Competition between microcystin- and non-microcystin-producing Planktothrix agardhii (cyanobacteria) strains under different environmental conditions
Competition between microcystin- and non-microcystin-producing Planktothrix agardhii (cyanobacteria) strains under different environmental conditions
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DOI：
10.1111/j.1462-2920.2008.01730.x
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发表时间：
2008-12-01
影响因子：
5.1
通讯作者：
Quiblier, Catherine
中科院分区：
文献类型：
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作者：
Briand, Enora;Yepremian, Claude;Quiblier, Catherine
在蓝藻水华期间控制微囊藻毒素（肝毒素）产生的因素以及这些代谢产物的功能在很大程度上仍然未知。在试图提供这些问题的答案，我们比较了适合微囊藻毒素（MC）生产和非MC生产的浮游发藻agardhii菌株在各种实验条件下。更具体地说，我们研究了温度，光照强度和硝酸盐浓度对几个MC生产和非MC生产菌株在单一培养和竞争实验的影响。在单一培养实验中，没有发现任何测试的环境条件下的细胞生长速率的显着差异。另一方面，在竞争实验结束时，我们发现，当环境条件限制细胞生长时，MC生产菌株明显优于非MC生产菌株。这表明，在生长限制条件下，生产MC的好处超过了成本。此外，在非生长限制条件下发现了相反的情况，这表明在有利于蓝藻生长的环境条件下，MC生产的成本必须超过其好处。这些研究结果表明，环境因素可能对MC生产率产生间接影响，并对MC生产和非MC生产菌株的选择，通过其直接影响的细胞生长速率和细胞密度的文化。关于MCs可能的功能，已经提出了几个假设，但似乎没有一个得到我们数据的支持。
The factors that control the production of microcystins (hepatotoxins) during cyanobacterial blooms, and the function of these metabolites remain largely unknown. In an attempt to provide answers to these questions, we compared the fitness of microcystin (MC)-producing and non-MC-producing Planktothrix agardhii strains under various experimental conditions. More specifically, we investigated the effects of temperature, light intensity and nitrate concentrations on several MC-producing and non-MC-producing strains in monoculture and competition experiments. In the monoculture experiments, no significant difference in cell growth rates was found for any of the environmental conditions tested. On the other hand, at the end of the competition experiments, we found that when the environmental conditions limited cell growth, MC-producing strains were clearly winning out over the non-MC-producing ones. This suggested that, under growth-limiting conditions, the benefits of producing MC outweigh the cost. Moreover, the reverse was found under non-growth-limiting conditions, suggesting that under environmental conditions that favour cyanobacterial growth, the cost of MC production must outweigh its benefits. These findings suggest that environmental factors may have an indirect effect on the MC production rate, and on the selection of MC-producing and non-MC-producing strains, via their direct impact on both the cell growth rate and the cell densities in the cultures. Several hypotheses have been advanced concerning the possible function of MCs, but none of them seems to be supported by our data.