Research on novel degradation enzymes and genes essential to microbial degradation of persistent chlorinated organophosphorus triesters

氯化有机磷（OP）化合物磷酸三（2-氯乙基）酯（TCEP）和磷酸三（1，3-二氯-2-丙基）酯（TDCPP）分别广泛用作塑料泡沫、树脂和胶乳以及液体不饱和聚酯树脂的生产中的阻燃剂。它们不仅在环境中难以消除，而且在污水处理厂中也难以消除。本研究以TDCPP和TCEP为唯一磷源，从土壤中分离到一株降解三卤代烷基磷酸盐的新细菌--鞘氨醇单胞菌TDK 1和鞘氨醇杆菌TCM 1。这两株菌不仅能降解和同化氯代OP阻燃剂，还能降解其他几种OP阻燃剂和增塑剂，且对磷酸三烷基酯的底物专一性不同。我们分别从鞘氨醇杆菌属TCM 1和鞘氨醇单胞菌属TDK 1中纯化并表征了催化TCEP和TDCPP降解第一步的磷酸三酯酶。对酶的相关基因进行了克隆和分析。结果表明，这两种酶的亲缘关系很近，与磷酸三酯酶的亲缘关系很远。

The chlorinated organophosphorus(OP) compounds tris(2-chloroethyl) phosphate(TCEP) and tris(1, 3-dichloro-2-propyl) phosphate(TDCPP) are widely used as flame retardants mainly in a range of plastic foams, resins, and latexes and in the production of liquid unsaturated polyester resins, respectively. They are hard to eliminate not only in the environment but also in sewage treatment plants. Many studies have shown several toxic effects of the compoundsIn this study, novel bacteria degrading trihaloalkyl phosphates, Sphingomonas sp. strain TDK1 and Sphingobium sp. strain TCM1, were isolated from soil by growth on TDCPP or TCEP as a sole phosphorus source, respectively. The two strains were able to degrade and assimilate not only the chlorinated OP flame retardants but also several other OP flame retardants and plasticizers, and the strains possessed different substrate specificity for trialkyl phosphates. We purified and characterized phosphotriesterases, catalyzing the first step of TCEP and TDCPP degradation, from Sphingobium sp. TCM1 and Sphingomonas sp. TDK1, respectively. The corresponding genes of the enzymes were cloned and analyzed. The results suggested that both the enzymes were very closely related each other and very distantly related to phosphotriesterases so far reported.