能低温降解木质纤维素的大型真菌菌株的筛选

Screening of macrofungal strains capable of degrading lignocellulose at low temperatures

摘要:

目的 为发掘具有高效降解秸秆能力的微生物资源，提高秸秆在低温条件下的资源化利用效率，对955株大型真菌的木质纤维素降解能力进行了筛选。方法 采用平板筛选法初步筛选具有羧甲基纤维素酶(carboxymethyl cellulase, CMCase)、木聚糖酶(xylanase)和漆酶(laccase)活性的菌株；通过滤纸崩解试验进一步筛选具备纤维素降解能力的菌株；对筛选得到的菌株进行液体发酵培养，并在第3、6、9和12天测定其酶活性，以筛选出降解木质纤维素能力较强的优势菌株。结果 筛选得到11株在低温(15 ℃)条件下具有较强木质纤维素降解能力的优势菌株，分别为香栓孔菌(Trametes suaveolens) ZRL20181126、乳白耙齿菌(Irpex lacteus) ZRL20200020、乳白蛋巢菌(Crucibulum leave) ZRL20211707、韧革菌(Stereum hirsutum) ZRL20211291、糙皮侧耳(Pleurotus ostreatus) GX20170029、枫生射脉革菌(Phlebia acerina) ZRL20221433、黄斑蘑菇(Agaricus xanthodermus) QL20170055、灰孔新小层孔菌(Neofomitella fumosipora) GX20170468、多瓣鳞伞(Pholiota multicingulata) GX20170329、褐伞残孔菌(Abortiporus biennis) GX20172649和黄小蜜环菌(Armillaria cepistipes) ZRL20190819。其中，乳白蛋巢菌、黄斑蘑菇和多瓣鳞伞是首次报道具有较高木质纤维素降解能力的菌株。测定结果显示，这11株菌的羧甲基纤维素酶、木聚糖酶和漆酶的最高活性分别达到262.31、91.03和196.50 U/mL。香栓孔菌的羧甲基纤维素酶活性在15 ℃条件下达到168.17 U/mL，显著高于常温条件下的67.88 U/mL；糙皮侧耳的羧甲基纤维素酶活性为150.78 U/mL，漆酶活性为154.32 U/mL；韧革菌的漆酶活性为63.27 U/mL，是常温条件下的2倍。结论 本研究筛选得到11株在低温(15 ℃)条件下降解木质纤维素能力较强的优势菌株，为寒冷地区木质纤维素资源的降解及低温工业应用提供了重要的理论支持。

关键词:低温耐受;大型真菌;木质纤维素降解

Abstract:

Objective To mine the macrofungal strains capable of efficiently degrading straw at low temperatures, thereby improving the utilization efficiency of straw resources, we measured the lignocellulose degradation abilities of 955 macrofungal strains.Methods First, we employed the plate method to screen the strains with carboxymethyl cellulase, xylanase, and laccase activities. Then, we carried out a filter paper degradation test to screen the cellulose-degrading strains. Finally, we performed liquid fermentation with the selected strains and measured their enzyme activities on days three, six, nine, and 12 to identify the dominant strains with strong lignocellulose-degrading abilities.Results We identified 11 macrofungal strains exhibiting strong lignocellulose degradation capabilities at a low temperature (15 ℃). The 11 strains were Trametes suaveolens, Irpex lacteus, Crucibulum laeve, Stereum hirsutum, Pleurotus ostreatus, Phlebia acerina, Agaricus xanthodermus, Neofomitella fumosipora, Pholiota multicingulata, Abortiporus biennis, and Armillaria cepistipes. Notably, C. laeve, A. xanthodermus, and P. multicingulata were newly reported for their high lignocellulose-degrading abilities. The maximum activities of carboxymethyl cellulase, xylanase, and laccase in the 11 strains reached 262.31, 91.03, and 196.50 U/mL, respectively. T. suaveolens exhibited carboxymethyl cellulase activity of 168.17 U/mL at 15 ℃, which was significantly higher than that (67.88 U/mL) observed at room temperature. P. ostreatus showed the carboxymethyl cellulase activity of 150.78 U/mL and the laccase activity of 154.32 U/mL. S. hirsutum achieved the laccase activity of 63.27 U/mL at 15 ℃, which was twice the level measured at room temperature.Conclusion We successfully identified 11 macrofungal strains with strong lignocellulose-degrading abilities at 15 ℃. The findings provide valuable microbial resources for the degradation of lignocellulose in cold regions and lay a theoretical basis for application of these strains in low-temperature industries.

Key words:low-temperature tolerance;macrofungi;lignocellulose degradation