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

Abstract

The production of enzymes involved in lignin degradation (laccase, ligninase), carbon cycling (β-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 µg PNP min⁻¹ ml⁻¹, respectively, which was more than the control on the 21st day (11.63 ± 0.21 µg PNP min⁻¹ ml⁻¹). β-Glucosidase production increased with the days of incubation in the presence of pesticides than in the control. β-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 µg PNP min⁻¹ ml⁻¹, respectively, as compared to control (15.3 ± 0.6 µg PNP min⁻¹ ml⁻¹). Thus, chlorpyrifos, carbofuran, and their mixture were found to have a positive effect on the production of laccase, β-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.