Enhanced Biofilm Formation by Escherichia coli LPS Mutants Defective in Hep Biosynthesis

Nakao, Ryoma; Ramstedt, Madeleine; Wai, Sun Nyunt; Uhlin, Bernt Eric

doi:10.1371/journal.pone.0051241

Cited by 116 publications

(132 citation statements)

References 59 publications

(60 reference statements)

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“…Significance was determined by one-way ANOVA followed by Dunnett's multiple-comparison test, comparing the deletion mutants to the C6706 wild-type strain. NS, not significant; *, P Յ 0.05; ***, P Յ 0.001. brane of Gram-negative bacteria, have been shown to affect biofilm formation in P. aeruginosa and E. coli (40,41). The impact of modifications to LPS on V. cholerae biofilm formation and biofilm physiology has not been previously studied.…”

Section: Discussionmentioning

confidence: 99%

Polymyxin B Resistance and Biofilm Formation in Vibrio cholerae Are Controlled by the Response Regulator CarR

et al. 2015

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Two-component systems play important roles in the physiology of many bacterial pathogens. Vibrio cholerae's CarRS two-component regulatory system negatively regulates expression of vps (Vibrio polysaccharide) genes and biofilm formation. In this study, we report that CarR confers polymyxin B resistance by positively regulating expression of the almEFG genes, whose products are required for glycine and diglycine modification of lipid A. We determined that CarR directly binds to the regulatory region of the almEFG operon. Similarly to a carR mutant, strains lacking almE, almF, and almG exhibited enhanced polymyxin B sensitivity. We also observed that strains lacking almE or the almEFG operon have enhanced biofilm formation. Our results reveal that CarR regulates biofilm formation and antimicrobial peptide resistance in V. cholerae.

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Section: Discussionmentioning

confidence: 99%

Polymyxin B Resistance and Biofilm Formation in Vibrio cholerae Are Controlled by the Response Regulator CarR

et al. 2015

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“…Cells were then separated from the supernatant containing the eDNA fraction by centrifugation at 14,000 ϫ g for 2 min. The eDNA and intracellular DNA (iDNA) from the supernatant and cell pellet, respectively, were extracted using the phenol-chloroform method as described before (29,30). The DNA concentration and purity were determined with a NanoDrop spectrophotometer, and the eDNA/iDNA ratio was calculated.…”

Section: Methodsmentioning

confidence: 99%

Surface Polysaccharide Mutants Reveal that Absence of O Antigen Reduces Biofilm Formation of Actinobacillus pleuropneumoniae

et al. 2016

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c Actinobacillus pleuropneumoniae is a Gram-negative bacterium belonging to the Pasteurellaceae family and the causative agent of porcine pleuropneumonia, a highly contagious lung disease causing important economic losses. Surface polysaccharides, including lipopolysaccharides (LPS) and capsular polysaccharides (CPS), are implicated in the adhesion and virulence of A. pleuropneumoniae, but their role in biofilm formation is still unclear. In this study, we investigated the requirement for these surface polysaccharides in biofilm formation by A. pleuropneumoniae serotype 1. Well-characterized mutants were used: an Oantigen LPS mutant, a truncated core LPS mutant with an intact O antigen, a capsule mutant, and a poly-N-acetylglucosamine (PGA) mutant. We compared the amount of biofilm produced by the parental strain and the isogenic mutants using static and dynamic systems. Compared to the findings for the biofilm of the parental or other strains, the biofilm of the O antigen and the PGA mutants was dramatically reduced, and it had less cell-associated PGA. Real-time PCR analyses revealed a significant reduction in the level of pgaA, cpxR, and cpxA mRNA in the biofilm cells of the O-antigen mutant compared to that in the biofilm cells of the parental strain. Specific binding between PGA and LPS was consistently detected by surface plasmon resonance, but the lack of O antigen did not abolish these interactions. In conclusion, the absence of the O antigen reduces the ability of A. pleuropneumoniae to form a biofilm, and this is associated with the reduced expression and production of PGA.A ctinobacillus pleuropneumoniae is a Gram-negative bacterium belonging to the Pasteurellaceae family and is the causative agent of porcine pleuropneumonia, a disease causing important economic losses to the swine industry worldwide (1). Several virulence factors of A. pleuropneumoniae have been identified. These factors include the Apx toxins, iron uptake systems, and surface polysaccharides. These polysaccharides are divided into three categories: the lipopolysaccharides (LPS), the capsular polysaccharides (CPS), and the poly-N-acetyl-D-glucosamine polymer (PGA) present in the biofilm matrix (2-4).LPS are large biomolecules composed of three well-defined regions: (i) lipid A, anchored in the outer membrane; (ii) the core oligosaccharide; and (iii) the O antigen, a polysaccharide consisting of repeating units. Altman and coworkers described the structure of the A. pleuropneumoniae serotype 1 O antigen to be branched tetrasaccharide repeating units composed of two Lrhamnopyranosyl residues, one D-glycopyranosyl residue, and one 2-acetamido-2-deoxy-D-glucose residue (5). The LPS inner core oligosaccharide is relatively conserved among A. pleuropneumoniae serotype 1, 2, 5a, and 5b strains and is composed of 2-keto-3-deoxyoctulosonic acid and heptose, whereas the outer core oligosaccharide is variable among serotypes and is generally made of a variable number of branching hexoses (6). The A. pleuropneumoniae LPS has been identified to b...

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“…Quantification of biofilm formation by S. aureus and S. epidermides on abiotic surfaces was assessed as previously described by Nakao et al [10]. In brief; The wells of sterile 96-well U shaped-bottomed polystyrene microplates were filled with 200 µl of an overnight nutrient broth (bacterial concentration was adjusted to be equivalent to McFarland standard no.…”

Section: Biofilm Formationassaymentioning

confidence: 99%

Staphylococcus epidermidis Prevails Staphylococcus aureus in Multispecies Biofilm under Gentamicin Stress

2017

IJSR

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Out of 60 staphylococcal isolates isolated form different sources, the results revealed that 20 and 10 were identified as S. aureus and S. epidermidis, respectively. These results were confirmed by detecting 16sRNA gene. Remarkably, 80% of S. aureus and 80% of S. epidrmidis isolates developed Methicillinresistance. Findings of the current work demonstrated that most of methicillin resistant S. aureus (MRSA) and methicillin resistant S. epidermidis (MRSE) formed weak biofilm. The competition between S. aureus and S. epidermidis in multispecies biofilm were tested at several conditions encompassed temperature, pH, and starvation. Results showed that the numbers of biofilm cells have intensely decrease to undetectable limits in the presence of Gentamicin, approximately, at all tested conditions. With few exceptions, S. epidermidis showed a noticeable dominance in all species combinations.

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Enhanced Biofilm Formation by Escherichia coli LPS Mutants Defective in Hep Biosynthesis

Cited by 116 publications

References 59 publications

Polymyxin B Resistance and Biofilm Formation in Vibrio cholerae Are Controlled by the Response Regulator CarR

Polymyxin B Resistance and Biofilm Formation in Vibrio cholerae Are Controlled by the Response Regulator CarR

Surface Polysaccharide Mutants Reveal that Absence of O Antigen Reduces Biofilm Formation of Actinobacillus pleuropneumoniae

Staphylococcus epidermidis Prevails Staphylococcus aureus in Multispecies Biofilm under Gentamicin Stress

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