Details zur Publikation |
| Kategorie | Textpublikation |
| Referenztyp | Zeitschriften |
| DOI | 10.1128/aem.01429-26 |
Lizenz  |
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| Titel (primär) | The diatom Thalassiosira gravida under Arctic change: algal exudates and their microbial transformation under contrasting temperatures and photoperiods |
| Autor | Bussmann, F; Giesler, J.K.; Wohlrab, S.; Lechtenfeld, O.J.
; Kaesler, J.; Harder, T.; Koch, B.P. |
| Quelle | Applied and Environmental Microbiology |
| Erscheinungsjahr | 2026 |
| Department | EAC |
| Band/Volume | 92 |
| Heft | 10 |
| Seite von | e01429-26 |
| Sprache | englisch |
| Topic | T9 Healthy Planet |
| Keywords | diatom; extracellular release; dissolved organic carbon; dissolved organic matter; bacterial transformation; Thalassiosira gravida; microbial carbon pump; FT-ICR-MS |
| Abstract | Climate change threatens polar ecosystems through rising temperatures and changing light regimes. Phytoplankton release of dissolved organic carbon (DOC) is a major carbon-cycle component, yet it remains unclear how temperature, light, and associated bacteria jointly affect DOC and dissolved organic matter (DOM) composition. Here, we analyzed axenic and xenic cultures of the Arctic diatom Thalassiosira gravida at 9°C and 13.5°C under 16:8 h and 24:0 h light:dark cycles. Extracellular DOC was quantified, and molecular composition characterized by untargeted ultrahigh-resolution mass spectrometry in original culture filtrates. In axenic cultures, growth rates were 266% higher at 13.5°C 24:0 h, and cell-normalized DOC concentrations 52% lower compared to 9°C 16:8 h, suggesting a shift in carbon allocation. Xenic cultures contained 50–80% lower cell-normalized DOC concentrations than axenic cultures and converged at 11.7 ± 0.9 pmol DOC cell−1. Despite similar DOC concentrations in xenic cultures, the 13.5°C 24:0 h treatment showed lower chemodiversity (−8%), H/C ratios (−7%), and higher oxidation (+24%) than 9°C 16:8 h, consistent with more strongly processed DOM. At 9°C, axenic 24:0 h cultures showed higher chemodiversity (+14%) and H/C ratios (+7%) compared to 16:8 h, indicating that prolonged photoperiods altered DOM composition toward signatures associated with greater putative bioavailability. Contrasting axenic-xenic patterns suggest that bacterial presence weakened the treatment-dependent DOM responses observed in axenic cultures. Overall, temperature and photoperiods altered algal DOC quantity and quality, and its microbial transformation, with implications for carbon cycling. |
| Bussmann, F, Giesler, J.K., Wohlrab, S., Lechtenfeld, O.J., Kaesler, J., Harder, T., Koch, B.P. (2026): The diatom Thalassiosira gravida under Arctic change: algal exudates and their microbial transformation under contrasting temperatures and photoperiods Appl. Environ. Microb. 92 (10), e01429-26 10.1128/aem.01429-26 |
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