The ability of specific strains of probiotic bacteria to remove the cyanobacterial peptide toxin microcystin-LR from aqueous solutions was assessed. Lactobacillus rhamnosus strains GG and LC-705, Bifidobacterium longum 46, Bifidobacterium lactis 420 and Bifidobacterium lactis Bb12 were shown to be the most effective in toxin removal among 11 tested strains. The highest removal percentage of microcystin-LR was 58.1%, observed with B. lactis Bb12 (toxin concentration 100 microg L(-1), 10(10) CFU mL(-1), 37 degrees C, 24 h). Freshly cultured bacteria were shown to be more efficient in microcystin removal than lyophilized or nonviable bacteria. Removal of microcystin-LR was shown to be dependent on both temperature and bacterial concentration. It is concluded that some of the tested strains have good potential in removing microcystins from aqueous solutions.