The Study Of The Mixed Culture And The Mutualistic Characteristics Of The Cellulolytic Strains

This paper studies the characteristic of the four strains that screened from the decomposed straw and the soil of the ox, and studies the conditions of the fermentation and the solid-state culture medium that the strains can well grow on. Then we mix the strains by different combinations and find out the best one that can decompose the cellulose and study the symbiosis of the combinations. Then we culture the best combinations on the solid-culture medium made of the conduct of the agriculture, and proved to have best capability to decompose the straw. Finally we find out the better combinations and the condition of fermentation that can be used in commercial manufacture.Four strains named as Ml, B3, S7, S12 are obtained that the suitable pH values should be 6.5, 7.5,6.5 and 7.5. At the same time, the four strains all grow well at 30-40# with enough oxygen. And the S7 has the ability to bear preferable temperature. Ml, B3 and S7 have the same amount of enzyme in the cell and out of the cell, but S12 has more in the cell than out of the cell.The optimized recipe of the solid-state culture of the strains is obtained as follows: powder of the bean, 5%; bran, 7.5%. The strains grow well on the culture medium for three days.The optimized combinations are S7/S12 and M1/S7, and the optimized mix-strain inoculation proportion is tested to be S7/S12:1 : 1, M1/S7:2 : 1,1 : 2. The sequence of the inoculation is that for S7/S12, S7 first and for M1/S7, Ml first.When culturing on the solid-state culture medium, the optimized combinations are also showing better ability to decompose the cellulose, the content of the cellulose drops from 36.89% (before fermentation) to 27.73% and 27.20% (after fermentation), the rate of the decomposing reach at 24.83% and 26.27%. The outward appearance of the product assumes black, viscous with mechanical strength decreasing largely.The four strains studied in this paper can grow on the cheap solid-state culture medium in the optimized condition by the optimized combinations, and well decompose the cellulose. If combine with the disposal of the waste of the city and the technology of the phosphoric fertilizer, it will develop each other, and add new content to the exploiting of the straw resource and administering the pollution.