纤维素降解真菌Y5的筛选及其对小麦秸秆降解效果

Isolation and Identification of a Cellulose Degrading Fungus Y5 and Its Capability of Degradating Wheat Straw

为了利用纤维素降解菌促进作物秸秆快速腐解还田,解决秸秆资源浪费和污染环境问题,进行了高效秸秆纤维素降解微生物的筛选和降解效果研究.采用固体平板和液体摇瓶培养,从黑龙江黑土样品中筛选出1株能够降解羧甲基纤维素、秸秆木质纤维素、高产纤维素酶的丝状真菌Y5,通过形态学观察和ITS rDNA序列分析对该真菌进行了初步鉴定.利用DNS还原糖方法,对菌株在不同的培养时间、纤维素类型、氮源种类以及初始pH值情况下纤维素酶活力进行了研究.采用失重法、液体摇瓶法对菌株降解小麦秸秆的能力进行了研究.结果表明,筛选的秸秆降解菌株Y5经鉴定为赭绿青霉(Penicilliumochrochloron).菌株Y5液体培养4 d的全酶活(FPA)和内切酶活(EG)最高,分别为53 IU/mL和55 IU/mL,比对照菌株(绿色木霉AS3.3711)高出22.6%和18.2%;Y5菌株以小麦秸秆为作用底物时的酶活最高,2种酶活分别比对照菌株提高27.5%和24.8%;以NaNO3为氮源时酶活性最大,FPA和EG比菌株AS3.3711分别提高35.7%和14.9%;培养液初始pH为6时全酶活最大为51.4 IU/mL.菌株Y5培养10 d降解小麦秸秆纤维素、半纤维素、木质素分别达到了43.5%、49.7%和9.3%,对小麦秸秆纤维素与半纤维素降解能力强.赭绿青霉Y5对小麦秸秆纤维素具有很强的降解能力,其纤维素酶活高于已报道的菌株,该菌株的获得为秸秆降解菌剂的研究与应用提供了具有较高潜力的菌种.

In order to promote the decomposition of crop straw and return it to soil rapidly and solve the problems such as the waste of straw resources and pollution, we screened the bacterial or fungi with high-efficient degradation of straw lignocelluloses and studied its capability of degradating wheat straw. An isolate of filamentous fungus with higher eellulase activity and ability to decompose CMC and straw lignocellulose was screened from black soil samples taken from Heilongjiang province by using the soil dilution, plating and liquid culture methods. Morphological status on various media, and ITS rDNA sequences homology analysis were performed to identify the taxonomy of the isolate. The effects of different time, different N resources, different cellulose resources and different pH values on enzyme activities produced by fungus was analyzed, and The ability of wheat straw degradation of Y5 was determinated by using weight loss method and liquid culture. The fungus was identified as Penicillium ochrochloron and named Y5. Filter paper activity（FPA） and endo-1,4-β-D-glucanase （EG） were both reached the maximum after the first fourth day inoculated, averaged 53 IU/mL and 55 IU/mL, respectively, which were 22. 6% and 18.2% higher than that of strain Trichoderma viride（ AS3. 3711 ） , respectively. Enzyme activities were the highest under the condition of wheat straw used as C resources, which were 27.5% and 24. 8% higher than that of AS3. 3711. The FPA and EG activities were 35.7% and 14. 9% higher than the AS3. 3711 strain with NaNO3 as nitrogen source. The optimal pH value of liquid culture was 6. The cellulose, hemicellulose and lignin contents were degraded by 43.5% , 49.7% and 9. 3% after the first 10 days inoculated, respectively, which indicated that Y5 had strong enzyme activities on degradation of cellulose and hemicelluloses of wheat straw. The PeniciUium ochrochloron Y5 has strong ability of wheat straw cellulose degradation, and its cellulase activities are higher than some published researches. The Penicillium ochrochloron Y5 strain has the great potential in research and development for inoculant of crop straw decomposition.