耐低温降解纤维素菌株筛选、鉴定及产酶条件优化

低温是制约北方寒冷地区秸秆生物持续、高效转化的主要因素,也是影响北方寒区沼气发酵全年持续运行的关键因素。研究以秸秆利用富集限制性培养技术,从腐殖质丰富的大庆扎龙湿地土样中筛选出1株产生较高纤维素酶的耐低温降解纤维素菌株,经菌株18S rDNA序列及形态学分析,鉴定该菌株为奥尔森青霉属,命名为L-11。经响应曲面法优化产酶条件,获得影响奥尔森青霉菌株L-11产酶最优条件为麸皮11.05 g·L~(-1)、豆粉2.32 g·L~(-1)、初始pH 5.23、卵磷脂2.30 g·L~(-1),羧甲基纤维素酶活(CMCase)达48.809 IU·mL~(-1)。低温下菌株L-11具有较强的纤维素降解能力,在沼气生产领域应用前景良好,可为高转化能力基因菌株改良及富含纤维素类废弃物综合利用提供菌种资源。

Screen,identification and optimization of enzyme-producing conditions of a low temperature-resistant cellulose degradation strain

Low temperature was key factor restricting high continuous efficiency conversion of straws, also limiting the continuous operation of biogas fermentation in cold regions of North China. A newly isolated low temperature-resistant strain was successfully isolated from humus-rich soil in Daqing Zhalong wetland region by restrictive cultures and was found to be a potential cellulase producer. The isolate was identified as Penicilliumon basis of 18 S ribosomal DNA sequencing and morphological observation. The optimal conditions affecting the enzyme production of strain L-11 were obtained by response surface methodology(RSM). CMCase reached the maximum 48.809 IU·mL~(-1) under optimized conditions, which were bran 11.05 g ·L~(-1), soybean flour 2.32 g ·L~(-1), initial pH 5.23 and 2.30 g ·L~(-1) lecithin, indicating a high potential cellulose-degradation capacity and its better application prospect in biogas utilization field under cold environment. It also provided important seed resources for the improvement of genetic strain with high conversion capacity and comprehensive utilization of cellulose waste.