Screening On The Cellulose-decomposing Microorganism And Their Application In Biogas Production By Dry-fermentation With Straw

Agricultural straw, which mainly consists of lignocelluloses, is the richest renewable resource. In this essay, by using decayed straws and soil in the field as the raw materials, a strain called J33 which can effectively degrade cellulose appears under separation and purification. J33 is put into experiment after identifying both the physiological and biochemical character and molecules of it and preliminarily analyzing its zymologic characterization. In the experiment, straws are used to ferment which produces methane. After improving technological conditions of the experiment and learning results of biogas residue's fertileness, we get the conclusions as follows:The purpose of study is to gain high efficiency cellulose degrading bacteria, through CMC-Na solid medium as the screening medium. The bacteria were isolated from a rotten wood which has strong ability of cellulose degradation, named J33. According to analysis the strains morphological, physicochemical property and 16S-rDNA sequence, the results showed that, J33 bacteria strain is Bacillus pumilus.The Endoglucanase (Cx) has the highest enzyme activity among the cellulose of J33. The highest enzyme activity of Cx occurs on the condition that the pH 5 and the temperature is 40℃which proves to be the most appropriate reaction condition. In the 70℃, 60 min conditions, the enzyme activity is 28.4 percent of the enzyme activity in 40℃, 60 min conditions. It is ordinary in thermo stability, Mg2+ and Ca2+ will obviously result in an increase in enzyme activity while the Na2+,Fe2+,Zn2+,K+ lead inhibiting effect on several levels.This experiment uses the J33 strain to pretreatment the rice straw and fermentation to product the biogas. The result showed that, compared with natural heap retting processing, the straw which pretreated by J33 strain was increased 26.7 percent of biogas. The optimal case determined by the orthogonal test when the pH7.5, the temperature was 33℃, sludge inoculation was 35% and moisture content was 80%. As a result, it was increased 21.9%.The nutrients in biogas residue and biogas have some differences, the crude protein in biogas is 0.98 percent, and the organic matter 0.35. While in biogas residue, the crude protein takes up 28 percent, and the organic matter 28 percent, so does the humic acid. But the abiotic substance in biogas residue is much higher than that in biogas. The observation of the peppers seedlings growing situation and the output of peppers fruit after transplantation, according to the differences in matching biogas residue and seedbed, the result shows that the proper amount of biogas residue as peppers seedlings organic fertilizer can obviously assist in improving the quality of the peppers seedlings, as well as the output, in the long run. Compared with the control group, the biogas residue and the seedbed in the same amount is the optimum condition, the stem length will increase by 16.5 percent, with the corm weight will gain 24.1 percent. The area of largest leaf will increase 7.7 percent, and the output is enhanced by 9.1 percent, as well as the average fruit weight gains 0.6 percent.