温度和光照对微藻的生长,总脂肪含量及脂肪酸组成的影响

用温度梯度法、二因子重复试验法分别研究温度、光照周期和光照强度对绿色巴夫藻的生长、总脂肪含量以及脂肪酸组成的影响,用正交试验法研究以上三因子对等鞭藻3011的影响。结果表明,温度20℃、光照强度120．19μmol／（m2·s）、光照周期L：D＝16：8最适于等鞭藻3011的生长及脂肪和PUFA的合成。绿色巴夫藻适宜在15～30℃内生长,但在20℃、9615μmol／（m2·S）及L：D＝18:6的条件下,能促使它较快生长且能合成较多的脂肪和必需脂肪酸。两种微藻ω3／ω6显著性地受到环境因子的综合影响。     

Do strain differences in microalgae alter their relative quality as a food for the rotifer Brachionus plicatilis?

Brachionus plicatilis is used in aquaculture to feed larval fish and crustaceans. It is well established that different prey species alter rotifer productivity. Isochrysis galbana is one microalgal prey that is commonly fed to rotifers, and there are several strains of this flagellate available to aquaculturists. As microalgae strains may differ in their composition and growth attributes, we rigorously examined if growth and biochemical differences in I. galbana strains elicit differences in the growth and biochemical attributes of B. plicatilis. Four I. galbana strains and one strain of the flagellate Nanochloropsis were grown under standard conditions. Growth rate, cell volume, production, and composition (dry weight, carbohydrate, protein, lipid) were measured. Significant differences occurred between strains in all of these attributes (at times 2 to 3 fold), but no clear pattern emerged that one strain was superior. Of note was that for some measurements, strain differences were significantly greater than differences between species. The strains were then fed to rotifers, and a number of parameters were measured: growth rate, reproductive rate, fecundity attributes, a number of developmental rates, and composition (dry weight, carbohydrate, protein, lipid). There were significant effects of prey strain on some of these attributes, but none was dramatic (rarely more than 10% and occasionally up to 30%), suggesting that aquaculturists need not be too concerned regarding which I. galbana strain they use. However, we do indicate subtle differences, induced by different prey strains and suggest that for maximum productivity these differences should be considered.     

2种微藻间的化感作用

[目的]研究球等鞭金藻和纤细角毛藻间的化感作用。[方法]利用交叉培养和添加胞外滤液萃取物2种方法,确定2种微藻间的化感作用。最后,通过气相色谱测定两种微藻细胞及胞外滤液萃取物中脂肪酸的组成。[结果]球等鞭金藻滤液对纤细角毛藻的生长有显著的促进作用,仅当滤液浓度为100%时表现抑制作用。纤细角毛藻滤液对球等鞭金藻的生长有显著的抑制作用,滤液浓度越高,抑制作用越强。球等鞭金藻(或纤细角毛藻)胞外滤液萃取物对纤细角毛藻(或球等鞭金藻)生长的影响近似于其胞外滤液对纤细角毛藻(或球等鞭金藻)生长的影响,这暗示着2种微藻培养液中的化感物质可以用有机溶剂进行提取。[结论]通过气相色谱分析,笔者认为球等鞭金藻对纤细角毛藻的化感作用主要由饱和脂肪酸和不饱和脂肪酸的混合物共同作用引起;而纤细角毛藻对球等鞭金藻的化感作用主要由饱和脂肪酸引起。     

室内袋式和管道式光生物反应器对湛江等鞭金藻生长及生化组分的比较分析

为探索湛江等鞭金藻室内大规模培养的可行性,分析比较了在管道式光生物反应器和聚乙烯袋培养模式下,湛江等鞭金藻生长密度、比生长速率、叶绿素含量及有机物含量的变化情况。试验将接种藻密度控制在10.0×10⁴ cells/mL,培养周期为16 d。结果显示,在管道式光生物反应器培养模式下,藻密度可达1.97×10⁶ cells/mL,显著高于聚乙烯袋培养模式下的藻密度（0.99×10⁶ cells/mL）(P<0.05);两种模式下,湛江等鞭金藻的比生长速率分别达到0.396 7、0.327 5/d;管道式光生物反应器模式下,叶绿素a、叶绿素b、总叶绿素、最高总蛋白、最大可溶性糖的质量浓度分别为0.46、0.44、0.92、107.267 7、9.587 8 mg/L,最大生物量（干质量）为0.160 1 g/L,聚乙烯袋培养模式下,叶绿素a、叶绿素b、总叶绿素、最高总蛋白、最大可溶性糖的质量浓度分别为0.26、0.26、0.52、62.564 5、5.559 1 mg/L,最大生物量（干质量）为0.098 6 g/L,管...     

Nutrient Deprivation Coupled with High Light Exposure for Bioactive Chrysolaminarin Production in the Marine Microalga Isochrysis zhangjiangensis

Chrysolaminarin, a kind of water-soluble bioactive β-glucan produced by certain microalgae, is a potential candidate for food/pharmaceutical applications. This study identified a marine microalga Isochrysis zhangjiangensis, in which chrysolaminarin production was investigated via nutrient (nitrogen, phosphorus, or sulfur) deprivations (-N, -P, or -S conditions) along with an increase in light intensity. A characterization of the antioxidant activities of the chrysolaminarin produced under each condition was also conducted. The results showed that nutrient deprivation caused a significant increase in chrysolaminarin accumulation, though this was accompanied by diminished biomass production and photosynthetic activity. -S was the best strategy to induce chrysolaminarin accumulation. An increase in light intensity from 80 (LL) to 150 (HL) µE·m⁻²·s⁻¹ further enhanced chrysolaminarin production. Compared with -N, -S caused more suitable stress and reduced carbon allocation toward neutral lipid production, which enabled a higher chrysolaminarin accumulation capacity. The highest chrysolaminarin content and concentration reached 41.7% of dry weight (%DW) and 632.2 mg/L, respectively, under HL-S, with a corresponding productivity of 155.1 mg/L/day achieved, which exceeds most of the photoautotrophic microalgae previously reported. The chrysolaminarin produced under HL-N (Iz-N) had a relatively competitive hydroxyl radical scavenging activity at low concentrations, while the chrysolaminarin produced under HL-S (Iz-S) exhibited an overall better activity, comparable to the commercial yeast β-glucan, demonstrating I. zhangjiangensis as a promising bioactive chrysolaminarin producer from CO₂.