Ubiquity and Dominance of Comammox Over AOB and AOA and their Links To ARGs in Antarctic Lake Sediments

Q: What was the study aiming to investigate in Antarctic lake sediments?

The study examined the distribution patterns and community structure of comammox, AOA, and AOB in West Antarctic lake sediments, and evaluated associations between ammonia oxidizers and antibiotic resistance genes (ARGs).

Q: Which ammonia oxidizers were dominant in the collected sediments?

Comammox clade B and AOB were dominant ammonia oxidizers, and clade B occurred in all sediments and generally showed higher abundance than AOB and AOA.

Q: How did environmental variables relate to the community structure of ammonia oxidizers?

Comammox clade B abundance showed a significant positive correlation with NH4+-N and a negative correlation with C:N ratios. Overall community structure was most strongly shaped by pH, modulated by penguin guano input.

Sep 30, 2026

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Complete ammonia oxidizers (comammox), which oxidize ammonia directly to nitrate, are widely present across environments, yet their distribution in Antarctic settings remains insufficiently characterized. Sediments from West Antarctic lakes were collected to determine comammox, AOA, and AOB distribution patterns and community structure, and to assess associations between ammonia oxidizers and antibiotic resistance genes (ARGs). Comammox clade B and AOB were dominant, with clade B present in all samples and linked to NH4+-N, pH shaped community structure, and comammox acted as important ARG hosts.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages20

Reading Time50 min

AccessFree to download

Abstract

Introduction

Background: nitrification and key players

Comammox biology and phylogeny

Knowledge gap in Antarctic environments

Antarctic microbial biogeochemical context

Microbial Ecology (2026) 89:14 [https://doi.org/10.1007/s00248-025-02664-4](https://doi.org/10.1007/s00248-025-02664-4) RESEARCH Ubiquity and Dominance ofComammox Over AOBandAOA and their Links To ARGs in Antarctic Lake Sediments Mengjie Guo1 · Zeming Zhou1 · Yanling Zheng2 · Dongsheng Fu1 · Lijun Hou1 · Renbin Zhu1 Received: 30 August 2025 / Accepted: 17 November 2025 © The Author(s) 2025 Abstract Complete ammonia oxidizers (comammox), oxidizing ammonia to nitrate directly, have been found to exist widely in multiple environments, but their distribution patterns are still under-explored in Antarctic environments. For the first time, the sediments were collected from West Antarctic lakes to investigate distribution patterns and community structure for comammox, ammonia oxidizing archaea (AOA) and bacteria (AOB), and nitrite-oxidizing bacteria (NOB), as well as the associations between ammonia oxidizers and antibiotic resistance genes (ARGs) . Comammox clade B and AOB were dominant ammonia oxidizers, with the abundances of (1 .62 ± 0 . 10) × 102 –(5 .21 ± 0 .74) × 106 and (0 . 17 ± 0 .05) × 105 –(4 .79 ± 0 .65) × 105 copies g− 1 sediment, respectively. Comammox clade B, instead of clade A, occurred in all sediments, exhibiting higher abundances than AOB and AOA in most of the sediments. The abundances for comammox clade B demonstrated significant positive correlation (p< 0 .01) with NH4+-N levels, but negative correlation (p< 0 .05) with C: N ratios. The coexistence of ammonia oxidizers in lake sediments was jointly structured by niche differentiation and environmental variables, and pH, modulated by penguin guano input, was found to be the most crucial factor in shaping their community structure. Co-occurrence network analyses revealed strong synergistic interactions between comammox and AOB, AOA, NOB, which played a critical role in nitrification processes. Our results further confirmed that comammox could act as important hosts for ARGs, hence stimulated their transmission and proliferation in the sediments. This study presented novel insights into the distribution patterns for ammonia oxidizers, their niche differentiation and the associations with ARGs in natural lake sediments of West Antarctica. Keywords Comammox · Ammonia oxidizer · ARGs · Antarctica · Lake sediment · Nitrification Introduction Nitrification, a microbial process converting ammonia into nitrate, is an important link in the nitrogen cycle, serving as a vital oxidative bridge between nitrogen fixation and denitrification processes in environments [1] . For over one 􀀍 Renbin Zhu [zhurb@ustc.edu.cn](zhurb@ustc.edu.cn) Yanling Zheng [ylzheng@geo.ecnu.edu.cn](ylzheng@geo.ecnu.edu.cn) 1 Institute of Polar Environment & Anhui Province Key Laboratory of Polar Environment and Emerging Pollutants, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China 2 State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200241, China century, nitrification has been regarded as a two-step process involved in the oxidation of ammonia into nitrite by ammonia-oxidizing microorganisms, and subsequent oxidation of nitrite into nitrate by nitrite-oxidizing bacteria (NOB) [2] . In nitrification, ammonia oxidation is mediated by ammonia oxidizing archaea (AOA) and bacteria (AOB) as the first rate-limiting step [3] . Recently, complete ammonia oxidizers (comammox) have been identified, which overturned long-held conception of nitrification [4, 5] . Comammox has been documented in various environments, including soil [6], river and lake water and sediment [7–9], tidal flats [10], and estuaries [11] . However, there is a notable lack of reports on comammox in extreme Antarctic environments. Comammox oxidizes ammonia directly to nitrate via nitrite because their genomes contain a complete set of genes encoding enzymes for both ammonia and nitrite oxidation [4, 5] . Com

FAQs

What was the study aiming to investigate in Antarctic lake sediments?

The study examined the distribution patterns and community structure of comammox, AOA, and AOB in West Antarctic lake sediments, and evaluated associations between ammonia oxidizers and antibiotic resistance genes (ARGs).

Which ammonia oxidizers were dominant in the collected sediments?

Comammox clade B and AOB were dominant ammonia oxidizers, and clade B occurred in all sediments and generally showed higher abundance than AOB and AOA.

How did environmental variables relate to the community structure of ammonia oxidizers?

Comammox clade B abundance showed a significant positive correlation with NH4+-N and a negative correlation with C:N ratios. Overall community structure was most strongly shaped by pH, modulated by penguin guano input.

Sep 30, 2026

Upload by Oliver