高效降解纤维素低温真菌的筛选、鉴定及发酵优化

Screening, identification and fermentation optimization of cold-adapted fungi with high efficiency of cellulose degradation

摘要:

【背景】纤维素的生物转化已经成为能源、环境和化工领域的研究热点，但可降解纤维素的低温真菌鲜有报道。【目的】从西藏高海拔的植物根际土壤中筛选具有高效降解纤维素能力的低温真菌，优化其产酶条件，为其工业化应用奠定基础。【方法】利用稀释平板涂布法、刚果红定性及酶活定量分析进行低温降解菌的筛选；根据菌株形态学特征及ITS rDNA序列分析对其进行鉴定；利用单因素实验和响应面优化法优化其产酶条件。【结果】分离筛选到一株高效产纤维素酶的低温真菌NLS-2；鉴定菌株NLS-2为青霉菌属；在低温15 °C下，其产纤维素酶的最佳培养条件为稻草粉2.5%，酵母粉0.5%，KH2PO4 0.5%，发酵时间 7 d，pH 6.5，摇床转速170 r/min。【结论】青霉菌NLS-2可在低温条件下生长并具有较强的纤维素酶生产能力，具有良好的应用前景。

Abstract:

[Background] The bioconversion of cellulose has become a research hotspot in the energy, food and chemical industries. However, there are few reports on the cold-adapted fungi with the ability to degrade cellulose. [Objective] To isolate and screen the cold-adapted fungi with high efficiency of cellulose degradation from the rhizosphere soil in the high altitude area of Tibet, and optimize their enzyme production conditions, so as to lay a foundation for their industrial application. [Methods] Cellulolytic strains were screened by the dilution plate coating method, the qualitative analysis of Congo red and the quantitative analysis of enzyme activity. Strains were identified by morphology and ITS rDNA sequence analysis. The fermentation condition was optimized by single factor and response surface methodology. [Results] A cold-adapted fungus, namely NLS-2, was obtained and identified as Penicillium sp. At 15 °C, the optimized culture conditions of strain NLS-2 for producing cellulase were straw powder 2.5%, yeast powder 0.5%, KH2PO4 0.5%, fermentation time 7 d, pH 6.5, shaker speed 170 r/min. [Conclusion] Penicillium sp. NLS-2 can grow at low temperature and efficiently produce cellulose, which has a good application prospect.