Isolation of pentachlorophenol decomposing bacteria from soil

Abstract

The bacteria capable of degrading pentachlorophenol (PCP) were isolated from soil. In the soil perfused with 40 ppm PCP solution, PCP was decomposed and five chlorine atoms of PCP were liberated as chloride ion after about 3 weeks. Re-addition of PCP after its degradation, accelerated the rate of PCP degradation and de-chlorination. After the addition of PCP to the soil three times, bacteria which grew on PCP agar were counted to be about 2 × 10⁷ per gram dry soil. In the liquid medium inoculated with the perfused soil, PCP degradation and complete de-chlorination were found. In this case, multiplication of bacteria capable of growing on PCP agar was found. The bacteria capable of growing on and degrading PCP in the medium with inorganic salts and 40 ppm PCP as a sole source of carbon were isolated from the agar plates for enumeration of the bacteria. From the morphological and physiological properties of the isolated bacteria, the genus of the bacteria was considered to be Pseudomonas or a closely related one. In the culture medium with PCP and inorganic salts, the bacteria degraded PCP and completely de-chlorinated it. The de-chlorination process corresponded approximately to PCP disappearance. Pathways of PCP metabolism are not yet elucidated.