Genomic insights and process optimization of a heterotrophic nitrification-aerobic denitrification strain, Pseudomonas sp. JQ-H3, for nitrogen removal and polycaprolactone degradation

This study investigated the nitrogen removal characteristics and genomic features of the heterotrophic nitrification-aerobic denitrification bacterium Pseudomonas sp. JQ-H3. Genomic sequencing analysis revealed a genome size of 1.30 Gb, comprising 22 contigs, with a Guanine and Cytosine content of 65.4% and 4215 predicted genes. Functional annotation and metabolic pathway analysis identified key genes involved in nitrogen metabolism, including amoA, narG, napA, nirB, etc. Furthermore, the genome of JQ-H3 contains numerous gene sequences associated with lipase synthesis, such as PROKKA_00523, PROKKA_00655, PROKKA_00951, PROKKA_02885, and PROKKA_03529. Response surface methodology (RSM) identified the optimal conditions for nitrogen removal as pH 7.13, temperature 29.42°C, shaking speed 140.28 rpm, and an initial PCL concentration of 3.12 g/L. The strain achieved removal efficiencies of 95.3% for ammonium and 93.7% for nitrate, with the average rates of 2.63 and 2.3 mg N/(L·h), respectively, under the optimal condition designed by RSM. This work presents the first detailed genomic insight into an HN-AD bacterium capable of simultaneous nitrogen removal and PCL biodegradation.