纤维素水解液培养粘红酵母产微生物油脂
发布时间：2018-10-30 07:55
【摘要】：当今社会,寻找新型可再生的、可持续的、高效经济的生物质能源受到了国际社会的广泛关注。纤维素原料具有来源丰富、分布广泛、廉价以及可再生等特点,其水解液含有丰富的可发酵五碳和六碳糖,因此探究利用纤维素水解液培养粘红酵母(Rhodotorula glutinis)产油脂具有重要的指导意义。本文首先探究了粘红酵母的基本生长特性,重点对比研究了利用不同比例五碳、六碳糖产油脂的情况。结果表明,粘红酵母总是优先利用葡萄糖,其次木糖,最后阿拉伯糖,且葡萄糖(六碳糖)的存在对木糖和阿拉伯糖(五碳糖)的利用有抑制作用,抑制程度与葡萄糖含量呈正相关。然后,本文利用纤维素水解液对粘红酵母进行培养。研究表明,粘红酵母可利用纤维素水解液产油脂,但水解液中的抑制物也严重影响了酵母细胞的生命活动。为保障粘红酵母充分利用水解液,需要补充额外的营养元素。纤维素原料的粒径大小对纤维素预处理效果影响较小,但1mm的粒径的酶解效果优于1mm的粒径。进一步研究发现,纤维素水解液常见抑制物乙酸和糠醛对粘红酵母利用五碳、六碳糖均有抑制作用,对葡萄糖利用的抑制效果更显著,但在以葡萄糖为单一碳源的培养基中生物量和油脂的积累情况依然是最好的。在0-1.5 g/L的浓度范围内,糠醛对粘红酵母的抑制程度与糠醛浓度呈正相关,但抑制程度差别并不大,其抑制作用常表现为细胞生长延滞期延长、对数生长期缩短、生物量积累下降、油脂产量减少、色素合成减少以及糖利用率下降等。糠醛存在时,粘红酵母倾向于生成更多的18碳长链脂肪酸或18碳长链不饱和脂肪酸以抵御逆境。最后,本文从发酵水平和代谢水平两方面重点探究了糠醛对粘红酵母的抑制机理。结果表明,糠醛对粘红酵母的抑制作用体现在生成了毒性更大的糠醇和糠酸,其相对毒性大小为：糠酸》糠醇糠醛。糠醛对粘红酵母糖代谢的抑制作用是可恢复的,对油脂代谢和色素代谢的影响可能更复杂,这可能与粘红酵母对糠醛的转化密切相关。糠醛还原为糠醇,以及糠醇氧化为糠酸所需的转化力均来自于粘红酵母。从代谢水平上来看,粘红酵母细胞在延滞期的代谢水平受到明显抑制,对数生长期代谢水平恢复甚至略有上升,但稳定期后酵母可能逐渐裂解死亡,检测不到代谢物的存在。
[Abstract]:Nowadays, the search for new renewable, sustainable, efficient and economical biomass energy has been paid more and more attention by the international community. Cellulose raw materials are rich in sources, widely distributed, cheap and renewable, and their hydrolysates contain abundant fermentable pentacarboxylic and hexacarboxylic sugar. Therefore, it is of great significance to explore the use of cellulose hydrolysate to culture (Rhodotorula glutinis) for oil production. In this paper, the basic growth characteristics of Rhodotorula pastoris were studied, and the production of oil with five carbon and six carbon sugars was compared. The results showed that glucose was preferentially used by Rhodotorula pastoris, followed by xylose and arabinose, and the presence of glucose (hexaccharide) inhibited the utilization of xylose and arabinose (pentaccharide). The degree of inhibition was positively correlated with glucose content. Then, the yeast was cultured with cellulose hydrolysate. The results showed that red yeast could produce oil by cellulose hydrolysate, but the inhibitor in the hydrolysate also seriously affected the life activity of yeast cells. Additional nutrients are needed to ensure the full use of the hydrolysate by Rhodotorula pastoris. The particle size of cellulose had little effect on the pretreatment effect of cellulose, but the particle size of 1mm was better than that of 1mm. It was further found that acetic acid and furfural, the common inhibitors of cellulose hydrolysate, could inhibit the utilization of pentacarboxylic and hexacarbonose by Rhodotorula pastoris, and the inhibition effect on glucose utilization was more significant. However, the accumulation of biomass and oil was still the best in the medium with glucose as a single carbon source. In the concentration range of 0-1.5 g / L, the inhibition degree of furfural on Rhodotorula pastoris was positively correlated with the concentration of furfural, but the inhibition degree was not significant. The inhibitory effect of furfural on the cell growth delay period and logarithmic growth period was usually prolonged, and the logarithmic growth period was shortened in the range of 0-1.5 g / L. Biomass accumulation decreased, oil yield decreased, pigment synthesis decreased and sugar utilization rate decreased. In the presence of furfural, red yeast tended to produce more 18 carbon long chain fatty acids or 18 carbon long chain unsaturated fatty acids to resist stress. Finally, the inhibition mechanism of furfural on Rhodotoryces pastoris was studied from two aspects: fermentation level and metabolism level. The results showed that the inhibitory effect of furfural on Rhodotorula pastoris was reflected in the formation of more toxic furfurol and furfuric acid. The relative toxicity of furfural was furoic acid > furfural. The inhibition of furfural on glucose metabolism of Rhodotoryces pastoris is recoverable, and the effects on lipid metabolism and pigment metabolism may be more complicated, which may be closely related to the transformation of furfural by Rhodotorula pastoris. The conversion ability of furfural to furfural alcohol and furfural alcohol to furfuric acid was obtained from Rhodotorula pastoris. From the level of metabolism, the metabolic level of erythromyxomyces pastoris cells in the delayed phase was significantly inhibited, the metabolism level of logarithmic growth phase recovered or even slightly increased, but after stable phase, the yeast may gradually decompose and die, and no metabolites can be detected.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ926;TE667
本文编号：2299406
[Abstract]:Nowadays, the search for new renewable, sustainable, efficient and economical biomass energy has been paid more and more attention by the international community. Cellulose raw materials are rich in sources, widely distributed, cheap and renewable, and their hydrolysates contain abundant fermentable pentacarboxylic and hexacarboxylic sugar. Therefore, it is of great significance to explore the use of cellulose hydrolysate to culture (Rhodotorula glutinis) for oil production. In this paper, the basic growth characteristics of Rhodotorula pastoris were studied, and the production of oil with five carbon and six carbon sugars was compared. The results showed that glucose was preferentially used by Rhodotorula pastoris, followed by xylose and arabinose, and the presence of glucose (hexaccharide) inhibited the utilization of xylose and arabinose (pentaccharide). The degree of inhibition was positively correlated with glucose content. Then, the yeast was cultured with cellulose hydrolysate. The results showed that red yeast could produce oil by cellulose hydrolysate, but the inhibitor in the hydrolysate also seriously affected the life activity of yeast cells. Additional nutrients are needed to ensure the full use of the hydrolysate by Rhodotorula pastoris. The particle size of cellulose had little effect on the pretreatment effect of cellulose, but the particle size of 1mm was better than that of 1mm. It was further found that acetic acid and furfural, the common inhibitors of cellulose hydrolysate, could inhibit the utilization of pentacarboxylic and hexacarbonose by Rhodotorula pastoris, and the inhibition effect on glucose utilization was more significant. However, the accumulation of biomass and oil was still the best in the medium with glucose as a single carbon source. In the concentration range of 0-1.5 g / L, the inhibition degree of furfural on Rhodotorula pastoris was positively correlated with the concentration of furfural, but the inhibition degree was not significant. The inhibitory effect of furfural on the cell growth delay period and logarithmic growth period was usually prolonged, and the logarithmic growth period was shortened in the range of 0-1.5 g / L. Biomass accumulation decreased, oil yield decreased, pigment synthesis decreased and sugar utilization rate decreased. In the presence of furfural, red yeast tended to produce more 18 carbon long chain fatty acids or 18 carbon long chain unsaturated fatty acids to resist stress. Finally, the inhibition mechanism of furfural on Rhodotoryces pastoris was studied from two aspects: fermentation level and metabolism level. The results showed that the inhibitory effect of furfural on Rhodotorula pastoris was reflected in the formation of more toxic furfurol and furfuric acid. The relative toxicity of furfural was furoic acid > furfural. The inhibition of furfural on glucose metabolism of Rhodotoryces pastoris is recoverable, and the effects on lipid metabolism and pigment metabolism may be more complicated, which may be closely related to the transformation of furfural by Rhodotorula pastoris. The conversion ability of furfural to furfural alcohol and furfural alcohol to furfuric acid was obtained from Rhodotorula pastoris. From the level of metabolism, the metabolic level of erythromyxomyces pastoris cells in the delayed phase was significantly inhibited, the metabolism level of logarithmic growth phase recovered or even slightly increased, but after stable phase, the yeast may gradually decompose and die, and no metabolites can be detected.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ926;TE667
【参考文献】
相关期刊论文 前1条
1 薛照辉,吴谋成;微生物油脂进展[J];山西食品工业;2002年02期
，本文编号：2299406
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