IRNASUS   26003
INSTITUTO DE INVESTIGACIONES EN RECURSOS NATURALES Y SUSTENTABILIDAD JOSE SANCHEZ LABRADOR S.J.
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
INTERACTION OF BACILLUS SUBTILIS WITH A FUNGAL PATHOGEN DRIVES SELECTIVE MUTATION OF REGULATORY GENES FOR NATURAL PRODUCT PRODUCTION
Autor/es:
TOBARES, ROMINA ALIN; MOYANO, ALEJANDRO; SMANIA, ANDREA M.; ALBARRACIN ORIO, ANDREA; SAYAGO, PAMELA; DORRESTEIN, PIETER C.; PETRAS, DANIEL; JUNCOSA, FLORENCIA; DUCASSE, DANIEL A
Lugar:
Buenos Aires
Reunión:
Congreso; XIV Congreso Argentino de MicrobiologĂ­a General (SAMIGE); 2019
Resumen:
Introduction and objectives: Various environmental species of bacteria and fungi coexist and interact showing antagonistic and mutualistic behaviors, mediated by exchange of small diffusible metabolites, driving microbial adaptation to complex communal lifestyles. The soil bacterium Bacillus subtilis and related species are used extensively as biological control agents in agriculture, mainly because they produce a wide variety of antimicrobial compounds. Here, we show that a wild strain of Bacillus subtilis (Bs) undergoes heritable phenotypic variation following interaction with the soil fungal pathogen Setophoma terrestris (ST) in co-culture. Materials and methods: We combined phenotypic characterization; non-targeted liquid chromatography tandem mass spectrometry (LC-MS/MS) based metabolomics analysis and comparative genomics to distinguish the differences between Bacillus subtilis before and after interacting with the fungus. Results: Mass spectrometry-based metabolome analysis revealed a differential profile in Bs before (pre-ST) and after (post-ST) interacting with the fungus, which paradoxically involved the absence of lipopeptides (surfactin and plipastatin) production and yet antifungal activity in post-ST variants. Apart from the high fungal inhibition activity, we observed that the ability to form robust biofilms in vitro was a prevailing feature of postST. Disruption of the srfAA gene implicated in surfactin synthesis resulted in an abolition of the ST-driven antifungal activity and ST growth inhibition levels similar to those observed for post-ST variants. The post-ST phenotype was stable after several passages on solid media, indicating that a mutation-based process underlies this phenotypic adaptation process. We finally investigated the genetic bases of post-ST conversion by performing comparative whole-genome analyses and observed that all conversion events were convergently originated from loss-of-function mutations in the comA and comP genes of the ComQPXA quorum-sensing system. Conclusions: Mutations in the ComQXPA quorum-sensing system appeared to be responsible for the stable phenotypic and metabolomics profile changes and might be necessary for an appropriate activity/functioning of antifungal metabolites that mediate an adaptive response in conditions of competitive interaction with the fungus.