降解棉秸秆耐热菌株的鉴定及降解条件优化

Identification of degradation cotton straw thermophilic strains and optimal degradate conditions

摘要:

【目的】鉴定从新疆棉花秸秆高温堆肥中分离出的两株耐热真菌Z1、Z2的属种, 并通过优化影响菌株产生纤维素酶的因素来提高菌株对秸秆的降解率。【方法】经形态学和菌株的ITS区克隆与序列分析确定属种, 以液体摇瓶发酵产滤纸酶活性(FPA)变化为衡量指标, 对Z1、Z2以及二者混合菌(MS)的纤维素酶产生条件进行优化。【结果】菌株Z1为曲霉属烟曲霉(Aspergillus fumigatus Fresen), Z2为蚀丝霉属(Myceliophthora Cost.)。确定Z1以棉秸秆为碳源、以NaNO3为氮源、起始pH 9.5、接种量11%、50 °C摇床培养10 d, 对棉秸秆降解率为10.19%; Z2以麦秸秆为碳源、以NaNO3为氮源、起始pH 5.5、接种量9%、50°C摇床培养10 d, 对麦秆降解率为27.50%; MS以棉花秸秆为碳源、以蛋白胨为氮源、起始pH 5.5、接种量11%、50°C摇床培养10 d, 对棉秸秆的降解率为53.45%。【结论】实验表明, MS (Z1、Z2混合)对秸秆的降解效果优于单株菌, 降解率达到一半以上, 两株耐热真菌在降解棉花秸秆、小麦秸秆等农作物废弃秸秆中具有较高的应用价值。

Abstract:

[Objective] Two thermophilic fungal species which were isolated from the compost of cotton residue in Xinjiang were identified, and increased degradation rate of straw by optimizing the impact factors for cellulase production. [Methods] Two thermophilic fungal species were identified by morphological observation and analyzed the clone of the ITS gene fragment, The filter paper enzyme activity (FPA) of fungi was determined when they grown in a series of liquid state media containing pretreated natural cellulose as the carbon source, different nitrogen source, different initial pH, different inoculated amount and culture time, by analyzing the change of the FPA. [Results] Z1 is Aspergillus fumigatus Fresen and Z2 belongs to Myceliophthora Cost. (homology 97%). The filter paper enzyme activity (FPA) of fungi was determined when they grown in a series of liquid state media containing pretreated natural cellulose as the carbon source, different nitrogen source, different initial pH, different inocu-lated amount and culture time, by analyzing the change of the FPA, we had got the optimal conditions of fermentation. Under the optimal conditions, the decomposing (cotton residue) rate of Z1 was 10.19% and MS was 53.45% for 10 days, the decomposing (wheat straw) rate of Z2 was 27.50% for 10 days. [Conclusion] Degradation rate of straw MS better than single strains was more than half. It has great potential in recycling natural cellulose of Xinjiang when applied the fungal, which can degrade not only cotton residue but also wheat and rice straw, it has great potential for further apply in straw degradation.