Sadatoshi HORINO

Screening of microorganisms degrading tris(2-chloroethyl) phosphate, a persistent organic compound.

Ryo-hei YAMADA, Yoshio KERA, Shouji TAKAHASHI

Large quantities of organophosphoric acid triesters have been produced and widely used as flame retardants, plasticizers and pesticides. The compounds are therefore widely distributed in the natural environment. Some of them are known to have acute toxicities, mutagenicity and neurotoxicity, similar to those of organophosphorus pesticides. Although chlorinated triesters such as tris(1,3-dichloro-2-propyl) phosphate (TDCPP) and tris(2-chloroethyl) phosphate (TCEP) are highly toxic among them, there is no information on the microbial degradation of these chlorinated triesters. Thus, the aim of this study is to obtain TCEP-degrading microorganisms.
TCEP-degrading microorganisms were selected from 46 soil samples by growth on TCEP as a sole phosphorus source. Additionally, TDCPP-degrading enrichment cultures were also tested for their growth ability on TCEP. Among them examined, significant growth was found in culture broth from 13 different soil samples and all the TDCPP-degrading cultures, concomitant with the decrease of TCEP content. Further enrichment by continuous subcultivation accelerated the TCEP reduction rate in almost all the cultures. The enrichment culture after the 9th subcultivation on TCEP from the soil sample named No. 67 showed the highest TCEP reduction rate, it was further examined and found to release chloride ion to the medium.