半纤维素酶高产菌株的筛选及产酶条件的研究

Screening of Hemicellulase Producing Strains and Enzyme Production Conditions

以半纤维素为唯一碳源,采用平板透明圈和摇瓶发酵相结合的方法,筛选得到1株半纤维素酶高产菌株Hc-3,经形态学初步鉴定为曲霉属.通过液体发酵对该曲霉菌株发酵生产半纤维素所需碳源、氮源、培养温度、起始pH、培养时间等进行研究,结果表明上述因素对酶产量均有一定的影响.在单因素结果的基础上,设计3因素3水平的正交试验,根据试验结果确定菌株Hc-3发酵产酶的最佳条件:豆粕20 g/L,(NH4)2SO43 g/L,装液量80 mL(250 mL三角瓶),培养温度30℃,起始pH值为5.5,培养时间46 h,发酵液半纤维素酶活性可以达到2 000 U/mL以上,其中,起始pH值为影响最为明显的因素.

Hemicellulase is widely applied to food and feedstuff fields. In this research,by using hemi- cellulose as only carbon source a highly hemicellulase-producing strain Hc-3 was screened from the soil samples, by two-step method based on transparent ring and shake-flask. The strain was preliminarily iden- tified as Aspergillus spp. by morphological taxonomy. The effect of some factors on hendcellulase produc- tion was studied, which includes carbon source, nitrogen source, the culture time, the temperature, the ini- tial pH, and the results indicated that all factors had certain effect on the output of enzyme. At the basis of the result of single factor tests, the orthogonal test were designed. The results showed that the optimal cul- ture condition for enzyme production was： bean cake 20 g/L, （ NH4 ） 2 SO4 3 g/L, initial pH 5.5,80 mL medium in 250 mL flask, 30 ℃, culture for 46 h. Under the optimized fermentation process, hemicellulase production by strain 3# was increased to 2 000 U/mL. Initial pH was the most obvious factor.