Cloning and sequence analysis of a partial L-lactate dehydrogenase gene of Bacillus coagulans Tl-4v

Bacillus coagulans TL-4 strain is a thermophilic bacterium for high L-lactate production. We reported here that its 779-bp partial NAD⁺-dependent L-lactate dehydrogenase (LDH) gene sequence (GenBank accession no. GU354320) encoding a deduced 259 amino acid peptide was cloned by using one pair of designed degenerate primers. The amino acid sequence alignment and the built phylogenetic tree revealed that this partial LDH of B. coagulans TL-4 shared high homology with the conserved LDH stretches from 59.17% to 74.70% among other 10 Bacillus species and 48.81% to that of Lactobacillus sp. MD-1. Furthermore, three highly conservative LDH regions, one (Val1~Asp³⁴) for NADH binding site and two (Asp⁵⁹~Ile⁸⁶ and Asn¹⁰⁷~Arg¹³⁹) for the distinct active sites, were also found in this NAD⁺-dependent LDH stretch.