桑天牛幼虫肠道菌产纤维素酶条件优化

Optimization of cellulase production conditions by Apriona germari larval gut bacteria

使用CMC-刚果红染色法从桑天牛幼虫肠道中筛选分离出产纤维素酶的Gibbsiella acetica SGA菌株,并对其进行形态学鉴定、分子生物学鉴定和发酵条件的优化。通过单因素试验,确定了菌株的最佳培养条件,包括培养时间24 h、起始pH值为7、接种量为5%、装液量为100 mL、培养温度为32℃、碳源为14 g/L的葡萄糖、氮源为6 g/L的酵母粉。通过正交优化试验,确定最好配比为葡萄糖添加量为1.4%,酵母粉添加量为0.6%,装液量为50%,pH值为6。在此最优发酵条件下,产纤维素酶活力达到203.24μg/(h·mL),比初始培养条件下提高了1.35倍。这项研究为进一步应用G.acetica SGA菌株提供了理论基础,有利于丰富纤维素降解的菌种资源。

In this study,we screened and isolated a cellulase-producing strain Gibbsiella acetica SGA from the gut of the Apriona germari larvae using CMC-Congo red staining method,and conducted morphological identification,molecular biological identification,and optimization of fermentation conditions.Through single-factor experiments,optimal cultivation conditions for the strain were determined,including a 24-hour incubation period,initial pH of 7,5%inoculum size,100 mL liquid volume,a cultivation temperature of 32℃,14 g/L glucose as the carbon source,and 6 g/L yeast extract as the nitrogen source.Orthogonal optimization experiments established the best ratio of glucose at 1.4%,yeast extract at 0.6%,liquid volume at 50%,and pH at 6.Under these optimized fermentation conditions,the CMC enzyme activity of SGA reached 203.24μg/h/mL,representing a 1.35-fold increase compared to the initial culture conditions.This research lays a foundation for the future application of the G.acetica SGA strain,facilitating the diversification of cellulose-degrading microbial resources.