菌物研究

为解决我国东北高寒地区低温环境下玉米秸秆不易降解的难题，利用平板快速筛选方法结合低温发酵培养对耐低温生长的45个真菌菌株进行筛选，获得能够在低温条件下同时产生漆酶、纤维素酶、半纤维素酶及过氧化物酶等多种木质素纤维素酶的6株真菌菌株，并对该6株菌株进行玉米秸秆低温腐解效果的评价，分别在处理10,20,30,40,50 d时测定其产生的木质素纤维素酶活性及其玉米秸秆中各组分的降解率。结果发现：在20℃条件下进行液体发酵培养10 d后，这些菌株产生的漆酶活性可达7.47 U/mL(L2431)和7.2 U/mL(X1957)，纤维素酶活可达239 U/mL (L743)和167 U/mL(L1675)，半纤维素酶活可达179.3 U/mL(YF410)、120.0 U/mL (H382)和113.3 U/mL (L2431)，过氧化物酶活可达为25.1 U/mL(L2431-3)、24.9 U/mL(2423)和15.9 U/mL(L2419)。6种菌株在低温条件下产生各种木质素纤维素酶活性达到最大值的时间不完全一致，且对玉米秸秆各组分的降解率存在着显著的差异（P<0.05），但对玉米秸秆组分的总降解率均随着时间的延长而增加，在处理50 d后的木质素降解率为18.2%～25.1%，纤维素降解率为24.1%～44.6%，半纤维素降解率为19.3%～26.3%，玉米秸秆总降解率为61.8%～87.0%。本研究筛选到在低温环境下生长较快且产酶能力较强和高效腐解玉米秸秆的真菌菌株，对我国东北寒冷地区玉米秸秆还田措施具有积极的推动作用和应用前景。

Forty-five fungal strains were screened to show the activity of laccase, cellulase,hemicellulose or peroxidase by a plate rapid screening method combined with fermentation culture at low temperatures. Within these strains, the high enzyme activity reached up to 7.47 U/mL(L2431) and 7.2 U/mL(X1957) for laccase, 239 U/mL(L743) and 167 U/mL(L1675) for cellulase, 179.3 U/mL(YF410), 120.0 U/mL(H382) and 113.3 U/mL(L2431-3) for hemicellulose, and 25.1 U/mL(L2431),24.9 U/mL(2423) and 15.9 U/mL(L2419) for peroxidase respectively under the liquid fermentation cultured at 20 ℃ in 10 days. After that, six strains were selected furthermore for the decomposition test of corn straws at low temperatures. Enzyme activities and degradation rates of corn straw components were measured in 10, 20, 30, 40 and 50 days, respectively, indicating that the time needed by the enzymes to reveal their maximum activities at the low temperature varied among strains. Although there existed significant differences in the degradation rates for each component of corn straws among the above strains, the total degradation rates of corn straws increased as time proceeded for all the strains. The degradation rates of lignin, cellulose and hemicellulose in corn straws were 18.2%-25.1%, 24.1%-44.6% and 19.3%-26.3%, respectively while the total degradation rates of corn straws were 61.8%-87.0% in 50 days. The above results demonstrated clearly that the fungal strains screened at the present study were able to adapt to the low-temperature environments without the loss of their high enzymatic activity and high efficiency in decomposition of corn straws, providing strong and positive evidence for future promotion and application of straw returning measures in the cold areas of northeast China.