Abundance and community succession of nitrogen-fixing bacteria in ferrihydrite enriched cultures of paddy soils is closely related to Fe(III)-reduction

Rong Jia; Kun Wang; Lina Li; Zhi Qu; Weishou Shen; Dong Qu

doi:10.1016/j.scitotenv.2020.137633

Abundance and community succession of nitrogen-fixing bacteria in ferrihydrite enriched cultures of paddy soils is closely related to Fe(III)-reduction

Sci Total Environ. 2020 Jun 10:720:137633. doi: 10.1016/j.scitotenv.2020.137633. Epub 2020 Feb 28.

Authors

Rong Jia¹, Kun Wang², Lina Li³, Zhi Qu⁴, Weishou Shen⁵, Dong Qu⁶

Affiliations

¹ Key Laboratory of Land Resources Evaluation and Monitoring in Southwest China, Ministry of Education, Sichuan Normal University, Chengdu, Sichuan Province 610066, PR China; College of Natural Resources and Environment, Northwest A & F University, Yangling, Shaanxi Province 712100, PR China.
² College of Natural Resources and Environment, Northwest A & F University, Yangling, Shaanxi Province 712100, PR China.
³ College of Resources and Environment, Shanxi Agricultural University, Jinzhong, Shanxi Province 030801, PR China.
⁴ State Key Laboratory of Eco-hydraulics in Northwest Arid Region of China, Xi'an University of Technology, Xi'an, Shaanxi Province 710048, PR China.
⁵ Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, PR China.
⁶ State Key Laboratory of Soil Erosion and Dryland Farming on Loess Plateau, Northwest A&F University, Yangling, Shaanxi Province, PR China. Electronic address: dongqu@nwafu.edu.cn.

PMID: 32146407
DOI: 10.1016/j.scitotenv.2020.137633

Abstract

In flooded paddy soils, some metal reducers are also capable of nitrogen (N) fixation, which is essential in ensuring a reliable N-supply for rice growth. Microbial iron [Fe(III)] reduction is an important biogeochemical process that can be stimulated by ferrihydrite amendment to paddy soil. Therefore, this study aimed to investigate the abundance and succession of the N₂-fixing bacterial community in ferrihydrite enriched paddy soils collected from Hunan (HN) and Sichuan (SC) provinces, China. The relationship between the N₂-fixing bacterial community and Fe(III) reduction was also assessed. When compared with the control treatment, ferrihydrite enrichment significantly enhanced nitrogenase (nifH) gene abundance by 8.05 × 10⁵ to 4.45 × 10⁶ copies g^-1 soil during the 40-day flooding of HN soil, while nifH gene abundance in SC soil was remarkably increased by 5.90 × 10⁷ to 9.56 × 10⁷ copies g^-1 soil during day 1 to 5 in response to ferrihydrite amendment. The relative abundance of N₂-fixing bacteria peaked on day 5 (21.5% in HN soil and 5.4% in SC soil) and gradually decreased to a stable abundance after day 20. Remarkable increases in relative abundance of N₂-fixing bacteria during the first 10 days of flooding were detected in both soils with ferrihydrite enrichment, whereas little difference was found after day 10 of flooding. During the early stage of flooding, the Shannon and Simpson indexes of N₂-fixing bacteria with ferrihydrite enrichment were significantly decreased, and the community structure changed greatly. Most N₂-fixing bacteria in ferrihydrite enriched paddy soils were phylogenetically related to the order Clostridiales, with some of those potentially capable of Fe(III) reduction. The community succession of N₂-fixing bacteria closely correlated with Fe(III) reduction. Thus, improving N₂-fixation via stimulation of Fe(III) reduction might aid in the reduction of N-fertilizer application to paddy field.

Keywords: Community succession; Fe(III) reduction; Nitrogen-fixing bacteria; Paddy soil; nifH gene abundance.

MeSH terms

China
Ferric Compounds
Nitrogen-Fixing Bacteria*
Oryza
Soil
Soil Microbiology

Substances

Ferric Compounds
Soil
ferric oxyhydroxide