Department of Earth System Science, Stanford University, Green Earth Sciences Building, 367 Panama St., Room 129, Stanford, CA, 94305-4216, USA.
Instituto Español de Oceanografía, Centro Oceanográfico de Gijón/Xixón, Av. Príncipe de Asturias, 70 bis 33212, Gijón, Asturias, Spain.
Environ Microbiol. 2020 Apr;22(4):1381-1396. doi: 10.1111/1462-2920.14954. Epub 2020 Mar 1.
Heterotrophic bacteria associated with microphytoplankton, particularly those colonizing the phycosphere, are major players in the remineralization of algal-derived carbon. Ocean warming might impact dissolved organic carbon (DOC) uptake by microphytoplankton-associated bacteria with unknown biogeochemical implications. Here, by incubating natural seawater samples at three different temperatures, we analysed the effect of experimental warming on the abundance and C and N uptake activity of Rhodobacteraceae and Flavobacteria, two bacterial groups typically associated with microphytoplankton. Using a nano-scale secondary ion mass spectrometry (nanoSIMS) single-cell analysis, we quantified the temperature sensitivity of these two taxonomic groups to the uptake of algal-derived DOC in the microphytoplankton associated fraction with C-bicarbonate and N-leucine as tracers. We found that cell-specific C uptake was similar for both groups (~0.42 fg C h μm ), but Rhodobacteraceae were more active in N-leucine uptake. Due to the higher abundance of Flavobacteria associated with microphytoplankton, this group incorporated fourfold more carbon than Rhodobacteraceae. Cell-specific C uptake was influenced by temperature, but no significant differences were found for N-leucine uptake. Our results show that the contribution of Flavobacteria and Rhodobacteraceae to C assimilation increased up to sixfold and twofold, respectively, with an increase of 3°C above ambient temperature, suggesting that warming may differently affect the contribution of distinct copiotrophic bacterial taxa to carbon cycling.
与微藻相关的异养细菌，特别是那些定植在藻周体的细菌，是藻类衍生碳再矿化的主要参与者。海洋变暖可能会影响与微藻相关的细菌对溶解有机碳（DOC）的吸收，这对未知的生物地球化学意义产生影响。在这里，我们通过在三个不同温度下孵育天然海水样本，分析了实验变暖对与微藻相关的 Rhodobacteraceae 和 Flavobacteria 这两个通常与微藻相关的细菌群体的丰度和 C 和 N 吸收活性的影响。我们使用纳米级二次离子质谱（nanoSIMS）单细胞分析技术，使用 C-碳酸氢盐和 N-亮氨酸作为示踪剂，定量了这两个分类群对微藻相关部分中藻类衍生 DOC 的吸收的温度敏感性。我们发现，这两个群体的细胞特异性 C 吸收相似（~0.42 fg C h μm ），但 Rhodobacteraceae 在 N-亮氨酸吸收方面更活跃。由于与微藻相关的 Flavobacteria 丰度较高，该群体的碳吸收量是 Rhodobacteraceae 的四倍。细胞特异性 C 吸收受温度影响，但 N-亮氨酸吸收没有显著差异。我们的结果表明，Flavobacteria 和 Rhodobacteraceae 对 C 同化的贡献分别增加了六倍和两倍，这与环境温度升高 3°C 有关，这表明变暖可能会以不同的方式影响不同的富营养细菌类群对碳循环的贡献。
