Screening Of A Cellulase-producing Bacteria Bacillus Endophyticus N2 From The Fermented Yellow Water Of The Traditional Chinese Liquor And Studying On The Condition Of The Cellulase Production

Cellulose is the most abundant renewable biological resources on earth. Rationally using cellulose resources and converting them to human much-needed energy, food or chemical raw materials, will have important significance for sustainable development of mankind. Cellulase can not only effectively convert cellulose into oligosaccharides or monosaccharides, also have widely application value in many industry fields, has become a hot point of research in China and abroad recently. Microorganisms as the main producer of cellulase, widely exist in nature, but only a few real high-yield strains were obtained at present. The production of cellulase is still low yield and high cost, so the research of screening for cellulase-producing microbe and cellulase production is still very necessary.A total of 12 bacterial strains showing cellulose hydrolysis ability on carboxymethyl cellulose(CMC) agar plates were isolated from fermented yellow water of the traditional Chinese liquor fermentation, and numbered M1、M4、M5、M18、M34、N1、N2、N3、N4、N5、N9、N13. The results of morphological study indicate that all of them are gram-positive bacterium, combining with physiological, and biochemical characterization and 16 S rRNA gene analysis, M1, M4, M5 and M18 were identified as Bacillus cereus, M34 was identified as Bacillus circulans, N1 and N5 were identified as Bacillus megaterium, N2 was identified as Bacillus endophyticus, N3 and N4 were identified as Bacillus simplex, N9 and N13 were identified as Bacillus bataviensis. Their cellulase activity were detected by liquid fermentation, and N2 showed higher cellulase activity than the others, the endoglucanase(carboxymethyl cellulase, CMCase), exoglucanase(avicelase), β-glucosidase and total cellulase(FPase) activity were 0.132 U/m L, 0.012 U/mL, 0.158 U/mL and 0.041U/mL respectively.The research used the strain N2 as research object due to its high extracellular cellulase activities compared to other isolates, and the effect of operational conditions for cellulase production by N2 had been researched by using single-factor experimental analysis. Among the substrates used, results showed that 6%(W/V) wheat bran and 2%(W/V) ammonium sulfate were found to be the best combination of carbon and nitrogen sources for the cellulase production by N2. The maximum production of CMCase(0.426 U/mL), avicelase(0.049 U/mL), β-glucosidase(0.35 U/mL) and FPase(0.168 U/mL) were obtained at inoculum size of 4%(V/V), pH of 7.0, incubation temperature of 37℃ and incubation time of 72 h, and the enzyme activity increased by about 222.73%, 308.33%, 121.52% and 309.76% compared with previous standards.In this research, some cellulolytic bacterias were isolated from fermented yellow water of the traditional Chinese liquor, and one of them showed the higest production capability of cellulase in the liquid medium had been investigated for the effect of different operational conditions on cellulase production, which not only provide certain theoretical guidance for the study of the system of microorganisms in the yellow water, and broaden the germplasm resources of cellulase-producing microbes, also provide the theory basis for the research of liquid fermentation and industrial utilization of cellulase.