Construction And Decomposition Characteristics Analysis Of Complex Microbial System YM-1Decomposing The Corn Stalks Efficiently

The decomposition rate of corn straw returned field was slow under natural conditions,which influenced the crop growth and production in northern region. In this paper, soil wassampled from De zhou and Tai an, Shandong province, where had been treated with cornstalks for a long time. The cellulose-degrading strains were screened and complexmicrobial system YM-1was constructed through the antagonism test. The research on itsstability and function was followed in the liquid and solid fermentation test, such as theactivity of CMC enzyme, FPA and xylanase producted by YM-1. Finally, the applicationeffect of compound strains YM-1was evaluated in the laboratory simulation field test.. Themain results were shown as follows:1) Fifteen cellulose-degrading strains were separated from the soil using CMC-Congo redstaining and a low temperature induction experiment was followed. The results showedthat, strain M11, identified as a Penicillium oxalicum, could decompose celluloseefficiently by producing extracellular cellulose under13℃. Its cellulose activity couldreach to33.08U/mL in the ninth day, under a condition of13℃,200r/min and only cornstraw for carbon and nitrogen sources. The results of its cellulase characterization revealedthat, the optimum pH was5.0and reaction temperature was20℃. The relative cellulaseactivity still reached to90%in the range of5℃~20℃.2) Four efficient strains X11、M11、M14、F7were screened from15strains mentionedabove by means of cellulose activity in the liquid fermentation. They were combined withTrichoderma reeseri DSM768and composite system CSS-1to construct the complexmicrobial system YM-1.3) The enzyme activity of YM-1was analysized in the liquid and solid fermentation test.The results showed that, under the fermentation conditions of28℃,200r/min, the activityof cellulose and FPA could be maximum as29.87U/mL and17.14U/mL in the7th day,respectively. The xylanase activity could reach to23.6U/mL in the9th day. The pHappeared a trend of rising after decline first.4) The results of function stability for YM-1presented that, in the process ofdecomposition, the cruves of enzyme activity for different generations were mainly same,with a trend of low-high-low, which confirm the stability of enzyme production. 5) The PCR-DGGE results for composition stability of YM-1showed that, the compoundYM-1of different generations (F2、F5、F10、F15、F20、F25) remained stable. Thebrightness and position of DGGE stripe were different in the different fermentation time ofthe same generation. The composition of microbe presented diversity.6) In the laboratory simulation experiment, the weightlessness rate of corn straw was testedto evaluate the degradation effect of YM-1. The results showed that, the dry weight ofstraw were reduced for all treatments, such as, CK, microbial inoculum A, CSS-1andYM-1, with the degradation rate of13.1%,19.5%36.9%and30.6%, respectively.Therefore, compound strains YM-1was the efficient for the degradation of straw.7) Biolog was used to analysized the metabolic activity of microbe. Average Well ColorDevelopment (AWCD) in micro plate characterized the utilization degree of carbon source.The slope of AWCD curve for YM-1among12h~96h was largest, and the AWCD valuecould reached up to3.69in168h, as well as3.03,2.80and2.78of microbial inoculum ACSS-1and CK, which suggested the efficient complex microbial system YM-1for thedegradation of corn-stalk.