INTERACTION OF METAL OXIDE NANOPARTICLES WITH NITRIFYING BACTERIA IN SOIL

The use of metal oxide nanoparticles (MeO NPs) in a wide range of commercial products has grown exponentially in recent years.The introduction of MeO NPs into agricultural soils can be toxic to microorganisms carrying out important biogeochemical processes within the soil ecosystem. Among these processes, nitrogen (N) cycle is an essential and critical process, in which nitrification and denitrification processes control soil inorganic N availability and subsequent soil fertility. The strong coupling between nitrification and denitrification makes the N cycle an ideal model to study the impacts of environmental disturbances on microbial functioning.we will investigate the effects of ZnO NPs and CuO NPs, along with bulk ZnO and CuO, on the physiological, transcriptional and metabolic responses of nitrifying bacteria in agricultural soils. Subsequently, we will develop a path analysis to integrate the different variables measured in our study to assess the multifaceted consequences of MeO NPs on nitrifying microorganisms in soil ecosystems. We will study the interactions of nitrifying bacteria, in lab-scale soil microcosms, with MeO NPs for environmentally relevant concentrations and transformations of these nanoparticles in soils. We will also compare how the nature (bulk versus particle) of MeO affects the nitrifying communities typically present in soil systems. Integrating the use of molecular biology tools with conventional biochemical methods to describe the causal model of MeO NPs interaction with nitrifying communities in soil is the overall goal of this research plan. There are three specific objectives of this project: (1)Determine the impact of MeO NPs (ZnO NPs and CuO NPs) and bulk material (ZnO and CuO) on the functional gene expression and microbial diversity of soil bacterial communities and evaluate how MeO NPs inhibit nitrification at the molecular level, (2)Determine the effects of MeO NPs and bulk-MeO on the physiological and metabolic responses of nitrifying bacteria in soil, which in turn impacts the N cycle, and (3)Integrate the results of molecular biology tools with biochemical and analytical methods to elucidate causal links between MeO NP concentration and nitrification in soil.