Mechanistic insights into nitrogen source influence on microalgal-bacterial granular sludge: Community dynamics and metabolic functions

Yuting Shi; Shicheng Zuo; Ziqi Zhang; Anjie Li; Bin Ji

doi:10.1016/j.biortech.2025.132895

Mechanistic insights into nitrogen source influence on microalgal-bacterial granular sludge: Community dynamics and metabolic functions

Bioresour Technol. 2025 Jun 26:132895. doi: 10.1016/j.biortech.2025.132895. Online ahead of print.

Authors

Yuting Shi¹, Shicheng Zuo², Ziqi Zhang², Anjie Li³, Bin Ji⁴

Affiliations

¹ Department of Water and Wastewater Engineering, School of Urban Construction, Wuhan University of Science and Technology, Wuhan 430065, China; Hubei Key Laboratory for Efficient Utilization and Agglomeration of Metallurgic Mineral Resources, School of Resource and Environmental Engineering, Wuhan University of Science and Technology, Wuhan 430065, China.
² Department of Water and Wastewater Engineering, School of Urban Construction, Wuhan University of Science and Technology, Wuhan 430065, China.
³ Key Laboratory of Water and Sediment Sciences of Ministry of Education, State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China.
⁴ Department of Water and Wastewater Engineering, School of Urban Construction, Wuhan University of Science and Technology, Wuhan 430065, China. Electronic address: binji@wust.edu.cn.

PMID: 40581059
DOI: 10.1016/j.biortech.2025.132895

Abstract

This study investigated the effects of nitrogen source (different ammonia to urea ratios) on pollutant removal, microbial community evolution and function in the MBGS system. Results showed that a higher ammonia proportion significantly enhanced total nitrogen removal during the initial 7-day operation compared to urea (p < 0.05). However, this nitrogen source-dependent effect adapted and diminished during the subsequent 14 days (p > 0.05). Microbial analysis revealed that urea enriched Proteobacteria (specifically Alphaproteobacteria including Roseomonas), while ammonia stimulated Firmicutes (specifically Clostridia including Acetoanaerobium), Betaproteobacteria, and Cyanophyceae. Metagenomic analysis identified that Alphaproteobacteria played a dominant role in key genes (ureA/B/C, GLUD, gltB) involved in nitrogen metabolism. Robust correlations between nitrogen source composition and microbial population dynamics underscores the self-regulating capacity of the MBGS system. These comprehensive findings demonstrate the excellent adaptability of the MBGS to varying nitrogen compositions through microbial community regulation.

Keywords: Ammonia; Microalgal-bacterial symbiosis; Microbial responses; Organic nitrogen; Wastewater treatment.