Screening Of High-efficiency Degrading Bacteria For Corn Stover And Determination Of Degradability Of Mixed Strains

Crop straw is an important raw material resource,most of the straw is burned on the spot,this is not only a waste of straw resources,but also greatly damaged the ecological environment.Thus,the efficient use of straw straw processed into agriculture and environmental protection key scientific problems.Chemical treated have environmental pollution problems,physical method due to the high cost of equipment and can not be large-scale applications.Therefore,there need to solve the straw treatment from an environmental and cost point of view.Use of microbial processing of straw,can accelerate the decomposition of straw in place,improve soil fertility,improve soil microbial structure and can be large scale applications.In this paper,the isolation and identification of a strain that have able to degrade cellulose and lignin,and combine the isolated straw degradation strains with the cellulose and lignin that pre-screening of laboratory,to screen the composite strains which have high efficiency degradation,and to optimizate degrading straw lignocellulose complex strains fermentation conditions;and to study the corn stalk structure after processed by lignocellulosic composite strains.The study will resolve straw incorporation,improve soil fertility and crop yields have important practical significance and economic significance,and this study also solve environmental pollution,has certain social and ecological benefits.Results as follows:1.Screen out five cellulose degrading bacteria,named strain HDZK-DLCB1,strain HDZK-DLCB2,strain HDZK-DLCB4,strain HDZK-DLCB8,strain HDZK-DLCB9,respectively,strain HDZK-DLCB4 and HDZK-DLCB9 have a efficiently degrade cellulose ability.Combined strain morphological,physiological and biochemical tests and molecular biology identification results,identified the strain HDZK-DLCB4 isBacillus cereus,the strain HDZK-DLCB9 is Bacillus subtilis;2.Screening out a fungus which have a strong ability to degrade lignin,designated as strain HDZK-DLCF1.Combined strain morphological and molecular biological identification results,identified the strain HDZK-DLCF1 is Rhizopus microsporus;3.Fermentation test results show that the HDZK-DLCB4 and HDZK-DLCB9 has a strong ability to produce cellulase.HDZK-DLCF1,laboratory preservation HDZK-DLCB5 and HDZK-DLCB12 has a strong ability to produce lignin enzymes;4.Composite microbial system consists of Cellulose degradation strains HDZK-DLCB4,HDZK-DLCB9,and laboratory preservation of cellulose degradation strain HDZK-BYTF620 has higher corn straw degradation effect than other composite microbial system.Composite microbial system consists of lignin degradation strain HDZK-DLCB5 and HDZK-DLCF1 has higher corn straw degradation than other composite microbial system;5.Lignocellulose degradation composite microbial system consists of HDZK-DLCB4,HDZK-DLCB5,HDZK-DLCB9,DHZK-DLCF1,HDZK-BYTF620 treated corn stover 14 days latter,the results show that corn straw weight loss was(29.83±0.37)%,cellulose degradation rate was(53.27±1.32)%,hemicellulose degradation rate was(53.57±2.90)%,lignin degradation rate was(30.73±2.41)%;6.Composite microbial system(Bacillus cereus,Bacillus subtilis,Bacillus thuringiensis,small Rhizopus,Aureobasidium pullulans)optimum fermentation conditions: medium initial pH6.0,the optimum temperature is 25 ?,inoculation amount is 2:1(v/m),C/N is 25:1.After optimized,corn straw weight loss,degradation rate of cellulose,degradation rate of hemicellulose,degradation rate of lignin were(46.81±0.24)%,(67.79±1.52)%,(71.02±4.31)%,(57.20±3.3)%,respectively.Compared with the previous optimization increased by 16.98%,14.52%,17.45%,26.47%,respectively;7.After the corn straw was degraded by lignocellulosic composite microbialsystem,scanning electron microscope observation showed that corn stover structure has completely destroyed.8.From lignocellulosic degrading bacteria strains composite processing corn stalks isolated six kinds of phenolic acids included p-hydroxybenzoic acid,caffeic acid,vanillic acid,syringate,p-coumaric acid,ferulic acid,etc,and were significantly lower than the control group which did not inoculated.This study will to solve the straw,improve soil fertility and crop production has important practical significance and economic significance;at the same time,this study can also be to solve the environmental pollution,has a certain social and ecological benefit.