A novel micro‐organism for removing excess ammonia‐N in seawater ponds and the effect of Cobetia amphilecti on the growth and immune parameters of Litopenaeus vannamei

To investigate the feasibility of using micro‐organisms for ammonia‐N removal, six strains were isolated from Chinese white shrimp, Fenneropenaeus chinensis, seawater culture ponds in Dongying (Shandong, China). Of these, strain DY‐01, which exhibited the highest capacity to degrade ammonia‐N, removed 61.7% of the total ammonia‐N (50 mg/L) in 8 hr. An investigation of the factors affecting the removal efficiency indicated the optimum conditions to be 30°C, pH 8.0, and a salinity level of 30 g/L; 16S rDNA gene sequencing and biochemical analysis identified strain DY‐01 as Cobetia amphilecti, which has not previously been reported to degrade ammonia‐N. This strain also boosted the growth of Pacific white shrimp, Litopenaeus vannamei (p < .05), at a concentration of 10⁷ CFU/mL, with no harmful effects on the shrimp's immune system. This study has thus identified a novel aerobic nitrifying bacterium that is potentially an excellent candidate for improving the water quality in mariculture ponds.