The Research On Seperation And Application Of The Microbs To Degrade Corn Stover

At present,corn straw in China was the largest agricultural waste,but due to the lack of a suitable solution,which had caused great environmental pollution.By using the straw effectively,it not only can reduce the persecution of straw waste,but also can reduce production costs and save resources.In this study,different pretreatment methods were used to pretreat the straw.The effects of different pretreatment methods were compared by analyzing straw composition,observing with electron microscope and enzymolysis analysis.The pretreated straw was used to select the high production cellulase strain which separateing from the soil.The optimized high-yielding strains was used to degrade the corn stover to analyze the degradation effect.Lignocelluloses mainly composed of cellulose,hemicellulose and lignin.The intertwined structure of the lignocelluloses reduced degradation efficiency,thus,the corn stover need to be pretreated with NaOH,H₂SO₄,H₂O₂to break the original structure of the lignocellulose.The content of cellulose in the straw pretreated with NaOH increased obviously from 35.83%to 44.69%,while the decrease of lignin was obvious.However,the cellulose content of the straw increased after pretreatment with H₂SO₄,Its hemicellulose content decreased significantly from 35.34%to 22.63%.The strain of producing high yield cellulase was screened with the pretreated straw as substrates.The strains No.2,No.13,No.26 and No.30 had higher cellulase activity with enzyme activities of 0.168 IU/ml,0.143 IU/ml,0.150 IU/ml,0.174 IU/ml.Strains numbered 30 gave highest value of cellulase activity up to about 0.0174 IU/ml.Compared with the other three kinds of commercial bacteria,the strains of high-yielding cellulase could degrade the corn stover more efficiently.In the fermentation bag experiments,the corn stover was degraded more efficiently with high-yielding strains,and the weight loss rate of corn stover reached 60.2%.And then in the amplification experiments,the straw weight loss and composition changes was analysis,which demonstrated that the degradation effect of selected strain was higher than the other commercial bacteria.