Effects of potassium monopersulfate on nitrification activity and bacterial community structure of sponge biocarrier biofilm in aquaculture system.

Effects of potassium monopersulfate (KMPS) on the nitrification activity, aquacultural water quality and bacterial community structure of sponge biocarriers with pre-cultured biofilm (SBBF) were analysed through shaking flask experiments and aquaculture experiments. Changes in the ammonia oxidation rate (AOR) and nitrite oxidation rate (NOR) of SBBF under six KMPS concentration treatments (0, 1, 2, 3, 4 and 5 mg/L) were studied. The results showed that the AOR and NOR of SBBF treated with high concentrations of KMPS (3, 4 and 5 mg/L) were significantly lower than those of the control group (CK) ( < 0.05). However, compared with the first dosing of NHCl and NaNO, the inhibition of AOR and NOR by KMPS on AOR and NOR was weakened after the second and third dosing times. That is, AOR and NOR can recover partially or completely over time. The aquaculture experiment was performed using four concentrations of KMPS (0, 2, 4 and 8 mg/L). The results showed that with increasing KMPS dosage, the average and peak concentrations of NH-N and NO-N in each treatment significantly increased ( < 0.05), and the final body weight of shrimp significantly decreased ( < 0.05). Furthermore the highest dose (8.0 mg/L) of KMPS reduced the survival rate by 9.33% compared to the CK. High-throughput sequencing analysis of the biofilm structure showed that the relative abundances of Nitrospirota, and which are related to nitrogen cycling, and beneficial bacteria including Firmicutes and decreased with the addition of KMPS ( < 0.05).