Identification of a polysaccharide produced by the pyruvate overproducer Candida glabrata CCTCC M202019.
Candida glabrata has great potential for the accumulation of pyruvate as a preferred strain in pyruvate production by fermentation. However, its substrate conversion rate is relatively low. In this study, a novel polysaccharide containing α-1,4-glucosidic bonds was observed accidentally in screening a high-titer pyruvate strain by atmospheric and room temperature plasma mutagenesis of C. glabrata. Chemical analysis of the partially purified polysaccharide S4-C10showed the main components were 1.2% (w/w) protein and 94.2% (w/w) total sugar. Fourier transform infrared and molecular mass distribution analysis indicated that the main component (PSG-2) of S4-C10was a small molecular homogeneous protein-bound polysaccharide. Monosaccharide analysis of PSG-2 showed it consisted of glucose, mannose, and fructose. By optimizing the vitamin mix content, 77.6 g L-1S4-C10polysaccharide could be obtained after 72 h fermentation at 30 °C in 500-mL flasks. RT-qPCR analysis showed that transcriptional level of some key genes related to polysaccharide biosynthesis was upregulated compared to that of wild-type strain. By knocking out two most significantly upregulated genes, CAGL0H02695g and CAGL0K10626g, in the wild-type strain, the pyruvate consumption rate was significantly reduced in late pyruvate fermentation phase, while the titer of polysaccharides was reduced by 18.0%. Besides the potential applications of the novel identified polysaccharide, this study provided clues for increasing the conversion ratio of glucose to pyruvate in C. glabrata by further decreasing the accumulation of polysaccharides.
School of Biotechnology and Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu, 214122, China.
Zhengshan
Z
Luo
School of Biotechnology and Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu, 214122, China.|Synergetic Innovation Center of Food Safety and Nutrition, 1800 Lihu Road, Wuxi, Jiangsu, 214122, China.
Song
S
Liu
School of Biotechnology and Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu, 214122, China.|Synergetic Innovation Center of Food Safety and Nutrition, 1800 Lihu Road, Wuxi, Jiangsu, 214122, China.
Guocheng
G
Du
School of Biotechnology and Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu, 214122, China. zhoujw1982@jiangnan.edu.cn.|Synergetic Innovation Center of Food Safety and Nutrition, 1800 Lihu Road, Wuxi, Jiangsu, 214122, China. zhoujw1982@jiangnan.edu.cn.
Jingwen
J
Zhou
School of Biotechnology and Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu, 214122, China. jchen@jiangnan.edu.cn.|Synergetic Innovation Center of Food Safety and Nutrition, 1800 Lihu Road, Wuxi, Jiangsu, 214122, China. jchen@jiangnan.edu.cn.
Jian
J
Chen
D041221:Candida glabrata / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D005285:Fermentation; D005947:Glucose / Q000378:metabolism; D009005:Monosaccharides / Q000737:chemistry; D011134:Polysaccharides / Q000096:biosynthesis* / Q000737:chemistry* / Q000302:isolation & purification; D011506:Proteins / Q000378:metabolism; D019289:Pyruvic Acid / Q000378:metabolism*; D014815:Vitamins / Q000494:pharmacology
D009005:Monosaccharides; D011134:Polysaccharides; D011506:Proteins; D014815:Vitamins; D019289:Pyruvic Acid; D005947:Glucose
Glycogen synthase gene CAGL0H02695g and CAGL0K10626g; Organic acids; Protein-bound polysaccharide; Torulopsis glabrata; α-1,4-glucosidic bonds