| China can produce 700 million tons stalk per year. It is undoubtedly a valuable resource for our shortage of cultivated land and grassland (HAN Jiahui et al. 2009). Microbial degradation of corn stalks, can not only effectively improve the comprehensive utilization rate, but also have the economic and environmental characteristics. It has gradually become a research focus in recent years (SHI Yang et al. 2002; Masohiro N?et al. 2001; Rizzatti A C S?et al. 2001). At present, the determination of CMCA and xylanase become a common strain selection method in the study of microbial degradation of stalk, but the study of degradation rate after inoculated strains with high acativity is lake, particulary on the relationship between activity and the degradation rate of the quantitative research is rarely reported. There are few formal studies about the interaction quantitative model of each factor in the actual fermentation process of stalk. Therefore, in this study, the strains in selected samples were isolated and selected, performance analysed and idetificated. At the same time, the relationship between their enzyme production capacity and degradation rate was studied. Followed by a good biological characteristics of strains and optimization of solid fermentation of straw, it provided a theoretical basis for microbial degradation of corn stalk. The main findings are as follows:1. This study had filtered 3 strains degradability microorganisms, one mold, the number is F6.After enriching the sample, isolating the strains in enriched medium by spread-plate-method and rotating them repeatedly, and screening the remaining strains by microcrystalline cellulose medium, then selecting the results by filter paper degradation test, 5 mold, 5 actinomycete and 5 bacteria was selected. Mold F6, actinomycete A4 and bacteria B4 with excellent stalk degradability were obtained by CMCA and xylanase activity assay and degradation rate assay. Their max CMCA and max xylanase activity are 14.57μmol/min·g and 25.69μmol/min·g, 8.62μmol/min·g and 27.07μmol/min·g, 6.41μmol/min·g and 20.79μmol/min·g, and F6 had the topist degradation rate, 44.80 %. It was identified as Trichoderma viride. Trichoderma viride F6 of them has the best corn stalk degradability, and it was determined as the strain for solid fermentation test. 2. Max CMCA of different strains closely correlate to their max xylanase activity.In this study, the max CMCA of 5 mold, 5 actinomycete and 5 bacteria all respectively and closely correlate to their max xylanase. It means xylanase acabivity increase may promote CMCA and helpful to the degradation of fiber structures.3. Corn stalk degradability of different strains were influenced effectively by their max CMCA and max xylanase activity.In this study, regression equation on the relation between max CMCA and max xylanase activity of the 5mold, 5 actinomycete and 5 bacteria by selecting were derived, and it was significant by the variance to verify correlation. It is means that the stalk degradability of different strains was affected strongly by their max CMCA and max xylanase activity.4. F6 can use a variety of carbon sources, growing a wide range of temperature and pH.The impact of different culture medium, temperature and pH on the growth of F6 was sinificance.The biological characteristics test results of F6 showed that, F6 can grow in all Czapek ager, Martin ager, potato dextrose ager, potato sucrose ager, and water ager, and it grows fastest and has most spore in Czapek ager. It grows best on CA, and has the largest Spore density. The order of medium which appropriate for F6 is CA>PDA>PSA>WA>MA. F6 can grow between 18±1℃~38±1℃, has a best growth and spore rate in 33±1℃. F6 could die in 15 min under 55℃. F6 preferences micro acidic conditions, could grow from pH4 to 8, grow best under pH 6. The results of analysis of variance show that, the effect of different culture medium, temperature and pH on hypha growth rate is significant.5. Technological parameter of corn stalk degradation with F6 was concluded by model optimization.Optimum technology of biological degradation of corn stalk is 32.0, with 62.2 % water, inoculums 1.0 ml/g (culture medium) and pH 5.8. The increase of temperature and humidity plays a significant role on the improvement of stalk degradation rate. Temperature is the key factor in the fermentation process. The interaction of temperature and humidity, inoculum concentration and initial pH can play a beneficial effect to the results, and the appropriate increment of test parameters may improve corn stalk degradation rate.
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