Propazine degradation by intra- and extracellular enzymes from Pleurotus ostreatus INCQS 40310

The propazine herbicide has been used worldwide in different crops of economic relevance. Due to its recalcitrance and leaching capacity, propazine is often found in water bodies in several countries above the allowed levels. Besides preventing contamination, it is crucial to improve the current degradation processes. Within this context, the aim of the present study was the evaluation of propazine degradation by Pleurotus ostreatus INCQS 40310, considering the contribution of intra-and extracellular enzymes during the process. Two culture media were used, namely PMP 7 and PMP 12, which were previously optimized through factorial design for atrazine degradation. The best results for propazine degradation were obtained from P. ostreatus INCQS 40310 cultivated in PMP 12 culture medium. Pleurotus ostreatus INCQS 40310 grown in PMP 12 degraded 90% of the propazine after 32 d. In a separate experiment that used only resting cells of P. ostreatus INCQS 40310, which were previously washed with phosphate buffer, 37.5% propazine degradation was observed after 7 d (32 d of cultivation in PMP 12 for growth and 7 d of resting cell incubation), which indicates the participation of intracellular enzymes. However, when the same degradation test was conducted using crude supernatant obtained from P. ostreatus INCQS 40310 cultivation, 31% of the propazine was degraded in PMP 12 after 7 d suggesting that extracellular enzymes are also involved. The highest percentage of propazine degradation, 90%, was only obtained during the full cultivation of P. ostreatus INCQS 40310. In addition, the isolated tests with resting cells and crude supernatant showed the participation of intra-and extracellular enzymes in a complementary manner and suggested the synergistic action of both.