Lactobacillus plantarum ldhL gene: overexpression and deletion.

摘要: Lactobacillus plantarum is a lactic acid bacterium that converts pyruvate to L-(+)- and D-(-)-lactate with stereospecific enzymes designated dehydrogenase (LDH), respectively. A gene (designated ldhL) encodes L-(+)-lactate from L. DG301 was cloned by complementation in Escherichia coli. The nucleotide sequence of the ldhL predicted protein 320 amino acids closely related pentosus. multicopy plasmid bearing without modification its expression signals introduced plantarum. L-LDH activity increased up 13-fold through this dosage effect. However, change had hardly any effect on production D-(-)-lactate. stable chromosomal deletion then constructed two-step homologous recombination process. Inactivation resulted absence exclusive D isomer lactate. global concentration lactate culture supernatant remained unchanged.