高产(+)γ-内酰胺酶菌株的筛选与发酵产酶研究

从土壤中筛选获得高产(+)γ-内酰胺酶的微生物菌株,并鉴定和保藏为Delftia sp.CGMCC No.5755.对该Delfiia sp菌株的发酵产酶条件进行了研究,结果表明,最适发酵培养基为:蔗糖30 g/L,蛋白胨30 g/L,牛肉膏25 g/L,乙酰胺5 g/L,MgS04 1 g/L;最适发酵温度及初始pH分别为32℃和pH 7.0.该菌株在上述条件下发酵培养20 h,菌体生物量为16.0 g/L,(+)γ-内酰胺酶的酶活为692 U/L.采用Delftia sp.静息细胞对100 g/L的外消旋底物2-氮杂二环-2.2.1]-庚烷-5-烯-3-酮(简称(±)γ-内酰胺)的水解拆分反应中,产物(-)γ-内酰胺光学纯度大于99.9％e.e.,转化率为53.7％.研究为生物催化法高效制备光学纯(+)γ-内酰胺提供了可行的途径.

Isolation and Fermentation Optimization of a(+)γ-Lactamase-producing Strain

A(+)γ-lactamase-producing microorganisms with high enantioselectivity was isolated from soil,and was identified and deposited as Delftia sp.CGMCC No.5755.The optimized fermentation medium consists of: 30 g/L sucrose,30 g/L peptone,25 g/L beef extract,5 g/L acetamide,and 1 g/L MgSO4;and the optimum temperature and initial pH are 32 ℃ and pH 7.0,respectively.Under the optimized conditions,15.6 g/L of Delftia cells and 687 U/L of(+)γ-lactamase were obtained after 20 h of fermentation.Biotransformation using Delftia resting cells was carried out at 100 g/L of(±)γ-lactam substrate,the optical purify of product(-)γ-lactam reached over 99.9%e.e.,and the conversion rate was 53.7% after 12h.The study provides a feasible approach for the biocatalytic preparation of(-)γ-lactam.