Genome-Wide Screening of Genes Required for Swarming Motility in Escherichia coli K-12

Department of Oral Microbiology, Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, 2-5-1, Shikata, Okayama 700-8525, Japan.
Journal of Bacteriology (Impact Factor: 2.81). 03/2007; 189(3):950-7. DOI: 10.1128/JB.01294-06
Source: PubMed


Escherichia coli K-12 has the ability to migrate on semisolid media by means of swarming motility. A systematic and comprehensive collection
of gene-disrupted E. coli K-12 mutants (the Keio collection) was used to identify the genes involved in the swarming motility of this bacterium. Of
the 3,985 nonessential gene mutants, 294 were found to exhibit a strongly repressed-swarming phenotype. Further, 216 of the
294 mutants displayed no significant defects in swimming motility; therefore, the 216 genes were considered to be specifically
associated with the swarming phenotype. The swarming-associated genes were classified into various functional categories,
indicating that swarming is a specialized form of motility that requires a wide variety of cellular activities. These genes
include genes for tricarboxylic acid cycle and glucose metabolism, iron acquisition, chaperones and protein-folding catalysts,
signal transduction, and biosynthesis of cell surface components, such as lipopolysaccharide, the enterobacterial common antigen,
and type 1 fimbriae. Lipopolysaccharide and the enterobacterial common antigen may be important surface-acting components
that contribute to the reduction of surface tension, thereby facilitating the swarm migration in the E. coli K-12 strain.

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    • "Regarding the latter, these changes indicate that swarming represents a complex lifestyle adaptation. It has also been demonstrated in Salmonella and E. coli that a full TCA cycle is needed for swarming motility, a behavior that consumes a lot of energy [51],[55]. Similarly, up-regulation of the TCA cycle in the Pw rsmA− strain would be predicted to be needed for up-regulation of virulence factor synthesis. "
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    ABSTRACT: The posttranscriptional regulator RsmA controls the production of plant cell wall degrading enzymes (PCWDE) and cell motility in the Pectobacterium genus of plant pathogens. In this study the physiological role of gene regulation by RsmA is under investigation. Disruption of rsmA gene of the Pectobacterium wasabiae strain, SCC3193 resulted in 3-fold decrease in growth rate and increased virulence. The comparison of mRNA levels of the rsmA(-) mutant and wild-type using a genome-wide microarray showed, that genes responsible for successful infection, i.e. virulence factors, motility, butanediol fermentation, various secretion systems etc. were up-regulated in the rsmA(-) strain. The rsmA(-) strain exhibited a higher propensity to swarm and produce PCWDE compared to the wild-type strain. Virulence experiments in potato tubers demonstrated that in spite of its more efficient tissue maceration, the rsmA(-) strain's ability to survive within the host is reduced and the infection site is taken over by resident bacteria. Taken together, in the absence of RsmA, cells revert to a constitutively infective phenotype characterized by expression of virulence factors and swarming. We hypothesize that lack of control over these costly energetic processes results in decreased growth rate and fitness. In addition, our findings suggest a relationship between swarming and virulence in plant pathogens.
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    • "After surface attachment, P. aeruginosa moves by surface motility known as twitching (Kearns et al. 2001). E. coli exhibits two flagella-driven motility types, swimming and swarming (Harshey 2003; Go´mez-Go´mez et al. 2007; Inoue et al. 2007). L. monocytogenes can also swim by means of flagella-based motility to access nutrient sources. "
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    ABSTRACT: The activity of two phenolic acids, gallic acid (GA) and ferulic acid (FA) at 1000 μg ml-1, was evaluated on the prevention and control of biofilms formed by Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Listeria monocytogenes. In addition, the effect of the two phenolic acids was tested on planktonic cell susceptibility, bacterial motility and adhesion. Biofilm prevention and control were tested using a microtiter plate assay and the effect of the phenolic acids was assessed on biofilm mass (crystal violet staining) and on the quantification of metabolic activity (alamar blue assay). The minimum bactericidal concentration for P. aeruginosa was 500 μg ml-1 (for both phenolic acids), whilst for E. coli it was 2500 μg ml-1 (FA) and 5000 μg ml-1 (GA), for L. monocytogenes it was >5000 μg ml-1 (for both phenolic acids), and for S. aureus it was 5000 μg ml-1 (FA) and >5000 μg ml-1 (GA). GA caused total inhibition of swimming (L. monocytogenes) and swarming (L. monocytogenes and E. coli) motilities. FA caused total inhibition of swimming (L. monocytogenes) and swarming (L. monocytogenes and E. coli) motilities. Colony spreading of S. aureus was completely inhibited by FA. The interference of GA and FA with bacterial adhesion was evaluated by the determination of the free energy of adhesion. Adhesion was less favorable when the bacteria were exposed to GA (P. aeruginosa, S. aureus and L. monocytogenes) and FA (P. aeruginosa and S. aureus). Both phenolics had preventive action on biofilm formation and showed a higher potential to reduce the mass of biofilms formed by the Gram-negative bacteria. GA and FA promoted reductions in biofilm activity >70% for all the biofilms tested. The two phenolic acids demonstrated the potential to inhibit bacterial motility and to prevent and control biofilms of four important human pathogenic bacteria. This study also emphasizes the potential of phytochemicals as an emergent source of biofilm control products.
    Full-text · Article · Aug 2012 · Biofouling
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    • "It has been hypothesized that this behavior might help the cells of P. aeruginosa to move to locations that offer sufficient supply of iron to meet the requirements for biofilm formation [51]. Notably, surface motility by flagella-mediated swarming is similarly stimulated by iron limitation in E. coli and Vibrio parahaemolyticus [57]–[59], and during swarming of P. aeruginosa iron acquisition is downregulated in the fast moving cells at the tendril tips [60]. Thus, the availability of iron appears to be a common signal for microbial group behaviors at surfaces, as in most environments microbes have to compete for this important nutrient due to the low solubility of Fe(III). "
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    Preview · Article · Jul 2012 · PLoS ONE
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