Pluricellularity and adhesive properties of the anti-infective probiotic bacterium Bacillus subtilis

ROVETTO A., SABAL E., SALVARREY M., GRAU R.

Mar del Plata

Congreso; SAIB; 2007

SAIB

In nature, microbes are able to express sophisticate and elaborate social behaviors that allow adaptation, survival and evolution. Here we report the social behavior of the undomesticated and probiotic strain B. subtilis RG4365. We demonstrated that the threemaster developmental regulators Spo0A, AbrB and SinR are crucial for the expressionof social behaviors in B. subtilis. Biofilm development and colony morphogenesis were under the positive and negative control of Spo0A and AbrB /SinR respectively. The requirement of Spo0A during colony differentiation was not only due to its known antagonistic effects on abrB and sinR expression but also for its unique role in maintaining the structure of the aerial colony at late developmental stages. In addition, we demonstrated that B. subtilis was able to adhere with high affinity and specificity to the extracellular matrix representative proteins fibronectinand collagen. This specific binding was under the negative control of AbrB and counteracted by Spo0A. B. subtilis was able to compete and inhibit the adherence of pathogenic Staphylococcus aureus to immobilized-fibronectin, a propertythat it would be of importance for the expression of the anti-infective properties ofprobiotic B. subtilis. Finally, we present a working model summarizing how wild strains of B. subtiliscan alternate between different communitarian styles of behaviors.