Effects Of Different Nitrate And Hydrophosphate Concentration On Glycolipid Accumulation In Microalgae

Glycolipid is a kind of a complex carbohydrate made of sugar and fat by covalently bound.It has a great research and development value in food,medicine,cosmetics and other fields.Microalgae are with abundant glycolipid and can easy grow,and different environmental conditions may affect the growth of microalgae cells and cause biochemical compoments'change.In this study,the effects of different nitrate and hydrophosphate concentrations on glycolipid accumulation in Chlorella pyrenoidosa and Synechococcus sp.were investigated.The highest glycolipid contents of 24.61%?DCW%?for Chlorella pyrenoidosa and15.37%for Synechococcus sp.were obtained in the absence of nitrate.Under low or hydrophosphate free conditons,higher glycolipid contents of 17.19%for Chlorella pyrenoidosa(0.01 g L^-1)and 10.99%for Synechococcus sp.(0 g L^-1)were obtained.The change of glycolipid content under environmental stress may be caused by the change of three main glycolipids?MGDG,DGDG and SQDG?.Nitrate absence induced at least 8.5%increase in MGDG,DGDG and SQDG,while hydrophosphate absence resulted in over 21.2%increase in DGDG and over 48.4%increase in SQDG and more than 22.2%decrease in MGDG in two microalgae.Centre-complex test was used to optimize the glycolipid production conditions,low nitrate hydrophosphate levels(0-0.6 g L^-11 nitrate and 0-0.021 g L^-1 hydrophosphate concentration)were suitable for Chlorella pyrenoidosa glycolipid accumulation,which was more than 25%for Chlorella pyrenoidosa;while lower nitrate?0-0.15 g L-1?and higher hydrophosphate(0.025-0.04 g L^-1)or higher nitrate(1.21-1.5 g L^-1)and lower hydrophosphate(0-0.007 g L^-1)levels were suitable for Synechococcus sp.glycolipid accumulation,which were more than 21%for Synechococcus sp.These results suggest that nitrate and hydrophosphate levels may have influence on microalgae glycolipid accumulation.