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D-Alanine Metabolism in L. johnsonii

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Lactic acid bacteria play important roles in food conservation because of their fermentative ability and contribute to the equilibrium of the gastrointestinal tract microbiota. Lactobacillus johnsonii is commonly found in the gastrointestinal tract and adhere to intestinal cells. Such interactions of bacteria with the gastrointestinal tract contribute to its protection against pathogenic microorganisms. A close association between the bacteria and their environment undoubtedly results in adaptation of their metabolic capacities (Ref.1 & 2).

D-Alanine occurs to the extent of 1 to 2 per cent of the dry cells of various lactic acid bacteria including L. johnsonii and L-Alanine is essential for L. johnsonii growth. The naturally occurring L-Alanine isomer is racemized to its D-form through the action of AlRs (Alanine Racemase) [...]


1.L-alanine auxotrophy of Lactobacillus johnsonii as demonstrated by physiological, genomic, and gene complementation approaches.
van der Kaaij H, Desiere F, Mollet B, Germond JE.
Appl Environ Microbiol. 2004 Mar; 70(3):1869-73.
2.The complete genomes of Lactobacillus plantarum and Lactobacillus johnsonii reveal extensive differences in chromosome organization and gene content.
Boekhorst J, Siezen RJ, Zwahlen MC, Vilanova D, Pridmore RD, Mercenier A, Kleerebezem M, de Vos WM, Brussow H, Desiere F.
Microbiology. 2004 Nov; 150(Pt 11):3601-11.
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