CAREER: Bacterial adaptation mechanism to chronic exposure to nanoparticles and its implications to nanomanufacturing and public health

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Craver1350789Intellectual merit: The overall goal of this research is to elucidate the phenotypic and genomic changes that bacteria can present due to chronic exposure to metal nanoparticles and their implications to the manufacture of nano-based products and public health. The proposed project focuses on filling the gap regarding the need to: i) determine if bacteria can adapt to chronic exposure to metalnanoparticles and simultaneously develop resistance to pharmaceuticals of importance to public health and ii) to elucidate the impact of the bacterial physiological stage on the stress-response to metal nanoparticles. Both of these aspects have important implications for nano-manufacturing and public health. Metal- and metal oxide-based nanoparticles, such as silver, zinc oxide, and titanium dioxide, currently are being used extensively in industrial and consumer products for applications that range from cosmetics to water treatment. Also, due to the optimization of extraction procedures, the use of rare earth elements has increased sharply due to their unique paramagnetic properties, and the production of REE-based nanoparticles and nano-based products is one of the most attractive uses of these materials. This project proposes to elucidate whether bacterial adaption to metal nanoparticles depends on the composition of the metal nanoparticles, physicochemical properties, and/or the physiological stage of the cells. The physiological stage will be tested using batch and continuous culture tests. High-throughput batch tests will be used to screen a wide range of physicochemical and environmental conditions that could lead to bacterial adaptation to metal nanoparticles. Adaptation will be determined using kinetic, phenotypic, and genomic parameters. However, in batch systems, both the concentration of the substrate and the physiological state of the cells change as a function of time, therefore the impact of the physiological stage of the bacteria in the adaptation response cannot be assessed properly with this type of approach. To overcome these limitations, a second experimental phase is proposed in which a continuous culture will be used. In the continuous culture, an equilibrium concentration of the growth-controlling substrate is established, and this concentration is independent of the density of the culture and time. A continuous culture can provide more precise and reproducible data than those obtained from batch cultures. Chemostats have been usedextensively to study the stress response and bacteria's development of resistance to antibiotics; however, to the best knowledge of the PI, no study has systematically evaluated the adaptation of bacteria to nanoparticles using this approach.Broader Impacts: This project will generate experiential learning opportunities to a wide audience, consisting on K-12 teachers and students, undergraduate students, graduate students and users of metal nanoparticle-based products. Through the activities, the PI seeks to achieve an integrative development of her academic career while contributing to scientific discovery, education, and societal prosperity. This study also is likely to determine unintended impacts, such as resistance to antibiotics, which can have a significant impact on public health. This effort will impact the current protocols used to assess the toxicological response of nanoparticles on microorganisms and provide important information to managers of wastewater treatment facilities concerning the health impacts of nanoparticles that reach their facilities. The proposed activities will provide important knowledge to non-profit organizations and stakeholders who are deploying or may deploy point-of-use water treatment technologies containing nanoparticles in rural, developing communities; this will minimize potential negative effects on human health and the environment. Activities from this project will engage and inspire students to pursue STEM careers while being environmental stewards at the same time. Student success cannot be achieved without the right professional skill set. This proposal seeks to promote information on nanotoxicology and the stress-response of bacterial populations due to chronic exposure to nanoparticles. Activities from this project will engage and inspire people with diverse educational and experiential backgrounds. The PI will elaborate a series of opportunities for teachers andstudents to understand the benefit and concerns about the use metal nanoparticles in consumer products. Finally, the PI is committed to distributing the results obtained in the project in the fastest manner possible, through publications, conferences, and the public media.