Anatoxin-a (ATX-a) is a neurotoxin produced by some species of cyanobacteria. Due to its water solubility and stability
in natural water, it could pose health risks to human, animals, and plants. Conventional water treatment techniques are not
only insufficient for the removal of ATX-a, but they also result in cell lysis and toxin release. The elimination of this toxin
through biodegradation may be a promising strategy. This study examines for the first time the biodegradation of ATX-a
to a non-toxic metabolite (Epoxy-ATX-a) by a strain of Bacillus that has a history of dealing with toxic cyanobacteria
in a eutrophic lake. The Bacillus strain AMRI-03 thrived without lag phase in a lake water containing ATX-a. The strain
displayed fast degradation of ATX-a, depending on initial toxin concentration. At the highest initial concentrations (50 &
100 μg L− 1), total ATX-a degradation took place in 4 days, but it took 6 & 7 days at lower concentrations (20, 10, and
1 μg L− 1, respectively). The ATX-a biodegradation rate was also influenced by the initial toxin concentration, reaching its
maximum value (12.5 μg L− 1 day− 1) at the highest initial toxin concentrations (50 & 100 μg L− 1). Temperature and pH
also had an impact on the rate of ATX-a biodegradation, with the highest rates occurring at 25 and 30 ºC and pH 7 and
8. This nontoxic bacterial strain could be immobilized within a biofilm on sand filters and/or sludge for the degradation
and removal of ATX-a and other cyanotoxins during water treatment processes, following the establishment of mesocosm
experiments to assess the potential effects of this bacterium on water quality