【摘要】：當(dāng)今社會(huì),尋找新型可再生的、可持續(xù)的、高效經(jīng)濟(jì)的生物質(zhì)能源受到了國(guó)際社會(huì)的廣泛關(guān)注。纖維素原料具有來(lái)源豐富、分布廣泛、廉價(jià)以及可再生等特點(diǎn),其水解液含有豐富的可發(fā)酵五碳和六碳糖,因此探究利用纖維素水解液培養(yǎng)粘紅酵母(Rhodotorula glutinis)產(chǎn)油脂具有重要的指導(dǎo)意義。本文首先探究了粘紅酵母的基本生長(zhǎng)特性,重點(diǎn)對(duì)比研究了利用不同比例五碳、六碳糖產(chǎn)油脂的情況。結(jié)果表明,粘紅酵母總是優(yōu)先利用葡萄糖,其次木糖,最后阿拉伯糖,且葡萄糖(六碳糖)的存在對(duì)木糖和阿拉伯糖(五碳糖)的利用有抑制作用,抑制程度與葡萄糖含量呈正相關(guān)。然后,本文利用纖維素水解液對(duì)粘紅酵母進(jìn)行培養(yǎng)。研究表明,粘紅酵母可利用纖維素水解液產(chǎn)油脂,但水解液中的抑制物也嚴(yán)重影響了酵母細(xì)胞的生命活動(dòng)。為保障粘紅酵母充分利用水解液,需要補(bǔ)充額外的營(yíng)養(yǎng)元素。纖維素原料的粒徑大小對(duì)纖維素預(yù)處理效果影響較小,但1mm的粒徑的酶解效果優(yōu)于1mm的粒徑。進(jìn)一步研究發(fā)現(xiàn),纖維素水解液常見(jiàn)抑制物乙酸和糠醛對(duì)粘紅酵母利用五碳、六碳糖均有抑制作用,對(duì)葡萄糖利用的抑制效果更顯著,但在以葡萄糖為單一碳源的培養(yǎng)基中生物量和油脂的積累情況依然是最好的。在0-1.5 g/L的濃度范圍內(nèi),糠醛對(duì)粘紅酵母的抑制程度與糠醛濃度呈正相關(guān),但抑制程度差別并不大,其抑制作用常表現(xiàn)為細(xì)胞生長(zhǎng)延滯期延長(zhǎng)、對(duì)數(shù)生長(zhǎng)期縮短、生物量積累下降、油脂產(chǎn)量減少、色素合成減少以及糖利用率下降等。糠醛存在時(shí),粘紅酵母傾向于生成更多的18碳長(zhǎng)鏈脂肪酸或18碳長(zhǎng)鏈不飽和脂肪酸以抵御逆境。最后,本文從發(fā)酵水平和代謝水平兩方面重點(diǎn)探究了糠醛對(duì)粘紅酵母的抑制機(jī)理。結(jié)果表明,糠醛對(duì)粘紅酵母的抑制作用體現(xiàn)在生成了毒性更大的糠醇和糠酸,其相對(duì)毒性大小為：糠酸》糠醇糠醛�？啡⿲�(duì)粘紅酵母糖代謝的抑制作用是可恢復(fù)的,對(duì)油脂代謝和色素代謝的影響可能更復(fù)雜,這可能與粘紅酵母對(duì)糠醛的轉(zhuǎn)化密切相關(guān)�？啡┻�原為糠醇,以及糠醇氧化為糠酸所需的轉(zhuǎn)化力均來(lái)自于粘紅酵母。從代謝水平上來(lái)看,粘紅酵母細(xì)胞在延滯期的代謝水平受到明顯抑制,對(duì)數(shù)生長(zhǎng)期代謝水平恢復(fù)甚至略有上升,但穩(wěn)定期后酵母可能逐漸裂解死亡,檢測(cè)不到代謝物的存在。
[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.
【學(xué)位授予單位】：北京化工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：TQ926;TE667

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 薛照輝,吳謀成;微生物油脂進(jìn)展[J];山西食品工業(yè);2002年02期

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本文編號(hào)：2299406