Effects of Facilitated Bacterial Dispersal on the Degradation and Emission of a Desorbing Contaminant

The quantitative relationship between a compound's availability for biological removal and ecotoxicity is a key issue for retrospective risk assessment and remediation approaches. Here, we investigated the impact of facilitated bacterial dispersal at a model soil atmosphere interface on the release, degradation, and outgassing of a semivolatile contaminant. We designed a laboratory microcosm with passive dosing of phenanthrene (PHE) to a model soil atmosphere interface (agar surface) in the presence and absence of glass fibers known to facilitate the dispersal of PHE-degrading Pseudomonas fluorescens LP6a. We observed that glass fibers (used as a model to mimic a fungal hyphal network) resulted in (i) increased bacterial surface coverage, (ii) effective degradation of matrix-bound PHE, and (iii) substantially reduced PHE emission to locations beyond the contamination zone even at low bacterial surface coverage. Our data suggest that bacterial dispersal networks such as mycelia promote the optimized spatial arrangement of microbial populations to allow for effective contaminant degradation and reduction of potential hazard to organisms beyond a contaminated zone.