【作者】 陈俊辉；

【导师】 魏东；

【作者基本信息】 华南理工大学 ， 制糖工程， 2011， 硕士

【摘要】 生物柴油一般是将动植物类油脂等与短链醇在一定条件下通过酯交换等方法生成的,是一种优质、安全、环保的可再生能源。利用小球藻作为原料生产生物柴油具有诸多优点。在制备生物柴油的过程中,对小球藻胞内活性物质进行综合开发,可以进一步降低其生产成本,具有良好的应用前景。木薯渣等生物质资源废弃物污染环境,产量高,对其进行综合利用显得非常必要。本文对生物质资源废弃物蔗渣和木薯渣进行预处理和酶解,并将制备的水解液用于异养小球藻的发酵,系统分析了不同处理方法对蔗渣和木薯渣的水解糖化得率以及不同水解液对小球藻细胞生长和脂肪酸积累的影响。主要实验结果如下所示:1.采用多种预处理和酶解方法对蔗渣和木薯渣进行水解糖化,并对其进行酶解放大,系统分析了不同方法对蔗渣和木薯渣水解糖化的影响。结果表明:采用NaClO2和HCl联合处理可以显著提高蔗渣的水解得率,葡萄糖含量达到25.4g/L,木糖含量为2.2g/L,蔗渣总损失率仅为19.3%。在7L生物反应器中对蔗渣酶解进行放大,葡萄糖浓度为15.1g/L,葡萄糖产率为0.63g/L/h,还原糖产率为1.13g/L/h。直接采用纤维素酶对木薯渣进行酶解,酶解效果最好,可以制得葡萄糖浓度高达34.9g/L的酶解液。在5L生物反应器中进行木薯渣酶解放大,制得酶解液中葡萄糖浓度为27.4g/L,还原糖浓度为34.8g/L,在酶解前进行酸解预处理后,还原糖浓度增加到43.9g/L,而在100L反应釜中制备得到的酶解液中还原糖浓度为31.0g/L。2.采用蔗渣酶解液为碳源对异养小球藻进行培养,系统分析了不同碳氮源浓度对异养小球藻生长和脂肪酸积累的影响。结果表明:碳源浓度对小球藻生物量有显著影响,氮源浓度对小球藻胞内脂肪酸积累有显著影响。当葡萄糖浓度为15g/L时,获得最大生物量(10.7g/L)和最高脂肪酸产量(0.55g/L),优于葡萄糖对照。当氮源浓度为0.1mmol/L时,脂肪酸产量最高为0.87g/L,略低于葡萄糖对照组中得到的1.2g/L。3.分别以木薯渣酸解-酶解液、木薯渣酶解液和葡萄糖为碳源在5L生物反应器中对异养小球藻进行培养,系统分析了不同碳源对小球藻生物量、中性脂和脂肪酸积累的影响。结果表明:当培养异养小球藻144h时,采用木薯渣酶解液为碳源分批培养异养小球藻,同酸解-酶解液相比可以显著增加小球藻生物量,达到7.2g/L。小球藻脂肪酸产量(2.5g/L)和中性脂含量(48.6%DW)同葡萄糖对照相比有显著降低,但是脂肪酸占中性脂的含量(70.6%)有显著增加。以木薯渣酶解液为碳源对异养小球藻进行补料分批培养360h后,异养小球藻生物量达到9.7g/L,脂肪含量为38.9%DW,脂肪酸产量为3.7g/L,小球藻生物量产率为26.9mg/L/h,生物量对葡萄糖等总糖的得率为0.37g/g总糖。此外对木薯渣水解液中副产物进行了定性和定量分析,结果表明水解液中乙酸、糠醛和苯甲酸的含量较高,其中木薯渣酶解液中乙酸和苯甲酸的含量分别为78.1mg/L和62.5mg/L。该研究结果对于改进木薯渣酶解液的制备以及异养小球藻的培养方法具有重要的意义。更多还原

【Abstract】 Biodiesel is a high-quality, safe, environmental and renewable energy, produced from plant and animal oil reacted with short-chain alcohol under a certain condition by transesterification. Using Chlorella as one source of commercial biodiesel has a lot of advantages. During the production of biodiesel, the comprehensive development of high-value bioactives in Chlorella would reduce the cost and make the biodiesel industry have a good application prospect. Biological resources such as cassava rediues have a high yield and pollute the environment, it is necessary to deepen the application of these resources. In this paper, these biological residues such as sugarcane bagasse and cassava bagasse were hydrolyzated, meanwhile the oil-rich heterotrophic Chlorella was obtained using these hydrolysates as carbon sources, the systematic analysis of the enzymatic saccharification yields of these residues by diffenent methods and the effects of different hydrolysates on growth and fatty acids accumulation of Chlorella were investigated. The main results were as follows:1. Sugarcane bagasse and cassava bagasse were hydrolyzated for saccharification by different methods of preatment and hydrolysis, and the effects of different methods on enzymatic saccharification yield were analyzated. The results showed that the hydrolysis yield of sugarcane bagasse was improved significantly by NaClO2 and HCl preatment. The glucose and xylose concentration were 25.4 and 2.2g/L,however the total weight loss was only 19.3%. The glucose concentration and the productivity of glucose and reducing sugar were 15.1g/L, 0.63g/L/h and 1.13g/L/h respectively when the sugarcane bagasse was hydrolyzated in 7L bioreactor. The glucose concentration was achieved at 34.9g/L when the cassava bagasse was hydrolysated by cellulose directly. The hydrolysate containing 27.4g/L glucose and 34.8g/L reducing sugar was obtained in 5L bioreactor, meanwhile the reducing sugar concentration was increased to 43.9g/L after dilute acid preatment of cassava. The reducing sugar concentration was only 31.0g/L when the hydrolysate was achieved in 100L reactor.2. Effects of different carbon sources and nitrogen sources on cell growth and fatty acids accumulation was analyzated in batch cultivation of Chlorella using sugarcane bagasse hydrolysate as carbon source. The results showed that the carbon source concentration had a significant effect on cell growth, but the nitrogen source concentration had a significant effect on introcelluar fatty acids accumulation. The highest biomass(10.7g/L) and fatty acids yield(0.55g/L) were achieved when the glucose concentration in the medium was 15g/L, which were higher than that of the control. When the nitrogen was 0.1mmol/L,the highest fatty acids yield was 0.87g/L, which was a little lower compared to the control (1.2g/L).3. Cultivation of heterotrophic Chlorella was achieved in 5L bioreactor using cassava bagasse acid-hydrolysate, cassava bagasse hydrolysate and glucose as carbon source respectively and the systematic analysis of effects of different carbon sources on cell growth, neutral lipids and fatty acids accumulation was investigated. The results showed that the biomass was achieved at 7.2g/L after 144h in batch cultivation of Chlorella using cassava bagasse hydrolysate as carbon source. Compared with cassava bagasse acid-hydrolysate, the biomass was significantly increased. The fatty acids yield (2.5g/L) and neutral lipids content(48.6%DW) was significantly lower than that of control. However the ratio of fatty acids in neutral lipids (70.6%) was significantly higher than that of control. After 360h in fed-batch cultivation of heterotrophic Chlorella using cassava bagasse hydrolysate, the biomass, fatty acids content and yield were 9.7g/L, 38.9%DW and 3.7g/L respectively, meanwhile the biomass productivity and yield on total sugar were 26.9mg/L/h and 0.37g/g. Qualitative and quantitative analysis of the compounds in these hydrolysates were studied by GC-MS. It was found that acetic acid, furfural and benzenecarboxylic acid were the main compounds. The acetic acid and benzenecarboxylic acid concentration in cassava bagasse hydrolysate were 78.1mg/L and 62.5mg/L, respectively. The results above had a great significance in the preparation of cassava bagasse hydrolysate and the cultivation of heterotrophic Chlorella using these hydrolysates as carbon sources.更多还原