Microbial Metabolism and Environmental Controls of Acetate Cycling in the Northwest Pacific Ocean

• Published in: Geophysical research letters Vol. 51; no. 17
• Main Authors: Mao, Shi‐Hai, Zhou, Zhen, Yan, Shi‐Bo, Xu, Gao‐Bin, Li, Xiao‐Jun, Zhang, Hong‐Hai, Yang, Gui‐Peng, Zhuang, Guang‐Chao
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 16.09.2024; Wiley
• Subjects: acetate; acetate metabolism; Acetates; Acetic acid; Bacteria; Biogeochemical cycles; Biological effects; Biomass energy production; Carbon; Carbon cycle; Carbon sources; Deposition; Energy metabolism; Energy sources; Environmental control; Kuroshio‐Oyashio extension; Marine biology; marine carbon cycling; Metabolism; Microorganisms; Mineralization; northwest Pacific Ocean; Nutrients; Oceans; Organic matter; Oxidation; Seawater; Surface water; Upper ocean; Water mass mixing; Water masses; Pacific Ocean
• DOI: 10.1029/2024GL109692
• ISSN: 0094-8276

Microbial acetate metabolism is an important part of marine carbon cycling. We present a comprehensive study to constrain microbial acetate metabolism and its regulation in surface seawater of the northwest Pacific Ocean. We found that acetate oxidation (rate constant k: 0.016–0.506 day−1) accounted for 77.6%–99.4% of the total microbial acetate uptake, suggesting that acetate was predominantly used as a microbial energy source. Acetate also served as a significant biomass carbon source, as reflected by the elevated contribution of acetate assimilation to bacterial carbon production. Acetate turnover was largely influenced by water mass mixing and nutrient conditions. Atmospheric deposition was a source of acetate in surface water and this process can also impact the microbial acetate uptake. Microbial utilization of acetate could account for up to 25.9% of the bacterial carbon demand, suggesting the significant role of acetate metabolism in microbial carbon cycling in the open ocean. Plain Language Summary Acetate is a key metabolic intermediate during the mineralization of organic matter and microbial acetate metabolism plays a crucial role in marine carbon cycling. However, the microbial metabolism of acetate and its environmental controls in pelagic waters remain poorly understood. We investigated biogeochemical cycling of acetate in the Kuroshio‐Oyashio extension region of northwest Pacific Ocean. Acetate concentrations in surface waters were generally low and atmospheric deposition was a source of acetate in the upper ocean. Acetate was used preferentially as a microbial energy source and the proportion of acetate devoted to bacterial growth or respiration largely depended on local nutrient conditions. Rapid biological turnover of acetate contributed significantly to bacterial carbon demand, exceeding the contributions of other compounds such as methanol. These results constrain the atmospheric sources and microbial sinks of marine acetate and reveal the ecological significance of microbial acetate metabolism in the open ocean. Key Points Microbial uptake rates of acetate ranged from 1.7 to 495 nmol L−1 day−1 in surface waters of the northwest Pacific Ocean Acetate is used preferentially as a microbial energy source rather than as a biomass carbon source Microbial acetate metabolism is influenced by water mass mixing and atmospheric deposition