| Cellulose is a kind of energy material, which can be used as a kind of biodegradable and renewable energy, which is widely existed in nature. Microbial degradation of cellulose is a better way for the utilization of cellulose. In this study, using sodium carboxymethyl cellulose(CMC-Na) as the sole carbon source, decayed wood or branches as the source of bacteria, 16 strains(CY01-CY16) with the ability to degrade cellulose were screened out by enrichment culture, separation and purification and by Congo red staining and enzyme activity assay. Among them, the enzyme activity of the strain CY10 and CY16 was comparatively strong. All strains will be observed and rRNA 16 S gene sequence homology analysis through molecular biology techniques and methods. Preliminary identification of the strains CY10 and CY16 were respectively the Streptomyces genus(Streptomyces sp. CY10) and the Lysobacter genus(Lysobacter sp. CY16).Cellulose degrading bacteria isolated from decayed wood and branches. After primary screening test and the second screening test, the 2 strains with good enzyme activity were named as CY10 and CY16. According to preliminary screening test, the diameter of the transparent circle and colony diameter ratio(D/d) were 6.82 and 4.51, respectively. From the second screening test, the activity of CMCase was 3.39 U/m L and 3.05 U/mL, respectively, and the activity of FPase was 4.12 U/mL and 3.65 U/m L, respectively.The optimal strain CY10 was used as the starting target strain. The effects of different time, nitrogen source, nitrogen source, temperature and pH value on the enzyme activity of strain CY10 were determined. The culture conditions of strain CY10 in the optimum enzyme production were as follows: Carbon source was wheat bran(2.0%), nitrogen source is yeast powder(0.5%), the culture temperature was 30 ℃, pH vaue was 6.5, culture time was 42 h, Inoculum size was 8% and liquid volume was 50 m L/250 m L.In order to better understand the enzymatic activity of cellulose degrading enzymes, the enzymatic properties of cellulose degrading enzymes were studied. Study on enzymatic characteristics showed that The optimum temperature of CMC enzyme and filter paper enzyme activity of the strain CY10 was 45℃ and the optimal pH is 6.5. Metal ions Mg2+ and Zn2+ had a certain activation effect on both CMC and FPA, while Ag+, Pb+, Mn2+ and Co2+ inhibited the activity of CMC and FPA. From the point of view of the stability of temperature and pH, enzymatic reaction temperature maintained at 25 to 45℃, two kinds of enzyme activity were reduced only 4.51 U/m L and 541 U/m L. From pH stability, their results showed that it is favorable for the enzymatic reaction in the acidic environment, while the stability of the enzyme was poor in the partial alkaline environment, and the activity of the enzyme decreased rapidly.The enzyme production characteristics of high efficient cellulose degrading bacteria CY10 and CY16 were studied in this experiment and their growth characteristics were understood. We can improve cellulose degradation bacteria degradation efficiency. And this will provide a theoretical basis for the further analysis of the relationship between structure and function. It also provides a good source of bacteria and scientific basis for the development and comprehensive utilization of crop strawsand other cellulose resources. |
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