【摘要】：生物柴油具有可生物降解、低毒、低排放特性,是最有前景的化石能源替代燃料,但原料油供應(yīng)不足成為限制生物柴油發(fā)展的瓶頸。微生物油脂是生物柴油的潛在理想原料油,本論文擬從自然界中篩選油脂高產(chǎn)真菌,并對(duì)其油脂發(fā)酵工藝進(jìn)行優(yōu)化,取得的主要研究結(jié)果如下:(1)從牧場(chǎng)土壤篩選獲得一株油脂含量為30.2%的真菌,其脂肪酸組份主要為油酸(46.26%)、棕櫚酸(22.58%)、γ-亞麻酸(13.68%)和亞油酸(6.68%),與植物油脂肪酸組成相似,堿法制備生物柴油得率89.6%,且其生物柴油特性指標(biāo)基本符合國(guó)際生物柴油生產(chǎn)標(biāo)準(zhǔn),表明該菌株可作為原料油生產(chǎn)生物柴油。(2)根據(jù)形態(tài)學(xué)、生理生化特征及18S rDNA序列分析,對(duì)篩得的菌株進(jìn)行分類鑒定。結(jié)果表明,該菌株的形態(tài)和生理特征與毛霉屬真菌相似,且其18S rDNA序列與Mucor sp.EA 2010b stain ERRL的18S rDNA序列相似度為99%,因此,將其歸屬于毛霉,并命名為Mucor sp.RBB 1-5。(3)采用單因子實(shí)驗(yàn)和響應(yīng)面分析優(yōu)化了Mucor sp.RBB 1-5的油脂發(fā)酵工藝,發(fā)現(xiàn)蛋白胨較酵母粉更有利于油脂積累,其最佳培養(yǎng)基配方為:葡萄糖103.32 g/L,蛋白胨3.21 g/L,豆粕粉蛋白濃度3.29 g/L,KNO3 3.0 g/L,Na2HPO4 2.0 g/L,MgSO4·7H2O1.0 g/L;最佳培養(yǎng)條件為:初始pH 6.0,裝液量50 m L/250 mL,溫度28℃,培養(yǎng)時(shí)間5 d。在優(yōu)化發(fā)酵條件下,油脂產(chǎn)量達(dá)10.38 g/L,相比未優(yōu)化之前提高2.15倍。(4)研究了蛋白胨和酵母粉對(duì)油脂發(fā)酵的影響機(jī)制。通過(guò)分析氮源對(duì)三羧酸循環(huán)(TCA)途徑中蘋果酸酶(ME)活性和戊糖磷酸(PP)途徑中葡萄糖-6磷酸脫氫酶(G6PDH)活性的影響,探討氮源對(duì)油脂發(fā)酵的影響機(jī)制。蘋果酸酶(ME)酶活與油脂變化趨勢(shì)一致,葡萄糖-6-磷酸脫氫酶(G6PDH)活性與油脂變化無(wú)明顯相關(guān)性,蛋白胨為氮源時(shí)ME酶活性高于酵母粉組,表明蛋白胨主要通過(guò)影響TCA途徑,增強(qiáng)ME活性,進(jìn)而增加還原力NADPH的供應(yīng)來(lái)提高油脂產(chǎn)量。
[Abstract]:Biodiesel has the characteristics of biodegradability, low toxicity and low emission, so it is the most promising alternative fuel for fossil energy. However, the shortage of raw oil has become the bottleneck to restrict the development of biodiesel. Microbial oil is a potential ideal raw oil for biodiesel. In this paper, high yield fungi were selected from nature, and the fermentation process was optimized. The main results were as follows: (1) A fungus with 30.2% oil content was obtained from pasture soil. Its fatty acid components were oleic acid (46.26%), palmitic acid (22.58%), 緯 -linolenic acid (13.68%) and linoleic acid (6.68%), which were similar to the fatty acid composition of vegetable oil. The yield of biodiesel prepared by alkali method was 89.6 and the characteristic index of biodiesel was basically in line with the international biodiesel production standard, which indicated that the strain could be used as raw oil to produce biodiesel. (2) according to morphology, physiological and biochemical characteristics and 18s rDNA sequence analysis, the strain could be used as raw oil to produce biodiesel. The screened strains were classified and identified. The results showed that the morphological and physiological characteristics of the strain were similar to those of Mucor, and its 18s rDNA sequence was similar to the 18s rDNA sequence of Mucor sp.EA 2010b stain ERRL. It was named Mucor sp.RBB 1-5. (3) single factor experiment and response surface analysis were used to optimize the fat fermentation process of Mucor sp.RBB 1-5. It was found that peptone was more favorable than yeast powder for oil accumulation. The optimum culture medium was: glucose 103.32 g / L, peptone 3.21 g / L, soybean meal protein concentration 3.29 g / L, Kno 3 3.0 g / L, Na2HPO 4 2.0 g / L, MgSO 4 7H2O1.0 g / L. the optimum culture conditions were as follows: initial pH 6.0, liquid volume 50 mL / 250 mL, temperature 28 鈩，

本文編號(hào)：2159868