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Rico, J, Yebra, MJ, Pérez-Martínez, G, Deutscher, J and Monedero, V (2008) Analysis of ldh genes in Lactobacillus casei BL23: role on lactic acid production. J. Ind. Microbiol. Biotechnol. 35:579-86


Lactobacillus casei is a lactic acid bacterium that produces L-lactate as the main product of sugar fermentation via L-lactate dehydrogenase (Ldh1) activity. In addition, small amounts of the D-lactate isomer are produced by the activity of a D-hydroxycaproate dehydrogenase (HicD). Ldh1 is the main L-lactate producing enzyme, but mutation of its gene does not eliminate L-lactate synthesis. A survey of the L. casei BL23 draft genome sequence revealed the presence of three additional genes encoding Ldh paralogs. In order to study the contribution of these genes to the global lactate production in this organism, individual, as well as double mutants (ldh1 ldh2, ldh1 ldh3, ldh1 ldh4 and ldh1 hicD) were constructed and lactic acid production was assessed in culture supernatants. ldh2, ldh3 and ldh4 genes play a minor role in lactate production, as their single mutation or a mutation in combination with an ldh1 deletion had a low impact on L-lactate synthesis. A Deltaldh1 mutant displayed an increased production of D-lactate, which was probably synthesized via the activity of HicD, as it was abolished in a Deltaldh1 hicD double mutant. Contrarily to HicD, no Ldh1, Ldh2, Ldh3 or Ldh4 activities could be detected by zymogram assays. In addition, these assays revealed the presence of extra bands exhibiting D-/L-lactate dehydrogenase activity, which could not be attributed to any of the described genes. These results suggest that L. casei BL23 possesses a complex enzymatic system able to reduce pyruvic to lactic acid.


PubMed Online version:10.1007/s10295-008-0319-8


Gene Order; Genes, Bacterial/genetics; L-Lactate Dehydrogenase/genetics; L-Lactate Dehydrogenase/metabolism; Lactic Acid/biosynthesis; Lactic Acid/metabolism; Lactobacillus casei/enzymology; Lactobacillus casei/genetics; Molecular Sequence Data; Multienzyme Complexes/metabolism; NADH, NADPH Oxidoreductases/metabolism; Sequence Deletion; Sequence Homology, Nucleic Acid



Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status


GO:0016491: oxidoreductase activity



Figure 3 shows that the deletion of the ldh1 gene does not contribute to HicD activity

CACAO 3931


GO:0004459: L-lactate dehydrogenase activity



Figure 2 shows ldh zymogram assays of diffrent strains of L. casei. The deletion of ldh1 leads to the increase in ldh activity in the absence of D-lactate and in the presence of L-lactate. This activity is independent of the deletion of hicD, ldh2, ldh3 and ldh4.

CACAO 4526

See also


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