Abstract
Fifty five percent of 152 lactic acid bacteria (LAB) isolated from 9 mature Cheddar cheeses were able to catabolise protein hydrolysates and individual amino acids in the Biolog MT1TM microplate assay. A more detailed study of 31 isolates confirmed a requirement for a-ketoglutaric acid and inter- and intra-species differences in the range and number of amino acids utilised. GCMS analysis of cell-free supernatants of 29 LAB isolates grown on a low-carbohydrate medium containing lactalbumin hydrolysate identified more than 90 compounds. Putative metabolites of valine, leucine, isoleucine, phenylalanine and sulphur-containing amino acids were detected although the metabolite profiles were isolate-specific. The occurrence and activity of amino acid converting enzymes was also monitored in the LAB isolates. Methionine, branched-chain and aromatic amino acid aminotransferase activities were detected with a-ketoglutarate as acceptor. There was no conclusive evidence for a widespread occurrence of deaminase, decarboxylase and demethiolase activities. The majority of isolates examined formed thiols from methionine via an aminotransferase-mediated reaction.
Original language | English |
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Pages (from-to) | 203-215 |
Number of pages | 13 |
Journal | International Dairy Journal |
Volume | 11 |
Issue number | 4-7 |
DOIs | |
Publication status | Published - 1 Jul 2001 |
Keywords
- lactic acid bacteria
- amino acid catabolism
- cheese