Bacillus subtilis undergoes mutagenic-mediated cell differentiation after interaction with Setophoma terrestris

ALBARRACÍN ORIO A; TOBARES RA; COLQUE CA; SAYAGO P; SMANIA AM; DUCASSE D

Córdoba

Congreso; LII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2016

Microbial interactions are ubiquitous in nature. Microorganisms grow and survive in these environments 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 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 bacterial colony and analyzed its morphology, biofilm formation, performed whole genome sequence analysis and compared with Bs not exposed to St (Bs-ctr). Bs grown after interaction with St (Bs-int) exhibited changes in morphology with an increase in fruiting body formation relative to Bs-ctr. Qualitative analysis by electron microscopy of Bs-int revealed a high number of longer and not sporulated cells. When re-inoculated onto a fresh medium, Bs-int maintained the structured colony morphology suggesting a phase variation after interaction with St. Comparative genome analysis revealed for Bs-int a T141N mutation in the comA gene that code for a regulator involved in the ComPQXA quorum sensing system. Our results suggest a role for a still unknown ComPQXA regulated pathway, which may be the responsible for the inducible cell differentiation experimented by our strain of Bs.