NEW DEVELOPMENTS IN THE BIOLUMINESCENCE ASSAY

Résumé

The industrial development, the use of pesticides in
agriculture and the urbanization threaten the natural water
resources. Legislation was introduced for monitoring and
preventing the release of toxic substances to protect water
quality. The traditional approach to toxicant monitoring in
water involves standard analytic procedures. In general
these techniques are selective and very sensitive. One is
able to detect very low concentrations of a single chemical.
However, these benefits have their drawback. Water may
contain thousands of chemicals. Because of the selectivity
only a limited number of compounds can be evaluated
adequately. A broad based chemical analysis is expensive
or sometimes impossible. Furthermore, most of the methods
are laborious and time-consuming and cannot assess
toxicity.
An alternative to the specific chemical methods is the
bioassay. In bioassays, whole organisms are used for testing
the quality of aqueous samples. Living organisms are
sensitive to a broad spectrum of bio-available substances.
The conventional aquatic bioassays use fish and waterfleas.
However, these tests are unpractical for routine screening,
because culturing and testing is costly and laborious as well
as time and space consuming. This has led to the
development of the microbiotests. Because microorganisms
are used in these tests, many of the drawbacks mentioned
above are overcome. They are cheap, available as kits and
use small test volumes. The demand was a test that was
technical simply, using organisms with sufficient sensitivity
to a broad spectrum of toxic compounds, an easy detection,
reproducible, rapid results and minimal sample preparation.
The bioluminescence assay fulfills these needs and the
Vibrio fischeri bioluminescence assay is standardized and
widely used now. Despite the benefits of this system, there
is a growing demand for bacteria that are more sensitive
than the previous mentioned bacteria especially to metals
and pesticides (chlorinated organic compounds). In this
presentation we will discuss the traditional Vibrio fischeri
assay and introduce some novel approaches in toxicity
testing using metal biosensors and a luminescent bacterial
strain which is much more sensitive to metals and organic
toxicants.