Multi-omics analysis revealed the selective enrichment of partial denitrifying bacteria for the stable coupling of partial-denitrification and anammox process under the influence of low strength magnetic field

Hafiz Adeel Ahmad; Shakeel Ahmad; Linjie Gao; Sherif Ismail; Zhibin Wang; Amro El-Baz; Shou-Qing Ni

doi:10.1016/j.watres.2023.120619

Multi-omics analysis revealed the selective enrichment of partial denitrifying bacteria for the stable coupling of partial-denitrification and anammox process under the influence of low strength magnetic field

Water Res. 2023 Oct 15:245:120619. doi: 10.1016/j.watres.2023.120619. Epub 2023 Sep 11.

Authors

Hafiz Adeel Ahmad¹, Shakeel Ahmad², Linjie Gao¹, Sherif Ismail¹, Zhibin Wang³, Amro El-Baz⁴, Shou-Qing Ni⁵

Affiliations

¹ Shandong Provincial Key Laboratory of Water Pollution Control and Resource Reuse, Shandong Key Laboratory of Environmental Processes and Health, School of Environmental Science and Engineering, Shandong University, Qingdao, Shandong 266237, China.
² Department of Soil and Environmental Sciences, Muhammad Nawaz Shareef University of Agriculture, Multan, Pakistan.
³ School of Life Sciences, Shandong University, Qingdao, Shandong 266237, China.
⁴ Environmental Engineering Department, Faculty of Engineering, Zagazig University, Zagazig 44519, Egypt.
⁵ Shandong Provincial Key Laboratory of Water Pollution Control and Resource Reuse, Shandong Key Laboratory of Environmental Processes and Health, School of Environmental Science and Engineering, Shandong University, Qingdao, Shandong 266237, China. Electronic address: sqni@sdu.edu.cn.

PMID: 37716295
DOI: 10.1016/j.watres.2023.120619

Abstract

The microbial consortium involving anaerobic ammonium oxidation (anammox) and partial denitrification (PD), known as PD-anammox, is an emerging energy-efficient and lower carbon nitrogen removal process from wastewater. However, maintaining a stable PD process by locking nitrate reduction until nitrite was challenging. This study established the first stable connection of anammox with constant nitrite generation by PD bacteria under a low-strength (1.3 mT) magnetic field (MF). When the nitrogen loading rate was 1.81 kg-N/m³/d, the nitrogen removal efficiency of the control reactor (R1) was 75%, lower than that of the experimental reactor (R2), which was 85%. The expression of Thauera and Zoogloea, potential PD bacteria was substantially lower in R1 (5.75% and 1.21%, respectively) than in R2 (10.25 and 6.61%, respectively), according to a meta-transcriptomic analysis. At the same time, the mRNA expression of anammox genera Candidatus Brocadia and Candidatus Kuenenia was 33.53% and 3.83% in R1 and 22.86% and 1.87% in R2. Moreover, carbon and nitrogen metabolism pathways were more abundant under the influence of low-strength MF. The selective enrichment of PD bacteria can be attributed to the increased expression of carbon metabolic pathways like the citrate cycle, glycolysis/gluconeogenesis, and pyruvate metabolism. Interestingly, the control reactor was dominated by a hydroxylamine-dependent anammox process while a low-strength MF-enhanced nitric-oxide-dependent anammox process. For successful anammox-centered nitrogen removal from wastewater, this study demonstrated that low-strength MF is a convenient and applicable technique to lock the nitrate reduction until nitrite.

Keywords: Anammox; Magnetic field; Meta-transcriptomics; Metagenomics; PD-anammox; Partial-denitrification.