| The total annual production of straw in China is as high as 800 million tons,the traditional straw burning treatment of air,soil caused serious pollution,but also led to the waste of biomass resources.Crop straw as the versatility and reproducible biological resources,how to build a high efficient bacteria in the degradation of cellulose of straw,by means of microbial degradation explore solve the problem of low efficiency of agricultural straw degradation,for the improvement of our country agricultural straw resource recycling and achieve steady rise of green circular agriculture has important theoretical significance and practical significance.In this study,corn field soil was used as the bacterial source material,and northeast corn straw was selected as the carbon source.By screening cellulose degrading bacteria,a high-efficiency cellulose degrading bacteria community was constructed to study its degradation effect.The purpose of this study was to realize the resource utilization of straw cellulose materials through high-efficiency microbial degradation methods.The main conclusions are as follows:(1)CMC-Na culture medium was used to isolate the strains from the soil,and the Congo red staining test and filter paper disintegration test were used for preliminary screening.The carboxymethyl cellulase activity(CMCase),filter paper enzyme activity(FPA)and ?-glucosidase activity(?-Gase)were determined.Strains Y-2 and Y-6 were identified by molecular biology as Cladosporium sp.,and strains Y-7 as Fusarium sp.Three strains of cellulose-degrading bacteria and Y-R(Trichoderma sp.)which were preserved in the laboratory were tested for their antagonism.The non-antagonistic strains were compounded to determine the enzyme activity of each combination.Finally,a group of complex bacteria(Y-6+Y-7+Y-R)with no antagonism and high enzyme activity were screened and labeled as Y-M.(2)The optimum conditions of enzyme production of Y-M were determined by studying the conditions of enzyme production of Y-M.The optimum conditions of enzyme production of Y-M were culture time of 4 days,culture temperature of 30?,initial p H of 7.5 and inoculation quantity of 5%.(3)The results of liquid fermentation degradation of corn straw showed that the peak value of the enzyme activity of the complex microbial system Y-M was much higher than that of single strain.The highest CMC enzyme activity,FPA enzyme activity and ?-glucosidase activity were 37.71 U/m L,37.12 U/m L and 38.93 U/m L,respectively.The degradation effect of the complex microbial system Y-M on corn straw was higher than that of the single strain.The total degradation rate of the straw reached 66.57%,which was 6.56%,24.36% and 12.05% higher than that of the single strain Y-6,Y-7 and Y-R,respectively,and 53.36% higher than that of the control group.The degradation efficiency of the three cellulose components of corn straw by the complex microbial system Y-M was higher than that of each single strain.The total degradation rates of cellulose,hemicellulose and lignin were 39.02%,57.69% and 25.79%,respectively,which were 16.25%,17.37% and 9.50% higher than that of each single strain,and 33.92%,46.20% and 17.55% higher than that of the control group.(4)The results of simulated straw mulching experiment in pot showed that the degradation effect of compound bacteria Y-M on corn straw was higher than that of each single strain,and the total degradation rate of corn straw in pot experiment reached 55.34%,which was 46.93%,5.02%,14.67% and 6.78% higher than the control group,strain Y-6,Y-7 and Y-R,respectively.In the pot experiment,the composite flora Y-M still has a high degradation capacity of corn straw,indicating that the composite flora Y-M has a high practical application value. |
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