Lignin degradation and nutrient cycling by white rot fungi under the influence of pesticides

The production of enzymes involved in lignin degradation (laccase, ligninase), carbon cycling (beta-glucosidase), and phosphorous cycling (phosphomonoesterase) by white rot fungi (Pleurotus sajor-caju) was studied. In the presence of chlorpyrifos, carbofuran, and their mixture, laccase activity was highest on the 7th day, i.e., 192.5 +/- 0.31 U ml(- 1), 213.6 +/- 0.31 U ml(- 1), and 164.6 +/- 0.31 U ml(- 1), respectively, compared to the control which produced maximum laccase on the 14th day (126.9 +/- 0.15 U ml(- 1)). Phosphomonoesterase activity in the presence of chlorpyrifos, carbofuran, and their mixture was 31.5 +/- 0.25, 24.1 +/- 0.15, and 29.2 +/- 0.35 mu g PNP min(-1) ml(-1), respectively, which was more than the control on the 21st day (11.63 +/- 0.21 mu g PNP min(-1) ml(-1)). beta-Glucosidase production increased with the days of incubation in the presence of pesticides than in the control. beta-Glucosidase activity on the 21st day in the presence of chlorpyrifos, carbofuran, and their mixture was 32.4 +/- 0.1, 24.2 +/- 0.3, and 28.4 +/- 0.25 mu g PNP min(-1) ml(-1), respectively, as compared to control (15.3 +/- 0.6 mu g PNP min(-1) ml(-1)). Thus, chlorpyrifos, carbofuran, and their mixture were found to have a positive effect on the production of laccase, beta-glucosidase, and phosphomonoesterase by P. sajor-caju, which can use these pesticides as a source of their nutrition, thereby improving the health of pesticide-polluted soils.