Research On Screening Of Bacteria With Banana Stalk Degradation And Preparation Of Alcohol

Celluloses biomass is a low-cost renewable resource, it can be potentially fermented into ethanol by microbial technology, which is significant to the sustainable development on energy industry and the environment. According to the abundant and potential by-products of banana stalk in south and their full-utilization, and microbial fermentation, the technology of producing of alcohol from banana stalk by microorganism method was studied. It breaks a new way to make the full use of banana stalk. And the main work and its results are as follows:4 species of strains are separated from the natural environment. Carbo-xymethyl cellulose sodium agar plate recognition and filter papers collapsing testing are carried out. Two specie of filamentous fungus which can decompose cellulose on a relatively-high scale was screened and identified. The results are as follows: the sequence of the strain LⅡhas 99.8% homology with the 16S rDNA of Stenotrophomonas maltophilia,and the sequence of the strain LB has 99.3% homology with the 18S rDNA of Eupenicillium javanicum.The pretreatment craft and hydrolysis craft of banana stalk are studied. Before enzymatic hydrolysis, by lignocelluloses may destroy crystal conFig.uration of cellulose, for aggrandizing approachability surface, improving efficiency of hydrolysis. The sodium hydroxide is utilized to carry on the pretreatment to the banana stalk, and the influentialfactors of pretreatment were studied including sodium hydroxide concentration, temperature, the ratio of solid to liquid and reaction time. And the pretreatment technological conditions are optimized. The results showed that: the best pretreatment effect could be abained at 25℃,3% sodium hydroxide,3h. The influential factors of hydrolysis craft were studied including sodium hydroxide pretreatment, amount of bacterial solution, hydrolysis time and hydrolysis PH. The orthogonal experiment of four factors and three levels finally confirmed that the effect sequence of each factor on each index of LⅡis pretreatment>bacteria amount>pH>hydrolysis time, the best condition combination is 3% NaOH, 3mL bacteria liquid of activating 12h, pH 8.0, hydrolysis 4d; the effect sequence of each factor on each index of LB is pretreatment>bacteria amount>pH>hydrolysis, the best condition combination is 3% NaOH, 2mL bacteria liquid of activating 12h, pH 7.0, hydrolysis 4d.Use the bacteria LⅡand mould LB by screened to blend with yeast in order to ferment banana stalk to prepare alcohol, preliminary determined the ferment technique of banana stalk prepare for alcohol. Established the microorganism cooperative ferment system is composedof bacteria LⅡ, mould LB and yeast. The technical proportion of ferment weight composition is about: banana stalk: microorganism liquid: yeast=1 : 0.1～0.5: 0.01～0.05, ferment time is 15～20d.