Biodegradation of pirimiphos-methyl using two types of microorganisms isolated from Fayoum governorate soil

Abstract EN

The results showed that the half-life of the pirimiphos-methyl ranged between 2.1 and 1.57 day in non- sterilized soil under 27˚C and moisture content 25 and 50 % respectively.

Also, at the same temperature degree in sterilized soil the half- life of the pirimiphos-methyl reached about 30.1 and 3.8 day under moisture content 25 and 50 % respectively.

The half- life of pirimiphos-methyl soil under 35?C was about 2 and 1.8 day in non- sterilized soil for both tested moisture content 25 and 50 % respectively.

In sterilized soil, the half-life of the same insecticide under 35˚C was about 6.01 and 3.5 day for 25 and 50 % moisture content, respectively.

Two strains of microorganisms were isolated from the soil one of them a positive gram bacteria strain and the other is a fungi strain.

The breakdown of pirimiphos–methyl through these organisms was investigated in a liquid media.

The degradation rate of pirimiphos-methyl was faster after first, second and third day by the fungi than the bacteria strain under 35˚C incubation temperature.

On the other hand the degradation by bacteria was accelerated up to the fourth day of incubation.

These effects may be due to the increase of the extracellular esterase activity, which tend to increase from the second day of incubation period.

Generally, the degradation of pirimiphos-methyl by the two tested microorganisms was higher under 35˚C than 27˚C.

The glucose consumption by the bacteria strain seemed to be correlated to the increase in the esterase activity up to the third day of incubation period.

No significant differences were found between the control and the fungi in its glucose consumption.