牛粪堆肥中纤维素高效降解菌的筛选与产酶条件优化

Screening of efficient cellulose degrading bacteria in cow manure compost and optimization of enzyme production conditions

摘要:

【背景】纤维素是一种有待开发利用的生物质资源，对于能源危机、环境污染问题的解决具有重要作用。【目的】从牛粪堆肥中分离出产纤维素酶的细菌，研究该菌株的纤维素降解能力。【方法】采用纤维素固体平板刚果红染色法进行初筛、液体发酵纤维素酶活测定法进行复筛。【结果】筛选获得一株具有高产纤维素酶活性的解淀粉芽孢杆菌(Bacillus amyloliquefaciens)，命名为N5。单因素分析试验结果显示，菌株N5具有较好的pH、温度和盐度耐受性，正交优化试验结果表明，菌株N5产纤维素酶的最佳条件为：发酵初始pH 5.0，发酵时间96 h，发酵温度40 ℃。在此条件下，羧甲基纤维素(carboxymethyl cellulose, CMC)酶活为189.27 U/mL。此外，菌株N5能够在7 d内使水稻秸秆减重率达到19.35%。扫描电镜结果表明菌株N5能够有效促进水稻秸秆降解。【结论】菌株N5具有较高的纤维素酶活力，具有开发成高效好氧堆肥菌剂的潜质，这为固体废弃物中纤维素的生物转化提供了优质菌种资源。

关键词:纤维素降解;解淀粉芽孢杆菌;产酶条件;秸秆降解

Abstract:

[Background] Cellulose is a biomass resource to be developed and utilized, which is important for solving energy crisis and environmental pollution. [Objective] To isolate cellulase-producing bacteria from cow manure compost and investigate their cellulose degradation ability. [Methods] The cellulose solid plate Congo red staining method was used for preliminary screening, followed by liquid fermentation and cellulase activity measurement for secondary screening. [Results] A bacterium with high cellulase activity was isolated and identified as Bacillus amyloliquefaciens strain N5. Single-factor analysis experiments demonstrated that strain N5 exhibited good tolerance to pH, temperature, and salinity. Orthogonal optimization experiments revealed that the optimal conditions for cellulase production by strain N5 were an initial fermentation pH of 5.0, fermentation time of 96 hours, and fermentation temperature of 40 ℃. Under these conditions, the enzyme activity reached 189.27 U/mL. Furthermore, strain N5 achieved a 19.35% reduction in weight of rice straw within 7 days, indicating its effective promotion of rice straw degradation. Scanning electron microscopy results confirmed the ability of strain N5 to facilitate rice straw decomposition. [Conclusion] Strain N5 exhibits high cellulase activity and holds potential for developing efficient aerobic composting agents. It provides a valuable bacterial resource for the biological transformation of cellulose in solid waste.

Key words:cellulose degradation;Bacillus amyloliquefaciens;enzyme production conditions;straw degradation