Screening And Identification Of Straw Degrading Bacteria And Study On Crop Straw Degradation Effect

With the development of the society,environmental problems are becoming more and more serious.As an important by-product of agricultural production and main agricultural waste,straw has a large output and is rich in cellulose.How to treat straw with value has been plaguing farmers and local environmental protection personnel.The feed used for direct animal use has low nutritional value and poor digestion;it is incinerated and pollutes the environment.Therefore,various forms of cellulose-degrading bacteria are widely studied,applied,and popularized in various industries and businesses because of their ability to produce cellulase.In order to guide agricultural residues to the relative economic feasibility and carbon emission reduction potential of developing biological resources,the cellulose degrading bacteria can be obtained through screening to realize the efficient utilization of straw as an ecological resource and accelerate the maturity of straw to solve the problems of fertile crops and ecological environment protection.In order to obtain an effective strain of high-yield cellulase,this study conducted targeted screening from organic fertilizer soil and soil in campus,and solidified medium using sodium carboxymethyl cellulose as the sole carbon source was cultured by high temperature enrichment and Congo red medium.And the DNS method was used to screen the enzyme activity,and then,the 16 S rDNA gene was sequenced,and finally the strain with higher cellulase activity was evaluated by the disintegration of the filter paper strip,the weight loss rate and the electron micrograph analysis before and after the straw degradation.The results showed that 20 high-efficiency cellulose-degrading bacteria were screened,and the highest CMC activity was 86.5 ± 0.51 U/mL.The strains B-1,B-2 and B-6 with three enzyme activities were selected.The three strains identified by the 16 S rDNA sequence were observed to be Bacillus subtilis,Bacillus sosonensis and Bacillus tequilensis.Subsequently,the filter strain disintegration test,straw weight loss rate and scanning electron microscope observation test were carried out on the B-1,B-2 and B-6 strains.The results showed that the three strains had obvious disintegration effect on the filter paper strip,and the solid fermentation was carried out.In the experiment,the three strains showed good degradation effect on corn stover.Under the condition of 45 °C,the weight loss rate of straw after shake flask fermentation was about 30%.By comparing the electron microscopy scans before,and after microbial degradation of corn stover,it can be found that the microorganisms exert a certain degradation effect to make the original lignocellulose structure become irregular,and further demonstrate the high-efficiency ability of the selected microorganisms to degrade the straw cellulose.The cellulose degrading bacteria obtained by this screening laid a foundation for further improving the research of straw degrading bacteria and the effective utilization of crop straw,and has broad application prospects.