Environmental and genetic factors affecting the expression of a biofilm-inducing transcriptional regulator in Salmonella

FIGUEROA, N. R.; SONCINI, F. C.; TULIN, G.

Ciudad Autónoma de Buenos Aires

Congreso; Reunión Conjunta de Sociedades de Biociencias, LIII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2017

Sociedades de Biociencias

Salmonella is a food-borne pathogen associated with animal and human infections ranging from gastroenteritis to enteric/typhoid fever, constituting an important problem for public health and causing important economics losses. The persistence, both inside and outside the host, relies on its ability to adjust its lifestyle to the different environmental conditions it faces. Many microorganisms, including Salmonella, respond to changes in their surrounding by switching their lifestyle from planktonic, motile, individual cells to a sessile, multicellular bacterial community embedded in a self-produced extracellular matrix, a biofilm, that allows them to support harsh conditions including nutrients limitations, resistance to antimicrobial agents, desiccation and disinfectants. In S. enterica, the two major components of the extracellular matrix are curli, a thin, coiled and aggregative fimbriae, and the exopolysaccharide cellulose. Production of these components depends of the master transcriptional regulator CsgD, which in turn is affected by cell growth stage and environmental stimuli through the action of other transcriptional factors, 3´,5´-cyclic diguanylic acid, and small RNAs. We have previously identified a Salmonella-specific transcription factor important for both biofilm production and csgD transcription. Furthermore, a recent report shows that this factor is of relevance for the intestinal colonization of food-producing animals. To gain insight into this factor?s expression, we generated a lacZ transcriptional fusion of its gene and analyzed its expression under different environmental conditions. Also, using the T-POP system to carry out a general screen for loci affecting its transcription, we identified 3 chromosomal regions whose mutations either activate or repress this gene. Altogether, these results define host-related conditions that trigger the activation of this regulator to induce biofilm and Salmonella intestinal colonization.