Nitrifier Toxicity and Bioassay Response - Alleman

Inhibitory Response and Bioassay Sensitivity of Nitrifying Bacteria
Professor J.E. Alleman & Lu Chen (Doctoral Candidate)


Bacterial bioassay strategies have drawn an escalating level of technical interest over the past decade given their expected ease of use, response sensitivity, and cost effectiveness. Four such strategies have been developed, including two based on mixed cultures (i.e., aerobic heterotrophs and methanogens) and two which employ specific bacterial groups (i.e., Vibrio fischeri and nitrifiers). As compared to mixed culture protocols, though,

the latter genus-specific options have an inherent advantage in terms of their expected levels of reproducibility. Indeed, the commercially-marketed Vibrio-based procedure (MicrotoxTM) has been widely applied in the business of bioassays. There is an inherent disadvantage with all of these existing tests, however, in that their current sensitivity levels with toxicants are usually at or above multiple-ppm levels.

Our research effort, therefore, is designed to improve this sensitivity using an advanced, respirometric-based testing protocol with nitrifying bacteria. This new method is considerably more sensitive, with IC50 values of 0.21 mg/l for phenol, 0.3 mg/l for benzene, and 0.85 mg/l for chlorobenzene having been identified. Overall, this improved method for nitrifier bioassay testing has several apparent attributes, in that it is not only simple and sensitive, but also rapid and inexpensive.




Email: alleman@ecn.purdue.edu / Page Date: 17 August 1998 / JEA