Fermentation Of γ-Linolenic Acid And Extraction Of Lipid

Gamma-linolenic acid, a polyunsaturated fatty acid, has medicinal effect and can beused to treat hyperlipidemia, diabetes and so on. As is essential fatty acid for bodies it isprecursor of prostaglandin and interleukin. Because there is growing awareness of thebiology effect of GLA, the market for specific production is predicted to expand.Microbial fermentation has its unique advantage as follows: the shorter productioncycle,using small room and no limit of material,producing area and season, thereforepeople attach importance to it. In this article, firstly we screen the strain producingGamma-linolenic acid; secondly the optimum fermentation composition and conditionswere studied; thirdly we investigate the extraction of oil. Through the studies we get theconclusion as follows:1. Using Motierella sp. as starting strain, mutagenized with ultraviolet. (UV) andLiCl, screened by selecting mutants resisting low temperature or high concentration ofglucose in culture medium, a mutant ZG17 was abtainted. With using fermentation of250ml conical flask and mensurating kinds of guide line, the result indicates that themutant ZG17 has good capability of utilizing glucose and translating glucose into singlecell oil. The biomass reached 18.62g/L, the content of lipid in mutant ZG17 myceliumwas up to 69.0%, lipid yield reached 13.45g/L, and GLA yield reached 645.60mg/L,increasing 11.8%,16.0%,29.7% and 24.4% respectively compared with original strain.2. Through single factor and Response surface methodology experiments, the effectof factors related to fermentation was studied. Finally we get the optimum fermentationcomposition and conditions as follows: inoculum amount 5.0%, inoculum age 24h, 6.0%glucose in inoculum culture, 10.2% glucose in fermentation culture, the ratio of peptoneto yeast extract being 1:1, C/N 29:1, initial pH 5.00. When mutant ZG17 was culturedunder these condition, the biomass, lipid content, lipid production and GLA productionwere 21.61g/L, 14.84g/L, 812.97mg/Land were 16.1%, 14.1% and 25.9% higher thanbefore respectively.3. Effect of several factors on ultrasonic wave process was explored. The optimumconditions for processing was obtained. The results showed that under the condition oftreatment time 20min, ratio of material to liquid 1:10(g/L), acting on-off ratio 1:5, theextraction rate of microbial oil is better. Compared with Soxhlet extraction the ultrasonicextraction has great efficicency and uses less organic solvent.