Characteristics of Paraquat-Degrading Microbes

Abstract

Three species of paraquat (1, 1′-dimethyl-4, 4′-bipyridinium ion)-degrading microorganisms were isolated from a paddy field soil; an unidentified yeast (F-12), a Fusarium sp. (F-14), and a Penicillium sp. (F-16). In a liquid medium containing paraquat, F-12 required nutrient sources to eliminate paraquat from the medium while F-14 and F-16 did not. When F-14 and F-16 were incubated in a liquid medium containing methyl-¹⁴C-paraquat, both fungi accumulated paraquat in the cells, some portion of which was metabolized to monoquat (1-methyl-4, 4′-bipyridinium ion), monopyridone (1′, 2′-dihydro-1, 1′-dimethyl-2′-oxo-4, 4′-bipyridinium ion) (only in F-14), N-methyl isonicotinic acid, methylamine and ¹⁴CO₂.