Bioassays with Luminescent Bacteria

Standardised test methods, such as ISO 11348 [59], could be used for aqueous samples and elutriates. Light-emitting marine bacteria, such as Vibrio fischeri or Photobacterium sp., are used. A defined bacterial inoculum is added to the sample solutions and the change of bioluminescence intensity is measured over a period of 30 min. Ready to use test kits, e.g., LumisTox (Dr. Lange) or ToxAlert (Merck) are available and comply with all the requirements defined in the standard methods. 

As the organisms are of marine origin, the biotest should preferably be used for samples deriving from marine environments, such as seawater or marine sediment. 

Nevertheless, the tests are commonly used for freshwater samples as well (sewage or wastewater treatment effluent) because of the short contact time they mainly detect universal cytotoxic effects. Sodium chloride must be added to freshwater samples and elutriates to reach a minimum salinity of 2%. 

Again the colour of compost elutriates may absorb the emitted light by the bacteria and lead to improper results. 

Currently, no results are available from the literature for the systematic testing of biodegradable polymers which give any further helpful comments. 

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Nohava, M., W.R. Vogel, and H. Gaugitisch. 1995. Evaluation of the luminescent bacteria bioassay for the estimation of the toxicological potential of effluent water samples—comparison with data from chemical analyses. Environ. Int. 21 33-37. 

The Microtox test system utilizes a strain of naturally occurring luminescent bacteria - Vibrio fischeri. Exposure to a toxic substance causes a disruption of the respiratory process of the bacteria resulting in reduced light output. The effective concentration (EC50) is determined as the concentration of a toxicant that causes a 50% reduction in light output over a prescribed period of time (typically 5, 15, or 30 min). The test is fast, fairly simple to conduct, uses small sample sizes, and is relatively inexpensive. Results correlate well with those from other toxicity bioassays such as fish and Daphnia. The test is used... 

Step 4 Compost analysis for conventional parameters determining any quality change compared with the blind and ecotoxicity test using at least two plant species if negative influences are detected additional bioassays should be performed using more plant species, daphnia, water lens, luminescent bacteria or special local species. 

A feasibility study on the potential use of a luminescent bacteria bioassay in the toxicity screening oftrichothecenes is presented. The toxic effects of four 12,13-epoxytrichothecenes to bioluminescent bacteria were determined for the first time using the Microtox " Toxicity Analyzer (TM Trademark of Microbics Corporation, Carlsbad, California). The influence of test temperature and exposure time on the toxic effect oftrichothecenes to the luminescent bacteria are discussed. The toxicities measured are compared with toxic effects determined using other bioassays. Potential relationships between the toxicities found and variations in the chemical structure of these compounds are considered. 

Step 4 Determination of ecotoxic effects using bioassays compatible with the degradation environment for example three plant species for soil applications or daphnia and two algae species for freshwater applications or marine algae and luminescent bacteria for marine applications. 

Other applications dealt with the development of a luciferin ester substrate to measure the luciferase activity in living cells [141], the detection of toxic compounds such as sodium azide, fluoroacetic acid, and antibiotics [142], the development of a biosensor for the determination of bioavailable mercury [143], the use of eukaryotic luciferases as bacterial markers with different colors of luminescence [144], the determination of complement-mediated killing of bacteria [145], and the development of a bioassay for the determination of HIV type 1 virus and HIV-1 Tat protein activity, valuable also for analysis of HlV-inhibi-tory agents [146],... 

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