Isolation,screening,and optimization of fermentation conditions for a cellulose-degrad-ing actinomycete
To identify cellulose-degrading bacteria,optimize enzyme-producing conditions of the target bac-teria,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 assess-ments,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 meth-odology(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.
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