| The Gram-positive soil bacterium Bacillus subtilis has been studied for many years for its ability to differentiate into an environmentally resistant spore. In this study, B. subtilis was shown to form biofilms, which are communities of bacterial cell living adherent to a surface to each other that are encased in a self produced polymeric matrix. Biofilm formation was shown to require the major sporulation transcription factor Spo0A. Biofilm formation was shown to be genetically distinct from sporulation as Spo0A must repress the transcription factor AbrB for biofilm formation, which is not required for sporulation, and activate the spoII genes for sporulation, which are dispensable for biofilm formation. Furthermore, data shows that biofilm formation and sporulation can occur under different conditions, and the decision to initiate one pathway or the other is made by the levels of Spo0A∼P. In an aim to identify structural genes required for forming the biofilm structure, microarray analyses were performed to identify genes activated by Spo0A through AbrB, and activated under biofilm formation conditions. Through these analysis, 39 operons were identified, and revealed new genes previously unknown to be regulated by AbrB. Furthermore, two mutants were found to have a role in biofilm formation, SipW, as signal peptidase, and YoaW a secreted protein of unknown function. These are the first two secreted proteins identified as having a role in B. subtilis biofilm formation. This study establishes a novel life style for a well studied bacterium, a novel role for a well studied transcription factor, and novel genes required for biofilm formation. |
