Bacteria-Mediated Synthesis of Iron Oxide Nanoparticles and Their Efficiency in Ammonia Removal from Fish Culture Tanks

Background: Aquaculture is one of the most rapidly expanding food production sectors. Due to intensification, declining water quality parameters negatively impact fish production and the surrounding environment. Thus, it is essential to maintain optimum water quality parameters and aquatic ecosystems for sustainable fish production. This study aims to synthesize nanoparticles (NPs) and evaluate their efficiency against ammonia in cultured fish tanks under diverse conditions. Methods: Bacillus megaterium from the soil sample was isolated and identified. Iron oxide NPs were synthesized using Bacillus megaterium collected from soil samples and characterized by DLS-zeta potential, UV-vis, XRD, FTIR, and TEM analysis. Next, synthesized NPs were evaluated under ex-situ and in-situ conditions to determine their efficacy in removing ammonia from Common carp, Cyprinus carpio culture tanks. Results: B. megaterium was isolated, identified, and 16S rRNA gene PCR-amplified sequences confirm the identification of B megaterium. DLS-zeta potential, UV-vis, XRD, FTIR, and TEM analysis revealed the quality of synthesized NPs. B. megaterium from the soil sample was isolated and identified. The mean zeta potential of the biosynthesized NPs was between -4.65 to -6.45 mV and had an average size of 5 nm. The concentration of ammonia in aerated tanks treated with iron NPs reduced to less than 0.03 mg/dL from 0.3 mg/L. Also, fish mortality in these tanks was significantly controlled with the application of NPs. The application of NPs considerably reduced fish mortality in these fish tanks. Iron oxide NPs from B. megaterium can produce high-quality NPs that are efficient in removing ammonia from fish culture tanks. Further, exploratory studies are necessary to determine the efficacy of iron oxide NPs on aquatic organisms cultured in different environments.