Effects Of Nitrogen And Phosphate On The Growth And Metaboilsm Of Scenedesmus SP-01

In this paper, the growth and metabolism of SP-01, a scenedesmus isolated fromGuangzhou Liuhua Lake, were further investigated. The experiment was mainly tostudy the effects of nitrogen and phosphate on the growth, fatty acids and carotenoidaccumulated of scenedesmus SP-01. Nitrogen source and N/P ratio were optimized. Thechange process of growth and metabolites in scenedesmus SP-01was track tested underdifferent nitrate concentration.Through comparison of five different nitrogen sources, it was found that nitratewas the most beneficial to the growth of scenedesmus SP-01, maximum cell dry weightwas3.2g/L and high specific growth rate was0.033h-1, which was also obtained inurea. Urea was found to stimulate growth and carotenoid accumulation of ScenedesmusSP-01, maximum productions of lutein and astaxanthin were4.43and0.45mg/g. Aminoacid was found to stimulate β-carotene and zeaxanthin, maximum productions ofβ-carotene and zeaxanthin were2.63and0.31mg/g obtained in glycine cultivationcondition.Scenedesmus SP-01mainly contained C16and C18series fatty acids and C18:1occupied the highest percentage content of total fatty acids. Total fatty acids and C18:1content of scenedesmus SP-01were significant influenced by nitrogens and theirconcentration, which increased as the nitrogen concentration decreased. The maximumcontent of total fatty acids and C18:1was47.33%of cell dry weight and49.85%of total fatty acids under0.55mM NH4Cl concentration. The content of C18:1was46.28%and41.26%of total fatty acids under0.55and1.1mM urea concentration.Scenedesmus SP-01grew fastest when nitrogen/phosphorus ratio was22:1,3.3g/Lmaximum cell dry weight and0.033h-1high specific growth rate was obtained. Thecontent of lutein and β-carotene was1.3and3.4times compared with whennitrogen/phosphorus ratio was5:1, which indicated the potential of scenedesmus SP-01product lutein and β-carotene and other carotenoids.After the nitrogen/phosphorus ratio of basal medium be turned into the optimalvalue, that was after the concentration of phosphate be reduced, nitrogen consumption,the content of cell dry weight, chlorophyll and carotenoid were track tested underdifferent nitrate concentrations. It was found that the growth of scenedesmus SP-01andthe accumulation of carotenoid were significantly influnced by nitrate concentrations.The growth of scenedesmus SP-01was severely limited under2.2mM nitrateconcentration, the content of β-carotene and astaxanthin were decreased separately fromthe sixth and the twelfth day,while the content of β-carotene and astaxanthin wereincreased continuously until the fourteenth day. This showed that the excessive lack ofnitrogen was disadvantage of the growth of scenedesmus SP-01and the accumulation ofcarotenoid, proper enough nitrogen was of benefit to gain higher biomass in the earlierculture and accumulate carotenoids in the later culture.In conclusion, the carotenoids accumulated by scenedesmus SP-01were mainlyconsist of lutein, β-carotene, zeaxanthin and astaxanthin, and the content of carotenoidscan be increased by optimize the culture conditions; the fatty acid compostion ofscenedesmus SP-01was simple and the content of total fatty acid was high, of whichthe content of C18:1was up to50%. Scenedesmus SP-01had the potential of productbiodioesel and high value carotenoids. Scenedesmus SP-01was to have much researchvalue. All these research results could provide theoretical basis for the large-scaleculture and industrial production of scenedesmus SP-01.