Mixotrophic uptake of organic compounds by coccolithophores

Godrijan, Jelena; Drapeau, David; Balch, William M. (2020) Mixotrophic uptake of organic compounds by coccolithophores. Limnology and oceanography, 65 (6). pp. 1410-1421. ISSN 0024-3590

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Abstract

Osmotrophy is one of the main modes of mixotrophic acquisition of carbon by phytoplankton, but historically it has been under‐investigated and its physiological and ecological relevance remains poorly understood. Here, we investigate osmotrophy in coccolithophores. Coccolithophores are one of the major contributors to the ocean biomass inhabiting both euphotic and subeuphotic depths in the marine environment. Coccolithophores demonstrate the potential to utilize a wide array of organic compounds in darkness. In experiments with BioLog Ecoplates, we screened a wide array of organic compounds as potential carbon sources, and observed that the major types of organic compounds taken up by coccolithophores were primarily carbohydrates along with a few amino acids and polymers. Furthermore, in subsequent radiotracer experiments, the uptake rates of 14C‐labeled dissolved organic carbon compounds in the dark were low relative to the maximal rates of photosynthetic carbon fixation in the light. The time course of uptake for some compounds suggests constitutive capacity for their transport, while for others the transport appears to be activated. Nonetheless, the collective slow uptake rate of a large array of organic compounds found in seawater, might be the only way that osmotrophy could fuel significant coccolithophore growth in the deep euphotic and subeuphotic zones in the sea.

Item Type:	Article
Uncontrolled Keywords:	BioLog EcoPlates ; heterotrophy ; haptophytes ; dissolved organic carbon ; osmotrophy
Subjects:	NATURAL SCIENCES > Biology NATURAL SCIENCES > Interdisciplinary Natural Sciences > Marine Science
Divisions:	Division for Marine and Enviromental Research
Depositing User:	Jelena Godrijan
Date Deposited:	17 Feb 2021 10:33
URI:	http://fulir.irb.hr/id/eprint/6333
DOI:	10.1002/lno.11396

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