It is now widely recognized that bacteria have the widespread capacity to form surface-associated multicellular aggregates, commonly refered to as "biofilms". When organisms, be it eukaryotes or prokaryotes, transition from unicellularity to multicellularity they produce an extracellular matrix that provides structural support and facilitates surface attachment. Within biofilms the constituent cells are embedded in matrices composed of diverse extracellular polymeric substances. Although the process of biofilm formation appears to be dependent upon the formation of an extracellular matrix, the content, regulation and precise function of these exported products are still largely unknown. Analysis of the B. subtilis genome revealed the presence of a cluster of genes, the yve genes, whose products are predicted to be involved in the biosynthesis of a possible extracellular polysaccharide. Experimentally, I will focus on characterizing the molecular mechanism of the spatio-temporal regulation of the yve operon and I will identify additional genes involved in matrix production in Bacillus subtilis biofilms. [unreadable] [unreadable]