Considerable declines in odor in a drinking water reservoir: Variations of odorous community, precursor enzymes abundance, distribution, and environmental dominant factors

The presence of 2-methylisoborneol (2-MIB) is acknowledged as a prevalent source of odor-related challenges in drinking water reservoirs. Among the three in situ experiments conducted in drinking water reservoir, the water-lifting aerator with bio-filling system exhibited the most pronounced overall effects. It achieved a remarkable 98.70 % removal of 2-MIB and a 99.30 % reduction in the abundance of the mic gene. Metagenomic sequencing identified key genes including methyl transferase gene (mtf), 2-MIB cyclase gene (mic), cyclic nucleotide-binding protein gene (cnb), underscoring the potential role of Actinobacteria, Cyanobacteria, and Proteobacteria communities in contributing to odor occurrences in the reservoir. Furthermore, the abundance of odorous precursor enzymes in the MVA pathway and MEP/DOXP pathway were inhibited in the systems with bio-filling. Total nitrogen (TN) and nitrate (NO₃^--N) were identified as pivotal factors influencing the presence of 2-MIB odor-producing microorganisms. Effective management of odor-producing species in reservoir water was closely related to the efficient removal of pollutants. These findings will provide valuable insights for the development of odor removal techniques in reservoirs and offer researchers deeper understanding into the mechanisms underlying odor processes.