Identification of spore-forming strains involved in biodegradation of acifluorfen

We isolated and identified four spore-forming bacteria from activated sludges and soil, three of which were able to degrade acifluorfen. Biochemical characteristics, DNA base composition and DNA-DNA homology indicated that the degrading strains belonged to the species Bacillus thuringiensis, Clostridium perfringens and Clostridium sphenoides. The fourth strain, identified as C. sphenoides and showing the same characteristics of the corresponding degrading strain, was unable to metabolize acifluorfen. Thus, the plasmid content of these strains was analysed to study the possible correlation between the presence of extrachromosomal elements and the ability to degrade this herbicide.