Salmonella-specific transcriptional regulators affecting biofilm formation

VITOR HOREN, LUISINA; ECHARREN, MARIA LAURA; SONCINI, FERNANDO C.; TULIN, GONZALO

Santiago

Congreso; XXIV Congreso Latinoamericano de Microbiología. ALAM 2018.; 2018

Salmonellosis is among the most common foodborne diseases, with millions of human infections occurring worldwide every year. A key aspect of Salmonella?s life cycle that contributes to its high prevalence is its ability to form biofilms, bacterial communities embedded in a self-produced extracellular matrix that allows them to adhere to each other and to diverse surfaces. This multicellular behavior facilitates persistence and transmission between hosts, and survival in the environment. In Salmonella, the extracellular matrix is composed mainly by cellulose and curli fimbriae whose synthesis are controlled at transcriptional level through the expression of its master regulator, CsgD. Expression of this transcriptional activator is in turn finely regulated by several transcription factors that integrate different environmental signals. We identified Salmonella-specific genes coding for transcription factors, that, according to in silico analysis, could participate in the control of biofilm-formation. Overexpression of these genes in different genetic backgrounds provoked marked differences in the characteristic Salmonella biofilm morphotypes, as well as on the expression of csgD, determined by the use of chromosomal reporter fusions to lacZ. Our results demonstrate that under specific conditions these Salmonella transcription factors affect biofilm-formation by either controlling the induction of the Csg regulon or the switch between planktonic and sessile lifestyles. In addition, we determined an increase in their expression under infection relevant conditions, allowing us to postulate them as link between the biofilm formation and Salmonella pathogenesis.