Cell Plasticity of Marine Mediterranean Diazotrophs to Climate Change Factors and Nutrient Regimes
Ocean acidification and warming are current global challenges that marine diazotrophs must cope with. Little is known about the effects of pH and temperature changes at elevated CO<sub>2</sub> levels in combination with different nutrient regimes on N<sub>2</sub> fixers, espe...
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MDPI AG
2023-02-01
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| Series: | Diversity |
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| Online Access: | https://www.mdpi.com/1424-2818/15/3/316 |
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| author | Víctor Fernández-Juárez Elisa H. Zech Elisabet Pol-Pol Nona S. R. Agawin |
| author_facet | Víctor Fernández-Juárez Elisa H. Zech Elisabet Pol-Pol Nona S. R. Agawin |
| author_sort | Víctor Fernández-Juárez |
| collection | DOAJ |
| description | Ocean acidification and warming are current global challenges that marine diazotrophs must cope with. Little is known about the effects of pH and temperature changes at elevated CO<sub>2</sub> levels in combination with different nutrient regimes on N<sub>2</sub> fixers, especially on heterotrophic bacteria. Here, we selected four culturable diazotrophs, i.e., cyanobacteria and heterotrophic bacteria, found in association with the endemic Mediterranean seagrass <i>Posidonia oceanica</i>. We tested different pH (from pH 4 to 8) and temperature levels (from 12 to 30 °C), under different nutrient concentrations of both phosphorus, P (0.1 µM and 1.5 mM), and iron, Fe (2 nM and 1 µM). We also tested different CO<sub>2</sub> concentrations (410 and 1000 particles per million (ppm)) under different P/Fe and temperature values (12, 18, and 24 °C). Heterotrophic bacteria were more sensitive to changes in pH, temperature, and CO<sub>2</sub> than the cyanobacterial species. Cyanobacteria were resistant to very low pH levels, while cold temperatures stimulated the growth in heterotrophic bacteria but only under nutrient-limited conditions. High CO<sub>2</sub> levels (1000 ppm) reduced heterotrophic growth only when cultures were nutrient-limited, regardless of temperature. In contrast, cyanobacteria were insensitive to elevated CO<sub>2</sub> levels, independently of the nutrient and temperature levels. Changes in N<sub>2</sub> fixation were mainly controlled by changes in growth. In addition, we suggest that alkaline phosphatase activity (APA) and reactive oxidative species (ROS) can be used as biomarkers to assess the plasticity of these communities to climate change factors. Unlike other studies, the novelty of this work lies in the fact that we compared the responses of cyanobacteria vs. heterotrophic bacteria, studying which changes occur at the cell plasticity level. Our results suggest that the responses of diazotrophs to climate change may depend on their P and Fe status and lifestyle, i.e., cyanobacteria or heterotrophic bacteria. |
| first_indexed | 2024-03-11T06:41:13Z |
| format | Article |
| id | doaj.art-ce42bc5db86b4bb0bb161aed7da0fd40 |
| institution | Directory Open Access Journal |
| issn | 1424-2818 |
| language | English |
| last_indexed | 2024-03-11T06:41:13Z |
| publishDate | 2023-02-01 |
| publisher | MDPI AG |
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| series | Diversity |
| spelling | doaj.art-ce42bc5db86b4bb0bb161aed7da0fd402023-11-17T10:36:58ZengMDPI AGDiversity1424-28182023-02-0115331610.3390/d15030316Cell Plasticity of Marine Mediterranean Diazotrophs to Climate Change Factors and Nutrient RegimesVíctor Fernández-Juárez0Elisa H. Zech1Elisabet Pol-Pol2Nona S. R. Agawin3Department of Biology, Marine Biological Section, University of Copenhagen, 3000 Helsingør, DenmarkArchaea Physiology & Biotechnology Group, Department of Functional and Evolutionary Ecology, Universität Wien, 1030 Wien, AustriaMarine Ecology and Systematics (MarES) Department of Biology, University of the Balearic Islands, 07122 Palma, SpainMarine Ecology and Systematics (MarES) Department of Biology, University of the Balearic Islands, 07122 Palma, SpainOcean acidification and warming are current global challenges that marine diazotrophs must cope with. Little is known about the effects of pH and temperature changes at elevated CO<sub>2</sub> levels in combination with different nutrient regimes on N<sub>2</sub> fixers, especially on heterotrophic bacteria. Here, we selected four culturable diazotrophs, i.e., cyanobacteria and heterotrophic bacteria, found in association with the endemic Mediterranean seagrass <i>Posidonia oceanica</i>. We tested different pH (from pH 4 to 8) and temperature levels (from 12 to 30 °C), under different nutrient concentrations of both phosphorus, P (0.1 µM and 1.5 mM), and iron, Fe (2 nM and 1 µM). We also tested different CO<sub>2</sub> concentrations (410 and 1000 particles per million (ppm)) under different P/Fe and temperature values (12, 18, and 24 °C). Heterotrophic bacteria were more sensitive to changes in pH, temperature, and CO<sub>2</sub> than the cyanobacterial species. Cyanobacteria were resistant to very low pH levels, while cold temperatures stimulated the growth in heterotrophic bacteria but only under nutrient-limited conditions. High CO<sub>2</sub> levels (1000 ppm) reduced heterotrophic growth only when cultures were nutrient-limited, regardless of temperature. In contrast, cyanobacteria were insensitive to elevated CO<sub>2</sub> levels, independently of the nutrient and temperature levels. Changes in N<sub>2</sub> fixation were mainly controlled by changes in growth. In addition, we suggest that alkaline phosphatase activity (APA) and reactive oxidative species (ROS) can be used as biomarkers to assess the plasticity of these communities to climate change factors. Unlike other studies, the novelty of this work lies in the fact that we compared the responses of cyanobacteria vs. heterotrophic bacteria, studying which changes occur at the cell plasticity level. Our results suggest that the responses of diazotrophs to climate change may depend on their P and Fe status and lifestyle, i.e., cyanobacteria or heterotrophic bacteria.https://www.mdpi.com/1424-2818/15/3/316phenotypic plasticityocean acidification and warming<i>Posidonia oceanica</i>CO<sub>2</sub>nutrientsdiazotrophs |
| spellingShingle | Víctor Fernández-Juárez Elisa H. Zech Elisabet Pol-Pol Nona S. R. Agawin Cell Plasticity of Marine Mediterranean Diazotrophs to Climate Change Factors and Nutrient Regimes Diversity phenotypic plasticity ocean acidification and warming <i>Posidonia oceanica</i> CO<sub>2</sub> nutrients diazotrophs |
| title | Cell Plasticity of Marine Mediterranean Diazotrophs to Climate Change Factors and Nutrient Regimes |
| title_full | Cell Plasticity of Marine Mediterranean Diazotrophs to Climate Change Factors and Nutrient Regimes |
| title_fullStr | Cell Plasticity of Marine Mediterranean Diazotrophs to Climate Change Factors and Nutrient Regimes |
| title_full_unstemmed | Cell Plasticity of Marine Mediterranean Diazotrophs to Climate Change Factors and Nutrient Regimes |
| title_short | Cell Plasticity of Marine Mediterranean Diazotrophs to Climate Change Factors and Nutrient Regimes |
| title_sort | cell plasticity of marine mediterranean diazotrophs to climate change factors and nutrient regimes |
| topic | phenotypic plasticity ocean acidification and warming <i>Posidonia oceanica</i> CO<sub>2</sub> nutrients diazotrophs |
| url | https://www.mdpi.com/1424-2818/15/3/316 |
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