Regulation of the bacterial sessile lifestyle

The development of biofilms on abiotic or biotic surfaces is a complex and highly regulated process. Our research group has done pioneering work on the characterization of structural and regulatory elements participating in biofilm formation and colonization of plant surfaces by beneficial bacteria, using Pseudomonas putida KT2440 as a model.

In many bacteria, the intracellular second messenger cyclic diguanylate (c-di-GMP) plays a key role in the transition between planktonic and sessile lifestyles. We are studying the signaling network associated to c-di-GMP in P. putida. We have characterized a two component system formed by a histidine kinase (CfcA) and a response regulator with diguanylate cyclase activity (CfcR). Overexpression of cfcR leads to increased c-di-GMP levels, resulting in a pleiotropic phenotype that includes enhanced biofilm formation and altered colony morphology.

We analyze the role of global and specific regulators on c-di-GMP signal transduction, and on expression and activity of CfcA and CfcR. These include the transcriptional regulators FleQ and ArgR, the stationary phase sigma factor RpoS and the post-transcriptional regulatory proteins RsmA, RsmE and RsmI.

We are also interested in the environmental and metabolic cues that influence biofilm formation, and the signal molecules participating in the interaction of P. putida with other bacteria, fungi and plants.