Biofilm Formation As a Response to Ecological Competition
"Mixing natural isolates of the pathogenic bacterium Pseudomonas aeruginosa shows that the formation of biofilm is a response to antibiotic stress from competing genotypes."
Biofilm is thought to be a manifestation of cooperative behaviour among bacteria. New work from the laboratory of Kevin Foster, just published in PLoS Biology explores a possibility that it is n fact an outcome of ecological competition. What they actually did was to co-culture natural isolates of the opportunistic pathogen Pseudomonas aeruginosa. They show that strain mixing leads to strong competition and enhances biofilm formation. They also show that pyocins, narrow-spectrum antibiotics made by other P. aeruginosa strains, can stimulate biofilm formation by increasing cell attachment. Further experiments, using microfluidic devices, revealed that response to cellular damage underpins increase biofilm formation. The authors say that their results are " inconsistent with the idea that sub-lethal concentrations of antibiotics are cooperative signals that coordinate microbial communities". Instead they propose that their work "is consistent with competition sensing where low-levels of antibiotics are used to detect and respond to the competing genotypes that produce them".
PLoS Biology July 9th DOI: 10.1371/journal.pbio.1002191