Long-term metal pollution shifts microbial functional profiles of nitrification and denitrification in agricultural soils

Lu Lu; Chen Chen; Tan Ke; Min Wang; Matthew Sima; Shan Huang

doi:10.1016/j.scitotenv.2022.154732

Long-term metal pollution shifts microbial functional profiles of nitrification and denitrification in agricultural soils

Sci Total Environ. 2022 Jul 15:830:154732. doi: 10.1016/j.scitotenv.2022.154732. Epub 2022 Mar 26.

Authors

Lu Lu¹, Chen Chen², Tan Ke³, Min Wang², Matthew Sima⁴, Shan Huang⁵

Affiliations

¹ State Key Laboratory of Urban Water Resource and Environment, School of Civil and Environmental Engineering, Harbin Institute of Technology, Shenzhen 518055, China. Electronic address: lulu@hit.edu.cn.
² State Environmental Protection Key Laboratory of Urban Ecological Environment Simulation and Protection, South China Institute of Environmental Sciences, Ministry of Ecology and Environment of China, Guangzhou 510535, China.
³ State Key Laboratory of Urban Water Resource and Environment, School of Civil and Environmental Engineering, Harbin Institute of Technology, Shenzhen 518055, China.
⁴ Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ 08544, USA.
⁵ Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ 08544, USA. Electronic address: shanh@princeton.edu.

PMID: 35346706
DOI: 10.1016/j.scitotenv.2022.154732

Abstract

The increasing contamination of heavy metals in agricultural soils and its impact on the nitrogen (N) cycle and N use efficiency have attracted considerable attention in recent years. In this study, agricultural soils neighboring the Dabaoshan copper mining area (DBS) and Qingyuan electronic-waste recycling area (QY), in Guangdong, China, were sampled to study the interaction between heavy metals and nitrification/denitrification processes, especially the related microbial functional profiles. Results showed that the contamination of heavy metals affected nitrifiers and denitrifiers differently. The potential nitrification activity was about four times lower in metal-polluted soils compared with the unpolluted ones, with a significant decrease in the abundance of amoA and nxrB (p < 0.05) in the polluted samples. On the other hand, the potential denitrification activity was more metal-resistant, which attributed to its complex species composition as shown by a slightly higher α-diversity index, and was slightly higher (p > 0.05) in the polluted samples. Among the five denitrifying genes tested, nosZ gene had the highest increase and the nirK gene the most decrease in numbers and in the polluted soils. The metal-polluted soils had fewer correlations among N functional genes based on the co-occurrence network analysis. In addition, the core taxa of the whole bacterial community changed from copiotrophic to oligotrophic bacteria in the presence of heavy metals. Mantel test indicated that heavy metals were the dominant factors determining N-related genes while the bacterial community composition was due to a combination of heavy metal presence and soil properties such as TOC, NO₂^-, and pH. It is concluded that long-term heavy metals pollution potentially affected nitrifiers and denitrifiers differently as indicated by the shift in N functional genes and the change in nitrification/denitrification processes.

Keywords: Agricultural soil; Heavy metals; Microbial community; Nitrogen cycling; Nitrogen functional genes.

MeSH terms

Bacteria / genetics
Denitrification
Electronic Waste* / analysis
Metals, Heavy* / analysis
Nitrification
Soil / chemistry
Soil Microbiology

Substances

Metals, Heavy
Soil