The Construction Of Efficient Miscanthus Lignocellulose Decomposer Complex And Research Of Its Degradation Characteristics

With the depletion of non-renewable energy consumption, the development of new types of green renewable energy is an inevitable trend that supports for the sustainable development of human society. Miscanthus grows fast, has strong resistance, and contains high cellulose content, which is an ideal material for biomass energy research, development and utilization, but the hard degradation of cellulose is a key factor to limit the miscanthus being biomass energy plants. The synergy of complex microbial system can degrade cellulose efficiently and rapidly, which provides a new way for the development and utilization of miscanthus resources.This study with the rotten miscanthus, rice straw, corn straw, composting soil and termite hindgut domesticated by miscanthus under natural conditions as a source of microbial strains, determined a set of complex microbial system Ⅱ-M that could degrade miscanthus cellulose efficiently and rapidly under evaluation of PCS restrictive medium screen and filter paper strip degradation speed. On the basis of single factor test,17sets of experimental programs about three factors affacting miscanthus lignocellulose degradation fermentation time (X1), fermentation temperature (X2), initial pH value (X3) with Box-Behnken was designed. By means of response surface methods analysis, the quadratic regression equation model was established with miscanthu degradation rate per day as response value, the optimal fermentation condition was:fermentation time9.02d, fermentation temperature36.3℃, initial pH value8.54. Under the condition of optimal fermentation, the daily average degradation rate of Ⅱ-M miscanthus was6.51%which was1.28times to before, the total weight of miscanthus reduced by60.77%, the cellulose with other ingredients, hemicellulose, and lignocellulose were respectively decreased by66.18%,67.80%and34.57%; In fermentation process Ⅱ-M of filter paper enzyme activity reached the maximum3.813U/mL in the8th day, total soluble sugar content in the fermented liquid reached the maximum47.61μg/mL in the8th day.Through the plate separation method and functional screening, six strains of bacteria with CMC enzyme activity or β-glycosidase enzyme activity were isolated from the complex system Ⅱ-M, but not to get fungus. It was found that five of the six strains of bacteria belonged to BacilLus, Cellvibrio and Paenibacillus via16S r DNA Molecular identification, one of them had close genetic relationship with uncultivate bacteria, and classification status was still unclear, using Clustal in MEGA5.0software to conduct sequence alignment analysis and to build phylogenetic tree. Compound strains Ⅱ-M had high diversity of microbial components, so that make sure it had strong stability and much synergy ability to degrade cellulose. This article provides a theoretical and technical basis for developing efficient composite engineering strains used by fern genus biomass under the study of the construction and degradation characteristics of efficient miscanthus degrading compound strains Ⅱ-M.