title: Reactions upstream of glycerate-1,3-bisphosphate drive Corynebacterium glutamicum (D)-lactate productivity under oxygen deprivation.
abstract: 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.
authors.affiliation: Research Institute of Innovative Technology for the Earth (RITE), 9-2, Kizugawadai, Kizugawa-shi, Kyoto, 619-0292, Japan.
authors.forename: Yota
authors.initials: Y
authors.lastname: Tsuge
authors.forename: Shougo
authors.initials: S
authors.lastname: Yamamoto
authors.forename: Masako
authors.initials: M
authors.lastname: Suda
authors.forename: Masayuki
authors.initials: M
authors.lastname: Inui
authors.forename: Hideaki
authors.initials: H
authors.lastname: Yukawa
mesh_terms: D001483:Base Sequence; D048230:Corynebacterium glutamicum / Q000378:metabolism*; D017931:DNA Primers; D005986:Glyceraldehyde 3-Phosphate / Q000378:metabolism*; D007773:Lactates / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D016133:Polymerase Chain Reaction
chemical_list: D017931:DNA Primers; D007773:Lactates; D005986:Glyceraldehyde 3-Phosphate; D010100:Oxygen