L-Arginine, an amino acid found in significant quantities in grape juice and wine, is known to be catabolized by some wine lactic acid bacteria. The correlation between the occurrence of arginine deiminase pathway enzymes and the ability to catabolize arginine was examined in this study. The activities of the three arginine deiminase pathway enzymes, arginine deiminase, ornithine transcarbamylase, and carbamate kinase, were measured in cell extracts of 35 strains of wine lactic acid bacteria. These enzymes were present in all heterofermentative lactobacilli and most leuconostocs but were absent in all the homofermentative lactobacilli and pediococci examined. There was a good correlation among arginine degradation, formation of ammonia and citrulline, and the occurrence of arginine deiminase pathway enzymes. Urea was not detected during arginine degradation, suggesting that the catabolism of arginine did not proceed via the arginase-catalyzed reaction, as has been suggested in some earlier studies. Detection of ammonia with Nessler's reagent was shown to be a simple, rapid test to assess the ability of wine lactic acid bacteria to degrade arginine, although in media containing relatively high concentrations (>0.5%) of fructose, ammonia formation is inhibited.

T h e wine lactic acid bacteria Leuconostoi. oenos OENO and Lactobacillus buchneri CUC-3 catabolize 1.-arginine to ornithine and ammonia as major end-products, with 1 mole of arginine converted into 2 moles of ammonia and 1 mole of ornithine. Some citrulline was also excreted into the medium. T h e excreted citrulline was reassimilated and catabolized by the lactobacillus strain, though not by the leuconostoc. Urea was not detected during arginine degradation. T h e activities of all three enzymes of the arginine deiminase pathway (arginine deiminase, ornithine transcarbamylase and carbamate kinase) increased significantly over time in the presence of arginine. O n the other hand, arginase and urease activities were undetectable in cell extracts of cultures grown in the presence of arginine. T h e results show that the arginine deiminase pathway, and not the arginase-urease pathway, is the route for arginine degradation in wine lactic acid bacteria.