Study On The Screening And Identifying Of Cellulolytic Strains And Solid-State Fermentation

The search and exploitation of efficient cellulolytic strains is the key for the exploiture and utilization of cellulose resources that is always the focus in the international research field. In order to obtain efficient cellulose-decomposing microbes, the author isolates 13 strains from putrid straw and wood, soil, and cattle feces etc, which can grow in the solid medium using CMC-Na as an only carbon source. On the basis of these strains, a strain of fungi that can decompose cellulose efficiently is screened through the experiments of decomposition of filter paper, identifying of cellulose-Congo red medium, liquid and solid fermentation, and preliminarily identified as Neurospora sp..The experiment of single factor optimization about the solid-state fermentation of the strain is carried out, and the results shows that the optimal carbon and nitrogen source are straw: bran=9:1, NH₄NO₃ 0.5%; and the optimal condition for culture are inoculum's age 72h, the ratio of solid to liquid 1:3, inoculum's size 1ml, culture temperature around 30℃, cultivating for 96h, natural pH. The carboxyl methyl cellulase(CMCase) activity and filter paper activity(FPA) of Fusarium are 3551.1 U ? ml^-1 and 386.7 U ? ml^-1 respectively under this optimal zymotic conditions. In the following mixed cultivation, the CMC activity and FPA enhance significantly, are 4347.06U ? ml^-1 and 469.92 U ? ml^-1 respectively. However, the FPA of strains that have been applied to the cellulase production in china is only 100U ? ml^-1. So it can be seen that Neurospora sp. is an efficient cellulose-decomposing strain, and the mixed cultivation can improve the whole enzyme activity of the cellulase system by the cooperative effect among the microbes, and promote the utilization of cellulose resources, as well as providing theoretic direction for the efficient treatment of crop straw in practical production.