The Screening Of Degradation Bacteria And Building Of Highly Efficient Degradation Bacteria For The Straw Cellulose In The Northeast

Straw is an important biological resource which is produced in agriculture. Comparing to mineral resources such as coal and oil, it is a renewable energy resource. The issue whether the straw resource can be used effectively directly influences the sustainable development and environmental protection of modern agriculture. At present, a large number of straw resources were wasted or burned, which causes the environmental problems and the waste of resources. The straw can be degraded rapidly and effectively with the action of microorganisms,which is an important, reasonable and useful method of promoting straw returning.With the action of microorganisms which can degrade the straw effectively, the degradation of straw will be promoted widely. The products of microbial degradation of straw can be used as an important source of soil humus aromatic ring formation and also can promote the formation of soil humus positively. The cellulose turns to be organic acid with the degradation of microorganisms. The organic acid can be used as the carbon source and nitrogen source of nitrogen fixing bacteria in the soil, which eliminates the inhibiting effect of decomposing bacteria of cellulose. The circulation pattern which is formed between the microbial population in the soil solves the problem of rapid decomposition of straw and also helps to improve soil microbial activity and at the same time it is of a great significance of improving agricultural production efficiency.In this study, in order to obtain the high efficient cellulose degrading strains and develop a new straw decomposition additive that can be used in the agricultural production, which can provide a technical support for the straw returning, we had carried on the research of the isolation,building and optimization of culture condition for the high efficiency degradation bacterium and also the effect of degradation of straw by the high efficient degradation bacteria department. And at last we had reached the following conclusion:1.At first we had obtained 25 strains with high cellulose degrading ability through the way of isolating from the CMC-Na medium and screening by the staining of Congo red. After the staining of Congo red,the transparent hydrosphere appeared around the cellulose degradation strain. Then along to the ratio of diameter that transparent hydrosphere with colony and also the enzyme activity of CMC and FPA that were measured through the process of cellulose degradation,we finally obtained 3 strains with high cellulose degrading ability and they are the strains that were named C9, F93 and D72.2.The 3 obtained strains were combined with each other and cultured together and then the enzyme activity of CMC and FPA were measured. with the comparison of the single strain, the enzyme activity of the combined strains improved greatly. According to the result that were measured,we had gained a combination of strains that can degrade the cellulose efficiently. The combination of the strains were named as group ZH4 and its enzyme activity that were measured reach to CMC as3.18 U/mL and FPA as1.67 U/mL.3.In this study,in order to make a better use and play its efficient straw degradation effect of the cellulolytic strains constructed in this research,the culture conditions on the effective degradation strains were also investigated in detail. Through the research of culture time, culture temperature, initial medium pH and nitrogen source that effects on the activity of enzyme production strains, the most suitable conditions for high enzyme production of high efficiency degradation bacterium series is measured. Finally, we get a conclusion that the most suitable conditions of the group ZH4 is: the peak of enzyme production is cultured at 4d, the optimum culture temperature enzyme production is 35 C, the most suitable for enzyme production of pH is 6.5, and the most suitable nitrogen source of the enzyme production medium is peptone and urea.4.In order to explore the application effect in the actual production of the Cellulolytic strains constructed in the experiment, in this research we had studied the effect that the high efficient cellulose degrading strains constructed on the of straw maize degradation. Make the high efficient cellulose degrading strains that were constructed and named as group ZH4 before cultured in the optimum enzyme producing conditions and then the strains of maize straw degradation rate were measured. At last, the experimental results show that the high efficient cellulose degrading strains effect on corn straw degradation greatly and the straw degradation rate reached to 34.52%, comparing with the single strain, the degradation rate of the straw has increased by 21.3%-59.6%.As for that the strains named ZH4 were screened in the normal condition,So it has important practical significance for the promotion of the strains to the production practice.