Screening and characterization of a low-temperature-resistant cellulose-degrading strain, Trichoderma harzianum L-8, from a primitive forest

Abstract

Low temperature is a major factor limiting the bio-sustainable and efficient conversion of cellulose-based resources in cold regions. In this study, a low-temperature resistant cellulose-degrading fungus with high cellulase production was screened from samples found in a primitive forest in Daqing by straw using the enrichment-restricted culture technique. The fungus was identified as genus Trichoderma harzianum, strain L-8 by morphological and molecular biological analysis. The enzyme production conditions were optimized via response surface methodology, and the optimal conditions for the enzyme production of Trichoderma harzianum L-8 were as follows: a CMC-Na addition of 10.63 g·L-1, an ammonium sulfate addition of 2.22 g·L-1, an initial pH of 5.29, and a lecithin addition of 5.18 g·L-1 when the CMCase reached 53.40 IU·mL-1. The leading enzyme families of Trichoderma harzianum L-8 were identified via proteomic analysis. Proteases including glycosyl hydrolase family 3-4 and cellobiohydrolase play important roles in cellulose degradation. The strain Trichoderma harzianum L-8 showed a strong cellulose degradation ability under low temperatures, providing strain resources for cellulose resource biotransformation technology in cold regions.