A dark-tolerant diatom (Chaetoceros) cultured from the deep sea
A dark-tolerant diatom (Chaetoceros) cultured from the deep sea
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从深海培养的耐暗硅藻（角毛藻）
DOI：
10.1111/jpy.13240
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发表时间：
2022-02-28
影响因子：
2.9
通讯作者：
Zhang, Yongyu
中科院分区：
文献类型：
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作者：
Mou, Shanli;Zhang, Zenghu;Zhang, Yongyu
虽然深海的极端条件通常不适合光合藻的生长，但越来越多的证据表明，这种环境中生活着各种健康的浮游植物。然而，生活在深海的浮游植物很少被隔离和培养，因此我们对它们来自哪里以及它们如何适应(或容忍)极端深海环境的了解有限。在这里，在长期的黑暗压力和随后的光照处理下，我们成功地从西太平洋1000米深的海底分离出了一种硅藻。形态观察和分子系统发育分析表明，它属于角毛藻属(Chaetoceros)，暂定名为Chaetoceros sp.DS1。我们观察到，该物种的叶绿体基因组与单纯角毛藻的基因组关系最为密切。它对黑暗有很强的耐受性，在室温下的完全黑暗中，它能保持形态的完整性和活力长达3个月。我们还证明了角毛藻Chetoceros sp.DS1具有兼性异养功能。在弱光条件下，多种有机碳源(如甘油、乙醇、乙酸钠)对其生长有促进作用。但在黑暗和强光条件下，有机碳的促生长作用不明显。的确，角毛藻Chetoceros sp.DS1在弱光条件下生长最好，表明它可能来自真光区的更深层。这种硅藻的兼性异养功能和对黑暗的耐受性可能有助于它在这些条件下生存或进入深海休眠期。
Although the extreme conditions of the deep sea are typically not suitable for the growth of photosynthetic algae, accumulating evidence indicates that there are diverse healthy phytoplankton living in this environment. However, living phytoplankton from the deep sea have rarely been isolated and cultivated, and so our understanding of where they come from and how they adapt to (or tolerate) the extreme deep-sea environment is limited. Here, under long-term dark stress and subsequent light treatment, we successfully isolated a diatom from a depth of 1,000 m in the Western Pacific Ocean. Morphological observations and molecular phylogenetic analysis revealed that it is affiliated to the genus Chaetoceros, and thus, we tentatively named it Chaetoceros sp. DS1. We observed that the chloroplast genome of this species, is most closely related to that of Chaetoceros simplex. It was shown to have a strong tolerance to darkness in that it maintained its morphological integrity and vitality for up to 3 months in complete darkness at room temperature. We also demonstrated that Chaetoceros sp. DS1 presented a facultative heterotrophic function. Its growth was promoted by many organic carbon sources (e.g., glycerine, ethanol, and sodium acetate) under low light conditions. However, under dark and high light conditions, the growth promotion effect of organic carbon was not obvious. Indeed, Chaetoceros sp. DS1 grew best under low light conditions, indicating that it likely came from the deeper layer of the euphotic zone. The facultative heterotrophic function of this diatom and tolerance to darkness may help it survive in these conditions or enter a dormant period in the deep sea.