|题名: ||金藻Poterioochromonas sp. DO-2004生理特性及控制藻类水华潜力的研究|
|关键词: ||金藻Poterioochromonas sp. DO-2004
|其他题名: ||The Physiological Characteristics of Poterioochromonas sp. DO-2004 and its Potential Role in Cyanobacteria Bloom Control|
|摘要: ||Poterioochromonas是金藻门（Chrysophyta）金藻纲（Chrysophyceae）色金藻目（Chromulinales）锥囊藻科（Dinobryonaceae）中的一属。本实验室在微囊藻的大量培养过程中分离获得了一株金藻Poterioochromonas sp. DO-2004，其营养细胞具有2根不等长鞭毛，能游动；具有色素体，能进行光合作用；同时还能吞噬引起水华现象的微囊藻，即其表现出混合营养生长的特点。在饵料充足时，Poterioochromonas sp. DO-2004 能够快速繁殖，短时间内生物量急剧增加。本文以Poterioochromonas sp. DO-2004 为研究对象，通过喂食人工培养的各种蓝藻，研究了其生理尤其是混养生长特性，包括各种环境因子对其生长和摄食饵料的影响，并开展了其控制微囊藻水华的初步尝试，为研究微型混养生物的生长特点及探讨其在控制藻类水华的潜力方面提供理论和实际指导意义。
经过大量实验发现：以藻类为饵料时，金藻Poterioochromonas sp. DO-2004不仅能吞食小于或与本身类似大小的运动或不运动的单细胞藻类，还能够吞噬由少量细胞组成的短的丝状或链状藻，其可吞噬饵料的大小范围为直径（或长度）不超过10µm的藻类。
通过对Poterioochromonas sp. DO-2004 在不同营养方式下生长情况的比较，本文发现金藻混养条件下的生长（比生长速率为0.252 ± 0.019 d-1）快于自养条件下的生长（比生长速率为0.151 ± 0.012 d-1），即喂食饵料藻能够显著促进其生长。进一步研究发现此株金藻不能长期以专性噬养或专性化养的方式生长繁殖。
以人工培养的铜绿微囊藻（Microcystis aeruginosa）为饵料，研究了起始饵料浓度、光强、温度和pH值等环境因子对金藻Poterioochromonas sp. DO-2004 生长和噬藻速率的影响，并对影响生长和噬藻速率的因素进行相关分析。结果显示：自养金藻生长的快慢与光强和温度强相关，而与pH值的相关性不显著。喂食饵料能显著促进金藻生长，其生长和噬藻速率与起始饵料浓度之间相关性强，它们之间的关系分别可以用Monod方程和Michaelis-Menten方程来拟合。提供相同量的饵料时，金藻的混养生长与光强相关性显著，而与温度和pH值的相关性不明显；其噬藻速率与pH值呈现强的负相关关系，而与光强和温度相关性不显著。除了在不同pH值培养液的生长外，混养金藻的生长速率与其噬藻速率之间存在强的正相关关系。结果表明适于Poterioochromonas sp. DO-2004生存并吞噬微囊藻的环境条件较广，这也是探索其控制微囊藻水华的前提。
将少量金藻Poterioochromonas sp. DO-2004（103 cells/mL）投入高浓度人工培养的蓝藻（107 cells/mL）中，金藻能够快速吞噬蓝藻，短时间内显著降低培养体系叶绿素 a水平。同时，金藻能够进行快速增殖，其最大生长速率可达0.128±0.014 h-1，并且吞噬大量产毒微囊藻后金藻的生长和摄食行为并未受到影响，这进一步表明金藻对微囊藻毒素不敏感。另外，这种“暴发性”的快速繁殖导致了培养体系中金藻细胞叶绿体变小或者消失，同时出现大量的嗜锇滴；当其进入静止生长期后，金藻体内的叶绿体又重新出现，嗜锇滴消失。这一方面说明金藻具备控制蓝藻水华的潜力，另一方面说明可以将其作为研究光合作用器官发生和发展的模式生物，并且还可以为研究其他混养赤潮藻类的暴发过程和机理提供参考。
将室内培养的金藻和微囊藻转移到户外湖水中后，金藻不仅能正常生长繁殖，还能快速吞噬微囊藻。处理组实验装置中微囊藻的生物量在短期内急剧下降，水体叶绿素 a 浓度也持续下降至较低水平。|
|英文摘要: ||Poterioochromonas sp. strain DO-2004, isolated from mass culture of Microcystis, can not only grow autotrophically, but also live on Microcystis. The present study attented its growth and ingest behavior along with different nutrition patterns, and focused further on the interaction between Poterioochromonas sp. and Microcystis in the following aspects: how fast was the growth rate of Poterioochromonas sp. when feeding on Microcystis; was Poterioochromonas sp. sensitive to toxic Microcystis; what was the environmental conditions for the growth of Poterioochromonas sp.. The answers to these questions may help illustrate the implications of this organism in dynamic of Microcystis bloom and explore the potential role of Poterioochromonas sp. as biological control agent.
The results showed that this golden alga has size-based prey selectivity. Poterioochromonas sp. were able to swallow preys, whose diameters varied from 1 to 10 μm, such as M. aeruginosa, Synechocystis sp.,Gloeocapsa alpicola, Chroococcus sp., Chlorella vugaris, Chlamydomonas reinhardtii. And Poterioochromonas sp. could swallow not only the immobile algae but also mobile ones when the size was suitable. Poterioochromonas sp. could swallow short catenarian and filiform organisms (eg: Anabaena flos-aquae and Phormidium mucicola) whose total length did not exceed 10 μm.
In different nutrition patterns, the growth rates of Poterioochromonas sp. were expressed in the decreasing order as mixotrophy, autotrophy, phagotrophy and osmotrophy. Feeding preys had a significant effect on the growth rate. Poterioochromonas sp. in mixotrophy (0.252 ± 0.019 d-1) reproduced more quickly than that in autotrophy (0.151 ± 0.012 d-1) when feeding on Microcystis aeruginosa FACHB469. And Poterioochromonas sp. could not maintain its growth only by obligate phagotrophy and osmotrophy. The shape and ultrastructure of Poterioochromonas sp. were diverse during the ingestion and digestion of prey.
The growth rate of autotrophic Poterioochromonas sp. was affected by light intensity and temperature significantly, while the correlation between growth rate and pH was not significant. When providing preys, the growth of Poterioochromonas sp. was accelerated significantly. The growth and ingestion rate of Poterioochromonas sp. increased hyperbolically with prey concentration. When there was commensurate prey, the correlation between the growth of mixotrophic Poterioochromonas sp. and light intensity was significant, while the correlations between the growth and temperature and pH were not significant. The negative correlation between the ingestion rate and pH was much significant, while the correlations between the ingestion rate and temperature and light intensity were not significant. In a word, this Poterioochromonas has the ability to live and graze Microcystis in many culture conditions.
In order to investigate whether Microcystis have negative effects on Poterioocromonas, the activity of several antioxidant enzymes and ultrastructures of autotrophic and mixotrophic Poterioocromonas sp. were compared. The results showed that both toxic and nontoxic Microcystis could accelerate the growth of Poterioocromonas. The contents of MDA and GSH between mixotrophic and autotrophic Poterioocromonas were not different significantly, while SOD and CAT in mixotrophy were much higher than those in autotrophy. The number of chloroplasts of mixotrophic Poterioocromonas increased and mitochondria became larger. In conclusion, both toxic and nontoxic Microcystis could accelerate the growth of Poterioocromonas sp. DO-2004.
When added into high concentration of preys (107 cells•ml-1), Poterioocromonas sp. (initial concentration: 103 cells•ml-1) reproduced quickly. Unlike most daphnids and rotifers, Poterioochromonas sp. was not sensitive to toxic Microcystis. The growth rates of Poterioocromonas were among 0.079 - 0.128 h-1 for different conditions. The highest growth rate (0.128 h-1) was observed when feeding on Gloeocapsa alpicola in aeration. On the other hand, the biomass of preys decreased quickly. Chlorophyll a concentration decreased to 17-30% at 120 h for the aerated groups, to 48-75% at 120 h for the unaerated groups.
The ultrastructure of Poterioocromonas sp. changed a lot during this special process. The chloroplasts of most predators became shrunken or disappeared in the first few days, and there were also many large osmiophilic globules located in the cytoplasm at the same time. When Poterioochromonas sp. entered a “stationary growth phase”, their chloroplasts could appear again, and the large osmiophilic globules disappeared simultaneously.
Field experiment in mini raceway ponds also confirmed that Poterioochromonas sp. affects the dynamic of Microcystis bloom significantly. In the treated ponds Poterioochromonas sp. increased quickly from 8.70×102 cells•ml-1 to about 7.7×104 cells•ml-1 in 3 d and M. aeruginosa PCC7806 decreased on the contrary. At the end of the experiment the residual Microcystis in the treated ponds was less than 5% of the control. This experiment demonstrated that Poterioochromonas sp. was able to grow and ingest Microcystis in the field and accelerate the disappearance of Microcystis.
The present study had also shed light on the possibility of utilizing this organism, together with other agents, for the control of Microcystis bloom.|
|Appears in Collections:||中科院水生所知识产出（2009年前）_学位论文|
|File Name/ File Size
金藻Poterioochromonas sp. DO-2004生理特性及控制藻类水华潜力的研究.郭胜娟[d].中国科学院水生生物研究所,2008.20-25