Isolation and characterization of Flavobacterium strains that degrade pentachlorophenol

Abstract

Bacteria able to mineralize 100 to 200 ppm of pentachlorophenol (PCP) were isolated by selective enrichment from PCP-contaminated soils from three geographic areas of Minnesota. Although differing somewhat in their responses to various biochemical and biophysical tests, all strains were assigned to the genus Flavobacterium. Five representative strains were examined in detail. All strains metabolized PCP as a sole source of carbon and energy; 73 to 83% of all carbon in the form of [U-14C]PCP was returned as 14CO2, with full liberation of chlorine as chloride. A comparison between strains in their ability to metabolize PCP showed some strains to be more efficient than others. Guanine-plus-cytosine contents of DNA ranged from 58.8 to 63.8%, and DNA/DNA hybridization studies with total DNA digests suggested substantial genetic homology between strains. All strains were shown to possess an 80- to 100-kilobase plasmid, and evidence suggested the presence of a larger plasmid (greater than 200 kilobases).