Despite the promutagenic/procarcinogenic poten-Chlamydomonas reinhardtii cells were used as an tial, polycyclic aromatic amines are widely spread activating system and the bacteria Salmonella typhiin the environment. Biotransformation of the polycy-murium TA98, YG1024, and yeast Saccharomyces clic aromatic amine 2-aminofluorene (2-AF) was cerevisiae D7 as the genetic indicator organisms. proved in mammals and higher plants. The algal It was converted to the mutagenic product(s) for the cell/microbe coincubation assay is an additional strain YG1024, but the strain TA98 did not exhibit system that complemented those proved in mam-any increase in the mutant yield of His / revertants. mals and higher plants, useful for detection and Consequently, metabolites from 2-AF are substrates conversion of environmental promutagens, mainly for O-acetyltransferase. A direct comparison of alin aquatic environments. The unicellular green al-gal 2-AF activation with mammalian activation sysgae may be a good activating system in coincuba-tem (S9 mix) proved the higher activity of mammation assays in that the algal cells exist as a natural lian microsome system (S9 mix). After the combinasystem. To increase the effectiveness of this metabo-tion of both activation systems, a slight synergetic lizing system, different modifications of the standard effect was found. Although the genetic endpoints experimental procedure were conducted. Algae induced by 2-AF using both modifications of the can accumulate and metabolize promutagenic pol-algal cell/S. cerevisiae coincubation assay and lutants, some of which may differ from those acti-those obtained in intact yeast cells were similar at vated by the animal microsome metabolizing sys-the equitoxic concentrations, 2-AF activation by the tem (S9 mix) and by the plant cell/microbe coincu-algal supernatant slightly increased the genetic endbation assay. 2-AF was activated in the algal cell/ points studied.