1. Physiological and Metagenomic Characterizations of the Synergistic Relationships between Ammonia- and Nitrite-Oxidizing Bacteria in Freshwater Nitrification.
- Author
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Cai, Mingwei, Ng, Siu-Kin, Lim, Chee Kent, Lu, Hongyuan, Jia, Yangyang, and Lee, Patrick K. H.
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METAGENOMICS ,AMMONIA ,NITRIFICATION - Abstract
Nitrification plays a crucial role in global nitrogen cycling and treatment processes. However, the relationships between the nitrifier guilds of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) are still poorly understood, especially in freshwater habitats. This study examined the physiological interactions between the AOB and NOB present in a freshwater aquarium biofilter by culturing them, either together or separately, in a synthetic medium. Metagenomic and 16S rRNA gene sequencing revealed the presence and the draft genomes of Nitrosomonas-like AOB as well as Nitrobacter-like NOB in the cultures, including the first draft genome of Nitrobacter vulgaris. The nitrifiers exhibited different growth rates with different ammonium (NH
4 + ) or nitrite concentrations (50-1,500 μM) and the growth rates were elevated under a high bicarbonate (HCO3 - ) concentration. The half-saturation constant (Ks for NH4 + ), the maximum growth rate (μmax ), and the lag duration indicated a strong dependence on the synergistic relationships between the two guilds. Overall, the ecophysiological and metagenomic results in this study provided insights into the phylogeny of the key nitrifying players in a freshwater biofilter and showed that interactions between the two nitrifying guilds in a microbial community enhanced nitrification. [ABSTRACT FROM AUTHOR]- Published
- 2018
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