Metagenomes and Metagenome-Assembled Genomes from Microbial Communities in a Biological Nutrient Removal Plant Operated at Los Angeles County Sanitation District (LACSD) with High and Low Dissolved Oxygen Conditions

Abstract Aeration represents one of the largest energy costs in water resource recovery facilities (WRRFs). Previous studies have shown that effective nitrification and phosphorus removal can be maintained in biological nutrient removal (BNR) systems operated under low dissolved oxygen (DO) conditions, significantly reducing energy use. To improve understanding of microbial community adaptation to reduced DO, we analyzed metagenomes and metagenome-assembled genomes (MAGs) from the Pomona WRRF (Los Angeles County Sanitation Districts) before and after a gradual decrease in operating DO from approximately 3.5 mg/L to 0.7 mg/L over 18 months. Metagenomic DNA was isolated from high and low DO samples, then sequenced using PacBio HiFi technology. A total of 492 MAGs were recovered of which 304 were unique after dereplication. These genomes expand current knowledge of microbial community dynamics in low-DO BNR systems and provide valuable genomic resources for understanding microbial adaptation to energy-efficient wastewater treatment processes.