The addition of Glomalin-related soil protein and functional microbial consortium increased bound PAH residue degradation in soil

Bound Polycyclic Aromatic Hydrocarbons (PAHs) residues are the "end point" of soil pollution remediation. However, bound PAH residues can be released and become bioavailable exerting ecological and human health impacts. Remediation of soils contaminated with bound PAHs is a critical pollution control issue that support safe and healthy agricultural production We conducted microcosmic experiments to study the degradation of bound PAH residues in the soil by exogenous functional microbial consortium with and without the addition of glomalin-related soil protein (GRSP). Our results showed limited degradation of bound PAHs by the functional microbial consortium, however, a high concentration of 1000 mg/kg could accelerate the process. The removal rates of low molecular weight PAHs, medium molecular weight PAHs, high molecular weight PAHs, and total PAHs increased by 6.6%-14.2%, 8.2%-14.6%, 5.2%-7.5% and 6.7%-12.0%, respectively. The application of high-concentration GRSP increased the content of PAHs degrading bacteria such as Sphingomonas and Arthro-bacter in soil and the abundance of some vital functional genes during PAH biodegradation (phe, nahAc, and nidA) thus promoting the degradation of bound PAHs residues. This study fills the cognitive gap of GRSP in regulating the degradation of bound PAH residues in soil, and provides an important basis for the subsequent development of bound PAH residue removal technology. These findings contribute to our understanding of the role of GRSP in regulating the degradation of soil-bound PAHs.