Ammonia nitrogen and nitrite removal by a heterotrophic Sphingomonas sp. strain LPN080 and its potential application in aquaculture

A safe, effective and simple method for ammonia nitrogen and nitrite removal in farming water has always been a goal of environmentally friendly farming models aimed at water saving and reducing the discharge of farming wastes. In this study, it was shown that a bacterial strain LPN080 isolated and screened from a shrimp culture pond can efficiently remove both ammonia nitrogen and nitrite. When supplemented with ammonia nitrogen and glucose in water samples, ammonia nitrogen (as the only nitrogen source) was reduced from an initial 8 mg/l to 0.3 mg/l in 48 h, and a removal rate of ammonia nitrogen of up to 96% was achieved. With the same addition of glucose in the water samples, nitrite (as the only nitrogen source) reduced from an initial 5 mg/l to 0.8 mg/l, and the removal rate was approximately 81% in 48 h. The LPN080 strain was identified as a member of Sphingomonas using 16S rDNA sequencing. Sphingomonas sp. LPN080 could indirectly inhibit the growth of Vibrio spp. in water supplemented with glucose and the inhibition was not caused by the production of antimicrobial substances. Sphingomonas sp. LPN080 showed high biosafety toward shrimp Litopenaeus vannamei. All these results demonstrated that Sphingomonas sp. LPN080 has a potential economic value in aquaculture and even in wastewater treatment.