We previously demonstrated the simplicity of oxygen-deprived
Corynebacterium glutamicum to produce
d-lactate, a primary building block of next-generation biodegradable plastics, at very high optical purity by introducing heterologous
D-
ldhA gene from
Lactobacillus delbrueckii. Here, we independently evaluated the effects of overexpressing each of genes encoding the ten glycolytic enzymes on
d-lactate production in
C.
glutamicum. We consequently show that while the reactions catalyzed by glucokinase (GLK), glyceraldehyde 3-phosphate dehydrogenase (GAPDH), phosphofructokinase (PFK), triosephosphate isomerase (TPI), and bisphosphate aldolase had positive effects on
d-lactate productivity by increasing 98, 39, 15, 13, and 10 %, respectively, in 10 h reactions in minimal salts medium, the reaction catalyzed by pyruvate kinase had large negative effect by decreasing 70 %. The other glycolytic enzymes did not affect
d-lactate productivity when each of encoding genes was overexpressed. It is noteworthy that all reactions associated with positive effects are located upstream of glycerate-1,3-bisphosphate in the glycolytic pathway. The
d-lactate yield also increased by especially overexpressing TPI encoding gene up to 94.5 %. Interestingly, overexpression of PFK encoding gene reduced the yield of succinate, one of the main by-products of
d-lactate production, by 52 %, whereas overexpression of GAPDH encoding gene increased succinate yield by 26 %. Overexpression of GLK encoding gene markedly increased the yield of dihydroxyacetone and glycerol by 10- and 5.8-fold in exchange with decreasing the
d-lactate yield. The effect of overexpressing glycolytic genes was also evaluated in 80 h long-term reactions. The variety of effects of overexpressing each of genes encoding the ten glycolytic enzymes on
d-lactate production is discussed.
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