Microtox measures the decrease in respiration, and
subsequent light output, of the luminescent bacterium Vibrio fischeri as the toxic response. Vibrio fischeri is a non-pathogenic rod shaped bacterium inhabiting marine environments. Because it is a marine species, samples must be osmotically adjusted (using sodium chloride) prior to testing.
While not approved by the
EPA for compliance toxicity testing, Microtox testing can be a
rapid, cost-effective tool in assessing toxicity of effluents, sediments,
leachates, soils, sludges, ground water and surface water. Test data can be available within as little
as 30 minutes and numerous samples can be easily processed during a standard workday.
Microtox
is most useful when the bacterial response correlates well with the response of
standard test species (which may be required in compliance tests) or indigenous
species within the receiving water or water body of concern. Because the cost effectiveness of Microtox
is greatest when large numbers of samples need to be processed at the same
time, uses include TRE/TIE testing, source toxicity identification (e.g. as part of a
pretreatment program), characterizing time-dependent toxicity, materials screening
and similar applications.
