CLONING, NUCLEOTIDE-SEQUENCE, AND TRANSCRIPTIONAL ANALYSIS OF THE PEDIOCOCCUS-ACIDILACTICI L-(+)-LACTATE DEHYDROGENASE GENE

Recombinant plasmids containing the Pediococcus acidilactici L-(+)-lactate dehydrogenase gene (ldhL) were isolated by complementing for growth under anaerobiosis of an Escherichia coli lactate dehydrogenase-pyruvate formate lyase double mutant. The nucleotide sequence of the ldhL gene predicted a protein of 323 amino acids showing significant similarity with other bacterial L-(+)-lactate dehydrogenases and especially with that of Lactobacillus plantarum. The ldhL transcription start points in P. acidilactici were defined by primer extension, and the promoter sequence was identified as TCAACT-(17 bp)-TATAAT. This sequence is closely related to the consensus sequence of vegetative promoters from gram-positive bacteria as well as from E. coli. Northern analysis of P. acidilactici RNA showed a 1.1-kb ldhL transcript whose abundance is growth rate regulated. These data, together with the presence of a putative rho-independent transcriptional terminator, suggest that ldhL is expressed as a monocistronic transcript in P. acidilactici.