Photophysiology of the marine cyanobacterium Prochlorococcus:: Ecotypic differences among cultured isolates
Photophysiology of the marine cyanobacterium Prochlorococcus:: Ecotypic differences among cultured isolates
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DOI：
10.4319/lo.1999.44.3.0628
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发表时间：
1999-05-01
影响因子：
4.5
通讯作者：
Chisholm, SW
中科院分区：
文献类型：
--
作者：
Moore, LR;Chisholm, SW
研究表明，来自地中海 (MED4) 和马尾藻海 (SS120) 的原绿球藻培养分离株在一定范围的辐照度下生长时，其色素成分和生长速率响应显着不同。此外，对北大西洋野外种群的分析表明，不同的生态类型可以在同一水体中共存。这些和其他观察结果得出这样的假设：原绿球藻由遗传上不同的生态型组成，这些生态型共同扩大了该属可以繁衍生息的光强度范围。在本文中，我们通过比较来自不同海洋状况的 10 种不同原绿球藻分离物的光生理学来探索这一假设。我们发现，根据 10 个分离株对不同光强度的生长响应及其叶绿素 b/a(2) (Chl b/a(2)) 比率，可以将其分为两个松散的簇。虽然两组在一定范围的光强度下生长时都能适应光环境，但具有明显较高叶绿素 b/a(2) 比率（高 B/A 生态型）的分离株在较低辐照度（I-k、I-g）下达到最大生长速率，具有高生长效率 (OLS)，并且在具有低叶绿素 b/a(2) 比率（低 B/A 生态型）的分离株最大生长的辐照度下生长受到抑制。高 Chl b/a(2) 比率导致高 B/A 生态型分离株相对于其他菌株在低生长辐照度下具有更高的光谱加权平均 chi at 特定吸收系数（(a) over bar）(chl)*、Chl a(2) 特定光捕获效率 (alpha(chla)) 和量子产率 (phi(m))。高 B/A 生态型和低 B/A 生态型之间的区别得到了使用 16S 核糖体核糖核酸 (rRNA) 基因构建的分子系统发育的支持。生态型之间的生理差异很可能导致给定水柱中不同的相对分布，以及作为季节动态和水柱稳定性函数的相对丰度的波动。
Cultured isolates of Prochlorococus from the Mediterranean Sea (MED4) and Sargasso Sea (SS120) have been shown to have dramatically different pigment composition and growth rate responses when grown over a range of irradiances. Moreover, analyses of field populations in the North Atlantic have shown that distinct ecotypes can coexist in the same water column. These and other observations have led to the hypothesis that Prochlorococcus is comprised of genetically distinct ecotypes that collectively expand the range of light intensities over which the genus can thrive. In this paper, we explore this hypothesis by comparing the photophysiology of 10 different Prochlorococcus isolates from diverse oceanographic regimes. We found that the 10 isolates could be grouped into two loose clusters based on their growth response to varying light intensity and their chlorophyll b/a(2) (Chl b/a(2)) ratios. Although both groups photoacclimate when grown over a range of light intensities, isolates with distinctly higher Chl b/a(2) ratios (high B/A ecotype) reach maximal growth rates at lower irradiances (I-k,I-g), have high growth efficiencies (OLS), and are inhibited in growth at irradiances where isolates with low Chl b/a(2) ratios (low B/A ecotype) are growing maximally. High Chl b/a(2) ratios resulted in higher spectrally weighted average chi at-specific absorption coefficient ((a) over bar)(chl)*, Chl a(2)-specific light-harvesting efficiency (alpha(chla)), and quantum yield (phi(m)) under low growth irradiances for the isolates of the high B/A ecotype relative to the others. The distinction between the high and low B/A ecotypes is supported by molecular phylogenies constructed using the 16S ribosomal ribonucleic acid (rRNA) gene. The physiological differences between the ecotypes most likely result in different relative distributions in a given water column and in fluctuations in their relative abundances as a function of seasonal dynamics and water-column stability.