Novel alkenone-producing strains of genus Isochrysis (Haptophyta) isolated from Canadian saline lakes show temperature sensitivity of alkenones and alkenoates

Araie, H. et al. (2018) Novel alkenone-producing strains of genus Isochrysis (Haptophyta) isolated from Canadian saline lakes show temperature sensitivity of alkenones and alkenoates. Organic Geochemistry, 121, pp. 89-103. (doi: 10.1016/j.orggeochem.2018.04.008)

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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 clade 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 C37 and C38 range of isomers, one strain isolated from Canadian salt lakes also produced novel C41 and C42 alkenones that are temperature sensitive. In addition, we showed that all alkenone unsaturation indices (e.g., UK37 and UK'37) are temperature-dependent in culture experiments, and that alkenoate indices (e.g., UA37, UA38, RIA38 and A37/A38) 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 °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.

Item Type:Articles
Additional Information:This study was partly supported by a fund of Core Research for Evolutional Science and Technology in Japan Science and Technology Agency (CREST/JST), Japan, to YS (FY2010–2016) and ERC funding for the ALKENoNE project [Project ID 63776] to JT (FY2015– 2020).
Glasgow Author(s) Enlighten ID:Toney, Professor Jaime and Plancq, Dr Julien
Authors: Araie, H., Nakamura, H., Toney, J. L., Haig, H. A., Plancq, J., Shiratori, T., Leavitt, P. R., Seki, O., Ishida, K.-i., Sawada, K., Suzuki, I., and Shiraiwa, Y.
College/School:College of Science and Engineering > School of Geographical and Earth Sciences
Journal Name:Organic Geochemistry
ISSN (Online):1873-5290
Published Online:17 April 2018
Copyright Holders:Copyright © 2018 Elsevier
First Published:First published in Organic Geochemistry 121:89-103
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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