Optimization Of Culture Of Marine Oil-rich Isochrysis Galbana CCMM5001

Biodiesel has received much attention by global researchers recently for dealing with the energy crisis and environment problems which become worse each day. The major components of lipids in microalgae are triglycerides, ideal materials in the prodution of biodiesel. Microalgae are more considerable because of several advantages: the cultivation of microalgae can reduce the competition for arable land and fresh water, has no effection on the food safety, and microalgae grow rapidly in every season in the year. However, the cost of biodiesel from microalgae is still too high for the sweeping production in commercial field. The culture of oil-rich microalgae is the basal step during biodiesel production, selecting microalgae with rich oil content, high biomass and low culture cost is a main problem recently.The present study investigate the oil-rich Isochrysis galbana CCMM5001. The heterotrophic growth characteristics, the fast measurement of lipid content and the effect of some environmental factors are investigated.Effcets of four different carbonaceous glucose, fructose, acetic natrium, glycerol on heterotrophic growth of Isochrysis galbana CCMM5001 are studied. The results show that the utilization of carbonaceous in Isochrysis galbana CCMM5001 is selective. Fructose is the best carbonaceous for heterotrophic growth, secondly glucose, then acetic natrium, glycerol is the worst. The heterotrophic productivity is better with fructose at 50mM concentration than 5mM, which opposite with other three carbonaceous.Consider with the heterotrophic productivity and commercial factor, effects of a variety of glucose concentration, light intensity and aeration level on heterotrophic growth of Isochrysis galbana CCMM5001 are studied. The results show that the optimal glucose concentration for heterotrophic Isochrysis galbana CCMM5001 is 2g/L. The maximum cells concentration reduces at both higher and lower glucose concentration value. The productivity is better under normal intensity of light than low intensity, non-aeration than aeration, and photoautotrophic than heterotrophic.The relation between lipid content and fluorescent intensity from Nile Red is investigated. The lipid content in Isochrysis galbana CCMM5001 cells is neutral, which can make the fluorescence from Nile Red become golden. The emission maximum of lipid is at 575nm wavelength, while the excitation wavelength is 480nm. The fluorescent intensity is linear relative with lipid content. The method that determining the lipid content in Isochrysis galbana CCMM5001 quickly by fluorescent measurement of Nile Red is found on the linear equation.The relation between the cells concentration of Isochrysis galbana CCMM5001 and fluorescent intensity determined by TD-700 fluorometer is investigated, and the linear equation is found out. A method that determining the cells concentration by fluorescent measurement using TD-700 fluorometer is found, in order to describe the growth of the microalgae.Effects of temperature, salinity, light intensity and pH on Isochrysis galbana CCMM5001 growth are studied when cultivated under a variety salinity with different temperature conditions and a variety pH with different lingt intensity. The results show that the temperature ranges for Isochrysis galbana CCMM5001 growth is 18~36℃, the optimal temperature is 24℃; the salinity ranges for growth is 12~38, the optimal salinity is 24; the light intensity ranges for growth is 2000lux~9000lux, the saturated light intensity is 3500lux; the pH ranges for growth is 6.8~7.8, the optimal pH range is 5.8~8.8. The maximum biomass concentration is 7.24×10~6 cells/ml when cultivated under the condition temperature 24℃, salinity 24, light intensity 3500lux, PH 7.8, which is 1.08 times compared with normal condition. Meanwhile, the investigation about effects of both temperature conditions and salinity show that Isochrysis galbana CCMM5001 can grow under high level of both temperature and salinity. The productivity under high salinity level becomes better while the temperature increased. The maximum biomass concentration can reach 3.90×10~6 cells/ml when cultivated under the condition temperature 36℃, salinity 38, much more than that cultivated under the same temperature with other variety of salinity.