Research About The Construction And Degradation Of A High Efficient Complex Microbial System For Rice Straw Degradation

China is one of the biggest rice cultivation countries, the promotion of hybrid rice makes rice yield substantial growth, which led to the improvement of farmers’ income as well as nearly 200 million tons of rice straw every year. For a long time, a lot of rice straw are stacked, or directly burned,which is a huge waste of resources and pollute the environment greatly, thus affecting the sustainable development of agriculture in China. This study screened efficient straw-degrading strains, built a complex system of straw-degrading strains and studied the functional microbial biodegradation of these strains on rice straw, rice straw is expected to be able to accelerate the use of macromolecules in the difficult transition small molecules available to provide technical support and theoretical basis for the realization of rice straw can be recycled. These strains were expected to be able to accelerate the transition of macromolecules to small molecules to provide technical support and theoretical basis for the realization of the recycling of rice straw. The main findings are as follows:Firstly, straw compost and decaying branches were used as raw materials, through "Hanging rice straw " enriching and single carbon plate screening to screen efficiently straw-degrading strains and got ten bacteria and two fungi. Identification results showed that the bacterial strain CD2-1 and ZJC-3 were related to the Pseudomonas, GS1-2 was related to the Staphylococcus saprophyticus, XJ1-1, ZJA-6 and ZJE-3 were related to Paenibacillus, ZJA-5 was related to Enterobacter, ZJA-7 was related to Stenotrophomonas, ZJE-4 was related to Bacillus pumilus. The fungul strain ZJB-5 was identified as Trichoderma harzianum and ZJC-1 was preliminarily identified as Trichoderma koningiopsis based on their morphological, physiological, and biochemical properties, as well as ITS sequence.Secondly, measured the ability of the filter paper activity(FPA), CMCase activity and xylanase activity of ten bacterial and two fungi and found that all of the strain had a certain enzyme production. In bacteria GS2-3 had the highest FPA(12.01 U/mL), ZJE-3 had the highest CMCase activity(85.21 U/mL) and ZJE-4 had the highest xylanase activity(2271.67 U/mL). As fungi the FPA, CMCase activity and xylanase activity of ZJC-1 were 40.66 U/mL,207.34 U/mL and 7015.01 U/mL, which were higher than bacteria. Rice straw degradation test were used to describe the ability of straw-degrading strains, after 7 days, the relative degradation rate of the strains on sterilized rice straw were since 11.15% to 35.00%, Combined with the results, selected bacterial GS2-3, ZJA-6 and fungi ZJB-5, ZJC-1 to to complete complex research.Thirdly, in order to obtain an evaluation of rice straw-degrading ability of the strains, Ten strains straw-degrading bacteria were used to study the relationship between the hydrolysis ring (CMC-Na plate), CMCase and Xylanase activity (pure rice straw powder as carbon for liquid fermentation medium) and the relative degradation rate on straw. The results showed that the hydrolysis zone diameter (D), the hydrolysis circle on CMC-Na plates-colony diameter ratio (D/d), the largest CMCase and Xylanase of the strains were not significantly correlated with their relative degradation rate (RDR) on rice straw, nor were the CMCase and Xylanase of each day. While positive correlations were observed between the CMCase or Xylanase activities accumulated for one week and RDR, in which the the total enzyme activity of CMCase and Xylanase in one week was significantly correlated with RDR. These results suggest that the cumulative enzyme activity of strain are better to evaluate the actual degradation effects.Finally, the relative degradation rate of GS2-3, ZJA-6, ZJB-5, ZJC-1 on rice straw in 28 days were 19.60%,17.99%,15.27%,23.42%. The four strains were complex combinations to study the rice straw degradation of different communities in 28 days From both the number and types of communities. Combined the antagon results of the four strains, the combination of GS2-3& ZJA-6& ZJC-1 had the highest relative degradation rate on rice straw, which was 45.80%. The results showed that the more strains involved in the degradation was better, and combination of bacterial & fungal was superior to the combination of bacteria or fungi, though the antagonistic effects between strains will affect the degradation of overall community.