A1 Journal article (refereed)
Metabolic plasticity of mixotrophic algae is key for their persistence in browning environments (2022)

Calderini, M. L., Salmi, P., Rigaud, C., Peltomaa, E., & Taipale, S. J. (2022). Metabolic plasticity of mixotrophic algae is key for their persistence in browning environments. Molecular Ecology, 31(18), 4726-4738. https://doi.org/10.1111/mec.16619

JYU authors or editors

Publication details

All authors or editors: Calderini, Marco L.; Salmi, Pauliina; Rigaud, Cyril; Peltomaa, Elina; Taipale, Sami J.

Journal or series: Molecular Ecology

ISSN: 0962-1083

eISSN: 1365-294X

Publication year: 2022

Publication date: 17/07/2022

Volume: 31

Issue number: 18

Pages range: 4726-4738

Publisher: Wiley

Publication country: United Kingdom

Publication language: English

DOI: https://doi.org/10.1111/mec.16619

Publication open access: Openly available

Publication channel open access: Partially open access channel

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/82964

Abstract

Light availability is the main regulator of primary production, shaping photosynthetic communities and their production of ecologically important biomolecules. In freshwater ecosystems, increasing dissolved organic carbon concentrations, commonly known as browning, leads to lower light availability and the proliferation of mixotrophic phytoplankton. Here, a mixotrophic algal species (Cryptomonas sp.) was grown under five increasing dissolved organic carbon concentrations to uncover the plastic responses behind the success of mixotrophs in browning environments and their effect in the availability of nutritionally important biomolecules. In addition to the browning treatments, phototrophic, heterotrophic and mixotrophic growth conditions were used as controls. Despite reduced light availability, browning did not impair algal growth compared to phototrophic conditions. Comparative transcriptomics showed that genes related to photosynthesis were down-regulated, whereas phagotrophy gene categories (phagosome, lysosome, and endocytosis) were up-regulated along the browning gradient. Stable isotope analysis of phospholipid fractions validated these results, highlighting that the studied mixotroph increases its reliance on heterotrophic processes with browning. Metabolic pathway reconstruction using transcriptomic data suggests that organic carbon is acquired through phagotrophy and used to provide energy in conjunction with photosynthesis. Although metabolic responses to browning were observed, essential fatty acid content was similar between treatments while sterol content was slightly higher upon browning. Altogether, our results provide a mechanistic model of how a mixotrophic algae responds to browning and how such responses affect the availability of nutritionally essential biomolecules for higher trophic levels.

Keywords: algae; microalgae; plankton; fresh water; dissolved organic carbon; fatty acids; biomolecules; light (electromagnetic radiation); aquatic ecosystems; environmental effects; state of waters; photobiology

Free keywords: browning; cryptomonas; dissolved organic carbon; fatty acids; mixotrophy; phagotrophy; transcripto mic

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Ministry reporting: Yes

Reporting Year: 2022

JUFO rating: 3