| Ruminants have more than one stomach.Rumen as the most important complex stomach of ruminants, it is an important place for animals to digest food. While in the rumen microorganism is important to perform the crude fiber digestion in ruminants.Because of the ecological environment in Gannan Tibetan areas of special and long-term natural selection, so that the local yak have cold and hypoxia resistant ability.And ability to secrete cellulolytic enzyme in the yak rumen microorganisms was also higher. In this experiment, Gannan yak rumen microorganisms as the research object, in order to select high-yield cellulase strains, and to identify its related enzymes, determination of the activity, and the fermentation of corn straw, in order to provide a new theoretical basis for the further industrialization of cellulase production and utilization.The results are as follows:1. From the collected yak rumen fluid samples, were screened from 17 strains of degradation of fiber, were numbered 1-17. Which the No.11 strain has the highest transparent circle diameter,reached as 2.95 cm.2. The 17 strains were identified based on morphological and molecular identification. And all the 17 strains were bacteria. Amplified 16 S rDNA fragment for sequencing.But only 2, 3, 4, 5, 6, 7, 8, 10, 11, 14, 15 and 16 strains were sequenced successfully. The 12 th sequences were compared and their homology is relatively high, reached as 83.88%.The 12 th sequences were compared in the NCBI database respectively. In which 12 th sequences, and most of them with the Enterobacter have the highest similarity. Therefore, this experiment screened bacteria most belong to Enterobacter spp.3. The 17 strains were related to enzyme activity determination, the determination results for No.11 strain of relative enzyme activity, the H:C value reached as 2.89.And the No.11 bacteria has the highest enzyme activity of cellulos endoglucanase. And the No.11 bacteria also has the highest enzyme activity of FPA and beta glucosidase.In the process of degradation of cellulose and straw powder, the No.11 bacteria produced the highest contents of the reducing sugar. According to the analysis of experimental results, the No.11 bacteria of the cellulose degradation ability to be higher.4. By the high efficient bacteria on Fermentation of corn stalk, the design of carbon source concentration, nitrogen source concentration, PH, surfactant concentration of four factors, and then each factor four levels, to study its effect on enzyme activity of strains with high activity. The results showed that four factors on the enzyme activity of strain are affected. Study the factors of carbon source concentration was 0.9%, nitrogen concentration was 1%, PH was 6, the concentration of surfactant is 0.3%,and under the condition of enzyme activity is the highest. The interaction analysis between the results of the orthogonal test of two factors, carbon source concentration is 0.9%, nitrogen concentration was 1%, PH was 5.5, the concentration of surfactant is 0.3%, Those were the appropriate fermentation conditions.In summary, this study screened 17 strains of cellulose degradation. And morphological identification and molecular biology identification of these strains.The determination of their associated enzyme activity were screened cellulose degradation ability of the highest strain No.11. And the design of experimental system to investigate the optimum fermentation conditions of No. 11 high activity strains. At the same time, proved the ability of cellulose degrading of strain No.11. This can be for the future application in the actual production, and provides a theoretical foundation and basis. |
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