Effect of growth phase on the fatty acid compositions of four species of marine diatoms

The fatty acid compositions of four species of marine diatoms (Chaetoceros gracilis MACC/B13, Cylindrotheca fusiformis MACC/B211, Phaeodactylum tricornutum MACC/B221 and Nitzschia closterium MACC/B222), cultivated at 22 ℃±1 ℃ with the salinity of 28 in f/2 medium and harvested in the exponential growth phase, the early stationary phase and the late stationary phase, were determined. The results showed that growth phase has significant effect on most fatty acid contents in the four species of marine diatoms. The proportions of 16:0 and 16: 1n-7 fatty acids increased while those of 16 :3n-4 and eicosapentaenoic acid (EPA) decreased with increasing culture age in all species studied. The subtotal of saturated fatty acids (SFA) increased with the increasing culture age in all species with the exception of B13. The subtotal of monounsaturated fatty acids (MUFA) increased while that of polyunsaturated fatty acids (PUFA) decreased with culture age in the four species of marine diatoms. MUFA reached their lowest value in the exponential growth phase, whereas PUFA reached their highest value in the same phase.     

长菱形藻(Nitzschia longissima)和新月细柱藻(Cylindrotheca closterium)分子分类研究

本研究自胶州湾分离了两种底栖硅藻,形态学初步鉴定为长菱形藻和新月细柱藻。对其18S rDNA和rbcL基因进行了测序并用邻接法构建了系统树。结果表明,两藻在18S rD-NA和rbcL基因序列上均存在较大的差异,基于DNA序列的分类结果与形态学分类结果一致。在依据形态指标难以确定藻类分类地位的情况下,18S rDNA和rbcL基因序列是有用的鉴定工具。     

Cylindrotheca closterium Is a Species Complex as Was Evidenced by the Variations of rbcL Gene and SSU rDNA

The genus Cylindrotheca consists of a small group of marine diatoms with a few species described. Eleven isolates of diatoms identified as Cylindrotheca closterium morphologically were obtained from Jiaozhou Bay with their nuclear-encoded small-subunit ribosomal RNA （SSU rDNA） and chloroplast-encoded rbcL gene sequences determined in this study. Interestingly, very high sequence divergences of SSU rDNA and rbcL gene were found among these isolates, and numerous nucleotide variation of rbcL gene caused relatively few variation of deduced amino acid sequence. Phylogenetic analyses based on SSU rDNA and rbcL gene, respectively, grouped the isolates into 6 clades. Phylogenetic tree of SSU rDNA placed all the Cylindrotheca isolates together, separating them into two lineages clearly. LineageⅠ was composed of the eleven C. closterium isolates obtained in this study together with another C. closterium isolate, but some clades were not well supported. LineageⅠwas contained two C. closterium isolates and one C. fusiformis isolate. Phylogenetic analysis of rbcL gene also separated the Cylindrotheca isolates into two well-defined lineages. The eleven C. closterium isolates formed a lineage and all clades were supported strongly. Statistical comparisons of SSU rDNA indicated that the average distance within lineageⅠwas significantly higher than that of other microalgae species （P 〈0.01）. These results suggested the existence of cryptic species within C. closterium.     

不同培养基对筒柱藻Cylindrotheca fusiformis生长及脂肪酸组成的影响

在温度为22±1℃,盐度为28的条件下,同不同培餐基对青岛海洋大学微藻种质库保存的简柱藻Cylindrotheca fusiformis造行培养,测定了细胞的生长情况及脂肪酸组成.实验结果表明,用8F培养基((F/2培养基的16倍)培养5天后,达到的细胞密度最大(376.56×104细胞/mL).用2F培养基培养,EPA含量最高(占总脂肪酸的18.1%).细胞生长较好、EPA含量最高、成本较低的培养基是2F培养基.     

两株硅藻筒柱藻和纤细角毛藻的油脂生产

通过气泡柱光反应器评价了两株硅藻筒柱藻(Cylindrotheca fusiformis)和纤细角毛藻(Chaetoceros gracilis)的生物量、油脂及甘油三脂的积累.结果发现,其生物量与油脂产率相当,脂肪酸组成方面,也均以C16:0和C16:1为主,但是筒柱藻的油脂组成以甘油三酯为主,纤细角毛藻的油脂以单酰甘油酯、磷脂和糖脂为主.通过培养条件的优化,发现相比于降低初始氮元素与硅元素,降低培养液盐度,能够获得更高的生物量、油脂以及甘油三脂产率.通过筒柱藻批次培养最高获得了0.36 g/(L·d)的甘油三脂产率,且甘三酯占收获干物质的50%以上,具有相当好的应用潜力.     

对筒柱藻属33株总脂含量及脂肪酸组成的比较研究

在温度为２５±１℃,盐度为２８的条件下,用Ｆ／２培养基对青岛海洋大学微藻种质库保存的３３株筒柱藻进行培养。在指数生长期末期进行收获。测定了３３株筒柱藻的脂肪酸组成,总脂含量,收获时的细胞密度,生物量。其主要脂肪酸为１４∶０,１６∶０,１６∶１（ｎ－７）和２０∶５（ｎ－３）,其中Ｂ２００的２０∶５（ｎ－３）含量最高,占总脂肪酸的１５．９％。     

EFFECTS OF HARVEST STAGE ON THE TOTAL LIPID AND FATTY ACID COMPOSITION OF FOUR CYLINDROTHECA STRAINS

ＩＮＴＲＯＤＵＣＴＩＯＮＰｅｏｐｌｅｓｈｏｗｅｄｇｒｅａｔｉｎｔｅｒｅｓｔｓｉｎｍｉｃｒｏａｌｇａｅｄｕｅｔｏｔｈｅｉｒｇｏｏｄｃｈａｒａｃｔｅｒｉｓｔｉｃｓ,ｓｕｃｈａｓｈｉｇｈｅｆｆｉ ｃｉｅｎｃｙｏｆｕｓｉｎｇｓｏｌａｒｅｎｅｒｇｙ,ｓｍａｌｌｓｉｚｅ ,ｎｕｔｒｉｔｉｏｎａｌｖａｌｕｅ ,ｒａｐｉｄｇｒｏｗｔｈａｎｄｍｕｌｔｉｐｌｉｃａｔｉｏｎｒａｔｅ .Ｍｉ ｃｒｏａｌｇａｅｈａｖｅａｎｉｍｐｏｒｔａｎｔｒｏｌｅｉｎｍａｒｉｃｕｌｔｕｒｅａｓｆｏｏｄｆｏｒｌａｒｖａｌｓｔａｇｅｓｏｆｃｒｕｓｔａ…     

流加-连续培养的筒柱藻营养成分分析

对筒柱藻(Cylindrotheca fusiformis)的主要营养成分进行了分析,其中筒柱藻中含有的粗蛋白、粗灰分、粗脂肪和粗纤维含量分别占干重的31.96％、15.10％、12.25％和0.85％.结果表明:所测定的18种氨基酸总量为26.60 g/100g干品,占粗蛋白的83.23％;必需氨基酸(EAA)占粗蛋白的30.79％;呈味氨基酸占粗蛋白的42.12％.筒柱藻还含有多种高不饱和脂肪酸,尤其是EPA,其含量为19.43mg/g干品,达到总脂肪酸含量的15.85％.因此底栖硅藻筒柱藻是一种优良的水产动物苗种饵料.