Biodegradation of 14C- diflubenzuron pesticide by penicillium notatum

Abstract EN

Three fungi, Aspergillus flavous, Aspergillus nigar and Penicillium notatum were selected in the current study for their tendency to tolerate Difluobenzuron (DFB) pesticide.

Regarding fresh and dry weight (g/100ml) P.

notatum showed to be the least affected by the presence of DFB (200ppm)).

When Glutathione-S-Transferase (GST) was measured in the three fungi, the highest level was detected in P.

notatum.

These finding prompted further studies in which P.

notatum tolerated up to1000 ppm of DFB.

Another attempt was conducted to increase the production of GST using gamma irradiation.

The gamma radiation showed a significant effect on the concentration of GST especially on the intercellular GST (mycelia GST).

This was recognized upon applying the lowest dose of gamma radiation (10Gy).

As the radiation dose increased the effect was more pronounced where both inter and extracellular enzyme (GST secreted in media) activity started showing statistically significant increase from control untreated group.

After inoculation of pesticide with14C- DFB for 10 days the data showed that 91.2 % of the 14 C- activity could be recovered.

The 14 C- activity was distributed, in mycelia (65.8%) and in the media (25.4%).

The CHCl3 extract of the mycelia contributed 41.0% of 14 C radioactivity while 23.0% was in the water phase.

The amount that remained without extraction (bound residues) did not exceed 1.8%.

In the media, of the total recovered radioactivity, 15.4 % was in the organic phase while 10% was in the water phase.

The TLC analysis of chloroform extract of external extract of fungi revealed the following: In the media, the intact parent compound (DFB) identified by co-chromatography showed a 74%, while the metabolites of concern, 4 chloro phenyl urea(CPU) showed 10.0% , 2,6difluorobenzamide (DFBAM) 6.8% and 4-chloro aniline (CA) contributed to 8.6% , however, 2,6-difluorobenzoic acid (DFBA) was not detected in the current experiment.

On the other hand, the internal extract showed percent of 72.0, 7.2 and 20.6 for BFB, CPU and DFBAM, respectively.

Again, DFBA was not detected in addition to CA.