Matsushita Taku, Matsui Yoshihiko, Saeki Ryo, Inoue Takanobu
Department of Civil Engineering, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.
Chemosphere. 2005 Dec;61(8):1134-41. doi: 10.1016/j.chemosphere.2005.02.057. Epub 2005 Apr 13.
Previous studies have revealed that the mutagenicity of fenitrothion increases during anaerobic biodegradation, suggesting that this insecticide's mutagenicity could effectively increase after it pollutes anaerobic environments such as lake sediments. To investigate possible changes to the mutagenicity of fenitrothion under aerobic conditions after it had already been increased by anaerobic biodegradation, batch incubation cultures were maintained under aerobic conditions. The mutagenicity, which had increased during anaerobic biodegradation, decreased under aerobic conditions with aerobic or facultative bacteria, but did not disappear completely in 22 days. In contrast, it did not change under aerobic conditions without bacteria or under continued anaerobic conditions. These observations suggest that the mutagenicity of anaerobically metabolized fenitrothion would not necessarily decrease after it arrives in an aerobic environment: this would depend on the presence of suitable bacteria. Therefore, fenitrothion-derived mutagenic compounds may pollute the water environment, including our drinking water sources, after accidental pollution of aerobic waters. Although amino-fenitrothion generated during anaerobic biodegradation of fenitrothion was the principal mutagen, non-trivial contributions of other, unidentified metabolites to the mutagenicity were also observed.
先前的研究表明，杀螟硫磷在厌氧生物降解过程中致突变性会增加，这表明这种杀虫剂在污染湖泊沉积物等厌氧环境后，其致突变性可能会有效增强。为了研究杀螟硫磷在厌氧生物降解使其致突变性增加后，在有氧条件下可能发生的变化，在有氧条件下进行了分批培养。在厌氧生物降解过程中增加的致突变性，在有氧或兼性细菌存在的有氧条件下会降低，但在22天内并未完全消失。相比之下，在无细菌的有氧条件下或持续厌氧条件下，其致突变性没有变化。这些观察结果表明，厌氧代谢的杀螟硫磷进入有氧环境后，其致突变性不一定会降低：这取决于是否存在合适的细菌。因此，在有氧水域意外污染后，杀螟硫磷衍生的致突变化合物可能会污染包括我们饮用水源在内的水环境。虽然杀螟硫磷厌氧生物降解过程中产生的氨基杀螟硫磷是主要诱变剂，但也观察到其他未鉴定的代谢产物对致突变性有显著贡献。
