【作者】 邓强；

【导师】 张焜；

【作者基本信息】 广东工业大学 ， 应用化学， 2008， 硕士

【摘要】 纤维素是一种廉价的可再生资源,由其发酵所产生的生物燃料乙醇对能源工业以及环境可持续发展具有重大意义。本文针对南方农作物香蕉大宗副产物香蕉秆的资源优势及香蕉秆的综合利用现状,根据微生物学及发酵工程理论,采用微生物方法,利用香蕉秆生产酒精,为香蕉秆的综合利用开辟一条新的途径,本文主要研究内容和研究结果如下:从自然环境中采集样品进行分离纯化得到4株疑似目的菌株。分别采用羧甲基纤维素钠相对活性法、滤纸条崩解试验,从中选出2株分解纤维素能力较强的菌株(LⅡ和LB)进行鉴定试验。经初步鉴定,菌株LⅡ与Stenotrophomonas maltophilia的16S rDNA序列有99.8%的同源性;用18S rDNA对LB进行序列分析,结果表明菌株LB与Eupenicilliumjavanicum的18S rDNA序列有99.3%的同源性。初步得出LⅡ是嗜麦芽寡养单胞菌,LB是爪哇正青霉。本论文研究了香蕉秆预处理工艺及水解工艺。纤维素原料在水解前经过预处理可破坏纤维素结晶结构,从而增大其接近表面,提高水解效率。采用氢氧化钠对香蕉秆进行预处理,考察了氢氧化钠溶液浓度、温度、固液比、时间等因素对预处理的影响,优化预处理工艺条件。实验最后确定在25℃条件下,按1:12的固液比(香蕉秆:氢氧化钠溶液),加入质量浓度3%的氢氧化钠溶液,处理3小时,可获得较佳的预处理效果。水解工艺分别考查了氢氧化钠预处理、菌液用量、时间及PH的影响,通过四因素三水平的正交实验,最终确定各个因素对LⅡ各个指标的影响顺序为:预处理＞菌用量＞PH＞水解时间,最佳条件组合为3%浓度氢氧化钠、3mL活化12小时的菌液、PH 8.0、水解4天;各个因素对LB各个指标的影响顺序为预处理＞PH＞菌用量＞水解时间,最佳组合为3%浓度氢氧化钠、PH 7.0、2mL活化12小时的菌液、水解4天。利用筛选所获得的细菌LⅡ、霉菌LB与酵母混合发酵制备酒精,初步确定香蕉秆生产酒精的发酵工艺。确立了由细菌LⅡ、霉菌LB及酵母组成的微生物混合协同发酵体系;发酵重量组分技术配比约为:香蕉秆:微生物菌液:酵母=1:0.1～0.5:0.01～0.05,发酵时间为15～20天。更多还原

【Abstract】 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.更多还原