ACCELERATED microbial degradation of fenamiphos pesticide (nemacur) in liquid culture and uncultivated and cultivated soil
by the efficient strains of Paenibacillus polymyxa, Pseudomonas
fluorescens and Streptomyces aureofaciens were investigated.
Fenamiphos amounts in liquid cultures of the three microorganisms
decreased with elapsed time when it was used as a sole source of
carbon and nitrogen. P. polymyxa proved to be able to decompose the
pesticide at a higher rate than did Ps. fluorescens and S. aureofaciens.
In pot experiment, soil amended with fenamiphos and inoculated with
the aforementioned biodegrading strains showed higher values of N2-
ase, dehydrogenase and phosphatase activity than uninoculated soil.
The mixture of strains gave higher enzyme activities than when each
strain was inoculated individually. Furthermore, soil cultivated with
tomato showed higher activities of these enzymes than uncultivated
soil. Uncultivated soil inoculated with only S. aureofaciens showed the
most rapid disappearance of fenamiphos compared to soil inoculated
with P. polymyxa, Ps. fluorescens or the mixture of the three organisms. However the rate of fenamiphos decomposition by the bacterial strains was higher in cultivated soil than in uncultivated soil, and cultivated soil exhibited the most rapid disappearance of fenamiphos with the mixture of the three strains. When soil samples were analyzed for the fenamiphos biodegradation after 22 days of the pesticide addition and 15 days after inoculation with the biodegradants, three metabolites of fenamiphos were detected. Results show that fenamiphos degradation can be effectively accelerated in soil by these microorganisms.
Keywords: Biodegradation, Pesticide, Fenamiphos, Paenibacillus
polymyxa, Pseudomonas fluorescens, Streptomyces aureofaciens, Persistence. |
