Environmental signals and regulatory pathways that influence biofilm formation

Abstract

SummaryIn nature, bacteria often exist as biofilms. Here, we discuss the environmental signals and regulatory proteins that affect both the initiation of bacterial biofilm formation and the nature of the mature biofilm structure. Current research suggests that the environmental signals regulating whether bacterial cells will initiate a biofilm differ from one bacterial species to another. This may allow each bacterial species to colonize its preferred environment efficiently. In contrast, some of the environmental signals that have currently been identified to regulate the structure of a mature biofilm are nutrient availability and quorum sensing, and are not species specific. These environmental signals evoke changes in the nature of the mature biofilm that may ensure optimal nutrient acquisition. Nutrient availability regulates the depth of the biofilm in such a way that the maximal number of cells in a biofilm appears to occur at suboptimal nutrient concentrations. At either extreme, nutrient-rich or very nutrient-poor conditions, greater numbers of cells are in the planktonic phase where they have greater access to the local nutrients or can be distributed to a new environment. Similarly, quorum-sensing control of the formation of channels and pillar-like structures may ensure efficient nutrient delivery to cells in a biofilm.

Role of (p)ppGpp in biofilm formation and expression of filamentous structures in Bordetella pertussis

“…Biofilm formation is a multi-step process that includes initial attachment, microcolony formation, architectural development via cell-cell attachments and production of extracellular polysaccharides for protection (Stanley & Lazazzera, 2004). Recent studies show that biofilm formation in the host respiratory tract is important for adaptation and survival of B. pertussis during an infection (Serra et al, 2007(Serra et al, , 2008.…”

Fis regulates the competitiveness of Pseudomonas putida on barley roots by inducing biofilm formation

“…Such microcolonies eventually develop into mature biofilms (Ramos-González et al, 2005;Rudrappa et al, 2008;Stanley & Lazazzera, 2004;Villacieros et al, 2003). The formation of biofilms is important, as it protects plants against pathogens.…”

Dietary Bacillus subtilis B2A strain in laying hens challenged with Salmonella gallinarum: effects on egg production, egg quality, blood haptoglobin and targeted intestinal Salmonella shedding

“…Germination of B. subtilis strain spores causes a lower pH in the intestine due to Lactobacillus proliferation and more lactic acids, thus promoting the inhibition of Salmonella growth. Apart from the germinating or vegetative characteristics of B. subtilis spores, another prominent mechanism which is believed to play a crucial role is the biofilm and peptides released in the gut lumen which may cause inhibition of adhesion or colonization of pathogens (Stanley & Lazazzera 2004). Biofilms are microbial communities that are able to adhere to epithelial cells to form pathogenic ecosystems (Stanley & Lazazzera 2004).…”

“…Apart from the germinating or vegetative characteristics of B. subtilis spores, another prominent mechanism which is believed to play a crucial role is the biofilm and peptides released in the gut lumen which may cause inhibition of adhesion or colonization of pathogens (Stanley & Lazazzera 2004). Biofilms are microbial communities that are able to adhere to epithelial cells to form pathogenic ecosystems (Stanley & Lazazzera 2004). Sporulating B. subtilis cells produce and export the antibiotic-like killing factor and also surfactin (Gonzalez-pastor et al 2003) in a biofilm and, interestingly, surfactin is also able to inhibit biofilm formation in the human pathogen Salmonella (Mireles et al 2001).…”