ABSTRACT
Homofermentative lactic bacteria usually produces > 85% lactate as an end product, and heterofermentative bacteria form mixed end products containing acetic acid or ethanol besides lactic acid. Lactic bacteria ferment D-or L-lactic acid, or both, depending on the growth conditions, such as the oxygen concentration, temperature, pH, and sugars or other catabolites supplied, and also on the nature of the LDHs contained in bacterial strains. D-and L-LDHs play key roles in the fermentation of D-and L-lactic acids in lactic bacteria, respectively, and the amount and properties of each LDH greatly affect the fermentation patterns of lactic bacteria. Bacteria that possess L-LDHs activated by fructose-1,6-bisphosphate (Fru-1,6-P2) (see below) produce mainly L-lactic acid when Fru1,6-P2 is accumulated in the cells, but under other growth conditions the bacteria may ferment a large amount of D-lactic acid, or some other end products, rather than L-lactic acid (3).
