Isolation and characterization of a denitrifying monocrotophos-degrading Paracoccus sp M-1

A bacterium strain, which is capable of degrading monocrotophos, was isolated from sludge collected from the bottom of a wastewater treatment system of a chemical factory, and named M-1. On the basis of the results of the cellular morphology, physiological and chemotaxonomic characteristics and phylogenetic similarity of 16S rDNA gene sequences, the strain was identified as a Paracoccus sp. The ability of the strain to mineralize monocrotophos was investigated under different culture conditions. Other organophosphorus insecticides and amide herbicides were also degraded by M-1. The key enzyme (s) involved in the initial biodegradation of monocrotophos in M-1 was shown to be a constitutively expressed cytosolic protein. The addition of M-1 (10(6) CFU g(-1)) to fluvo-aquic soil and a high-sand soil containing monocrotophos (50 mg kg(-1)) resulted in a higher degradation rate than that obtained from noninoculated soil. This microbial culture has great potential utility for the bioremediation of wastewater or soil contaminated with organophosphorus pesticides and amide herbicides.