Manami KAWASAKI

Isolation and characterization of bacteria degrading Tris(2-chloroethyl)phosphate, a persistent organophosphorus 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) have been known to be highly toxic among them, there is no information on the microbial degradation of these chlorinated triesters. In the present study, we succeed in isolating 5 strains capable of degrading TCEP.
Two mixed cultures, No.45-DE and No.67-E, were found capable of growing on TCEP as the sole phosphorous source. The two mixed cultures also showed chloride ion release after degradation of TCEP, suggesting that these can degrade 2-chloroethanol, putative metabolite of TCEP. Denaturing gradient gel electrophoresis (DGGE) pattern of No. 45-DE showed multiple bands, indicating that various microorganisms exist in the mixed culture.

Five strains that grew with TCEP as the sole phosphorous source were isolated from the two mixed cultures. In addition, these strains were also grown on TDCPP. The 16S rRNA gene sequence suggested that two strains is a member of the genus Sphingomonas and three strains is a member of the genus Sphingobium.