NEW DEVELOPMENTS IN THE BIOLUMINESCENCE ASSAY

The industrial development, the use of pesticides inagriculture and the urbanization threaten the natural waterresources. Legislation was introduced for monitoring andpreventing the release of toxic substances to protect waterquality. The traditional approach to toxicant monitoring inwater involves standard analytic procedures. In generalthese techniques are selective and very sensitive. One isable to detect very low concentrations of a single chemical.However, these benefits have their drawback. Water maycontain thousands of chemicals. Because of the selectivityonly a limited number of compounds can be evaluatedadequately. A broad based chemical analysis is expensiveor sometimes impossible. Furthermore, most of the methodsare laborious and time-consuming and cannot assesstoxicity.An alternative to the specific chemical methods is thebioassay. In bioassays, whole organisms are used for testingthe quality of aqueous samples. Living organisms aresensitive 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 wellas time and space consuming. This has led to thedevelopment of the microbiotests. Because microorganismsare used in these tests, many of the drawbacks mentionedabove are overcome. They are cheap, available as kits anduse small test volumes. The demand was a test that wastechnical simply, using organisms with sufficient sensitivityto a broad spectrum of toxic compounds, an easy detection,reproducible, rapid results and minimal sample preparation.The bioluminescence assay fulfills these needs and theVibrio fischeri bioluminescence assay is standardized andwidely used now. Despite the benefits of this system, thereis a growing demand for bacteria that are more sensitivethan the previous mentioned bacteria especially to metalsand pesticides (chlorinated organic compounds). In thispresentation we will discuss the traditional Vibrio fischeriassay and introduce some novel approaches in toxicitytesting using metal biosensors and a luminescent bacterialstrain which is much more sensitive to metals and organictoxicants