Disruption of the sole ldhL gene in Lactobacillus sakei prevents the production of both L- and D-lactate.
A 7 kb DNA fragment was cloned from Lactobacillus sakei which contains the IdhL gene encoding the L(+)-lactate dehydrogenase (L-LDH). Analysis of the DNA sequence, Northern experiments and primer extension experiments showed that IdhL is transcribed from a single promoter, leading to a monocistronic 1.15 kb mRNA which yields the L-LDH. A stable mutant was constructed by chromosomal integration of a chloramphenicol cassette into IdhL by a double-crossover event. Both L- and D-lactate were produced by the wild-type strain whereas only residual amounts of both isomers were produced by the mutant. This demonstrates that L. sakei possesses an L-LDH producing L-lactate and a lactate racemase able to transform it to D-lactate, but is devoid of D-LDH activity. Moreover the ability to degrade L-lactate present in the medium that was observed with the mutant strain grown aerobically suggests that an L-lactate oxidase activity is also present in L. sakei.
Maleret
Christine
C
Laboratoire de Recherches sur la Viande and Laboratoire de Génétique Microbienne F-78352 Jouy en Josas cedex, France.
Lauret
R
R
Laboratoire de Recherches sur la Viande and Laboratoire de Génétique Microbienne F-78352 Jouy en Josas cedex, France.
Ehrlich
S Dusko
SD
Institut National de la Recherche Agronomique, Domaine de Vilvert, F-78352 Jouy en Josas cedex, France.
Morel-Deville
Françoise
F
Laboratoire de Recherches sur la Viande and Laboratoire de Génétique Microbienne F-78352 Jouy en Josas cedex, France.
Zagorec
Monique
M
Laboratoire de Recherches sur la Viande and Laboratoire de Génétique Microbienne F-78352 Jouy en Josas cedex, France.
D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000032:analysis; D004926:Escherichia coli; D015964:Gene Expression Regulation, Bacterial; D007770:L-Lactate Dehydrogenase / Q000235:genetics*; D042844:L-Lactate Dehydrogenase (Cytochrome); D007773:Lactates / Q000378:metabolism*; D007778:Lactobacillus / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D016296:Mutagenesis; D017422:Sequence Analysis, DNA; D013237:Stereoisomerism; D014158:Transcription, Genetic
D004269:DNA, Bacterial; D007773:Lactates; D007770:L-Lactate Dehydrogenase; D042844:L-Lactate Dehydrogenase (Cytochrome)