具有差向选择性还原(R)-6-氰基-5-羟基-3-羰基己酸叔丁酯活性的微生物菌株筛选和鉴定

从土样中分离得到一株具有差向选择性还原(R)-6-氰基-5-羟基-3-羰基己酸叔丁酯活性的微生物菌株ZJB-09225,经生理生化特征鉴定和18S rDNA测序后鉴定为卡里比克毕赤酵母(Pichia caribbic ZJB-09225)。研究结果发现,在最适发酵条件下培养32 h,生物量为8.8 g/L,体积酶活达7.2 U/L;P.caribbic ZJB-09225最适作用温度、最适作用pH值分别为35℃和7.5。在最适的催化条件下,P.caribbic ZJB-09225细胞催化50.0 g/L(R)-6-氰基-5-羟基-3-羰基己酸叔丁酯3 h后,产物6-氰基-(3R,5R)-二羟基己酸叔丁酯得率3.4%,产物d.e.值99.5%以上。

Screening for microbe displaying diastereoselective ketoreductase activity towards t-butyl 6-cyano-(5R)-hydroxyl-3-oxohexanoate

A strain ZJB-09225 displaying diastereoselective ketoreductasc activity towards t-butyl 6-cyano- （5R）-hydroxyl-3-oxohexanoate was isolated and identified as Pichia caribbic by phenotypic, biochemical characteristics and alignment analysis of 18S rDNA sequence. Results revealed that after 32h culture under the optimized fermentation conditions, the volumetric activity and the biomass density of P. caribbic ZJB-09225 were 7.2 U/L and 8.8 g/L, respectively. P. caribbic ZJB-09225 was most active to t-butyl 6- cyano-（5R）-bydroxyl-3-oxohexanoate at 35 ℃ and pH 7.5. In addition,50. 0 g/L t-butyl 6-eyano-（5R）- hydroxyl-3-oxohexanoate was diastereoselectively reduced to t-butyl 6-cyano-（ 3R, 5R ）- dihydroxyhexanoate by P. caribbic ZJB-09225 for 3h, in a yield of 3.4% with d. e. value over 99.5%.