Study On Culturing Of Microalgaes Rich In Functional Components And Their Applications

Due to the high functional components,especially DHA and EPA in unsaturated fatty acids,marine microalgaes are widely used in various fields of food industry and aquaculture.Meanwhile,the microalgaes also have huge advantages in water purification.However,the growth and fatty acids composition of microalgaes can be affected by several environmental factors,so microalgaes rich in functional components can be obtained by changing the culture conditions of them.This paper studied the effects of nutrients,salinity and temperature on the growth and fatty acids composition of Pavlova viridis and Isochrysis galbana,as well as the feasibility of adding fresh microalgae to abalone aquaculture.In addition,the prepamtion of microencapsulated algal oil was studied,which laying a foundation for the application of certain research of marine microalgae.1.By researching Pavlova viridis culture conditions,the results showed that:with the increase of NaNO3 concentration and NaH2PO4 concentration,the cell density and specific growth rate both increased;Higher fatty acids contents could be harvested at lower NaNO3 concentration and NaH2PO4 concentration,certain nitrogen concentration might get higher EPA content in total fatty acids;As NaH2PO4 concentration increased,EPA output showed a downward trend after the first rise.The microalgae growed best when the salinity was 20‰ and the optimal salinity for fatty acids synthesis was 27‰;At the temperature of 25?,the growth of microalgae was better.As the temperature rised,EPA content gradually decreased.2.By researching Isochrysis galbana culture conditions,the results showed that:with the increase of the concentrations of NaNO3 and NaH2PO4,the cell density and specific growth rate increased;Nitrogen and phosphorus deprivation could promote fatty acids accumulation in microalgae cells,plenty of nitrogen and phosphorus concentration might get higher EPA and DHA content in total fatty acids;The growth of microalgae was best when the salinity was 20‰;At the temperature of 25?,the microalgae growed better,the ability to synthesize fatty acids decreased with the increasing temperature;With temperature rising,EPA and DHA content in the fatty acids gradually decreased.3.By adding the fresh microalgae to abalone aquaculture water,the results showed that:in the juvenile abalone aquaculture process,aquaculture water absorption value could not be too large,preferably not more than 0.500.After 45 d of aquaculture,microalgae of GY-H16-20001x group(adding Pavlova viridis to seawater,light intensity of 2000 lx)growed best in aquaculture water.Total nitrogen,total phosphorus and ammonia nitrogen increased least,the survival rate was the highest and reached 95 percent;LCR(shell length growth rate)and WGR(mass growth rate)was more 4.81 percent and 16.26 percent than the control group(seawater)respectively.Therefore,the addition of fresh microalgae to the water of abalone aquaculture was feasible,not only purifying water but also promoting the growth of abalone.4.On the basis of single factor experiments,using a central composite experimental design BBD using Design-Expert software,a mathematical model was made to determine the microencapsulated algal oil optimum conditions.Results showed the optimal conditions of wall material concentration of 6.18%,SPI/KGM-1 of 1.93,wall material/core material of 4.37,achieving embedding rate of 71.03%.The information of microencapsulated algal oil was verified,and microencapsulated algal oil could maintain the stability of algal oil by FESEM and TG.