缅甸魔芋(Amorphophallus Muelleri)资源分布及产业基本概况

在缅甸13个含葡甘聚糖的野生魔芋种中，黄魔芋、白魔芋和红魔芋是当地民众习惯上按色泽进行区分的3类魔芋，每类又各包含几个种。其中, 上缅甸以红魔芋和缅甸白魔芋居多，下缅甸则以黄魔芋和耐热型白魔芋(A. variabilis)为多。缅甸魔芋现仍以野生资源为主，加工品以干片为多，大宗产品出口中国，部分销往日本。因比较优势明显，日本已开始与缅方合作在缅规模化种植弥勒魔芋。     

Outdoor mass microalgae production in Bahia Kino, Sonora, NW Mexico

The diatom Chaetoceros muelleri was grown in outdoor mass cultures under the winter, spring and summer conditions of Bahia Kino, Sonora, NW Mexico. The solar irradiance in winter was close to 60% of that available in spring and summer, but the cell concentrations and the harvestable biomass were one order of magnitude higher in spring and summer than in winter. There was no difference between the biomass harvested after 2 and 3 days in winter and summer, whereas in spring it was higher after 3 days. The protein content was significantly lower in winter, and carbohydrates and lipids were higher in winter and spring. The number of cells and the amount of harvestable biomass of outdoor cultures of C. muelleri depend on the temperature prevailing in each season, which causes significant differences in growth rates and in biochemical composition.     

Growth and proximate composition of the Chaetoceros calcitrans f. pumilus under different temperature, salinity and carbon dioxide levels

The marine diatom Chaetoceros calcitrans f. pumilus has been examined for its potential source as live feed in aquaculture. The present study investigated effects of temperature (20, 25 and 30 °C), salinity (25 and 35) and carbon dioxide addition (air+CO₂) on the growth and proximate composition of C. calcitrans under laboratory conditions. The growth and biomass of C. calcitrans were primarily affected by carbon dioxide addition, and to a lesser extent by temperature and salinity. In general, lipid and carbohydrate contents were higher at lower temperatures (20 and 25 °C), while the protein content was unaffected. Carbon dioxide addition increased protein, while lowering carbohydrates, but had no effect on lipid content. Carbohydrates were increased while lipids and protein decreased at the highest salinity (35±0.9). These results should be taken into consideration when evaluating the dietary value of this micro alga for aquaculture.     

Assessment of the performance of Pacific oyster (Crassostrea gigas) larvae fed with fresh and preserved Pavlova lutheri concentrates

The Prymnesiophycea Pavlova lutheriwas produced using a traditional technique (batch mode in carboys) and by an innovative technique (semi-continuous mode in alveolarphotobioreactor). Two experimental feedingtrials were carried out with Pacific oyster(Crassostrea gigas) larvae with freshand preserved (4 °C and 1 °C)P. lutheri concentrates used inmonospecific and bispecific diets, incombination with fresh Chaetoceroscalcitrans forma pumilum. Nodifferences in terms of gross composition andlarval performance were noticed between thefresh algae biomass produced by the twotechniques. The low temperatures allowedpreservation of the nutritionalcharacteristics of the P. lutheri freshculture for the time period considered (27days). The P. lutheri concentratespreserved at 4 °C or 1 °C didnot differ substantially in terms ofnutritional value. Larvae fed a monospecificdiet of P. lutheri, both fresh andpreserved, exhibited a modest growth rate (<2.1 µm day^–1), in some cases notsignificantly different from that observed inthe unfed larvae (the control), and a lowsurvival rate. In contrast, when Chaetoceros calcitrans forma pumilumwas used as a monospecific diet, good growthperformance (>4.5 µm day^–1) and ahigh survival rate (>86%) were observed inlarvae. A substitution of 50% (trial 1) or80% (trial 2) of fresh C. calcitransforma pumilum with the preserved P. lutheri concentrates did not adverselyaffect growth rate or survival of C.gigas larvae.     

7种试剂对3种饵料微藻絮凝效应的研究

[目的]探讨絮凝剂对牟氏角毛藻、微绿球藻、湛江等鞭金藻3种海洋饵料微藻的絮凝效应。[方法]采用5种无机试剂和2种有机试剂分别以6种不同的浓度处理藻液,连续4h跟踪测定藻细胞的沉淀情况。[结果]5种无机试剂对3种海洋饵料微藻均有一定的絮凝作用,而2种有机试剂的絮凝效果均不明显。硫酸锌和硫酸铝对牟氏角毛藻的絮凝效果明显;明矾、硫酸锌和聚合氯化铝对微绿球藻的絮凝效果明显;硫酸铝对湛江等鞭金藻的絮凝效果较明显。[结论]为生产性海洋饵料微藻的采收提供理论依据。     

阳光紫外辐射对2种微藻的短期影响

为了阐明2种赤潮藻柔弱角毛藻(Chaetoceros debilis)和绿色巴夫藻(Pavlova viridis)对阳光紫外辐射(UVR, 280～400 nm)变化的响应,比较研究了它们在全波段阳光下和滤除UVR/UV-B条件下的有效光化学效率变化,同时探讨了室内无UVR的低光条件下其有效光化学效率的恢复。结果表明,阳光UVR抑制藻细胞的有效光化学效率,其抑制程度随着接受辐射处理时间的延长而增大,在10 min左右细胞内的修复与损伤速率达到平衡,抑制率不变,且阳光UVR对二种藻的抑制程度相差不大。转移到无UVR的弱光条件下,藻细胞的有效光化学效率得到恢复,但恢复过程中柔弱角毛藻恢复明显快于绿色巴夫藻,体现了不同藻细胞对阳光UVR响应的种间差异。     

杀鲑气单胞菌杀藻作用的初步研究

为了研究几丁质酶对硅藻杀灭作用,以杀鲑气单胞菌(Aeromonas salmonicida)和其几丁质酶敲除菌为研究对象对牟氏角毛藻(Chaetoceros muelleri)进行共培养并探究其作用差异。结果表明:杀鲑气单胞菌野生株和缺失株分别与牟氏角毛藻共培养48 h后,野生株对牟氏角毛藻的杀藻率达到9.18%,而缺失株无明显杀藻活性;通过扫描电镜进一步发现野生株细菌能够裂解牟氏角毛藻的细胞壁,而缺失株不能。结果证实杀鲑气单胞菌因具有几丁质酶而对藻类具有杀灭作用。     

离心·冷藏对牟氏角毛藻再培养的影响

[目的]探索牟氏角毛藻经浓缩运输和冷藏保存后再作藻种和饵料的可行性效果。[方法]通过离心和低温冷藏2种方法处理牟氏角毛藻,然后再继续进行再培养,以此来延长牟氏角毛藻的储存时间并减小运输量。[结果]试验表明,经不同离心速度和不同离心时间处理后的角毛藻进行再培养,生长速率不同。在3000 r/min的转速下离心7 min的角毛藻再培养效果最好,最大生长率可达0.83,并且在此离心条件下的藻泥静置5 d之内再添加培养基进行培养仍生长良好。但是经4℃冷藏后的角毛藻常温下再培养效果不好。[结论]低温冷藏会影响藻细胞的正常生长,而且随着冷藏时间的延长,细胞再培养愈来愈困难。因此,建议科研及生产中不采用此种方法作为保种技术。     

魔芋胶与瓜胶未来产业竞争态势分析

比较魔芋和瓜尔豆生物学特性、现有资源区位优势及魔芋胶和瓜胶产品性状等,魔芋胶在理化指标方面明显优于瓜胶,尤其是粘度及凝胶特性显著好于瓜胶。弥勒魔芋规模种植必将伴随魔芋产量的大幅增加,可提升我国魔芋产业在全球的市场份额及产业集中度,显著增强魔芋胶的竞争力,逐渐动摇瓜胶在传统产业中的现有竞争优势。     

Selectivity of the rotifer Brachionus plicatilis fed mixtures of algal species with various cell volumes and cell densities

The ability for food selectivity of rotifer Brachionus plicatiliswas studied in the laboratory by feeding mixtures of microalgae with various cell volumes. Chlorella sp. (≈22 µm³) was the reference algal species, and Asteromonas gracilis, (Chlorophyta) (≈2150 µm³), Tetraselmis suesica (≈268 µm³), Dunaliella salina (≈52 µm³) and Chaetoceros sp. (≈150 µm³) the experimental species. Each was mixed with Chlorella and fed in three experiments. In the first experiment, filtration and ingestion rates of rotifers each fed with algae revealed that the highest values were measured with the mixture of Chlorella + Asteromonas, and the lowest for Chlorella + Chaetoceros. In the second and the third experiments, by using several combinations of algal densities with the mixture of Chlorella + Asteromonas, a selectivity ability of the rotifers for Asteromonas was found. A hypothesis is presented that accounts for the preference of rotifers for Asteromonas, which is suggested as a new candidate species for use in live food production of fish hatcheries.