Signalling in bacterial biofilms
Bacteria often form complex patterns on surfaces called biofilms that increase resilience to diverse external insults such as antimicrobial treatments. While the importance of bacterial communities was previously demonstrated, the control mechanisms of the spatial organisation, differentiation and patterning remain unclear. The EU-funded project BACTERIAL PATTERNS (Network analysis of bacterial multi-cellular patterning) studied biofilm formation in the model Gram-positive bacteria Bacillus subtilis, which has developmentally different subpopulations. Gene expression studies revealed previously unknown data on biofilm formation in B. subtilis. Formation of bacterial biofilms is coordinated by means of quorum sensing, a signalling system controlling the population density. Scientists identified a novel quorum-sensing system called rapP-phrP in biofilm formation. Phosphatase rapP gene exists in a gene cassette with phrP, an encoding regulatory polypeptide. This signalling system was not identified before due to a mutation in the strain used by other researchers. After correcting the mutation, BACTERIAL PATTERNS showed that formation of inter-cellular signalling pathways substantially affects biofilm formation. A genetic screen approach helped identify multiple novel regulators of biofilm formation, and specifically of surfactin production. Surfactin, produced by B. subtilis, is a powerful surfactant and nonspecific antibiotic, acting on many kinds of bacterial membranes. Identifying the conditions in which the coupling between biofilm formation and sporulation is broken revealed the genetic regulation of this coupling process. Scientists' uncovered novel data about genetic regulatory mechanisms involved in biofilm formation. Effective anti-bacterial products for domestic, hospital and industrial sectors could be developed by disrupting these mechanisms.
Keywords
Signalling, bacteria, biofilm, B. subtilis, quorum sensing, surfactin
