Screening of Strains of Cellulase-Producing Bacteria in Compost of Sewage Sludge and Straw and Optimization of Cellulase-Producing Conditions

Samples collected from compost of sludge and straw were incubated for enrichment culture,and then strains of bacteria capable of decomposing cellulose were screened out with the Congo red staining plate method. Enzyme activities of the stains of bacteria were measured and one strain,relatively higher in cellulose-producing activity,was isolated as C1.Phylogenetic analysis based on 16S rRNA gene sequences revealed that the isolated strain of bacteria,C1,was preliminarily identified as Devosia sp. Single factor experiments were adopted to optimize the fermentation conditions for C1. Results show that for C1,60 hours of incubation at 30 ℃ with the culture medium being in the range of 7. 2-7. 5 in initial pH in the shaker rotating at a rate of 130 r·min-1 was the optimal cellulase-producing condition. Under such conditions,the activities of filter paper enzyme( FPase) and carboxymethyl cellulase( CMCase) produced by Strain C1 reached 23. 10 and54. 97 U·mL-1respectively.