花生四烯酸发酵的研究

【作者】 朱法科；

【导师】 姚汝华；

【作者基本信息】 华南理工大学 ， 发酵工程， 1997， 博士

【摘要】 花生四烯酸是廿碳多价不饱和脂肪酸，具有很多独特的生物活性，利用微生物发酵生产花生四烯酸已引起人们的极大兴趣。本论文利用一株被孢霉菌(Mortierella sp.)为出发菌株，对花生四烯酸高产菌株选育、培养条件优化、培养后菌丝体老化及发酵动力学等方面进行了较为深入的研究。 通过两次紫外线诱变在较低温度下筛选得到一株抗乙酰水杨酸的花生四烯酸高产菌Mortierella sp.M10，初步发酵表明该菌株的菌丝体得率和总油脂得率分别为31g／l、8.3g／l，而原菌株分别只有20.3g／l和5.4g／l。 通过研究温度、时间、pH、碳源、氮源、植物油等因素对菌丝体生长和产油脂的影响，确定了Mortierella sp.M10的最适培养条件，在此条件下通过5L发酵罐中葡萄糖补料发酵工艺发酵试验，其菌丝体得率和花生四烯酸得率分别达到43g／l和1.25g／l。 通过研究老化温度、时间和初始pH等因素对菌丝体中油脂含量的影响，发现将培养5天的Mortierella sp.M10菌丝体在25℃下贮存10天，其菌丝体中的花生四烯酸含量由贮存前的2.44％上升到3.07％。 根据碳源和氦源对菌丝体得率的影响特性，采用数学统计方法建立了碳源和氮源两种非相关因素对Mortierella sp.M10菌丝体积累影响的二元二次数学模型，通过该模型的理论计算值和实验结果比较，其平均相对偏差为0.5513。通过对Mortierella sp.M10在5L发酵罐中的发酵过程分析，建立了花生四烯酸发酵动力学模型。该模型较好地描述了发酵过程中的菌体生长、产物形成和底物消耗的变化规律。模型拟合值和实测之间的最大相对偏差少于6.0％。更多还原

【Abstract】 Arachidonic acid(AA) is a C-20 polyunsatured fatty acid and has several unique biological activities. AA fermentation by microorganisms has recently attracted great interest. In this paper, the breeding of high AA yield strains using Mortierella sp. as original strain was studied and fermentation conditions, aging of harvested mycelium and fermentation kinetics were investigated.Mortierella sp. was mutated in twice by UV and screened with asparin at lower temperature. A mutant strain Mortierella sp. M10 which could accumulated AA in large quantities was obtained. The results of primary fermentation showed that the dry cell weight(DC) and total lipids(TL) were 31g/l and 8.3g/l by Mortierella sp.MlO, but only 20.3g/l and 5.4g/l by original strain.According to the studies of the effects of several cultural conditions (i.e. temperature, culture time, pH, carbon source, nitrogen source, vegetable oils et. al.) on the mycelium growth and lipids accumulation, the optimum medium of the Mortierella sp. M10 was determined. Under the optimum culture conditions the dry cell weight(DC) and the production of AA reached 43g/l and 1.25g/l resepectively for 5L fermentor by feeding culture of glucose.By means of the investigation of the effects of several aging conditions(i.e. aging temperature, aging time and original pH, et al.) on the lipid content in mycelium, we found that when the Mortierella sp.M10 mycelium harvested after 5 days culture was aged 10 days at 25℃, the AAweight in dry mycelium increased from 2.44g/l to 3.07g/l.The quadratic polynomial equation mathematical models for the effects of carbon source and nitrogen source on DC was developed. The residual更多还原