Succinate production and citrate catabolism by Cheddar cheese nonstarter lactobacilli.
OBJECTIVE
To identify strains of Cheddar cheese nonstarter lactobacilli that synthesize succinate from common precursors and characterize the biochemical pathways utilized.


RESULTS
Whole cell incubations of Lactobacillus plantarum, Lactobacillus casei, Lactobacillus zeae and Lactobacillus rhamnosus, were used to identify strains that accumulated succinate from citrate, l-lactate, aspartic acid or isocitrate. In vivo 13C-nuclear magnetic resonance spectroscopy (13C-NMR) identified the biochemical pathway involved at pH 7.0, and under conditions more representative of the cheese ripening environment (pH 5.1/4% NaCl/13 degrees C). Enzyme assays on cell-free extracts were used to support the pathway suggested by 13C-NMR.


CONCLUSIONS
The Lact. plantarum strains studied synthesize succinate from citrate by the reductive tricarboxylic acid (TCA) cycle at either pH 7.0 or pH 5.1/4% NaCl/13 degrees C. Lactobacillus casei, Lact. zeae and Lact. rhamnosus strains lack one or more enzymatic activities present in this pathway, and do not accumulate succinate from any of the four precursors studied.


CONCLUSIONS
The addition of Lact. plantarum strains to milk during cheese manufacture may increase the accumulation of the flavour enhancer succinate.
Dudley
E G
EG
Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA.
Steele
J L
JL
D000818:Animals; D002417:Cattle; D002611:Cheese; D019343:Citric Acid / Q000378:metabolism*; D005260:Female; D005285:Fermentation; D005516:Food Microbiology; D007778:Lactobacillus / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008892:Milk / Q000382:microbiology; D013045:Species Specificity; D019802:Succinic Acid / Q000378:metabolism*
D019343:Citric Acid; D019802:Succinic Acid