Biotechniques-articles

Due to the effective antimicrobial properties of silver nanoparticles (Ag NPs), these particles are receiving an extensive interest for applying in wide range of consumer products and water purification systems. Entering the Ag-based material in wastewater system can influence the biological cycle such as nitrogen. Denitrification as a part of nitrogen cycle is an effective biological process in wastewater systems which can be affected by Ag NPs. The objective of this research was to study the impact of Ag NPs on aerobic nitrate reduction. We showed that Rhizobium sp and Azotobacter sp isolates were able to reduce nitrate aerobically. Adding 0.2 ppm of Ag NPs in culture medium of Azotobacter PHB+ enhanced the of the nitrate reduction activity about 20% and Ag NPs at this concentration has no significant effect on the nitrate reduction activity of periplasmic extracts of the selected isolates in aerobic conditions. Thus, entering certain ation of Ag NPs in environments has no significant impact on microbial aerobic denitrification as an important part of nitrogen cycle. Ag NPs can enhance the activity of nitrate reductase in native bacteria cells while have not such effect on cell free extracted enzyme. According to our finding, periplasmic nitrate reductase is responsible for aerobic nitrate reduction and specific concentrations of Ag NPs have no significant effect on this activity. Therefore, the results of this study suggest that Ag NPs at certain concentration can be a promising biocide for applying in recirculating wastewater treatment systems. Moreover, this study introduced an efficient method for extracting periplasmic nitrate reductase enzyme. This enzyme can apply for further applications in wastewater treatment, applying in reduction of metals and formation of nanoparticles and etc. [Shahrokh S, Hosseinkhani B, Emtiazi G (2014) The Impact of Silver Nanoparticles on Bacterial Aerobic Nitrate Reduction Process]

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Last date updated on April, 2024