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Hua-Zhong Li

Publications and source records attributed to Hua-Zhong Li.

2 recordsLinked to original sources

[Torulopsis glabrata neomycin-resistant mutant abolishes pyruvate production with enhancement of glucose consumption rate].

To further increase the rate of glucose consumption by multi-vitamin auxotrophic yeast Torulopsis glabrata. A neomycin-resistant mutant N07, with the activity of F1-ATPase decreased roughly 35% but glucose consumed per cell was increased 38% than that of parent strain, was breed based on analysis of energy metabolic pathway. The typical inhibitors of F1F0-ATPase, DCCD, NaN3 and neomycin, depressed the F1-ATPase activity of parental strain but no effect on that of mutant strain. Strain N07 was cultured in a pyruvate fermentation medium containing 100g/L of glucose using flask. It was found that the rate of glucose consumption and pyruvate production were higher by 34% and 42.9% in the mutant than in the parent, respectively. However, the rate and yield of growth (about 24%) of the mutant was lower than that of the parent. The content of intracellular ATP of the mutant also decreased 23.7% than that of the parent. The activities of key enzymes in glycolytic pathway and electron transfer chain of the mutant and the parent were determined. Enzymatic analysis revealed that, compared with the parent strain CCTCC M202019. The activities of key enzymes, phosphofructokinase, pyruvate kinase, glyceraldyde-3-phosphate dehydrogenase of the mutant N07 increased 63.7%, 28.8% and 14.4%, respectively, all the key enzymes of electron transfer chain in the mutant N07 also increased roughly 10%.

Adenosine Triphosphate↗

[The decrease of the activity of electron transfer chain of Torulopsis glabrata enhanced pyruvate productivity].

Torulopsis glabrata CCTCC M202019 was mutated by ethidium bromide to screen for respiratory-deficient mutants. Seven mutants that produced pyruvate higher than that of the parent were subjected to the tests of the capability assimilating fermentable substrate (glucose) and non-fermentable substrates (glycerol and acetate) to characterize true respiratory-deficient mutants. Mutants RD-16, RD-17 and RD-18 were unable to assimilate acetate or glycerol and were therefore identified as respiratory-deficient mutants. Compared to the parent strain, the growth the intracellular ATP content of those mutants decreased by 21% - 29% and 15% - 21%, respectively, while the glucose consumption per cell and the pyruvate production per cell of those mutants were enhanced by 20.7% - 30.7% and 30.7% - 55.5%, respectively. Qualitative analysis of cytochromes involved in electron transfer chain showed that mutants RD-16 and RD-18 lacked both cytochrome aa3 and b, while mutant RD-17 lacked cytochrome b. Enzymes analysis indicated that the activities of ATPase, succinate-cytochrome c reductase (complex I ), complex I + III , complex II + III, and complex IV of those mutants decreased by 14.6% - 22.2%, 34% - 41%, 38.6% - 52.6%, 21% - 25%, and 150% - 630%, respectively. However, increased glucose consumption per cell was not observed in those mutants, which might be due to that the NADH generated in glycolysis can not be completely oxidized via electron transfer chain. To avoid the accumulation of NADH, 2.1 mmol/L acetaldehyde was added to the culture broth of mutant RD-17 at 26h of fermentation. Using this strategy, the amount of pyruvate produced increased by 21.6% while the fermentation time was shortened from 62h to 48h.

Acetaldehyde↗