Final Report Summary - BACTERIAL PATTERNS (Network analysis of bacterial multi-cellular patterning) The specific aims of the grant were to study biofilm formation in the model Gram positive bacteria Bacillus subtilis by combining gene expression analysis and genetics with a novel light activation system. The logic of the proposal was that local activation of gene expression in a specific region and the ability to read gene expression reporters, will enable us to infer causality of cell non-autonomous and spatial interaction and that combining these measurments with mutant analysis will enable us to better infer community behavior of this model organism.The project therefore contained two paths, which were supposed to converge at the middle of the project: i) establishing the light-activation system in B. subtilis and constructing light activated constructs, and ii) studying gene expression and biofilm formation in mutants.Unfortunately, we have not been able to perform the first (and most novel path), the construction of light activation system. This part proved more problematic than expected. After significant exploration, we hypothesize that a crucial phosphorylation step in the light activation system is inhibited by an unidentified phoaphatse. We were therefore unable to perform the crucial part of the project.Nevertheless, we were able to continue with the second (more conservative) path of studying biofilms using genetics and gene expression studies. We have been able to obtain multiple results on the genetics of biofilm formation in B. subtilis. A first manuscript on the subject has been recently accepted to the journal of bacteriology, while other related works are under continuous work.In the accepted manuscript we have identified a role in biofilm formation for a novel quorum-sensing (signaling) system called rapP-phrP. We show that this system was not identified before due to a mutation in the strain used by other researchers. Once this mutation is corrected, we showed that inter-cellular signaling is formed and substantially affect biofilm formation. In the yet unpublished works, we have used a genetic screen approach to identify multiple novel regulators of biofilm formation, and specifically for the production of the surfactant surfactin. We were also able to find conditions in which the coupling between biofilm formation and sporulation is broken, allowing us to better study the genetic regulation of this coupling process.