Screening of macrofungal strains capable of degrading lignocellulose at low temperatures

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.