Active dark carbon fixation evidenced by 14C isotope assimilation and metagenomic data across the estuarine-coastal continuum,Science of the Total Environment

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Active dark carbon fixation evidenced by 14C isotope assimilation and metagenomic data across the estuarine-coastal continuum
Science of the Total Environment ( IF 8.2 ) Pub Date : 2024-01-06 , DOI: 10.1016/j.scitotenv.2023.169833
Bolin Liu ₁ , Yanling Zheng ₂ , Xinyu Wang ₁ , Lin Qi ₃ , Jie Zhou ₁ , Zhirui An ₁ , Li Wu ₃ , Feiyang Chen ₁ , Zhuke Lin ₃ , Guoyu Yin ₄ , Hongpo Dong ₁ , Xiaofei Li ₁ , Xia Liang ₁ , Ping Han ₄ , Min Liu ₄ , Lijun Hou ₁

Affiliation

Estuaries, as important land-ocean transitional zones across the Earth's surface, are hotspots of microbially driven dark carbon fixation (DCF), yet understanding of DCF process remains limited across the estuarine-coastal continuum. This study explored DCF activities and associated chemoautotrophs along the estuarine and coastal environmental gradients, using radiocarbon labelling and molecular techniques. Significantly higher DCF rates were observed at middle- and high-salinity regions (0.65–2.31 and 0.66–2.82 mmol C m d, respectively), compared to low-salinity zone (0.07–0.19 mmol C m d). Metagenomic analysis revealed relatively stable DCF pathways along the estuarine-coastal continuum, primarily dominated by Calvin-Benson-Bassham (CBB) cycle and Wood-Ljungdahl (WL) pathway. Nevertheless, chemoautotrophic communities driving DCF exhibited significant spatial variations. It is worth noting that although CBB cycle played an important role in DCF in estuarine sediments, WL pathway might play a more significant role, which has not been previously recognized. Overall, this study highlights that DCF activities coincide with the genetic potential of chemoautotrophy and the availability of reductive substrates across the estuarine-coastal continuum, and provides an important scientific basis for accurate quantitative assessment of global estuarine carbon sink.

中文翻译：

河口-海岸连续体的 14C 同位素同化和宏基因组数据证明了活跃的暗碳固定

河口作为地球表面重要的陆地-海洋过渡区，是微生物驱动的暗碳固定（DCF）的热点，但对河口-海岸连续体中 DCF 过程的了解仍然有限。本研究利用放射性碳标记和分子技术，探索了沿河口和沿海环境梯度的 DCF 活动和相关的化能自养生物。与低盐度区域（0.07-0.19 mmol C md）相比，中盐度区域和高盐度区域的 DCF 率显着较高（分别为 0.65-2.31 和 0.66-2.82 mmol C md）。宏基因组分析揭示了沿河口-海岸连续体相对稳定的 DCF 途径，主要由 Calvin-Benson-Bassham (CBB) 循环和 Wood-Ljungdahl (WL) 途径主导。然而，驱动 DCF 的化学自养群落表现出显着的空间变化。值得注意的是，虽然CBB循环在河口沉积物的DCF中发挥了重要作用，但WL途径可能发挥更重要的作用，而这一点此前尚未被认识到。总体而言，本研究强调DCF活性与化能自养的遗传潜力和河口-海岸连续体还原底物的可用性相一致，并为全球河口碳汇的准确定量评估提供了重要的科学依据。

更新日期：2024-01-06

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