Toxicity of 39 MEIC chemicals to bioluminescent photobacteria (the Biotox test): correlation with other test systems

By Kahru, A. - Borchardt, B.

Photobacterium phosphoreum are naturally luminescent marine bacteria, which emit light as a result of metabolism. Any damage to the cellular metabolism caused by a toxic substance can therefore be monitored by measuring the change in light output of the bacteria, the light loss being proportional to the degree of toxicity. The Biotox test, based on reconstituted freeze-dried (viable) Photobacterium phosphoreum as the test organism, was used for the short-term toxicity testing of 39 chemicals from the MEIC list. Concentration-effect curves for these 39 chemicals were measured and five-minute EC50 values (the concentration of chemical, mM which reduces the light output of the bacteria by 50% after contact for five minutes) were calculated. The EC50 data from the Biotox test were correlated with data from the literature: octanol/water partition coefficients. EC50 data from the Microtox test, minimal inhibitory concentration values for Escherichia coli and Bacillus subtilis and acute toxicity data from animal and human cell lines, rodents and man. The correlation coefficients ranged between 0.63 and 0.93.