Cellulose-degrading strains: their screening and application to corn straw in low-temperature environments

Cellulose-degrading strains play an important role in cellulose degradation at low temperatures. In this study, three cellulose-degrading strains with high carboxymethyl cellulase (CMCase) activity were isolated from the soil in a low temperature environment of 10ºC. ZS-7 was Cladosporium sp, ZS-8 was Alternaria porri, and ZS-10 was Trichoderma harzianum, based on 16s rDNA gene sequence analysis. They were mixed, marked as ZS-M, and used for corn straw degradation at 15ºC in order to determine their application properties. ZS-7, ZS-8, ZS-10, and ZS-M efficiently degraded corn straw by 45.98%, 47.96%, 34.215%, and 33.56%, respectively, after 30 days of stationary culture. The dynamics of CMC, β-Glucosidase, and FPA during corn straw degradation were determined. The CMCase activity of ZS-7 and ZS-8 was 31.732 U/ml and 31.111 U/ml, respectively, but the enzyme activities and degradation of ZS-M were lower than the single strain because of metabolic effects that influenced the degradation process. The pH values of ZS-7, ZS-10, and ZS-M were particularly stable, changing from 7.08 to 7.77 during the full degradation cycle. ZS-7, ZS-8, and ZS-10 could be applied more broadly to degrade corn straw in cold regions.