Insight into biodegradation of cellulose by psychrotrophic bacterium Pseudomonas sp. LKR-1 from the cold region of China: optimization of cold-active cellulase production and the associated degradation pathways

Abstract

In the cold regions of China, many lignocellulose-rich agricultural residues, such as corn stover, cannot be efficiently degraded due to low temperature. As the component of cellulose in corn stover was approximately 50%, the degradation of cellulose was considered as one of the most important processes in degrading corn stover. In this work, a psychrotrophic bacterial strain was screened from the soil in the cold region of China and identified as a Pseudomonas sp. named LKR-1, which is able to produce cold-active cellulase. To improve cellulase production, the fermentation conditions were optimized using the Box–Behnken design of the response surface methodology. The maximum cellulase activity was observed after 4 days of incubation at 13.7 °C and pH 7.6 with 8.18 g/L cellulose. HPLC, GC–MS and FTIR spectroscopy were used to describe the changes in residual cellulose and the products of cellulose degradation. In addition to glucose and cellobiose, 24 kinds of compounds were detected during cellulose degradation by psychrotrophic Pseudomonas sp. LKR-1. Furthermore, on the basis the data and references, the possible pathways of degradation by the psychrotrophic strain LKR-1 were speculated, which will help clarify and explain the mechanism of cellulose degradation by psychrotrophic bacteria. This result will provide valuable information that contributes to the exploration of the microbial degradation of corn stover polysaccharides in cold areas.