Autoinducer 2 regulates cell to cell communication and development in Bacillus subtilis

LOMBARDÍA E., ROVETTO A., GRAU R.

Mar del Plata

Congreso; Reunión Anual Congreso SAIB; 2007

SAIB

Cell to cell communication in bacteria is regulated by quorum sensing (QS). In particular, LuxS / AI-2 dependent QS has been proposed to act as a universal lexicon that mediates intra- and inter-specific bacterial behavior. Here we report that the model organism B. subtilis operates a luxS-dependent QS that regulates its morphogenesis and social behavior. We show that luxS is a growth-phase regulated gene that produces active AI-2 to mediate the inter-specific activation of light production in Vibrio harveyi. LuxS expression is under the control of a novel AI-2-dependent negative regulatory feedback loop pointing out AI-2 as a key signaling molecule. AI-2 production was negatively regulated by the master regulatory proteins of pluricellular behavior, SinR and Spo0A. Interestingly, wild and undomesticated B. subtilis cells require the LuxS-dependent QS to form robust and differentiated biofilms and also to swarm on solid surfaces. Furthermore, LuxS activity was required for the formation of sophisticated aerial colonies that behaved as giant fruiting bodies where AI-2 production and spore morphogenesis were spatially regulated at different sites of the developing colony. We proposed that LuxS constitutes a novel form of intraspecific quorum sensing where AI-2 behaves as a morphogen-like molecule that coordinates the social and pluricellular behavior of B. subtilis.