球等鞭金藻3011絮凝效应的研究

[目的]实现球等鞭金藻3011在生产性培养中的浓缩收集。[方法]采用一级保种培养、二级扩种培养及三级开放式生产性培养方式,研究絮凝试剂种类、浓度及絮凝时间对球等鞭金藻3011絮凝效应。[结果]在三角锥瓶中,明矾浓度为0.5～1.1g/L时,45min后90%以上的藻液絮凝;氢氧化钙浓度为0.7～1.1g/L时,15min后藻液上清液基本澄清;硫酸锌浓度为0.9和1.1g/L时,240min后80%以上的藻液絮凝;硫酸铝浓度为0.5～1.1g/L时,120min后藻液上清液基本澄清;聚合氯化铝浓度为0.7～1.1g/L时,45min后藻液上清液基本澄清。在白桶中,240min内1.0g/L氢氧化钙的絮凝效果最显著,硫酸锌的絮凝效果不显著;0.5和1.0g/L明矾和硫酸铝和1.0g/L聚合氯化铝均有一定的絮凝效果。在开放式水池中,0.5和1.0g/L明矾和氢氧化钙的絮凝效果显著。[结论]明矾和氢氧化钙适宜应用于藻种生产性培养的浓缩收集。     

大溪地金藻培养的生态条件研究

在实验室模拟条件下,研究了温度、光照、盐度和营养盐对大溪地金藻生长繁殖的影响,结果表明:大溪地金藻适宜温度为10～35℃,最适温度为20～30℃;适宜照度为1000～7000lx,最适照度为3000～6000lx;适宜盐度6 5～39 5,最适盐度为19 5～26 0。N、P单因子的优水平分别为N-1mg/L、P-0 1mg/L,Fe单因子作用不明显,N、P、Fe交互作用的优水平为N-1mg/L、P-1mg/L、Fe-0 1mg/L。     

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。     

不同光照条件对小新月菱形藻和等鞭金藻8701生长及生化成分的影响

研究了小新月菱形藻(Nitzschiaclosteriumf.minutissima)(MACC/B228)和等鞭金藻8701(IsochrysisgalbanaParke8701)(MACC/H060)在4种光照条件下的生长情况,以及不同光强下、不同时期收获的藻细胞中总脂和碳水化合物含量的变化。结果表明,小新月菱形藻在光强70μmol·s-1·m-2时细胞分裂频率(μ)最大,最适光强70～140μmol·s-1·m-2;260μmol·s-1·m-2光强能导致细胞分裂频率变慢,指数期缩短。等鞭金藻8701在光强140μmol·s-1·m-2时μ值最大,260μmol·s-1·m-2下略有降低。2种藻均在低光下脂肪含量多,小新月和等鞭金藻脂肪含量分别占干重的25.5%～35.3%和28.3%～37.5%;而碳水化合物含量少,分别占干重的5.5%～18.2%、3.9%～11.4%;在高光强下相反。不考虑光照条件的影响,2种藻细胞内碳水化合物的含量均在静止期达到最大,分别占干重的18.98%和23.32%。小新月菱形藻在70μmol·s-1·m-2光强下的指数期细胞有最大的脂肪含量,等鞭金藻的最高脂肪含量出现于光强20μmol·s-1·m-2下指数末期的细胞中。二者在光强140μmol·s-1·m-2下生长且进入静止期时均可获得较大生物量,同时细胞的脂肪和碳水化合物的含量也处于较高水平。     

金藻（Isochrysis galbana）培养液中铜锌离子的最佳活度↑（*）

本文研究了铜，锌离子在球等鞭金藻的培养液中最佳存在活度。采用了一种新的海水处理方法，除去海水中的重金属离子，同时，计算了培养液中铜，锌离子活度，结果表明，金藻培养液中，铜，锌离子的最佳活度为１０＾－１３．５７－１０＾－８．８０ｍｏｌ／Ｌ和０－１０＾－６．００ｍｏｌ／Ｌ；铜离子表现了对金藻生长繁殖的必需性，而锌离子未表现出对金藻生长繁殖的必需性；当铜，锌离子活度分别大于１０＾－８．８０和１０＾－６．     

等鞭金藻对次氯酸钠中有效氯耐受力的研究

采用不同质量分数的次氯酸钠 ,以不同的处理时间对等鞭金藻 30 11进行耐受力研究。结果表明 :在试验的取值范围内处理时间比有效氯质量分数对等鞭金藻的生长影响更显著。在实际应用中 ,次氯酸钠的质量分数 (有效氯 )以 4× 10 -6～ 8× 10 -6,处理时间约 2h为宜     

Growth of Artemia franciscana fed Isochrysis sp. and Chaetoceros muelleri during its early life stages

Survival, growth (length and weight), development, proximate composition, and energy content of Artemia franciscana fed for 7 days with Isochrysis sp. (TISO) or with Chaetoceros muelleri (CHGRA) were compared to evaluate the food value of these microalgae. Mean daily survival was not significantly different, and ranged from 86% to 93%. Diet‐related differences in growth were noted from the third day, and mean final dry weights (DWs) were 171 and 327 μg ind^?1 for Artemia fed TISO and CHGRA respectively. Rates of development were different between diets, with a higher developmental index for Artemia fed TISO before day 3, and a higher index for Artemia fed CHGRA for the rest of the experiment. Chemical analysis showed that carbohydrates decreased to approximately 35% of the initial value in Artemia during the first 24 h, after which they remained approximately stable and similar with both diets. In percentage of total DW, lipids and proteins remained close to their respective initial values, but A. franciscana fed TISO had a higher ash content. A major difference between the two microalgae was the higher protein content of TISO, but this did not result in better growth. Of the two, TISO was richer in docosahexaenoic acid, which might explain the initial faster development, but CHGRA was a better source of eicosapentaenoic acid, which is the most probable explanation of the higher food conversion index, specific growth rate, and energy gain of A. franciscana fed this algae.     

Effects of chloramphenicol, erythromycin, and furazolidone on growth of Isochrysis galbana and Chaetoceros gracilis

This study focused on determining the effects of antibiotics on microalgae used as food for scallop larvae. Six different dose levels of chloramphenicol, erythromycin, and furazolidone were added to cultures of Isochrysis galbana and Chaetoceros gracilis. An in vivo experiment was subsequently conducted to determine the effect of chloramphenicol and erythromycin on larval survival of the Pacific calico scallop Argopecten ventricosus in tanks and on the population of its associated bacteria. Results showed that growth of I. galbana was not significantly affected by chloramphenicol or erythromycin at the test doses of 0.5, 1.0, 3.0, 6.0, 9.0, and 12.0 mg/l. C. gracilis was significantly sensitive to erythromycin and chloramphenicol at doses higher than 0.5 and 3.0 mg/l, respectively. Furazolidone inhibited the growth of both I. galbana and C. gracilis at all test doses. Results showed that exposure of scallop larvae to a dose of 6 mg/l chloramphenicol or erythromycin did not significantly affect growth of I. galbana, significantly enhanced survival of the scallop larvae, and inhibited the growth of Vibrio spp. in tanks. This study demonstrated the adverse effect of chloramphenicol, erythromycin and furazolidone on I. galbana and C. gracilis microalgae but the positive effect on survival of the scallop larvae, decreasing associated bacterial population.     

Biobased Solvents for Pressurized Liquid Extraction of Nannochloropsis gaditana Omega-3 Lipids

To develop greener extraction alternatives for microalgae biomass, ultrasound assisted extraction (UAE) and pressurized liquid extraction (PLE) with different biobased solvents were investigated, demonstrating that both techniques are useful alternatives for algal lipid extraction. Specifically, Nannochloropsis gaditana lipids were extracted by UAE and PLE at different temperatures and extraction times with sustainable solvents like 2-Methyltetrahydrofuran (2-MeTHF) and its mixtures with ethanol and other alcohols. The best oil yields for both PLE and UAE of N. gaditana were achieved with the mixture of 2-MeTHF:ethanol (1:3), reaching yields of up to 16.3%, for UAE at 50 °C and up to 46.1% for PLE at 120 °C. Lipid composition of the extracts was analyzed by HPLC-ELSD and by GC-MS to determine lipid species and fatty acid profile, respectively. Different fractionation of lipid species was achieved with PLE and solvent mixtures of different polarity. Thus, for the extraction of glycolipids, ethanolic extracts contained higher amounts of glycolipids and EPA, probably due to the higher polarity of the solvent. The optimized method was applied to microalgae Isochrysis galbana and Tetraselmis chuii showing the potential of mixtures of biobased solvents like 2-methyl-THF and ethanol in different proportions to efficiently extract and fractionate lipids from microalgal biomass.     

Effects of single and combined microalgae on larval growth, development and survival of the commercial sea cucumber Holothuria spinifera Theel

The results of the study on the suitable algal feed for the mass rearing of holothurian larvae through hatchery system are presented. Auricularia larvae, after 48 h of fertilization, obtained from induced spawning of Holothuria spinifera, were fed with different algae Isochrysis galbana, Nanochloropsis salina, Pavlova lutheri, Tetraselmis chuii and Chaetoceros calcitrans as well as I. galbana+C. calcitrans to ascertain the effect of single and combined microalgal diet. The rate of feeding was 2 × 10⁴ cells larvae^–1 day^–1 for a period of 9–12 days. The growth rate of 59 μm day⁻¹ with 90% and 43 μm day⁻¹ with 100% occurrence of late auricularia in the larvae fed with C. calcitrans alone and I. galbana+C. calcitrans, respectively, indicated that C.calcitrans itself or in combination with I. galbana is the effective feed for the larvae of H. spinifera.