Effect of Neutral Trehalase Genes Deletion on the Freeze-tolerant Characteristics of Bread Yeast
Article
Figures
Metrics
Preview PDF
Reference
Related
Cited by
Materials
Abstract:
The effect of neutral trehalase genes deletion on the bread yeast was investigated by analysis of the growth curve, biomass, specific growth rate, neutral trehalase activity, intracellular trehalose content, degradation speed of intracellular trehalose, survival ratio, specific fermentation ability, CO2 production before and after freezing, and the relative fermentation ability after freezing of trehalase genes deletion mutants and the parental strain (BY6-9α). It was found that the trehalase genes had less significant effects on biomass, specific growth rate, intracellular trehalose content and the specific fermentation ability of bread yeast. The degradation speed of intracellular trehalose of TL-101(nth1△)and TL-201(nth1△nth2△) was 9.22% and 15.60% lower than the parental strain respectively. Meanwhile, the CO2 production after freezing of TL-101 and TL-201 increased 63.04% and 65.22% compared with the parental strain. Furthermore, the survival ratio of TL-101 and TL-201 after freezing for 28 days at -20 ℃ was 91.06% and 103.01%, respectively, higher than the parental strain, and the relative fermentation ability after freezing was 95.95% and 116.04% higher than the parental strain, respectively. These results revealed that deletion of NTH1 gene sufficiently improved the freeze-tolerance characteristics of bread yeast, and there was a negative correlation between the degradation speed of intracellular trehalose and freeze-tolerance characteristics of bread yeast. On the other hand, the freeze-tolerant characteristics of TL-102(nth2△) were not significant difference as that of the parental strain, which indicated that single NTH2-deleted was not significantly influence on the freeze-tolerant characteristics of bread yeast.
