AUTHOR=Ding Jiewei , Yang Wei , Liu Xinyu , Zhao Qingqing , Dong Weiping , Zhang Chuqi , Liu Haifei , Zhao Yanwei 

TITLE=Unraveling the rate-limiting step in microorganisms' mediation of denitrification and phosphorus absorption/transport processes in a highly regulated river-lake system

JOURNAL=Frontiers in Microbiology

VOLUME=Volume 14 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1258659

DOI=10.3389/fmicb.2023.1258659

ISSN=1664-302X

ABSTRACT=River–lake ecosystems are indispensable hubs for water transfers and flow regulation engineering, which have frequented and complex artificial hydrological regulation processes, and the water quality is often unstable. Microorganisms usually affect these systems by driving nutrient cycling process. Thus, understanding the key biochemical rate-limiting steps under highly regulated conditions was critical for water quality stability of river–lake ecosystems. This study investigated how the key microorganisms and genes involving the nitrogen and phosphorus cycling contributed to the stability of water by combining 16S rRNA and metagenomic sequencing using Dongping river–lake system as the case study. The results showed that nitrogen and phosphorus concentrations were significantly lower in lake zones than in river inflow and outflow zones (p < 0.05). Pseudomonas, Acinetobacter and Microbacterium were the key microorganisms associated with nitrate and phosphate removal. These microorganisms contributed to key genes that promote denitrification (nirB/narG/narH/nasA) and phosphorus absorption and transport (pstA/pstB/pstC/pstS). Partial least squares path modelling (PLS-PM) revealed that the environmental factors (especially flow velocity and COD concentration) have the significant negative effect on the key microbial abundance (p < 0.001). Our study provides theoretical support for the effective management and protection of water transfer and regulation function of the river–lake system.