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Titolo:
CONVERSION OF METHIONINE TO THIOLS BY LACTOCOCCI, LACTOBACILLI, AND BREVIBACTERIA
Autore:
DIAS B; WEIMER B;
Indirizzi:
UTAH STATE UNIV,DEPT NUTR & FOOD SCI,WESTERN DAIRY CTR LOGAN UT 84322 UTAH STATE UNIV,DEPT NUTR & FOOD SCI,WESTERN DAIRY CTR LOGAN UT 84322
Titolo Testata:
Applied and environmental microbiology
fascicolo: 9, volume: 64, anno: 1998,
pagine: 3320 - 3326
SICI:
0099-2240(1998)64:9<3320:COMTTB>2.0.ZU;2-K
Fonte:
ISI
Lingua:
ENG
Soggetto:
CYSTATHIONINE GAMMA-LYASE; FLAVOR COMPOUND FORMATION; CHEDDAR CHEESE; ESCHERICHIA-COLI; CREMORIS SK11; LACTIS SUBSP; AMINO-ACIDS; BETA-LYASE; PURIFICATION; LINENS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
33
Recensione:
Indirizzi per estratti:
Citazione:
B. Dias e B. Weimer, "CONVERSION OF METHIONINE TO THIOLS BY LACTOCOCCI, LACTOBACILLI, AND BREVIBACTERIA", Applied and environmental microbiology, 64(9), 1998, pp. 3320-3326

Abstract

Methanethiol has been strongly associated with desirable Cheddar cheese flavor and can be formed from the degradation of methionine (Met) via a number of microbial enzymes. Methionine gamma-lyase is thought toplay a major role in the catabolism of Met and generation of methanethiol in several species of bacteria. Other enzymes that have been reported to be capable of producing methanethiol from Met in lactic acid bacteria include cystathionine beta-lyase and cystathionine gamma-lyase, The objective of this study was to determine the production, stability, and activities of the enzymes involved in methanethiol generation in bacteria associated with cheese making. Lactococci and lactobacilliwere observed to contain high levels of enzymes that acted primarily on cystathionine. Enzyme activity was dependent on the concentration of sulfur amino acids in the growth medium, Met aminotransferase activity was detected in all of the lactic acid bacteria tested and alpha-ketoglutarate was used as the amino group acceptor. In Lactococcus lactis subsp. cremoris S2, Met aminotransferase was repressed with increasing concentrations of Met in the growth medium. While no Met aminotransferase activity was detected in Brevibacterium linens BL2, it possessed high levels of L-methionine gamma-lyase that was induced by additionof Met to the growth medium. Met demethiolation activity at pH 5.2 with 4% NaCl was not detected in cell extracts but was detected in wholecells. These data suggest that Met degradation in Cheddar cheese willdepend on the organism used in production, the amount of enzyme released during aging, and the amount of Met in the matrix.

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Documento generato il 05/12/20 alle ore 08:08:35