[Construction and stress tolerance of trehalase mutant in Saccharomyces cerevisiae].
OBJECTIVE
Accumulation of trehalose is critical in improving the stress tolerance of Saccharomyces cerevisiae. Two enzymes are capable of hydrolyzing trehalose: a neutral trehalase (NTH1) and an acidic trehalase (ATH1). We constructed trehalase disruption mutants to provide a basis for future commercial application.


METHODS
To retain the accumulation of trehalose in yeast cell, we constructed diploid homozygous neutral trehalase mutants (Deltanth1), acid trehalase mutants (Deltaath1) and double mutants (Deltaath1Deltanth1) by using gene disruption. We tested mutants'trehalose content and their tolerance to freezing, heat, high-sugar and ethanol concentrations.


RESULTS
These trehalase disruption mutants were further confirmed by PCR amplification and southern blot. All mutant strains accumulated higher levels of cellular trehalose and grew to a higher cell density than the isogenic parent strain. In addition, the levels of trehalose in these mutants correlated with increased tolerance to freezing, heat, high-sugar and ethanol concentration.


CONCLUSIONS
The improved tolerance of trehalase mutants may make them useful in commercial applications, including baking and brewing protein.
Lv
Ye
Y
Key Laboratory of Industrial Microbiology, Tianjin University of Science and Technology, Tianjin 300457, China. jessica0312@163.com
Xiao
Dongguang
D
He
Dongqin
D
Guo
Xuewu
X
D050260:Carbohydrate Metabolism; D000431:Ethanol / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D009154:Mutation; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism; D013312:Stress, Physiological; D014198:Trehalase / Q000235:genetics* / Q000378:metabolism; D014199:Trehalose / Q000378:metabolism
D029701:Saccharomyces cerevisiae Proteins; D000431:Ethanol; D014199:Trehalose; C097090:ATH1 protein, S cerevisiae; D014198:Trehalase