Identification Of A Strain Of Isolated Nannochloropsis The Effect On Fatty Acid Under Different PH

A strain of microalga isolated from mangrove sediment of Hainan wasidentified to be Nannochloropsis.maritima. The effect of different factors (nutrientmedium, nitrogen resource and corresponded nitrogen concentration, phosphorusconcentration, salinity, pH and temperature) on the growth of separatedNannochloropsis maritima were compared. Results showed that the strain of isolatedmicroalga grew relatively better at nutrient medium f/2with salinity30,74.8mg/LNaNO3(N mass concentration was1.705mg/L),6.6mg/L KH2PO4(P massconcentration was1.705mg/L), pH6.0. Cultured at26℃, its cell density could be upto5590×104/mL during seven days’ growth and relative growth rate was0.7861.Comparison with Nannochloropsis oculata on related reports, the isolated microalgashould be a fast-growing microalga with endurance to low nitrogen and sourishenvironment.pH has an obvious effect on the growth, total lipid content of marine microalgaNannochloropsis maritima Results showed that a high growth rate of the alga wasobtained underthe range of pH5.0-9.0, but the growth was very slowly at pH9.0. underdifferent pH conditions, the amount of fatty acids change there are certain rules tofollow, The total lipid of the species increased gradually as the culture aged except fora slight reduction in the early exponential phase. Analysisde found that he relativefluorescence intensity of Nannochloropsis maritima from pH5to pH9was a trend ofdecreasing, the relative fluorescence intensity when pH5was top and pH9relativefluorescence intensity of the lowest.pH also has an obvious effect on fatty acid composition of marine microalgaNannochloropsis maritima, Results showed that the fatty acid under the condition ofthe acid had more kinds than the kinds of fatty acid in alkaline conditions.AndSaturated fatty acids was the The highest level, C16:0was the highest proportion offatty acid species, Then was C14:0, With the increase of pH gradient, C14:0contentalso has a tendency to rise, we know that high pH culture conditions more conducive to the accumulation of C14:0. C16:0was the highest proportion of fatty acidspecies,Then was C14:0.Under the condion of pH5the content of C16:0was as highas35.76497%,but at the condion of pH6the content of C16:0was only23.653%.Itwas the lowest of all the condions. EPA is an important part of polyunsaturated fattyacid, is also important in Nannochloropsis.The accumulation of culture conditions ofpH6under the EPA content was the highest.The same culture conditions, the type of fatty acids of different growth timewill produce a greater difference, acidic culture conditions or alkaline cultureconditions, the relative content of saturated fatty acids is decreased as the increasingof culture time, while the mono-unsaturated fatty acids appeared in the opposite case,the content of mono-unsaturated fatty acid is increased as the culture time increases.inthe three culture conditions.But polyunsaturated fatty acids have a different trend,with the increase of culture time polyunsaturated fatty acids showed an increasingtrend under acidic conditions. Nannochloropsis oculata rich in EPA, as can be seenfrom the table, the prolongation of culture time can not effectively increase thecontents of EPA, pH in three gradient, culture conditions of pH5and pH9, cultured for8days and cultured for16days, while EPA content was decreased, were reduced by0.1%and6.4%. With the extension of time the content of EPA increased by8%inthe case of pH6.