Pseudomonas oligotrophica sp. nov., a Novel Denitrifying Bacterium Possessing Nitrogen Removal Capability Under Low Carbon–Nitrogen Ratio Condition

Pseudomonas is a large and diverse genus within the Gammaproteobacteria known for its important ecological role in the environment. These bacteria exhibit versatile features of which the ability of heterotrophic nitrification and aerobic denitrification can be applied for nitrogen removal from the wastewater. A novel denitrifying bacterium, designated JM10B5a(T), was isolated from the pond water for juvenile Litopenaeus vannamei. The phylogenetic, genomic, physiological, and biochemical analyses illustrated that strain JM10B5a(T) represented a novel species of the genus Pseudomonas, for which the name Pseudomonas oligotrophica sp. nov. was proposed. The effects of carbon sources and C/N ratios on denitrification performance of strain JM10B5a(T) were investigated. In addition, the results revealed that sodium acetate was selected as the optimum carbon source for denitrification of this strain. Besides, strain JM10B5a(T) could exhibit complete nitrate removal at the low C/N ratio of 3. Genomic analyses revealed that JM10B5a(T) possessed the functional genes including napA, narG, nirS, norB, and nosZ, which might participate in the complete denitrification process. Comparative genomic analyses indicated that many genes related to aggregation, utilization of alkylphosphonate and tricarballylate, biosynthesis of cofactors, and vitamins were contained in the genome of strain JM10B5a(T). These genomic features were indicative of its adaption to various niches. Moreover, strain JM10B5a(T) harbored the complete operons required for the biosynthesis of vibrioferrin, a siderophore, which might be conducive to the high denitrification efficiency of denitrifying bacterium at low C/N ratio. Our findings demonstrated that the strain JM10B5a(T) could be a promising candidate for treating wastewater with a low C/N ratio.