Lactobacillus casei and Lactobacillus plantarum initiate catabolism of methionine by transamination.
OBJECTIVE
To study the ability of Lactobacillus casei and Lact. plantarum strains to convert methonine to cheese flavour compounds.


RESULTS
Strains were assayed for methionine aminotransferase and lyase activities, and amino acid decarboxylase activity. About 25% of the strains assayed showed methionine aminotransferase activity. The presence of glucose in the reaction mixture increased conversion of methionine to 4-methylthio-2-ketobutanoate (KMBA) and 4-methylthio-2-hydroxybutanoate (HMBA) in all strains. The methionine aminotransferase activity in Lact. plantarum and Lact. casei showed variable specificity for the amino group acceptors glyoxylate, ketoglutarate, oxaloacetate and pyruvate. None of the strains showed methionine lyase or glutamate and methionine decarboxylase activities.


CONCLUSIONS
The presence of amino acid converting enzymes in lactobacilli is strain specific.


CONCLUSIONS
The findings of this work suggest that lactobacilli can be used as adjuncts for flavour formation in cheese manufacture.
Amarita
F
F
Department of Dairy Science and Technology, Instituto del Frío, Ciudad Universitaria, Madrid, Spain.
Requena
T
T
Taborda
G
G
Amigo
L
L
Pelaez
C
C
D013437:Carbon-Sulfur Lyases / Q000378:metabolism; D002262:Carboxy-Lyases / Q000378:metabolism; D002611:Cheese / Q000382:microbiology*; D005421:Flavoring Agents / Q000378:metabolism*; D005516:Food Microbiology; D007778:Lactobacillus / Q000378:metabolism*; D007780:Lacticaseibacillus casei / Q000378:metabolism*; D008715:Methionine / Q000378:metabolism*; D000637:Transaminases / Q000378:metabolism
D005421:Flavoring Agents; D008715:Methionine; D000637:Transaminases; C020656:glutamine-pyruvate aminotransferase; D002262:Carboxy-Lyases; D013437:Carbon-Sulfur Lyases; C021558:L-methionine gamma-lyase