Biodegradation of hydrocarbons exploiting spent substrate from Pleurotus ostreatus in agricultural soils

Abstract

In Acatzingo, Puebla, Mexico (east-central), oil spills have mainly affected agricultural fields. Pleurotus ostreatus is a white rot basidiomycete and produces extracellular enzymes (lacasses, manganese peroxidases, versatile peroxidases and veratryl alcohol oxidases). The production of edible mushrooms generates spent mushroom substrate that may have a biotechnological application. The aim of this study was to evaluate the mushroom substrate of P. ostreatus in a microcosm for the bioremediation of an agricultural soil contaminated with diesel. We evaluated the participation of microbial populations and specific enzymatic lacasses, manganese peroxidases, versatile peroxidases, veratryl alcohol oxidases activities of mushroom substrate in the biodegradation of a soil contaminated with 11030 ppm of diesel in four treatments: E1, E2, E3 and E4. All the experiments were performed in triplicate at 25 and 37°C for 28 days, with a soil:substrate ratio of 4:1. The treatments incubated at 37°C were quantified for diesel-tolerant bacteria, and treatments incubated at 25°C were quantified for diesel-tolerant fungi. Mushroom substrate participated in the biostimulation (91% organic material, 0.56% total nitrogen and 0.3% phosphorus) and bioaugmentation of the microorganisms of the mirocosm. Bacteria-tolerant populations increased significantly (p = 0.000) in all the treatments. Lacasses (8.62 U g^-1) activity was stimulated at 25°C and was the only one related to biodegradation; however, the highest biodegradation rate (72%) was at 37°C (bacterial biodegradation) being promising for future research.

Keywords: Bioremediation, diesel, laccase, veratryl alcohol oxidase, Pleurotus ostreatus.

African Journal of Biotechnology, Vol 13(31) 3385-3393