Isolation and characterization of a low-temperature and cellulose-degrading fungus <i>Tausonia pullulans</i> LC-6

Agricultural residues are frequently utilized as biomass fertilizers via compost, but their degradation is hindered by low temperatures in cold regions. Isolating strains capable of degrading cellulose at low temperatures is crucial for the effective recycling of agricultural residues in cold regions. In this study, the strains with cellulose degrading ability were selected from humus soil in cold region. Preliminary screening was performed by sodium carboxymethyl cellulose culture and Congo red staining. Cellulase activity was rescreened and identified by morphological observation, physiological and biochemical tests, and phylogenetic analysis of Internal Transcribed Spacer sequence. We isolated and identified a cellulose-degrading strain (LC-6) operating at low temperature (10°C-15°C). It was identified as <i>Tausonia pullulans</i> (GenBank entry number PQ227816 and PQ584837). The strain exhibited peak activities of Carboxymethyl cellulase, Cellobiohydrolase, <i>β</i>-Glucosidase, and Filter paper enzyme at 4.93, 7.62, 14.17 and 7.15 U/mL, respectively. After 15-days fermentation at 15°C, the degradation rates of hemicellulose, cellulose and lignin of the strain were 25.01%, 16.13% and 24.35%, respectively. The findings indicated that strain LC-6 can effectively degrade straw at low temperatures, demonstrating significant potential for applications in the utilization of lignocellulosic biomass.