Study On Screening And Mixed Fermentation Of Cellulose-degradating Microorganisms Under Low Temperature

With the development of society and economy,the rapid increase of population,environmentalpollution and lack of resources problem increasingly prominent, has become the two majorproblems facing humanity.In the agricultural environment pollution problem,crop straw andlivestock and poultry waste on the environment caused by pollution is most serious.As a kind ofeffective means which processing solid organic waste and make it harmless and resourcerecovery,composting method has long been widely research and application at home andabroad.Studies have shown that the main organic component of these organic wastes is cellulose,so,in the process of compost were, the degradation of cellulose is the key to composting fermentationrotten.Screening efficiency of cellulose degradation bacteria, and added to the compost,caneffectively achieve a goal which is to improve the composting efficiency and humification degreeand quality.In northern China,because low temperature and long time in the fall and winter,cellulose as akind of widespread renewable resources,because of the slow degradation has not been fullyutilized.Screening efficient cellulose degrading bacteria at low temperature will fundamentallyimprove the degradation of cellulose at low speed, and lay a foundation for the development ofcompound bacterium agent.At low temperature as a filter condition, the rural natural composting as a source of bacteria,cellulose as the sole carbon source,after domestication,separation and purification,82strains wereobtained.By Congo red staining, preliminary screened24strains of cellulose degradationbacteria.By temperature as a sieve,the experiment ultimately screened12strains of cellulosedegradation bacteria in the lowest temperature5℃.Including three strains of bacteria, named asX11, X36and X42;five strains of fungi, named as Z2, Z3, Z21, Z25and Z27;four strains ofactinomycetes, named as F5, F14, making and F74.According to the research of the enzyme activity,4strains of high efficient degradationbacteria was finally determined,they were X11、Z3、Z25and F74.The maximum of3kinds ofenzyme activity were significantly higher than other same type strains of bacteria, and had been inthe leading position in the whole measurement period.Among them,filter paper activity of X11was0.235IU/g,CMC-enzyme activity of X11was0.541IU/g,microcrystalline cellulose enzyme activity of X11was0.273IU/g;filter paper activity of Z3was0.269IU/g,CMC-enzyme activity ofZ3was0.564IU/g,microcrystalline cellulose enzyme activity of Z3was0.271IU/g;filter paperactivity of Z25was0.232IU/g,CMC-enzyme activity of Z25was0.532IU/g,microcrystallinecellulose enzyme activity of Z25was0.261IU/g;filter paper activity of F74was0.321IU/g,CMC-enzyme activity of F74was0.747IU/g,microcrystalline cellulose enzyme activity ofF74was0.262IU/g.According to the species identification,finalized X11belongs to Pseudomonassp.,Z3and Z25belong to Cladosporium sp.,F74belongs to Streptomyces sp..Use of synergy between the bacteria,through antagonism experiment, found that the bacteriaZ3and bacteria F74had antagonism reaction, other strains had no and could be mixed.Mixedsingle bacteria which was not antagonistic relation, by studying the mixed bacteria growth andenzyme activity,found that the mixed bacteria X11F74reached the peak of growth in the fifthday,and filter paper activity was0.327IU/g,CMC-enzyme activity was1.312IU/g,microcrystallinecellulose enzyme activity was0.289IU/g,which were higher than others significantly,consideredas the advantage bacterium group.And the enzyme activity of mixed bacteria X11F74wassignificantly higher than any single bacterium of its. There was synergy between the X11andF74.For the degradation of cellulose, mixed bacteria was better than single bacteria.According to the single factor experiment and the change of CMC-enzyme activity of mixedbacteria,the best condition of mixed bacteria enzyme production for training time was5days,theinitial pH of medium was6,temperature was20℃,the inoculation content was5%. Under thecondition of the optimal, degradation rate of mixed bacteria was22.84%.