Contribution of cyanobacterial alkane production to the ocean hydrocarbon cycle.

Lea-Smith, DJ and Biller, SJ and Davey, MP and Cotton, CA and Perez Sepulveda, BM and Turchyn, A. V. and Scanlan, DJ and Smith, AG and Chisholm, SW and Howe, CJ (2015) Contribution of cyanobacterial alkane production to the ocean hydrocarbon cycle. Proceedings of the National Academy of Sciences of the United States of America, 112 (44). pp. 13591-13596. ISSN 0027-8424 Online ISSN 1091-6490

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Official URL: http://www.pnas.org/content/112/44/13591.abstract

Abstract

Hydrocarbons are ubiquitous in the ocean, where alkanes such as pentadecane and heptadecane can be found even in waters minimally polluted with crude oil. Populations of hydrocarbon-degrading bacteria, which are responsible for the turnover of these compounds, are also found throughout marine systems, including in unpolluted waters. These observations suggest the existence of an unknown and widespread source of hydrocarbons in the oceans. Here, we report that strains of the two most abundant marine cyanobacteria, Prochlorococcus and Synechococcus, produce and accumulate hydrocarbons, predominantly C15 and C17 alkanes, between 0.022 and 0.368% of dry cell weight. Based on global population sizes and turnover rates, we estimate that these species have the capacity to produce 2-540 pg alkanes per mL per day, which translates into a global ocean yield of ∼ 308-771 million tons of hydrocarbons annually. We also demonstrate that both obligate and facultative marine hydrocarbon-degrading bacteria can consume cyanobacterial alkanes, which likely prevents these hydrocarbons from accumulating in the environment. Our findings implicate cyanobacteria and hydrocarbon degraders as key players in a notable internal hydrocarbon cycle within the upper ocean, where alkanes are continually produced and subsequently consumed within days. Furthermore we show that cyanobacterial alkane production is likely sufficient to sustain populations of hydrocarbon-degrading bacteria, whose abundances can rapidly expand upon localized release of crude oil from natural seepage and human activities.

Item Type: Article
Uncontrolled Keywords: 2015AREP; IA70;
Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions: 01 - Climate Change and Earth-Ocean Atmosphere Systems
08 - Green Open Access
Journal or Publication Title: Proceedings of the National Academy of Sciences of the United States of America
Volume: 112
Page Range: pp. 13591-13596
Depositing User: Sarah Humbert
Date Deposited: 28 Apr 2016 11:02
Last Modified: 28 Apr 2016 11:02
URI: http://eprints.esc.cam.ac.uk/id/eprint/3626

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