同步糖化淀粉质原料高产L-苹果酸菌株的选育

本研究选育了一株高糖化酶活性且传代稳定的突变株,在不添加商品糖化酶的情况下,可以通过对脱胚玉米粉的糖化发酵生产苹果酸。以Aspergillus oryzae(米曲霉)ME303为出发菌株,经ARTP诱变,2-脱氧葡萄糖(2-DG)筛选压力诱变处理,并通过比较原始菌株和诱变菌株的糖化酶活力和代谢特征,获得一株性能稳定的糖化酶活力较高的L-苹果酸生产菌株A. oryzae SS3,当粗淀粉质原料——脱胚玉米粉作为单一碳源时,30 ℃、150 r/min摇瓶发酵96 h后,糖化酶表现出较高的活力,为320.0 U/mL,与原始菌株相比(220.0 U/mL),酶活增加了45.45%,发酵后191 h,A. oryzae SS3菌株同步糖化发酵产苹果酸达到41.39 g/L,与原始菌株相比(33.98 g/L)提高了21.80%,为目前报道的利用淀粉质原料生产苹果酸且酶活性较高的米曲霉突变菌株,可进一步降低生产成本。

Breeding of L-malic Acid Strain with High Yield from Synchrosaccharified Starch Raw Material

In this study,the strain of Aspergillus oryzae(ME303)was screened by mutagenesis with 2-deoxyglucose 2-DG.By comparing the glucoamylase activity and metabolic characteristics of the original strain and the mutagenesis strain,a stable glucoamylase producing strain SS3 was obtained.The optimal conditions were as follows:fermented at 30℃for 150 r/min for 96 h,the glucoamylase showed high activity.The activity of the enzyme was increased by 45.45%compared with the original strain.The simultaneous saccharification and fermentation of A.oryzae SS3 were produced 41.39 g/L-malic acid at 191 h after fermentation,and 33.98 g/L compared with the original strain,which was increased 21.80%for the present reported use of starchy raw material by A.oryzae.This strain is a mutant of A.oryzae which had used crude starch raw materials to produce malic acid more efficiently and at a lower cost.