Roles of the spiA gene from Salmonella enteritidis in biofilm formation and virulence

Salmonella enteritidis has emerged as one of the most important food-borne pathogens for humans, and the formation of biofilms by this species may improve its resistance to disadvantageous conditions. The spiA gene of Salmonella typhimurium is essential for its virulence in host cells. However, the roles of the spiA gene in biofilm formation and virulence of S. enteritidis remain unclear. In this study we constructed a spiA gene mutant with a suicide plasmid. Phenotypic and biological analysis revealed that the mutant was similar to the wild-type strain in growth rate, morphology, and adherence to and invasion of epithelial cells. However, the mutant showed reduced biofilm formation in a quantitative microtitre assay and by scanning electron microscopy, and significantly decreased curli production and intracellular proliferation of macrophages during the biofilm phase. In addition, the spiA mutant was attenuated in a mouse model in both the exponential growth and biofilm phases. These data indicate that the spiA gene is involved in both biofilm formation and virulence of S. enteritidis.

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LuxS/AI-2 Quorum Sensing System in Edwardsiella piscicida Promotes Biofilm Formation and Pathogenicity

Infection and Immunity ◽

10.1128/iai.00907-19 ◽

2020 ◽

Vol 88 (5) ◽

Author(s):

Yongcan Sun ◽

Yu Li ◽

Qian Luo ◽

Jinjing Huang ◽

Jiakang Chen ◽

...

Keyword(s):

Quorum Sensing ◽

Biofilm Formation ◽

Type Strain ◽

Wild Type Strain ◽

Wild Type ◽

Content Type ◽

Sensing System ◽

Gene Mutant ◽

Quorum Sensing System ◽

Edwardsiella Piscicida

ABSTRACT LuxS/AI-2 is an important quorum sensing system which affects the growth, biofilm formation, virulence, and metabolism of bacteria. LuxS is encoded by the luxS gene, but how this gene is associated with a diverse array of physiological activities in Edwardsiella piscicida (E. piscicida) is not known. Here, we constructed an luxS gene mutant strain, the △luxS strain, to identify how LuxS/AI-2 affects pathogenicity. The results showed that LuxS was not found in the luxS gene mutant strain, and this gene deletion decreased E. piscicida growth compared to that of the wild-type strain. Meanwhile, the wild-type strain significantly increased penetration and motility in mucin compared to levels with the △luxS strain. The 50% lethal dose (LD50) of the E. piscicida △luxS strain for zebrafish was significantly higher than that of the wild-type strain, which suggested that the luxS gene deletion could attenuate the strain’s virulence. The AI-2 activities of EIB202 were 56-fold higher than those in the △luxS strain, suggesting that the luxS gene promotes AI-2 production. Transcriptome results demonstrated that between cells infected with the △luxS strain and those infected with the wild-type strain 46 genes were significantly differentially regulated, which included 34 upregulated genes and 12 downregulated genes. Among these genes, the largest number were closely related to cell immunity and signaling systems. In addition, the biofilm formation ability of EIB202 was significantly higher than that of the △luxS strain. The supernatant of EIB202 increased the biofilm formation ability of the △luxS strain, which suggested that the luxS gene and its product LuxS enhanced biofilm formation in E. piscicida. All results indicate that the LuxS/AI-2 quorum sensing system in E. piscicida promotes its pathogenicity through increasing a diverse array of physiological activities.

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Role Of Selected Fimbrial Adheins In Pathogenesis Of Acid-Induced Eneterohemorrhagic Escherichia Coli 0157:H7

10.32920/ryerson.14657628.v1 ◽

2021 ◽

Author(s):

Shahnaz Haque

Keyword(s):

Fatty Acid ◽

Type Strain ◽

Wild Type Strain ◽

Short Chain Fatty Acid ◽

Acid Stress ◽

Chain Fatty Acid ◽

Short Chain ◽

Wild Type ◽

Food Borne

Enterohemorrhagic Escherichia coli (EHEC) 0157:H7 is a food-borne pathogen that causes hemolytic uremic syndrome and hemorrhagic colitis. The mechanisms underlying the adhesion of EHEC 0157:H7 to intestinal epithelial cells are not well understood. Like other food-borne pathogens, ECEC 0157:H7 must survive the acid stress of the gastric juice in the stomach and short chain fatty acid in the intestine in order to colonize the large intestine. We have found that acid stress and short chain fatty acid stress significantly enhance host-adhesion of EHEC 0157:H7 and also upregulates expression of EHEC fimbrial genes, lpfA1, lpfA2 and yagZ, as demonstrated by our DNA microarray. We now report that disruption of the yagZ (also known as the E. coli common pilus A) gene results in loss of the acid-induced and short chain fatty acid-induced adhesion increase seen for the wild type strain. When the yagZ mutant is complemented with yagZ, the sress-induced and short chain fatty acid-induced adhesion increase seen for the wild type strain. When the yagZ mutant is complemented with yagZ, the stress-induced adhesion pehnotype is restored, confirming the role of yagZ in the acid as well as short chain fatty acid induced adhesion to HEp-2 cells. On the other hand, neither disruption in the long polar fimbria genes lpfA1 or lpfA2 in the wild type showed any effect in adherence to HEp-2 cells; rather displaying a hyperadherant phenotype to HEp-2 cells after acid-induced or short chain fatty acid-induced stress. The results also indicate that acid or short chain fatty acid stress, which is a part of the host's natural defense mechanism against pathogens, may regulate virulence factors resulting in enhanced bacteria-host attachment during colonization in the human or bovine host.

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Selective Pressure for Biofilm Formation in Bacillus subtilis: Differential Effect of Mutations in the Master Regulator SinR on Bistability

mBio ◽

10.1128/mbio.01464-18 ◽

2018 ◽

Vol 9 (5) ◽

Cited By ~ 6

Author(s):

Jan Kampf ◽

Jan Gerwig ◽

Kerstin Kruse ◽

Robert Cleverley ◽

Miriam Dormeyer ◽

...

Keyword(s):

Gene Expression ◽

Bacillus Subtilis ◽

Biofilm Formation ◽

Type Strain ◽

Wild Type Strain ◽

Selective Pressure ◽

Wild Type ◽

Master Regulator ◽

Form Complex ◽

Content Type

ABSTRACT Biofilm formation by Bacillus subtilis requires the expression of genes encoding enzymes for extracellular polysaccharide synthesis and for an amyloid-like protein. The master regulator SinR represses all the corresponding genes, and repression of these key biofilm genes is lifted when SinR interacts with its cognate antagonist proteins. The YmdB phosphodiesterase is a recently discovered factor that is involved in the control of SinR activity: cells lacking YmdB exhibit hyperactive SinR and are unable to relieve the repression of the biofilm genes. In this study, we have examined the dynamics of gene expression patterns in wild-type and ymdB mutant cells by microfluidic analysis coupled to time-lapse microscopy. Our results confirm the bistable expression pattern for motility and biofilm genes in the wild-type strain and the loss of biofilm gene expression in the mutant. Moreover, we demonstrated dynamic behavior in subpopulations of the wild-type strain that is characterized by switches in sets of the expressed genes. In order to gain further insights into the role of YmdB, we isolated a set of spontaneous suppressor mutants derived from ymdB mutants that had regained the ability to form complex colonies and biofilms. Interestingly, all of the mutations affected SinR. In some mutants, large genomic regions encompassing sinR were deleted, whereas others had alleles encoding SinR variants. Functional and biochemical studies with these SinR variants revealed how these proteins allowed biofilm gene expression in the ymdB mutant strains. IMPORTANCE Many bacteria are able to choose between two mutually exclusive lifestyles: biofilm formation and motility. In the model bacterium Bacillus subtilis, this choice is made by each individual cell rather than at the population level. The transcriptional repressor SinR is the master regulator in this decision-making process. The regulation of SinR activity involves complex control of its own expression and of its interaction with antagonist proteins. We show that the YmdB phosphodiesterase is required to allow the expression of SinR-repressed genes in a subpopulation of cells and that such subpopulations can switch between different SinR activity states. Suppressor analyses revealed that ymdB mutants readily acquire mutations affecting SinR, thus restoring biofilm formation. These findings suggest that B. subtilis cells experience selective pressure to form the extracellular matrix that is characteristic of biofilms and that YmdB is required for the homeostasis of SinR and/or its antagonists.

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Salmonella enterica subspecies enterica serovar Enteritidis Salmonella pathogenicity island 2 type III secretion system: role in intestinal colonization of chickens and systemic spread

Microbiology ◽

10.1099/mic.0.038018-0 ◽

2010 ◽

Vol 156 (9) ◽

pp. 2770-2781 ◽

Cited By ~ 18

Author(s):

Amanda L. S. Wisner ◽

Taseen S. Desin ◽

Birgit Koch ◽

Po-King S. Lam ◽

Emil M. Berberov ◽

...

Keyword(s):

Type Iii Secretion ◽

Salmonella Enterica ◽

Type Strain ◽

Wild Type Strain ◽

Type Iii Secretion System ◽

Secretion System ◽

Host Cells ◽

Wild Type ◽

Type Iii ◽

Systemic Spread

Salmonella enterica subspecies enterica serovar Enteritidis (S. Enteritidis) has been identified as a significant cause of salmonellosis in humans. Salmonella pathogenicity islands 1 and 2 (SPI-1 and SPI-2) each encode a specialized type III secretion system (T3SS) that enables Salmonella to manipulate host cells at various stages of the invasion/infection process. For the purposes of our studies we used a chicken isolate of S. Enteritidis (Sal18). In one study, we orally co-challenged 35-day-old specific pathogen-free (SPF) chickens with two bacterial strains per group. The control group received two versions of the wild-type strain Sal18: Sal18 attTn7 : : tet and Sal18 attTn7 : : cat, while the other two groups received the wild-type strain (Sal18 attTn7 : : tet) and one of two mutant strains. From this study, we concluded that S. Enteritidis strains deficient in the SPI-1 and SPI-2 systems were outcompeted by the wild-type strain. In a second study, groups of SPF chickens were challenged at 1 week of age with four different strains: the wild-type strain, and three other strains lacking either one or both of the SPI-1 and SPI-2 regions. On days 1 and 2 post-challenge, we observed a reduced systemic spread of the SPI-2 mutants, but by day 3, the systemic distribution levels of the mutants matched that of the wild-type strain. Based on these two studies, we conclude that the S. Enteritidis SPI-2 T3SS facilitates invasion and systemic spread in chickens, although alternative mechanisms for these processes appear to exist.

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vpaH, a Gene Encoding a Novel Histone-Like Nucleoid Structure-Like Protein That Was Possibly Horizontally Acquired, Regulates the Biogenesis of Lateral Flagella in trh-Positive Vibrio parahaemolyticus TH3996

Infection and Immunity ◽

10.1128/iai.73.9.5754-5761.2005 ◽

2005 ◽

Vol 73 (9) ◽

pp. 5754-5761 ◽

Cited By ~ 19

Author(s):

Kwon-Sam Park ◽

Michiko Arita ◽

Tetsuya Iida ◽

Takeshi Honda

Keyword(s):

Biofilm Formation ◽

Vibrio Parahaemolyticus ◽

Type Strain ◽

Wild Type Strain ◽

Enteric Bacteria ◽

Wild Type ◽

Gene Encoding ◽

Lateral Flagellum ◽

Global Gene Regulation ◽

Nucleoid Structure

ABSTRACT A histone-like nucleoid structure (H-NS) is a major component of the bacterial nucleoid and plays a crucial role in the global gene regulation of enteric bacteria. Here, we cloned and characterized the gene for the H-NS-like protein VpaH in Vibrio parahaemolyticus. vpaH encodes a protein of 134 amino acids that shows approximately 55%, 54%, and 41% identities with VicH in Vibrio cholerae, H-NS in V. parahaemolyticus, and H-NS in Escherichia coli, respectively. The vpaH gene was found in only trh-positive V. parahaemolyticus strains and not in Kanagawa-positive or in trh-negative environmental strains. Moreover, the G+C content of the vpaH gene was 38.6%, which is lower than the average G+C content of the whole genome of this bacterium (45.4%). These data suggest that vpaH was transmitted to trh-possessing V. parahaemolyticus strains by lateral transfer. The vpaH gene was located about 2.6 kb downstream of the trh gene, in the convergent direction of the trh transcription. An in-frame deletion mutant of vpaH lacked motility on semisolid motility assay plates. Western blot analysis and electron microscopy observations revealed that the mutant was deficient in lateral flagella biogenesis, whereas there was no defect in the expression of polar flagella. Additionally, the vpaH mutant showed a decreased adherence to HeLa cells and a decrease in biofilm formation compared with the wild-type strain. Introduction of the vpaH gene in the vpaH-negative strain increased the expression of lateral flagella compared with the wild-type strain. In conclusion, our findings suggest that VpaH affects lateral flagellum biogenesis in trh-positive V. parahaemolyticus strain TH3996.

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Inhibition of Food-Related Pathogenic Bacteria by god-Transformed Penicillium nalgiovense Strains

Journal of Food Protection ◽

10.4315/0362-028x-62.8.940 ◽

1999 ◽

Vol 62 (8) ◽

pp. 940-943 ◽

Cited By ~ 5

Author(s):

ROLF GEISEN

Keyword(s):

Antibacterial Activity ◽

Inhibitory Activity ◽

Type Strain ◽

Salmonella Enteritidis ◽

Pathogenic Bacteria ◽

Wild Type Strain ◽

Antibacterial Effect ◽

Wild Type ◽

Penicillium Nalgiovense ◽

And Staphylococcus Aureus

Two strains of Penicillium nalgiovense, which carried the god gene of Aspergillus niger and had increased glucose oxidase (GOD) activity compared with the wild-type strain, were tested for their ability to suppress the growth of certain food-related pathogenic bacteria. In contrast to the wild type, which showed no antibacterial effect when grown in mixed culture with different bacteria, the two tranformed strains were highly antagonistic. The strain that expressed higher amounts of GOD in general had higher inhibitory activity. Both strains showed antibacterial activity against Listeria monocytogenes, Salmonella Enteritidis, and Staphylococcus aureus. The inhibitory activity was dependent on the glucose concentration in the medium. S. aureus was completely inhibited at 1% glucose in the presence of the higher GOD-producing transformant. In contrast, if arabinose was used as a carbon source, no inhibition occurred. If catalase was added to the medium, the inhibitory activity of the transformants was completely inactivated, indicating that the hydrogen peroxide produced was responsible for the antibacterial activity of the transformants.

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Sigma B Contributes to Listeria monocytogenes Gastrointestinal Infection but Not to Systemic Spread in the Guinea Pig Infection Model

Infection and Immunity ◽

10.1128/iai.74.2.876-886.2006 ◽

2006 ◽

Vol 74 (2) ◽

pp. 876-886 ◽

Cited By ~ 86

Author(s):

M. R. Garner ◽

B. L. Njaa ◽

M. Wiedmann ◽

K. J. Boor

Keyword(s):

Listeria Monocytogenes ◽

Guinea Pig ◽

Guinea Pigs ◽

Type Strain ◽

Wild Type Strain ◽

Critical Role ◽

Host Cells ◽

Gastrointestinal Infection ◽

Wild Type ◽

Systemic Spread

ABSTRACT Contributions of the alternative sigma factor σB to Listeria monocytogenes infection were investigated using strains bearing null mutations in sigB, prfA, or inlA or in selected inlA or prfA promoter regions. The ΔP4 inlA strain, which has a deletion in the σB-dependent P4 inlA promoter, and the ΔsigB strain had significantly reduced invasion efficiencies relative to that of the wild-type strain in the Caco-2 human colorectal epithelial cell line, while the invasion efficiency of a strain bearing a deletion in the partially σB dependent P2 prfA promoter region did not differ from that of the wild type. The virulence of the ΔsigB and ΔP4 inlA strains was attenuated in intragastrically inoculated guinea pigs, with the ΔsigB strain showing greater attenuation, while the virulence capacity of the ΔP2 prfA strain was similar to that of the wild-type strain, suggesting that attenuation of virulence due to the ΔsigB mutation does not result from loss of σB-dependent prfA transcription. Our results show that σB-dependent activation of inlA is important for cell invasion and gastrointestinal infection and suggest that σB-regulated genes in addition to inlA appear to contribute to gastrointestinal infection. Interestingly, the virulence of the ΔsigB strain was not attenuated in intravenously infected guinea pigs. We conclude that (i) L. monocytogenes σB plays a critical role in invasion of human host cells, (ii) σB-mediated contributions to invasion are, in part, due to direct effects on inlA transcription but not on prfA transcription, and (iii) σB plays a critical role during the gastrointestinal stage of listeriosis in the guinea pig but is not important for systemic spread of the organism.

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Quorum-Sensing Systems in the Plant Growth-Promoting Bacterium Paraburkholderia phytofirmans PsJN Exhibit Cross-Regulation and Are Involved in Biofilm Formation

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-01-17-0008-r ◽

2017 ◽

Vol 30 (7) ◽

pp. 557-565 ◽

Cited By ~ 16

Author(s):

Ana Zúñiga ◽

Raúl A. Donoso ◽

Daniela Ruiz ◽

Gonzalo A. Ruz ◽

Bernardo González

Keyword(s):

Quorum Sensing ◽

Biofilm Formation ◽

Type Strain ◽

Wild Type Strain ◽

Homoserine Lactone ◽

Wild Type ◽

Transcript Levels ◽

Sensing Systems ◽

Plant Growth Promoting ◽

Growth Promoting

Quorum-sensing systems play important roles in host colonization and host establishment of Burkholderiales species. Beneficial Paraburkholderia species share a conserved quorum-sensing (QS) system, designated BraI/R, that controls different phenotypes. In this context, the plant growth-promoting bacterium Paraburkholderia phytofirmans PsJN possesses two different homoserine lactone QS systems BpI.1/R.1 and BpI.2/R.2 (BraI/R-like QS system). The BpI.1/R.1 QS system was previously reported to be important to colonize and produce beneficial effects in Arabidopsis thaliana plants. Here, we analyzed the temporal variations of the QS gene transcript levels in the wild-type strain colonizing plant roots. The gene expression patterns showed relevant differences in both QS systems compared with the wild-type strain in the unplanted control treatment. The gene expression data were used to reconstruct a regulatory network model of QS systems in P. phytofirmans PsJN, using a Boolean network model. Also, we examined the phenotypic traits and transcript levels of genes involved in QS systems, using P. phytofirmans mutants in homoserine lactone synthases genes. We observed that the BpI.1/R.1 QS system regulates biofilm formation production in strain PsJN and this phenotype was associated with the lower expression of a specific extracytoplasmic function sigma factor ecf26.1 gene (implicated in biofilm formation) in the bpI.1 mutant strain.

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Escherichia coliO157:H7 responds to phosphate starvation by modifying LPS involved in biofilm formation

10.1101/536201 ◽

2019 ◽

Cited By ~ 3

Author(s):

Philippe Vogeleer ◽

Antony T. Vincent ◽

Samuel M. Chekabab ◽

Steve J. Charette ◽

Alexey Novikov ◽

...

Keyword(s):

Escherichia Coli ◽

Biofilm Formation ◽

Inorganic Phosphate ◽

Type Strain ◽

Wild Type Strain ◽

Pho Regulon ◽

Wild Type ◽

E Coli ◽

Pi Starvation ◽

Pst System

ABSTRACTIn open environments such as water, enterohemorrhagicEscherichia coliO157:H7 responds to inorganic phosphate (Pi) starvation by inducing the Pho regulon controlled by PhoB. The phosphate-specific transport (Pst) system is the high-affinity Pi transporter. In the Δpstmutant, PhoB is constitutively activated and regulates the expression of genes from the Pho regulon. InE. coliO157:H7, the Δpstmutant, biofilm, and autoagglutination were increased. In the double-deletion mutant ΔpstΔphoB, biofilm and autoagglutination were similar to the wild-type strain, suggesting that PhoB is involved. We investigated the relationship between PhoB activation and enhanced biofilm formation by screening a transposon mutant library derived from Δpstmutant for decreased autoagglutination and biofilms mutants. Lipopolysaccharide (LPS) genes involved in the synthesis of the LPS core were identified. Transcriptomic studies indicate the influence of Pi-starvation andpstmutation on LPS biosynthetic gene expression. LPS analysis indicated that the O-antigen was deficient in the Δpstmutant. Interestingly,waaH, encoding a glycosyltransferase associated with LPS modifications inE. coliK-12, was highly expressed in the Δpstmutant ofE. coliO157:H7. Deletion ofwaaHfrom the Δpstmutant and from the wild-type strain grown in Pi-starvation conditions decreased the biofilm formation but without affecting LPS. Our findings suggest that LPS core is involved in the autoagglutination and biofilm phenotypes of the Δpstmutant and that WaaH plays a role in biofilm in response to Pi-starvation. This study highlights the importance of Pi-starvation in biofilm formation of E. coli O157:H7, which may affect its transmission and persistence.IMPORTANCEEnterohemorrhagicEscherichia coliO157:H7 is a human pathogen responsible for bloody diarrhea and renal failures. In the environment, O157:H7 can survive for prolonged periods of time under nutrient-deprived conditions. Biofilms are thought to participate in this environmental lifestyle. Previous reports have shown that the availability of extracellular inorganic phosphate (Pi) affected bacterial biofilm formation; however, nothing was known about O157:H7 biofilm formation. Our results show that O157:H7 membrane undergoes modifications upon PhoB activation leading to increased biofilm formation. A mutation in the Pst system results in reduced amount of the smooth type LPS and that this could influence the biofilm composition. This demonstrates how theE. coliO157:H7 adapts to Pi starvation increasing its ability to occupy different ecological niches.

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RstA, a two-component response regulator, plays important roles in multiple virulence-associated processes in enterohemorrhagic Escherichia coli O157:H7

Gut Pathogens ◽

10.1186/s13099-019-0335-4 ◽

2019 ◽

Vol 11 (1) ◽

Cited By ~ 3

Author(s):

Yutao Liu ◽

Shujie Li ◽

Wendi Li ◽

Peisheng Wang ◽

Peng Ding ◽

...

Keyword(s):

Gene Expression ◽

Escherichia Coli ◽

Biofilm Formation ◽

Type Strain ◽

Wild Type Strain ◽

Acid Tolerance ◽

Enterohemorrhagic Escherichia Coli ◽

Regulatory Function ◽

Wild Type ◽

Two Component

Abstract Background Enterohemorrhagic Escherichia coli O157:H7 (EHEC O157) causes bloody diarrhea and hemolytic-uremic syndrome. EHEC O157 encounters varied microenvironments during infection, and can efficiently adapt to these using the two-component system (TCS). Recently, a functional TCS, RstAB, has been implicated in the regulation of virulence of several bacterial pathogens. However, the regulatory function of RstAB in EHEC O157 is poorly understood. This study aimed at providing insights into the global effects of RstA on gene expression in EHEC O157. Results In the present study, we analyzed gene expression differences between the EHEC O157 wild-type strain and a ΔrstA mutant using RNA-seq technology. Genes with differential expression in the ΔrstA mutant compared to that in the wild-type strain were identified and grouped into clusters of orthologous categories. RstA promoted EHEC O157 LEE gene expression, adhesion in vitro, and colonization in vivo by indirect regulation. We also found that RstA could bind directly to the promoter region of hdeA and yeaI to enhance acid tolerance and decrease biofilm formation by modulating the concentration of c-di-GMP. Conclusions In summary, the RstAB TCS in EHEC O157 plays a major role in the regulation of virulence, acid tolerance, and biofilm formation. We clarified the regulatory function of RstA, providing an insight into mechanisms that may be potential drug targets for treatment of EHEC O157-related infections.

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