Isolation, screening, and optimization of fermentation conditions for a cellulose-degrading actinomycete

To identify cellulose-degrading bacteria, optimize enzyme-producing conditions of the target bacteria, and investigate their degradation effect on wheat bran, the carboxymethyl cellulose (CMC)-Congo red staining method was employed for initial screening. Subsequent re-screening employed CMC and Filter Paper Assay (FPA) enzyme activities as indicators. Morphological observations, physiological assessments, biochemical analysis, and molecular biological identification were conducted on the strain. Single-factor optimization was performed on its enzyme-producing conditions, followed by response surface methodology (RSM) optimization using CMC enzyme activity and FPA enzyme activity as response values. The results indicated that a high-cellulase-producing strain, XL-1, was obtained. Based on morphological observation, physiological and biochemical characteristics, and 16S rDNA sequence analysis, the strain was identified as Streptomyces aurantiogriseus. After optimizing its enzyme-producing conditions using RSM, with a fermentation temperature of 30 ℃, fermentation time of 4 days, pH of 7, and inoculum size of 10%, the CMC enzyme activity reached (13.29±0.05) U/mL and the FPA enzyme activity reached (4.52±0.04) U/mL. The experimental results can provide strain resources and optimal enzyme-producing conditions references for the industrial production and application of cellulase.