Relevance of the transcripton factor sigma B during stress adaptation and survival in Bacillus subtilis

GOÑI, A.; MENDEZ, M.; ROBERTO RICARDO GRAU

Viena

Congreso; 11th International Congress on Microbial Ecology, ISME 11; 2006

RELEVANCE OF THE TRANSCRIPTION FACTOR SIGMA B DURING GERMINATION AND STRESS ADAPTATION IN BACILLUS SUBTILIS       Anibal Goñi, Marcelo Méndez, Liliana Rateni, Lelia Orsaria, and Roberto Grau Facultad de Cs. Bioquímicas y Farmacéuticas Dpto. de Microbiología e IBR – CONICET – Rosario. anibaljuangoni@yahoo.com.ar.                         Spore development and stress resistance in the Gram-positive paradigm Bacillus subtilis are governed by the master transcription factors Spo0A and sB respectively. B. subtilis is a soil bacterium, and hence temperature changes would constitute a common environmental stress. We showed in previous reports that the coding gene for the regulatory protein sB is dramatically induced after a temperature downshift from 37°C to 20°C. Loss of sB reduces stationary-phase viability of cold-adapted cells 10 to 15-fold. Here we analyzed germination, outgrowth and resistance of spores formed at 37ºC and 20ºC. Besides, the location of sB in the sporulating cells was determined. We showed that sigB is important for spore robustness, because a mutation in this gene reduces the germination capacity of sB minus spores under alcohol-stressing conditions. Moreover, a delay in the outgrowth of the sB minus spores is observed when compared it with the outgrowth of wild type spores under similar conditions. On the other hand, wild type spores, that germinated and grew in the presence of ethanol at 20ºC, sporulated more efficiently than sigB mutant cells. In toto, these results argue for a novel and important role of sB for the formation, stress resistance, survival and outgrowth of bacterial spores.