Arginine catabolism and acid tolerance response in Lactobacillus reuteri isolated from sourdough

Abstract

The physiological role of arginine degradation by the arginine deiminase (ADI) pathway and its relationship with the acid tolerance response (ATR) in Lactobacillus reuteri CRL 1098 cells, a lactic acid bacterium of sourdough origin, were studied. The activity of the ADI pathway enzymes (ADI, ornithine transcarbamoylase and carbamate kinase) in L. reuteri CRL 1098 grown in presence of arginine and the formation of ammonia (1.39 mmol l −1) and citrulline (1.66 mmol l −1) from arginine catabolism indicated the presence of the ADI pathway in this micro-organism. This system would be involved in the ATR developed by cells grown with arginine and adapted at pH 5.0. The results indicated that the ADI system is triggered either by the adaptation of exponentially growing cells at low pH or by energy depletion of the cells during the stationary phase. Results suggest that ADI is an important component of the ATR observed at pH 5.0 since cells at the exponential phase grown without arginine and further adapted and challenged without this amino acid remained sensitive to acid stress. The findings of this work provide information about the arginine catabolism by L. reuteri, which can contribute to protect this micro-organism in acid environments.