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目的以木薯淀粉水解液替代葡萄糖异养培养小球藻,观察其对小球藻生物量和油脂积累的影响。方法采用双酶协同酶解法水解木薯淀粉,扫描电镜和X-射线衍射表征分析水解前后产物的物理特性;分别以精制葡萄糖和木薯淀粉水解液作为碳源,尿素作为氮源,采用异养模式培养小球藻;干重法测定藻细胞生物量,提取总脂,气相色谱-质谱联用技术(GC-MS)分析脂肪酸含量。结果双酶协同水解木薯淀粉的最佳工艺条件为:温度70℃,pH 4.0,时间3 h,酶添加量0.5%,底物浓度20 g/L,此时水解木薯淀粉转化成的葡萄糖含量为64.11%;表征分析显示,酶解发生在颗粒表面,整个淀粉颗粒仍能保持外形结构,酶水解作用未改变木薯淀粉的晶型;当培养基中葡萄糖浓度为40 g/L时,小球藻生物量和总脂产量分别为9.12和4.39 g/L;当培养基中木薯淀粉水解液的葡萄糖浓度为30 g/L时,小球藻生物量和总脂产量分别为9.50和4.51 g/L,比以葡萄糖为碳源时的生物量和总脂产量高4.17%和2.73%。结论木薯淀粉水解液作为碳源在异养培养提高微藻油脂产量和减少微藻生物柴油生产成本方面是一种比较理想的途径。
Objective To replace the glucose heterotrophic culture of chlorella with tapioca hydrolyzate and observe its effects on the biomass and lipid accumulation of Chlorella. Methods The enzymatic hydrolysis of cassava starch was carried out by enzymatic hydrolysis of two enzymes, scanning electron microscopy and X-ray diffraction were used to characterize the physical and chemical properties of the products before and after hydrolysis. The purified glucose and tapioca hydrolyzate were used as carbon source and urea as nitrogen source respectively. Chlorella; dry weight method was used to determine the biomass of algae cells, total fatty acids were extracted, and the content of fatty acids was analyzed by gas chromatography-mass spectrometry (GC-MS). Results The optimum conditions of enzymatic hydrolysis of tapioca starch by double enzymes were as follows: temperature 70 ℃, pH 4.0, time 3 h, enzyme dosage 0.5%, substrate concentration 20 g / L, and the glucose content of hydrolyzed tapioca starch was 64.11%. The characterization analysis showed that the enzymolysis occurred on the surface of the particles, and the whole starch granules remained the appearance structure. The enzymatic hydrolysis did not change the crystal form of the tapioca starch. When the glucose concentration in the medium was 40 g / L, Biomass and total lipid yield were 9.12 and 4.39 g / L, respectively. When the glucose concentration of tapioca hydrolyzate was 30 g / L in the medium, the biomass and total lipid yield of Chlorella were 9.50 and 4.51 g / L, respectively , 4.17% and 2.73% higher than the biomass and total fat yield when glucose was the carbon source. Conclusion As a carbon source, cassava starch hydrolyzate is an ideal way to enhance the oil production of microalgae and reduce the production cost of microalga biodiesel in heterotrophic culture.