Initiation of biofilm formation in Pseudomonas fluorescens WCS365 proceeds via multiple, convergent signalling pathways: a genetic analysis

Abstract

SummaryPopulations of surface-attached microorganisms comprising either single or multiple species are commonly referred to as biofilms. Using a simple assay for the initiation of biofilm formation (e.g. attachment to an abiotic surface) by Pseudomonas fluorescens strain WCS365, we have shown that: (i) P. fluorescens can form biofilms on an abiotic surface when grown on a range of nutrients; (ii) protein synthesis is required for the early events of biofilm formation; (iii) one (or more) extracytoplasmic protein plays a role in interactions with an abiotic surface; (iv) the osmolarity of the medium affects the ability of the cell to form biofilms. We have isolated transposon mutants defective for the initiation of biofilm formation, which we term surface attachment defective (sad ). Molecular analysis of the sad mutants revealed that the ClpP protein (a component of the cytoplasmic Clp protease) participates in biofilm formation in this organism. Our genetic analyses suggest that biofilm formation can proceed via multiple, convergent signalling pathways, which are regulated by various environmental signals. Finally, of the 24 sad mutants analysed in this study, only three had defects in genes of known function. This result suggests that our screen is uncovering novel aspects of bacterial physiology.

The role of cell-surface interactions in bacterial initial adhesion and consequent biofilm formation on nanofiltration/reverse osmosis membranes

“…Initial colonization of a surface is the first step in biofilm formation [7]. This transition from a planktonic to a sessile lifestyle is often in response to a variety of environmental cues, such as osmolarity, pH, carbon, iron availability, oxygen tension, and temperature [8].…”

Pseudomonas aeruginosa LecB Is Involved in Pilus Biogenesis and Protease IV Activity but Not in Adhesion to Respiratory Mucins

“…lecB, flagellar, and type IV pilus mutants of P. aeruginosa have been shown to be impaired in biofilm formation (14,21). We therefore compared the ability of the P. aeruginosa wild-type strain, lecA and lecB mutants, and a nonpiliated PAK strain (PAK-NP) to form biofilms (22). The behavior of the lecB mutant was identical to that of the pilA …”

Reduction ofCandida tropicalisbiofilm by photoactivation of aHeterophyllaea pustulataextract

“…After that, both microplates were incubated at 37 C for 48 h. Then, the supernatant was removed in order to measure the production of ROS and RNI, the SOD activity, and the total antioxidant activity of the biological system by FRAP assay. After removing the supernatant, the biofilm formation was quantified and the results were expressed as BBU (0.1 OD 595 nm ¼ 1 BBU) (O'Toole & Kolter, 1998;Arce Miranda et al 2011;Peralta et al 2015). The percentage of reduction was calculated using the following formula:…”