Study On Oil High-yield Strains And Tecnichs Of Extracting Microbial Oil

Oil which has a wide range of applications is one of primary substance that can make up and sustain life activity, and is important industrial raw materials. Currently, oil source is mainly from animals and plants.As microbial oil was studied by people, utilization of microbial fermentation was used to obtain oils, which not only can alleviate the situation of scarce resources of animal and plant oils, but also can reuse waste resource by oil-producing strains.That provides a new way for access to oil resources.Taking Rhodotorula glutinis 31596 as the research object in this paper, high-yielding strains of oil were obtained by three means, such as medium optimization, bacterial mutation and optimization of oil extraction. Major researches were as follows:1. Optimization of oil producing mediumBy studying, best fermentation medium components of Rhodotorula glutinis 31596 were as follows: glucose 80 g/L, (NH4)2SO4 1.11 g/L, KH2PO4 2.5 g/L, peptone 1.8 g/L, Under culture conditions: temperature 28℃, initial pH 5.8, inoculum size 5%, 250mL flask containing 40 mL medium. Its biomass and oil production respectively reached 18.18±3.34 g/L and 32.06±1.91 mg/g.2. Mutation breeding of high-yield strains of oilsIn order to further improve bacterial biomass and oil production of Rhodotorula glutinis 31596, low-energy ion implantation mutation and UV mutation were used to screen high-yield strains. Finally, one mutant strain VB19 was obtained. Biomass and oil production of this strain respectively reached 21.63±1.14 g/L and 42±1.78 mg/g, which was improved by 19% and 31% compared with original strain. Its production traits had no significant change after several times continuous generation.3. Oil Extraction Process Optimization of Rhodotorula glutinisBy comparing the effect of the acid-heating method, ultrasonic method and acid -heating coupling ultrasonic method on oil extraction of Rhodotorula glutinis, the results showed that acid-heating coupling ultrasonic method the best results. The technics of extracting oil from Rhodotorula glutinis were studied by acid-heating coupling ultrasonic in this experiment. Firstly, by the Plackett-Burnam design, three key factors were found from the following seven factors which would affect extracting oil: marinating time of HCL, disposing time of boiling water, ultrasonic treating time, ultrasonic power, rate of extracting solution(V_CHCl3:V_CH3OH), extracting time, concentration of NaCl. The result indicated that marinating time of HCL (P=0.036), ultrasonic time (P=0.0105) and rate of extracting solution (V_CHCl3:V_CH3OH) (P=0.0105) were significant factors for extracting oil. Then these three extraction parameters were optimized by Box-Behnken design, and better conditions of extracting oil were as follows: marinating time of HCL 34 min, ultrasonic treating time 7.5 min, rate of extracting solution(V_CHCl3:V_CH3OH) 1.9:1. Under the optimized conditions, the oil weight of 1 g wet thalli was improved to 57.33±2.4 mg, which was 36.5% higher than 42.67±1.43 mg under the original conditions.