Arginine, citrulline and ornithine metabolism by lactic acid bacteria from wine

The catabolism of arginine, an amino acid found in grape juice and wine, citrulline and ornithine was investigated in four lactic acid bacteria. Only Lactobacillus hilgardii X1B catabolized arginine and excreted citrulline into the medium. The recovery of arginine as ornithine was lower than the expected theoretical value. The arginase-urease pathway was not detected indicating that the amino acid degradation was carried out only by the arginine dihydrolase pathway. Oenococcus oeni m, a strain not able to utilize arginine, degraded citrulline that was completely recovered as ornithine, ammonia and CO2. Lactobacillus hilgardii X1B catabolized citrulline but it was only 44% recovered as ornithine. The citrulline utilization by Oenococcus oeni m may be important for two reasons: it can gain extra energy for growth from citrulline metabolism, and the amino-acid diminution could avoid the possibility of ethyl carbamate formation from the citrulline naturally present in wine.