A quick isolation method for mutants with high lipid yield in oleaginous yeast

A novel method has been developed to easily isolate the mutants with high lipid yield after irradiating oleaginous yeast cells with carbon ions of energy of 80 MeV/u. Pre-selection of the mutants after ion irradiation was performed with culture medium in which the concentration of cerulenin, a potent inhibitor of fatty acid synthetase, was at 8.96 mu mol/l. Afterwards, lipid concentration in the fermentation broth of the pre-selected colonies was estimated by the sulfo-phospho-vanillin reaction instead of the conventional methanol-chloroform extraction. Two mutants with high lipid yield have been successfully selected out by the combined method. This easy and simple method is much less time-consuming but very efficient in the mutant isolation, and it has demonstrated great potential on mutation breeding in oleaginous microorganism.

生物柴油原料资源利用与开发

发展生物柴油产业是解决我国石化能源短缺与环境污染问题的一个重要措施。在生物柴油产业发展过程中,原料不足成为规模化的瓶颈。我国现阶段油脂资源短缺,耕地资源匮乏,野生油料植物资源丰富,秸秆类农林废弃物资源量巨大。在结合我国国情基础上,分析现今我国生物柴油原料的来源,探讨建立生物柴油原料等级标准应重点考虑的指标,提出解决原料资源的四个措施。

一株掷孢酵母利用红薯淀粉酶解液积累油脂研究

本论文以红薯淀粉的双酶法水解液为碳源，从19 株红色酵母中筛选出一株油脂含量较高的菌株掷孢酵母（Sporobolomyces reseus）As.2.618。为了提高掷孢酵母（S.reseus）As.2.618 的油脂产量，考察了培养基组成对该菌生长情况及油脂积累的影响。用均匀设计法对培养基组成进行了优化，由DPS软件得出的优化结果为：还原糖103g/L、酵母粉11.5g/L、磷酸二氢钾0.3g/L、硫酸镁0.15g/L。生物量可达19.23 g/L,油脂含量为3.875 g/L。研究了添加二价离子对该菌的生长及油脂积累的影响,结果表明Zn2+对该菌生长和油脂积累都有显著促进作用。研究了发酵条件以及添加氧载体正十二烷对该菌发酵的影响，表明添加正十二烷有利用于该菌生长与油脂积累。得出最佳发酵条件是：在还原糖103g/L、酵母粉11.5g/L、磷酸二氢钾0.3g/L、硫酸镁0.15g/L。添加30mg/L 硫酸锌,接种量为5％，在24h 后添加2g/L 的碳酸钙和2%(v/v)正十二烷，pH6.0 培养温度为27℃，转速为200r/min，培养时间为7 天的条件下，该菌生物量干重可达35.05g/L,油脂含量也达11.98g/L。Lipid is one of the basic material for life-sustaining activities andimportant industrial materials. As lipid resources mainly come from the animal andthe plant, the problem of lipid lack is encountered at times. The lipid frommicroorganisms is the substitute and superior to the above lipid with a short period ofproduction and much cheaper fermentation materials such as agricultural and sidelineproducts or wastes of crop.Thus large scale production and broad application ofmicrobial lipid will be efficient not only in substitute of the animal and the plant lipidfor food and industrial field , but also inducing a new way leading to solve the energyproblem.For the purpose of exploring the characteristics of lipid production of redyeasts from sweet potato starch hydrolysates. 19 red yeasts are screened for thecapability of lipid producing and one strain Sporobolomyces reseus As.2.618 withsuperior performance is sellected.To improve the Sporobolomyces reseus As.2.618’s capability of lipidaccumulation , the components of the medium, which may influence the growth of thestrain and the lipid yield have been studied. To get the optimum mediumcomponents ,the “uniform design” was used .The DPS software gave the optimummedium component is: reducing sugar 103 g/L、yeast extract 11.5 g/L、KH2PO4 0.3g/L、MgSO4 0.15 g/L. The biomass could reach up to 19.23 g/L and lipid yield 3.87g/L with the above composition of fermentation medium.Furthermore the fermentation conditions , addition of the divalent metal ionsand the oxygen vector to increase the strain’s lipid producing capability are tested.The optimum condition is : reducing sugar 103 g/L、yeast extract 11.5 g/L、KH2PO40.3 g/L、MgSO4 0.15 g/L，Adding 30mg/L ZnSO4,and adding 2g/L CaCO3 2％(v/v)n-dodecane after 24h’s fermentation. the optimal fermentation condition were asfollow :30ml medium in the 500ml flask with initial pH 6.0,the flasks with 5%inoculation volume were at 200r/min shaking speed for 7d’s fermentation at27 .Under this kind of condition the high biom ¡æ ass which reach to 35.05 g/L could begot ,the yield of lipid also could reach to 11.98g/L.