Optimization Of Conidia-Production Condition And Application Of Fermentative Product PLA₂ Of Streptomyces Lividans LH001 In Rice Bran Oil Degumming

PhospholipaseA2(EC3.1.1.4) belonging to phospholipase family is an important enzyme,which has a huge potential in application of oil degumming, Phospholipid modification and so on. Commercialized phospholipase A2 mainly obtained from animal pancreas and microbial fermentation. the domestic production and application of phospholipase A2 began late comparatively and still in test phase.Streptomyces lividans LH 001 is a high yield PLA2 strain, which obtained by genetic engineering. The PLA2 is suitable for industry application because it has higher temperature tolerance and substrate specificity.This experiment contains two aspects:1. Optimization of the conditions for sporulation of Streptomyces lividansLH001; 2. Application of phospholipase A2 in the rice bran oil degumming.1. The result which optimization of the conditions for sporulation of Streptomyces lividansLH001 showed that the volume of spores were improved after 7 days incubation at the conditions of pH8,28℃, full-light, after inoculated a certain amount of sporulation on the wheat bran agar medium containing 0.03% NaNO3. after 7 days, the number of spores was obviously increased from 0.7 X 105/mm2 to 3.24×105/mm2.2.The experiment on degumming of rice bran oil using a by-self PLA2 which was designed by a single factor and orthogonal experiment, obtained the following optimized conditions:0.066% citric acid treated the oil for 30min, and then adding 0.07% NaOH, 3% dH2O,0.015% PLA2 under 4000r/min for lmin in order, finally placed oil samples in static reaction system at 45℃, reaction for 2h. After treatment, the phosphorus in the oil only contained 9.15mg/kg, which less than 10mg/kg. while the content of phosphorus in control group was 27.35 mg/kg, much higher than the phosphorus content of enzyme treatment.The results of 280℃heating test showed,after enzyme treatment, the oil in the heating process does not appear black coke and other undesirable phenomena, while the control group,were black and precipitation, indicating that the content of rice bran oil could be down to very low level by enzymatic degumming, which can meet the requirement of physical-refining process.