The Study On Growth And Lipid Accumulation Of Several Strains Of Filamentous Algae Under Different Culture Conditions

Microalgae cells are rich in proteins,polysaccharides,lipids and pigments,and have been widely used in the fields of food,feed,medicine,fine chemical and dyestuffs.In recent years,with the increasing depletion of fossil fuels?such as oil and coal?biomass based biorefinery has aroused great attention.The lipid producing microalgae is an ideal raw material for the production of biodiesel,and it has become the focus of attention of all researchers.This paper mainly studies that growth,cell morphology,intracellular lipid accumulation and intracellular fatty acid composition of the 4strains of filamentous Trentepohliaceae.The effects of growth and lipid accumulation of Tribonema sp.FACHB-1786 in different light intensity,nitrogen sources,light and concentrations of nutrients conditions,and then its lipid production performance was evaluated by the mathematical model of diesel quality.Finally,to obtain the optimum4 kinds of nutrients concentration of the growth and yield of lipid on the Tribonema SP.FACHB-1786 by response surface method.The main results are as follows:?1?There are four filamentous algae Cephaleuros sp.1204,1205,1215 and Trentepo-hlia sp.1047 were used as the research materials.The results showed that the growth of Cephaleuros sp.1204 was better than that of the other 2 strains in the 3 strains of Cephaleuros sp.,while the growth of Trentepohlia sp.1047 was better than that of the other.The composition analysis of GC-MS and HPLC on several strains of algae fatty acid,pigment composition,main fatty acid compositions of several strains of algae were oleic acid?C18:1?and palmitic acid?C16:0?and palmitoleic acid?C16:1?,palmitic two olefinic bond acid?C16:2?,and oleic acid?C18:1?has the highest content of total fatty acid content 50%.The pigments contained beta carotene,zeaxanthin,lutein and chlorophyll a&b,and the content of carotene was the highest,accounting for 50%-55%of the total pigment content.?2?In this paper,the Tribonema sp.FACHB-1786 were cultured in BG11 improved medium under the 2 kinds of nitrogen sources?NaNO₃ and CO?NH₂?₂?and 5 nitrogen concentrations?36,18,9,6 and 3 mmol/L?,4 different light intensity(60?mol·m^-2·L^-1,150?mol·m^-2·L^-1,300?mol·m^-2·L^-1,500?mol·m^-2·L^-1),and 5 kinds of light conditions.The results show that the biomass of Tribonema sp.FACHB-1786 can grow well under the conditions of two nitrogen sources,and the maximum biomass could reach6.12g/L and 7.18g/L respectively when NaNO₃ and CO?NH₂?₂ as the nitrogen source.Under different light intensity,the biomass of the alga increased with the increase of light intensity,and the biomass of CO?NH₂?₂ group was larger than that of NaNO₃group under every light intensity.The maximum total lipid content of sodium nitrate and urea groups can all reach 48%at 300?mol·m^-2·L^-1light intensity and 18mmol/L nitrogen concentration culture conditions.In different light conditions,that blue and green light may promote the growth of Tribonema sp.FACHB-1786 and yellow light may promote its lipid accumulation.The fatty acid composition was mainly myristic acid?C14:0?,palmitic acid?C16:0?,palmitoleic acid?C16:1?,arachidonic acid?C20:4?and eicosapentaenoic acid?C20:5?,which palmoleic acid content was highest and accounting for 50%-60%of the total fatty acid contents.?3?The biomass lipid content,fatty acid composition of Tribonema sp.FACHB-1786were compared under different culture conditions.It can achieve the best growth state and its lipid accumulation can be as high as 51.08%,when the K₂HPO₄ concentration is 80mg/L;the influence of different?NH₄?₃Fe C₁₂H₁₀O₁₄4 concentration was larger on the biomass of Tribonema,with significant differences between the biomass concentration?P<0.05?;the increase of MgSO₄ concentration would increase the content of EPA,and EPA is up to 16.68%of the total fatty acid content.?4?To get the optimum concentration of nutrient utilization of the biomass and lipid yield of Tribonema sp.FACHB-1786 by response surface optimization method.The results show that its optimal biomass:NaNO₃?1g/L?,?NH₄?₃FeC₁₂H₁₀O₁₄?10mg/L?,K₂HPO₄?130mg/L?,MgSO₄?300mg/L?;its optimal lipid yield:NaNO₃?1g/L?,?NH₄?₃FeC₁₂H₁₀O₁₄?3mg/L?,K₂HPO₄?140mg/L?,MgSO₄?170mg/L?.After optimizati-on,its biomass increased by 32.73%and oil yield increased by 16.74%compared with normal biomass and oil yield,they all were increased significantly.