Isolation, identification and characterization of a cellulase-producing strain

[Objective] To obtain microorganism strains for comprehensive utilization of cellulose, an ambient temperature cellulase-producing strain was isolated and identified. The optimal culture conditions for enzyme production were determined. [Methods] Filter paper medium was used to enrich the microorganism cultures. CMC-Na medium was used to screen the cellulose-degrading strains initially under the condition of ambient temperature. A strain, KZ-2, was isolated and purified using LB medium, followed by identification utilizing morphological, physiological and biochemical properties, and 16 S r RNA gene sequence profiles. Single factor test based on incubation time, culture temperate, initial p H and sodium chloride(Na Cl) concentration was performed to optimize the conditions for cellulase production. [Results] Strain KZ-2, capable of producing extracellular cellulase under ambient temperature, was isolated from decomposing maize straw. It was identified as a strain of Enterobacter sp. and potentially to be a novel species. The optimized enzyme production could be obtained when the strain was cultivated for 120 hours at 25-35 °C with initial p H 4.5-5.5, Na Cl concentration of 1.0%-2.0%. The maximum cellulase activity of 80.93 U/m L was achieved under the optimal conditions. Initial enzymatic property analyses of the cellulase produced demonstrated that the enzyme was most active at p H 7.0 with a temperature of 50 °C. [Conclusion] The cellulose-degrading strain KZ-2 is able to secrete cellulase under ambient temperature and is potentially a novel species. The strain is expected to be further studied and developed to explore its marketing values.