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高含油微生物的筛选及木质纤维素基生物柴油工艺构建
高莽
导师崔球 研究员 ; 冯银刚 研究员
2012-11
学位授予单位中国科学院研究生院
学位授予地点北京
学位专业生物工程
关键词木质纤维素 预处理 热纤梭菌 裂殖壶菌 Dha 单细胞油脂。
其他摘要

木质纤维素是地球上最丰富的能够转化成生物燃料的可再生资源。然而,由于木质纤维素的抗降解屏障,当前生物燃料产品单一,成本高昂等因素严重阻碍了其产业化进程。为了解决这一问题,本研究通过将纤维素的厌氧微生物降解糖化及含油微生物发酵产油过程串联耦合,开发一种新的工艺过程,以木质纤维素为原料,生产单细胞油脂,可用于生产生物柴油及高附加值副产品,从而为规模化原料提供、具有整体经济竞争力的木质纤维素基生物能源产业化奠定基础。本研究具体结果如下:

1.低成本的木质纤维素预处理方法开发;为了有效克服木质纤维素的抗降解屏障,本研究开发了一种能够破坏木质素结构并增加纤维素比表面积的混碱预处理方法,通过优化处理温度、混碱比例、反应时间等预处理参数,最终确定了最优预处理条件:氢氧化钠1% (w/w),氢氧化钙7% (w/w),固液比110100℃处理4h

2. 高含油微生物的筛选;从浙江、广东、云南、福建、海南等代表性生境中采样,利用松树花粉富集,结合复合抗生素筛选平板筛选得到高含油微生物(油脂含量>35%干重)32株,其中包括酵母3株,破囊壶菌科的真菌29株,对代表性菌株进行了鉴定及基本生理生化研究。

3. 代表性菌株的产油发酵优化及完整木质纤维素产微生物油脂的工艺构建;对筛选得到的裂殖壶菌Aurantiochytrium sp. SD116菌株进行了发酵优化研究,摇瓶实验表明,使用葡萄糖6%,酵母提取物2%,人造海水50%pH=7.0的培养基,温度28℃,可以得到最大油脂含量56.3%(占细胞干重),其中DHA含量占总脂肪酸含量的50.9%。以葡萄糖为碳源,酵母提取物为氮源,使用5L发酵罐连续补加葡萄糖与酵母提取物,细胞干重可达110g/L,油脂含量达到60g/LDHA产量达到21g/L。最后,使用具有高效纤维素降解能力的热纤梭菌Clostridium thermocellum DSM1313菌株为纤维素的糖化菌株,建立了从木质纤维素原料的混碱预处理,纤维素的热纤梭菌降解与糖化,混合糖经裂殖壶菌发酵转化成单细胞油脂的完整工艺流程。;

Lignocellulose is the most abundant renewable material which can be transformed into bioenergy. However, recalcitrance of the lignocellulose, the narrow varieties and the low price of downstream biofuel products had seriously restrained the industrialization of biofuels. To tackle this problem, this study couples an anaerobic bacteria which is used for cellulose saccharification with an oleaginous microorganism which is responsible to produce oil from the sugars. A new process is then constructed where lignocellulosic biomass is transformed into single cell oils, which can be used to produce biodiesel and high value-added product. The detailed results of this study are summarized as follows:

1. The development of low cost lignocellulose pretreatment: In order to overcome recalcitrance of the lignocellulose, a mixed alkali lignocellulose pretreatment technique which is able to isolate lignin and increase the enzymatic accessibility of cellulose was investigated. After optimizing the temperature, amount of alkali and reaction time, the final method is determined as adding 1%(w/w) sodium hydroxide, 7% calcium hydroxide and ten times water of the material before maintained at 100°C for 4 hours.

2. Screening microbial containing high level of lipids: Including 3 yeasts and 29 Traustochytriaceaes, 32 high lipids contained microbial was isolated from samples which were collected from typical biotic environment of Zhejiang, Guangdong, Yunnan, Fujian and Hainan Province with pine pollen enrichment and medium containing compound antibiotics. After strain identification, basic physiological and biochemical properties of the typical strains were investigated.

3. Fermentation optimization for oil production by strain SD116 and construction of complete process from lignocellulose to microbial oil: The highest oil contain of strain Aurantiochytrium sp. SD116 which was cultured in shake flask with 6.0% glucose, 2.0% yeast extract, and 50% artificial seawater (ASW) at a pH of 7 at 28°C was achieved at 56.3% of the dry cell weight (DCW). In this circumstance DHA reached 50.9% of the total fatty acid. Fermented in 5L bioreactor with glucose and yeast extract fed-batch, DCW, oil and DHA can reach 110g/L, 60g/L and 21g/L, respective. A biotransformation of lignocellulose was formed that the raw material is first pretreated by mixed alkali, then degraded to soluble carbohydrate by Clostridium thermocellum DSM1313, and finally converted into single cell oils by Aurantiochytrium sp. SD116.
作者部门代谢物组学团队
学科领域代谢物组学
公开日期2012-12-12
学位类型硕士
语种中文
文献类型学位论文
条目标识符http://ir.qibebt.ac.cn/handle/337004/1434
专题代谢物组学研究组
推荐引用方式
GB/T 7714
高莽. 高含油微生物的筛选及木质纤维素基生物柴油工艺构建[D]. 北京. 中国科学院研究生院,2012.
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