Mutation Breeding Of Aspergillus Niger, Trichoderma Viride And Its Application In Straw Decomposing Inoculant

China is a large agricultural country, as an kand of agricultural byproduct, there are hundreds of millions of tons straw produced every year. Only a few straw were utilized, most of them were wasted and turned to be pollution for environment. microorganisms can turn the waste into treasure, which has great realistic meaning for human being to solve environment pollution and energy crisis.The main work includes:1) Obtain the strains whose cellulase and xylanase activity was high from the nature and laboratory.2) Mutate the strains by ion implantation and60Co mutagenesis to breed mutant strains with high level cellulose and xylanase, and research the genetic stability of the mutant strains;3) study the properties of cellulase and xylanase excreted from mutant strains;4)develop an inoculant which is mainly made by the mutant strains, and research its composting effect of straw under laboratory conditions.The main results are as follows.1. A strain named H13was screened,which could producing xylanase,and the xylanase activity reached14000U/g after cultured68h in the culture-medium. Another strain named M100726was also screened,which could producing CMCase,and the CMCase activity reached400U/g after cultured48h in the culture-medium.2. When M100726and H13were mutated by ion implantation and60Co mutagenesis to breed with high level cellulose and xylanase, a strain named R16-1which CMCase activity reached587U/g, increased by46.5%than the original strain M100726, and another strain named N65-7which xylanase activity reached25700U/g, increased by83.5%than the original strain H13were screened.3. The properties of CMCase and xylanase enzyme were studied and results as follows: The optimum temperature of CMCase was50℃and it was stable between4℃and40℃after treatment for15minutes, the optimum pH value of CMCase was4.8and it was stable between pH3and pH11, Cu2+have active effects on CMCase activity, while Co2+have negative effects on CMCase activity; The optimal temperature of xylanase was50℃and it was stable between4℃and40℃after treatment for15 minutes, the optimum pH value of xylanase was5.4, and it was stable between pH5.4and pH10, Mg2+, Ca2+, tween80, Cu2+have active effects on xylanase aetivity, while Co2+, Mn2+have negative effects on xylanase activity;4. Compared with the control, this inoculant can significantly promote colonization and propagation of mycete, accelerate the decomposition of straw; The factors,include appearance, bacteria, mycete, c/n, breaking power of rice straw and straw residual ratea, had significant difference. The experimental group turned to maturity took about35days, while the straw had been fragmentized and dark brown, the dominant microorganisms were Trichoderma viride and Aspergillus niger, and the organic carbon of straw has dropped to34%, the c/n was19.50; after45days, the breaking power of rice straw was3.3%of the test beginning, and the straw residual rate was35.03%. All of above indicated that the inoculant made by R16-1and N65-7have good composting effect.