Depth-dependent variability of biological nitrogen fixation and diazotrophic communities in mangrove sediments

• DOI: 10.1186/s40168-021-01164-0
• Publication Date: 2021-10-27T03:32:21Z
• Authors: Zhiwen Luo; Qiuping Zhong; Xingguo Han; Ruiwen Hu; Xingyu Liu; Wenjun Xu; Yongjie Wu; Weiming Huang; Zhengyuan Zhou; Wei Zhuang; Qingyun Yan; Zhili He; Cheng Wang
• Keywords: Microbial mat

Abstract Background Nitrogen-fixing prokaryotes (diazotrophs) contribute substantially to nitrogen input in mangrove sediments, and their structure fixation rate (NFR) are significantly controlled by environmental conditions. Despite the well-known studies on diazotrophs surficial diversity, structure, ecological functions of diazotrophic communities along gradients sediment across different depths largely unknown. Here, we investigated how biological varied with depth sediments from perspectives both NFR communities. Results Through acetylene reduction assay, nifH gene amplicon metagenomic sequencing, found that increased but diversity decreased sediments. The at was driven salinity exhibited a clear divergence partitioning 50 cm. Among genera correlated NFR, Agrobacterium Azotobacter were specifically enriched 50–100 cm while Anaeromyxobacter , Rubrivivax Methylocystis Dickeya Methylomonas more abundant 0–50 Consistent higher analysis demonstrated elevated abundance genes ( nifH/D/K ) deep where nitrification amoA/B/C denitrification nirK norB became less abundant. Three metagenome-assembled genomes (MAGs) indicated facultatively anaerobic mixotrophic lifestyles as they contained for low-oxygen-dependent metabolism, hydrogenotrophic respiration, carbon fixation, pyruvate fermentation. Conclusions This study demonstrates depth-dependent variability terms communities, which certain extent relieves degree limitation