Biocatalytic Process of t-Butyl 6-cyano-(3R,5R)-dihydroxylhexanoate by Immobilized Cells
Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, China
Abstract：Chiral diol t-butyl 6-cyano-(3R,5R)-dihydroxyhexanoate synthetic process was established by using the celite-polyethyleneimine (PEI)-glutaraldehyde (GA) immobilized E. coli BL21(DE3)/pCDFDuet-gdh-cr cells in present work. The optimized batch bioconversion conditions for the celite-PEI-GA immobilized E. coli BL21(DE3)/pCDFDuet-gdh-cr were as follows: 30℃, pH 7.0, 100 g/L immobilized cell loading size, 50 g/L t-butyl 6-cyano-(5R)-hydroxyl-3-oxolhexanoate, mass ratio of glucose to t-butyl 6-cyano-(5R)-hydroxyl-3-oxolhexanoate at 1:1 (w/w). Results demonstrated that the celite-PEI-GA immobilized E. coli BL21(DE3)/pCDFDuet-gdh-cr cells can be reused for five intermittent batches. Further, its catalytic conditions were studied in the stirred tank bioreactor and packed bed reactor. Under the optimized biocatalytic conditions, 570 g/L t-butyl 6-cyano-(5R)-hydroxyl-3-oxolhexanoate was completely converted by the celite-PEI-GA immobilized cells in 72 h in the packed-bed bioreactor, which was improved 185% and 107.3% in comparison with those of the free cells and the celite-PEI-GA immobilized cells in the stirred tank bioreactor, respectively.
