A previously uncharacterized gene, yjfO (bsmA), influences Escherichia coli biofilm formation and stress response

Abstract

Bacteria growing as surface-adherent biofilms are better able to withstand chemical and physical stresses than their unattached, planktonic counterparts. Using transcriptional profiling and quantitative PCR, we observed a previously uncharacterized gene, yjfO to be upregulated during Escherichia coli MG1655 biofilm growth in a chemostat on serine-limited defined medium. A yjfO mutant, developed through targeted-insertion mutagenesis, and a yjfO-complemented strain, were obtained for further characterization. While bacterial surface colonization levels (c.f.u. cm "2 ) were similar in all three strains, the mutant strain exhibited reduced microcolony formation when observed in flow cells, and greatly enhanced flagellar motility on soft (0.3 %) agar. Complementation of yjfO restored microcolony formation and flagellar motility to wild-type levels. Cell surface hydrophobicity and twitching motility were unaffected by the presence or absence of yjfO. In contrast to the parent strain, biofilms from the mutant strain were less able to resist acid and peroxide stresses. yjfO had no significant effect on E. coli biofilm susceptibility to alkali or heat stress. Planktonic cultures from all three strains showed similar responses to these stresses. Regardless of the presence of yjfO, planktonic E. coli withstood alkali stress better than biofilm populations. Complementation of yjfO restored viability following exposure to peroxide stress, but did not restore acid resistance. Based on its influence on biofilm maturation and stress response, and effects on motility, we propose renaming the uncharacterized gene, yjfO, as bsmA (biofilm stress and motility).

Indole Production Promotes Escherichia coli Mixed-Culture Growth with Pseudomonas aeruginosa by Inhibiting Quorum Signaling

“…P. aeruginosa indole degradation appears to require rhl-mediated quorum signaling. Similar beneficial effects of indole on E. coli competition were seen in both biofilm and planktonic populations, and so we interpreted this phenomenon as a global effect, rather than a planktonic-or biofilm-specific effect, as reported in other studies (27,49). While indole production by bacteria has been known for over a century (19), this study shows that this metabolite provides a key mechanism to explain the natural ecological success of E. coli in mixed communities.…”

A role for reactive oxygen species in the antibacterial properties of carbon monoxide-releasing molecules

“…Furthermore, deletion of tqsA, a putative transport protein of the quorum-sensing signal autoinducer-2 involved in biofilm formation, yields a strain with higher resistance to CORM-2 (Nobre et al, 2009). Increased biofilm formation constitutes a defensive response of bacteria, which is triggered by several other stress agents such as hydrogen peroxide, acid and heavy metals and is associated with increased bacterial resistance (Zhang et al, 2007;Weber et al, 2010).…”

Bacteriophage Ecology in Escherichia coli and Pseudomonas aeruginosa Mixed-Biofilm Communities

“…These features, predicted by Costerton, Gilbert, and others (8,16), have been validated by subsequent research. Examples include patterns of global (42) and microenvironment-specific (24) gene expression, cell signaling (11), and biofilm-specific stress response genes (25,40). We now realize that, analogous to higher organisms, cell development and specialization occur within biofilm communi-ties (33).…”