Abstract：
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.
摘要：
Anatoxin-a（ATX-a）是由某些蓝细菌产生的神经毒素。由于其水溶性和在天然水中的稳定性，它可能会对人类造成健康风险，动物,和植物。传统的水处理技术不仅不足以去除ATX-a，但它们也会导致细胞裂解和毒素释放。通过生物降解消除这种毒素可能是一种有前途的策略。这项研究首次研究了一种芽孢杆菌菌株将ATX-a生物降解为无毒代谢物（Epoxy-ATX-a），该菌株具有处理富营养化湖泊中有毒蓝细菌的历史。在含有ATX-a的湖水中，芽孢杆菌菌株AMRI-03没有滞后期。该菌株显示出ATX-a的快速降解，取决于初始毒素浓度。在最高初始浓度(50&100µgL-1)下，总的ATX-a降解发生在4天，但在较低浓度下需要6和7天(分别为20、10和1µgL-1)。ATX-a生物降解速率也受初始毒素浓度的影响，在最高初始毒素浓度（50和100µgL-1）下达到最大值（12.5µgL-1天-1）。温度和pH也对ATX-a的生物降解速率有影响，最高的速率发生在25和30ºC和pH7和8。这种无毒的细菌菌株可以固定在砂滤器和/或污泥上的生物膜内，用于在水处理过程中降解和去除ATX-a和其他氰基毒素。在建立中观实验以评估这种细菌对水质的潜在影响之后。
