What do microbial biosensors tell us about the behavior of MTBE?

Although highly soluble and ubiquitous in the terrestrial environment there is little known about the impact of MTBE on microbial ecotoxicity tests. Microbial ecotoxicity tests are important as they are rapid indicators of environmental health and are also able to diagnose constraints to contaminant mineralisation. MTBE is rarely found in isolation and may have effects in combination with other hydrocarbons. To investigate the impact of MTBE on microbial ecotoxicity tests, the response of a range of lux-based biosensors was measured against aqueous samples of MTBE, benzene, and naphthalene, both individually and in combination. Metabolic sensors (indicative of general environmental stress) and catabolic sensors (induced by specific analytes) were used and the response modeled, enabling pollutant interactions to be identified. All concentrations were confirmed by PTI-GC-FID or HPLC. MTBE did not increase the toxicity of benzene or naphthalene to two of the sensors used but may have altered the pollutant bioavailability and indeed for some analytes reduced toxicity significantly.