Work

Microbial Network Restructuring and Functional Partitioning of Carbon Fixation Along a Natural Salinity Gradient in the Yalu River Estuary Wetland

Year: 2026

Type: article

Abstract: Estuarine wetlands are significant stocks of soil organic carbon (SOC) and play an essential role in carbon sequestration. However, how natural salinity gradients shape carbon-fixing microbial communities and functional genes remains poorly understood. Soil samples were collected from low-salinity (LS), medium-salinity (MS), and high-salinity (HS) zones of the Yalu River Estuary wetland. To assess the taxonomic composition and carbon-fixation potential of soil microbial communities under a natural salinity gradient metagenomic sequencing was used. Because analyses were based on metagenomic profiles, the results reflect potential functional capacity rather than direct measurements of in situ carbon-fixation activity. The carbon-fixing microbial community composition differed among LS, MS, and HS soils. Analysis of carbon-fixation pathways revealed that the reductive tricarboxylic acid (rTCA) pathway represented the largest proportion of carbon fixation-related genes across all salinity groups. Genes associated with the rTCA pathway accounted for 59.72–62.03% of all carbon-fixation-related genes. Specifically, the rTCA pathway-related genes korA and korB were significantly enriched in MS soils, whereas aclB and the Wood–Ljungdahl pathway-related genes acsA/cdhA exhibited higher abundances in both MS and HS soils. The abundance of carbon-fixation-related genes was highest in MS soils despite SOC concentrations not being maximal in this salinity zone, suggesting a decoupling between microbial carbon-fixation potential and SOC accumulation. Additionally, the co-occurrence networks of carbon-fixing microorganisms were more tightly connected in HS soils. This study provides a crucial scientific reference for further elucidating the ecological mechanisms underlying microbial carbon fixation in estuarine wetlands.

Source: Microorganisms

DOI: 10.3390/microorganisms14112514

Authors: Xinyan Zhao, Jiaqi Wang, Shujuan Fan, Ruju Zhang, Huiying Li

Institutions: Eastern Liaoning University, Jiangxi Agricultural University

Language: English

Topic: Soil Carbon and Nitrogen Dynamics

Subfield: Soil Science

Field: Agricultural and Biological Sciences

Domain: Life Sciences

SDGs: Climate action, Clean water and sanitation, Life on land

Open Access status: gold

Estimated APC paid: $3,258