Effects of industrial storage on the bioreduction capacity of brewer's yeast.
The effects of industrial storage on the changes of the cell viability and the activities of intracellular alcohol dehydrogenase (ADH) and glucose-6-phosphate dehydrogenase (G6PDH) in brewer's yeast, and the corresponding capacity for the bioconversion of ethyl-3-oxobutanoate (EOB) to ethyl (S)-3-hydroxybutanoate ((S)-EHB), were investigated. The viability of fresh brewer's yeast cells stored in industrial circulating cooling water at 1-2 degrees C showed 4 and 15% drop after the storage of 7 and 15 days, respectively, after which cells died rapidly. The pretreatment of the stored brewer's yeast cells by washing and screening significantly enhanced cell viability during industrial storage. The intracellular levels of ADH and G6PDH after permeabilization of these stored cells with cetyltrimetylammonium bromide (CTAB) were much higher, which showed only slight decrease within 2 weeks during the industrial storage. When the stored cells after the permeabilization treatment was used as the biocatalyst at 90-120 g/L, EOB was converted almost completely into enantiopure (S)-EHB with an enantiomeric excess (ee) more than 99% and a yield of over 96%, by fed-batch bioconversion of 560 mM EOB within 6 h.
Yu
Ming-An
MA
Chongqing Key Laboratory of Biochemistry and Molecular Pharmacology, College of Pharmaceutical Sciences, Chongqing Medical University, Chongqing, 400016, China. minganyu666@yahoo.com.cn
Hou
Yi
Y
Gong
Geng-Hao
GH
Zhao
Quan
Q
Zhu
Xiao-bing
XB
Jiang
Lan
L
Yang
Xiao-lan
XL
Liao
Fei
F
D000426:Alcohol Dehydrogenase / Q000378:metabolism*; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism*; D007218:Industrial Microbiology; D050296:Microbial Viability; D011309:Preservation, Biological / Q000379:methods*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*
D029701:Saccharomyces cerevisiae Proteins; D000426:Alcohol Dehydrogenase; D005954:Glucosephosphate Dehydrogenase