncA plasmid isolated from a clinical ST69 Escherichia coli strain from an Italian Long-Term Care Facility (LTCF) inpatient. Methods: An antimicrobial susceptibility test and conjugation assay were carried out, and the transferability of the bla_VIM-type gene was confirmed in the transconjugant. Whole-genome sequencing (WGS) of the strain 550 was performed using the Sequel I platform. Genome assembly was performed using “Microbial Assembly”. Genomic analysis was conducted by uploading the contigs to ResFinder and PlasmidFinder databases. Results: Assembly resulted in three complete circular contigs: the chromosome (4,962,700 bp), an IncA plasmid (p550_IncA_VIM_1; 162,608 bp), harboring genes coding for aminoglycoside resistance (aac(6′)-Ib4, ant(3″)-Ia, aph(3″)-Ib, aph(3′)-XV, aph(6)-Id), beta-lactam resistance (bla_SHV-12, bla_VIM-1), macrolides resistance (mph(A)), phenicol resistance (catB2), quinolones resistance (qnrS1), sulphonamide resistance (sul1, sul2), and trimethoprim resistance (dfrA14), and an IncK/Z plasmid (p550_IncB_O_K_Z; 100,306 bp), free of antibiotic resistance genes. Conclusions: The increase in reports of IncA plasmids bearing different antimicrobial resistance genes highlights the overall important role of IncA plasmids in disseminating carbapenemase genes, with a preference for the bla_VIM-1 gene in Italy. Full article

(This article belongs to the Special Issue Bacterial Responses to Environmental Stress and Their Specific Contribution to Escherichia coli and Vibrio spp. Survival and Virulence)

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16 pages, 1614 KiB

Open AccessArticle

Deciphering the Role of Colicins during Colonization of the Mammalian Gut by Commensal E. coli

by Amanda N. Samuels, Manuela Roggiani, Kathryn A. Smith, Jun Zhu, Mark Goulian and Rahul M. Kohli

Microorganisms 2020, 8(5), 664; https://doi.org/10.3390/microorganisms8050664 - 2 May 2020

Cited by 6 | Viewed by 2733

Abstract

Colicins are specific and potent toxins produced by Enterobacteriaceae that result in the rapid elimination of sensitive cells. Colicin production is commonly found throughout microbial populations, suggesting its potential importance for bacterial survival in complex microbial environments. Nonetheless, as colicin biology has been predominately studied using synthetic models, it remains unclear how colicin production contributes to survival and fitness of a colicin-producing commensal strain in a natural environment. To address this gap, we took advantage of MP1, an E. coli strain that harbors a colicinogenic plasmid and is a natural colonizer of the murine gut. Using this model, we validated that MP1 is competent for colicin production and then directly interrogated the importance of colicin production and immunity for MP1 survival in the murine gut. We showed that colicin production is dispensable for sustained colonization in the unperturbed gut. A strain lacking colicin production or immunity shows minimal fitness defects and can resist displacement by colicin producers. This report extends our understanding of the role that colicin production may play for E. coli during gut colonization and suggests that colicin production is not essential for a commensal to persist in its physiologic niche in the absence of exogenous challenges. Full article

(This article belongs to the Special Issue Bacterial Responses to Environmental Stress and Their Specific Contribution to Escherichia coli and Vibrio spp. Survival and Virulence)

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16 pages, 2571 KiB

Open AccessArticle

Comparative Genomics and Transcriptomics Analyses Reveal a Unique Environmental Adaptability of Vibrio fujianensis

by Zhenzhou Huang, Keyi Yu, Yujie Fang, Hang Dai, Hongyan Cai, Zhenpeng Li, Biao Kan, Qiang Wei and Duochun Wang

Microorganisms 2020, 8(4), 555; https://doi.org/10.3390/microorganisms8040555 - 13 Apr 2020

Cited by 12 | Viewed by 2634

Abstract

The genus Vibrio is ubiquitous in marine environments and uses numerous evolutionary characteristics and survival strategies in order to occupy its niche. Here, a newly identified species, Vibrio fujianensis, was deeply explored to reveal a unique environmental adaptability. V. fujianensis type strain FJ201301^T shared 817 core genes with the Vibrio species in the population genomic analysis, but possessed unique genes of its own. In addition, V. fujianensis FJ201301^T was predicated to carry 106 virulence-related factors, several of which were mostly found in other pathogenic Vibrio species. Moreover, a comparative transcriptome analysis between the low-salt (1% NaCl) and high-salt (8% NaCl) condition was conducted to identify the genes involved in salt tolerance. A total of 913 unigenes were found to be differentially expressed. In a high-salt condition, 577 genes were significantly upregulated, whereas 336 unigenes were significantly downregulated. Notably, differentially expressed genes have a significant association with ribosome structural component and ribosome metabolism, which may play a role in salt tolerance. Transcriptional changes in ribosome genes indicate that V. fujianensis may have gained a predominant advantage in order to adapt to the changing environment. In conclusion, to survive in adversity, V. fujianensis has enhanced its environmental adaptability and developed various strategies to fill its niche. Full article

(This article belongs to the Special Issue Bacterial Responses to Environmental Stress and Their Specific Contribution to Escherichia coli and Vibrio spp. Survival and Virulence)

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Review

Jump to: Research

14 pages, 1555 KiB

Open AccessReview

A Review of the Functional Annotations of Important Genes in the AHPND-Causing pVA1 Plasmid

by Hao-Ching Wang, Shin-Jen Lin, Arpita Mohapatra, Ramya Kumar and Han-Ching Wang

Microorganisms 2020, 8(7), 996; https://doi.org/10.3390/microorganisms8070996 - 3 Jul 2020

Cited by 18 | Viewed by 5180

Abstract

Acute hepatopancreatic necrosis disease (AHPND) is a lethal shrimp disease. The pathogenic agent of this disease is a special Vibrio parahaemolyticus strain that contains a pVA1 plasmid. The protein products of two toxin genes in pVA1, pirA^vp and pirB^vp, targeted the shrimp’s hepatopancreatic cells and were identified as the major virulence factors. However, in addition to pirA^vp and pirB^vp, pVA1 also contains about ~90 other open-reading frames (ORFs), which may encode functional proteins. NCBI BLASTp annotations of the functional roles of 40 pVA1 genes reveal transposases, conjugation factors, and antirestriction proteins that are involved in horizontal gene transfer, plasmid transmission, and maintenance, as well as components of type II and III secretion systems that may facilitate the toxic effects of pVA1-containing Vibrio spp. There is also evidence of a post-segregational killing (PSK) system that would ensure that only pVA1 plasmid-containing bacteria could survive after segregation. Here, in this review, we assess the functional importance of these pVA1 genes and consider those which might be worthy of further study. Full article

(This article belongs to the Special Issue Bacterial Responses to Environmental Stress and Their Specific Contribution to Escherichia coli and Vibrio spp. Survival and Virulence)

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