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乙醇型发酵产氢菌特性及其生物强化技术研究
党消消
Thesis Advisor邱艳玲
2016-05
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Discipline生物化学与分子生物化学
Keyword厌氧发酵 氢气 甲烷 玉米秸秆 生物强化
Abstract随着资源短缺、能源危机和环境污染等问题的加剧,人们逐渐认识到厌氧发酵技术(既能消除污染又能产生可再生能源:氢气或沼气)的重要性。在厌氧生物处理过程中,微生物处于整个工艺的核心地位,直接决定着发酵效率的高低。因此,选取高效关键菌株,优化菌群结构,对提高微生物菌群的活性及秸秆厌氧发酵产氢产甲烷的效率具有重要意义。基于本实验室分离得到的一株糖类发酵产氢产乙醇乙酸菌Hydrogenispora ethanolica LX-B,本课题研究了该菌株的产氢生理特征,并将该菌株投加到秸秆沼气发酵系统中,即使用生物强化法提高了秸秆甲烷产量,实验结果表明,该菌株具有较高的产氢效率,投加到秸秆沼气发酵系统中,实现了在低能耗、无污染、条件温和的反应过程中提高秸秆降解率和产能效率的目的。其主要研究内容和结果如下: 1、 以一株乙醇型发酵产氢厌氧细菌Hydrogenispora ethanolica LX-B为研究对象,首先研究了其对底物葡萄糖浓度及其产物乙酸、乙醇浓度和氢分压的耐受性,实验结果表明,该菌株具有产氢速率高、生长速率快、对底物和产物耐受性高的优点。该菌株能在高达41.5 g/L的葡萄糖底物浓度下生长,在1.1 g/L葡萄糖,温度37 °C,初始pH 7.0条件下,最大产氢率为1.8 mol H2/mol glucose,同时产生乙醇1.4 mol /mol glucose和乙酸0.8 mol /mol glucose(电子转化率为 114 %)。能耐受100 mM产物乙酸和乙醇(抑制率< 20%),且在较高的氢分压(27 mmol/L)下,能维持正常的生长和产氢;其次,以木质纤维素典型糖类组分为碳源,评价了Hydrogenispora ethanolica LX-B利用不同糖类产氢的情况,结果表明,该菌株能利用戊糖、己糖和多糖等生长,其中,葡萄糖、木糖、阿拉伯糖、甘露糖和半乳糖是较适合的碳源;同时研究了该菌对不同浓度热-NaOH碱处理玉米秸秆的利用性,研究发现,使用0.25% NaOH预处理,最大产氢量为67.8 mL/g-corn straw,比对照组提高了21.9%(对照组产氢量为55.6 mL/g-corn straw)。 2、 在研究了Hydrogenispora ethanolica LX-B产氢特性的基础上,为提高玉米秸秆厌氧发酵产甲烷的效率,在发酵系统中投加该菌株,探究了其对玉米秸秆沼气发酵的生物强化作用。结果表明,H. ethanolica使玉米秸秆厌氧发酵的甲烷产量提高16-18%,当5%接种时,最大甲烷产量达到233.8 mL/g-corn straw。H. ethanolica使甲基纤维素和木聚糖甲烷产量分别提高了21.7%、14.2%。推测H. ethanolica最可能的强化机制为:H. ethanolica将更多的木质纤维素生物质的水解产物,像五碳糖和六碳糖,转化为乙醇、乙酸和氢气,一方面促进了秸秆中纤维素和木聚糖的降解,另一方面为产甲烷菌提供了更多的底物。
Other AbstractWith the increasing of resources shortage, energy crisis and environmental pollution, much attention has been focusing on anaerobic digestion (owing to its high pollution removal ability and renewable energy generation: hydrogen or biogas). Microbes are the main vehicle for anaerobic digestion, which determine the production efficiency. Therefore, it is significant to pay attention to exploitations of highly more efficient microorganisms and optimize the fermentation conditions, which is responsible for the efficiency of anaerobic technology. Previously, we isolated a hydrogen producing ethanol-type bacterium Hydrogenispora ethanolica LX-B. In this study, the characteristic about anaerobic biohydrogen of this bacterium, application the bioaugmentation technology into the anaerobic digestion of corn straw was investigated. Results showed that the strain possess high hydrogen production efficiency, application into the anaerobic digestion of corn straw could accelerate the degradation of straw and improve production efficiency in the condition of energy saving, environmental friendly and mild conditions. Main contents and results of the present study are as follows: 1. The biohydrogen production potential of Hydrogenispora ethanolica LX-B was studied. Firstly, the effect of glucose and products inhibition by acetate, ethanol and hydrogen on the growth and hydrogen production was assayed. Results showed that Hydrogenispora ethanolica is a promising strain for hydrogen production with relatively high hydrogen yields, high growth rate, a wide rage of substrate utilization and production tolerance. The bacterium grew well and kept high hydrogen yield in a wide range of initial glucose concentrations up to 41.5 g/L. The maximal yields of 1.8 mol H2/mol glucose and 1.4 mol ethanol/mol glucose were observed at 1.1 g/L glucose at 37 °C and pH 7.0. Neither acetate nor ethanol exhibited significant inhibition: the addition of ethanol or acetate up to 100 mM only had less than 20% inhibition on the growth and glucose consumption during two weeks of incubation. Besides, under high hydrogen partial pressure of 27 mmol/L culture, the growth and glucose consumption of the pure culture was not inhibited. Secondly, hydrogen production ability on various sugars and corn straw was also investigated. Results demonstrated that the strain could grow on pentose, hexose and polyose, in which glucose, xylose, arabinose, mannose and galactose are the preferred carbon source. Besides, the strain would be an ideal candidate for hydrogen production with cellulosic biomass. The maximum H2 yield of 6.8 mL/g was achieved by NaOH-pretreated corn straw, which was 21.9% higher than the control (5.6 mL/g-corn straw). 2. The bioaugmentation effect of H. ethanolica LX-B on anaerobic digestion of corn straw was studied. Results showed that bioaugmentation with the strain could increase 16-18% methane yield of corn straw degradation. The maximum methane yield was 233.8 mL/g-corn straw with 5% inoculation. H. ethanolica could improve the methane yields from methyl cellulose and xylan (models for cellulose and hemicelluloses, respectively) by 21.7% and 14.2%. A proposed mechanism is that H. ethanolica promotes more hydrolysates of lignocellulosic biomass (such as pentose and hexose) to ethanol, acetate and hydrogen, and provides a source of substrates for the methanogens. As a result, the degradation of cellulose of corn straw were improved.
Department生物制氢与沼气团队
Subject Area环境微生物
Date Available2020-12-30
Subtype硕士 ; 学位论文
Language中文
Document Type学位论文
Identifierhttp://ir.qibebt.ac.cn/handle/337004/9775
Collection工业生物燃气研究组
Affiliation中国科学院青岛生物能源与过程研究所
Recommended Citation
GB/T 7714
党消消. 乙醇型发酵产氢菌特性及其生物强化技术研究[D]. 北京. 中国科学院大学,2016.
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