Catabolisme de l'arginine par Œnococcus œni : Aspects énergétiques et génétiques

Abstract

Most of the Oenococcus oeni strains are able to breakdown arginine, one of the main amino acid in wine, through the arginine deiminase pathway (ADI pathway). Citrulline is excreted and then reacts with ethanol to produce ethyl carbamate (or urethane). The carcinogenic effects on laboratory animals have been demonstrated for this compound when administrated at high concentrations. Thus, its level in wine might be monitored and regulated. Comparison between strains able or not to hydrolyse arginine has shown that degradation of this amino acid produces ATP. This energy can be used by growing cells and by "viable but non-culturable" cells that retrieve a growing state. Cloning of ADI pathway genes led to isolating the arcABC cluster. Upstream arcA, an open reading frame called orf229 encodes for a protein called ORF229p which shares common features with proteins involved in transcription activation. Moreover, a motif which matches the CRP binding domain was found in the promoter region of arcA. RT-PCR experiments on the arc cluster regulation showed that arginine stimulates transcription of the 4 genes. From sequence data, primers were chosen and applied in a PCR test, but failed to discriminate strains able or not to catabolise arginine.