Mutagenic-mediated differentiation in Bacillus subtilis after interaction with Setophoma terrestris

ALBARRACÍN ORIO, A.G.; SAYAGO, P.; COLQUE, C. A.; DUCASSE, D.A.; TOBARES, A.; SMANIA, A.

Córdoba

Congreso; LII Reunión Anual de la Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular (SAIB); 2016

Sociedad Argentina de Investigación Bioquímica y Biología Molecular

Microbial interactions are ubiquitous in nature. Microorganisms grow and survive in the environment either in mutualistic relationships or as antagonists. We have previously isolated a strain of Bacillus subtilis (Bs) from soil under continuous onion culture where co-exist with the fungal pathogen Setophoma terrestris (St). To understand the mechanisms that govern the interaction between Bs and St we performed in vitro co-cultures in Petri dishes. After 15 days, we recovered the bacteria (Bs-int) and analyzed its morphology, biofilm formation, performed whole genome sequence analysis and compared with Bs not exposed to St (Bs-ctr). Bs-int exhibited changes in morphology and apparent increase in biofilm formation relative to Bs-ctr. Electron microscopy of Bs-int revealed a high number of longer and non-sporulating cells. When re-inoculated onto a fresh medium, Bs-int maintained the structured colony morphology suggesting a phenotypic variation after interaction with St. Comparative genome analysis revealed for Bs-int a mutation in the comA gene, coding for a regulator involved in the ComPQXA quorum sensing (QS) system, and mutations in genes of uncharacterized non-ribosomal peptides (NRP) synthetases. NRP mediate competitive interactions and they may be controlled by QS. Our results suggest a role of these factors in the mutagenic-mediated cell differentiation experienced by Bs.