Novel alkenone-producing strains of genus Isochrysis (Haptophyta) isolated from Canadian saline lakes show temperature sensitivity of alkenones and alkenoates
Novel alkenone-producing strains of genus Isochrysis (Haptophyta) isolated from Canadian saline lakes show temperature sensitivity of alkenones and alkenoates
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DOI：
10.1016/j.orggeochem.2018.04.008
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发表时间：
2018-07-01
影响因子：
3
通讯作者：
Shiraiwa, Yoshihiro
中科院分区：
文献类型：
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作者：
Araie, Hiroya;Nakamura, Hideto;Shiraiwa, Yoshihiro
最近在不同的湖泊环境中发现了产生烯酮的物种，尽管分类信息间接来自环境基因组技术。在这项研究中，我们从加拿大盐湖中分离出产生烯酮的藻类，并建立了单藻培养的个别菌株，以确定其分类和分子生物学特性。从湖泊收集的水和沉积物首先在人工海水介质中富集在一定范围的盐度（5-40 g/L），以培养分类群在体外。利用SSU和LSU rRNA基因分析，在等鞭金藻沼泽中分离并分类了7个附着菌菌株的单藻培养物。与其他先前报道的产生烯酮的附着菌相比，分离菌株内的烯酮分布被确定为是新颖的。虽然所有菌株都产生典型的C-37和C-38异构体范围，但从加拿大盐湖分离的一种菌株还产生对温度敏感的新型C-41和C-42烯酮。此外，我们表明，所有烯酮不饱和指数（例如，U-37（k）和U-37（k ′）在培养实验中是温度依赖性的，并且烯化指数（例如，U-37（A）、U-38（A）、RIA（38）和A（37）/A（38））为基于这些新的湖藻菌株的温度校准提供了替代选择。重要的是，这些指数显示在低于10摄氏度的温度下培养实验中的温度依赖性，其中传统的烯酮代理不那么敏感。我们假设，这套校准可用于重建过去的水温在加拿大大草原的湖泊范围广泛。(C)2018爱思唯尔有限公司版权所有。
Alkenone-producing species have been recently found in diverse lacustrine environments, albeit with taxonomic information derived indirectly from environmental genomic techniques. In this study, we isolated alkenone-producing algal species from Canadian saline lakes and established unialgal cultures of individual strains to identify their taxonomical and molecular biological characteristics. Water and sediments collected from the lakes were first enriched in artificial seawater medium over a range of salinities (5-40 g/L) to cultivate taxa in vitro. Unialgal cultures of seven haptophyte strains were isolated and categorized in the Isochrysis Glade using SSU and LSU rRNA gene analysis. The alkenone distributions within isolated strains were determined to be novel compared with other previously reported alkenone-producing haptophytes. While all strains produced the typical C-37 and C-38 range of isomers, one strain isolated from Canadian salt lakes also produced novel C-41 and C-42 alkenones that are temperature sensitive. In addition, we showed that all alkenone unsaturation indices (e.g., U-37(k) and U-37(k)') are temperature-dependent in culture experiments, and that alkenoate indices (e.g., U-37(A), U-38(A), RIA(38) and A(37)/A(38)) provide alternative options for temperature calibration based on these new lacustrine algal strains. Importantly, these indices show temperature dependence in culture experiments at temperatures below 10 degrees C, where traditional alkenone proxies were not as sensitive. We hypothesize that this suite of calibrations may be used for reconstructions of past water temperature in a broad range of lakes in the Canadian prairies. (C) 2018 Elsevier Ltd. All rights reserved.