Expression of lactobacillus casei lactate dehydrogenase gene in bacillus subtilis

Abstract

A lactate dehydrogenase (LDH) gene of Lactobacillus casei origin was transferred into Bacillus subtilis and its expression in its new host cells was observed. The ldh gene contained in EcoRI-BamHI fragment of pLS65 was transferred into its corresponding site of pUP638 and constructed a new plasmid pUL85. With pUL85 cells of E. coli and B. subtilis were transformed and constructed new transformants, E. coli JM83 (pUL85) and B. subtilis RM125 (pUL85) were developed. The new transformants were grown in LB broth and expression of ldh gene in the new host cells was observed. Both transformants produced LDH in accordance with their growth with maximum production at late-log phase. It was also found that the L. casei originated ldh gene expressed in the new host cells using its own promoter. The expression efficiency of ldh gene in B. subtilis was about 20 times higher than in E. coli and B. subtilis RM125 (pUL85) produced LDH protein up to 20-30% of the total cellular protein. When the L. casei ldh gene promoter was fused to another gene, a structural gene of B. sublilis endoglucanse, however, its promoter activity in B. sublilis was not strong and produced only a moderate amount of endoglucanase.