Impact of Sodium Tungstate and Tungsten Alloys on the Growth of Selected Microorganisms with Environmental Significance

摘要

Tungsten is a transition metal with unique properties that permit its use in a range of applications, including household products and small caliber ammunition. Increased use has restored interest in tungsten and tungsten-based products in determining not only their impacts upon human health, but also on the environment. Given the dependence on microbes for environmental processes, it is appropriate to evaluate tungsten effect on microorganisms. The goal of this study was to investigate the impact of sodium tungstate (Na2WO4) and tungsten alloys on the growth of selected environmental microorganisms that play roles in metal reduction, biogeochemical cycling and biodegradation. A soil community was also evaluated for its tolerance to Na2WO4. Shewanella, a strong metal reducer, displayed the most robust ability to grow in the highest concentrations of Na2WO4 evaluated, whereas Pseudomonas displayed lower tolerances. Interestingly, bacteria cultivated from the environment displayed only minor delays and reduction in growth relative to pure cultures, suggesting that such a microbial consortium is better suited to cope with Na2WO4 exposure. Tungsten alloys also had profound effects on bacterial growth, however, these were dependent on the metals and nutrients present, suggesting the effect may be exacerbated in certain environmental settings where nutrients may be limited.