一株降解纤维素的放线菌分离筛选及发酵条件优化

    Isolation, screening, and optimization of fermentation conditions for a cellulose-degrading actinomycete

    • 摘要: 为了筛选纤维素降解菌,并对其产酶条件进行优化,采用羧甲基纤维素(CMC)-刚果红染色法进行初筛,以CMC酶活力和滤纸(FPA)酶活力为指标复筛,对目标菌株进行形态观察、生理生化分析及分子生物学鉴定,并对其产酶条件进行单因素优化,然后以CMC酶活力和FPA酶活力为响应值进行响应面优化。结果表明:筛选获得一株高产纤维素酶的菌株XL-1,经形态观察、生理生化特征和16S rDNA序列分析鉴定为橙灰链霉菌(Streptomyces aurantiogriseus);采用响应面优化其产酶条件,当发酵温度30 ℃、发酵时间4 d、pH 7、接种量10%时,得到CMC酶活力为(13.29 ±0.05) U/mL、FPA酶活力为(4.52 ±0.04) U/mL。试验结果可以为纤维素酶的工业生产及应用提供参考。

       

      Abstract: To identify cellulose-degrading bacteria, optimize enzyme-producing conditions of the target bacteria, and investigate their degradation effect on wheat bran, the carboxymethyl cellulose (CMC)-Congo red staining method was employed for initial screening. Subsequent re-screening employed CMC and Filter Paper Assay (FPA) enzyme activities as indicators. Morphological observations, physiological assessments, biochemical analysis, and molecular biological identification were conducted on the strain. Single-factor optimization was performed on its enzyme-producing conditions, followed by response surface methodology (RSM) optimization using CMC enzyme activity and FPA enzyme activity as response values. The results indicated that a high-cellulase-producing strain, XL-1, was obtained. Based on morphological observation, physiological and biochemical characteristics, and 16S rDNA sequence analysis, the strain was identified as Streptomyces aurantiogriseus. After optimizing its enzyme-producing conditions using RSM, with a fermentation temperature of 30 ℃, fermentation time of 4 days, pH of 7, and inoculum size of 10%, the CMC enzyme activity reached (13.29±0.05) U/mL and the FPA enzyme activity reached (4.52±0.04) U/mL. The experimental results can provide strain resources and optimal enzyme-producing conditions references for the industrial production and application of cellulase.

       

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