Effect of soil organic matter (SOM) on the degradation of polycyclic aromatic hydrocarbons using Pleurotus dryinus IBB 903-A microcosm study.

Bioremediation of polycyclic aromatic hydrocarbons (PAHs) in soil matrix is often arbitrated by the presence of soil organic matter (SOM). The present study focuses on determining the effect of the soil organic content on the mycoremediation of two model PAHs, phenanthrene (Phe) and benzo(a) pyrene (BaP) through microcosm studies. On comparing various microcosm strategies, a maximum degradation of Phe (99%) and BaP (48.5%) in soil bioaugmented with Pleurotus dryinus IBB 903, followed by, biostimulation with the degradation of Phe (89.9%) and BaP (24.8%) were noted. On relating the degradation pattern with lignolytic enzyme cocktail production, a laccase activity of 108 U/Kg at day 21, aryl alcohol oxidase (411 U/Kg) and manganese peroxidase (52.2 U/Kg) at day 14 along with lignin peroxidase (481 U/Kg) at day 21 were noted in fungal augmented soils, which were comparatively higher than levels observed in the bio-stimulation. Investigating the impact of different concentration of SOM (3-12%), a maximum remediation of Phe by 100% at 9% SOM in days 28 and 58.19% for BaP at 12% SOM, respectively was exhibited. Further, the biosorption effect of PAHs in abiotic condition showed a positive correlation with the increase in SOM, with a maximum adsorption of 3.78% Phe, and 6.93% BaP. The results support that the nominal adsorption ability of SOM, and helps in enhancing the microbial growth, thereby improving their degradation potentials, when less than 6% of SOM was utilized. Overall, this work establishes the critical role of organic matter in the soil with reference by simultaneous stimulation and degradation capability in complete PAHs remediation.