The in situ bioremediation of polycyclic aromatic hydrocarbons (PAHs) at hazardous waste sites has many unresolved research gaps including the identification of optimal methods for translating laboratory techniques to the field and for quantifying biodegradation potential in complex soil matrices. Here, we detail the use of a molecular tool to monitor the dissemination of PAH-degrading catabolic genes to quantify and track biodegradation potential. In addition, we present simultaneous efforts to increase the efficacy and efficiency of bioremediation through targeted bioaugmentation and biostimulation strategies. This experimental design takes fundamental methods, such as high-throughput sequencing and targeted molecular techniques, and applies them to the field. For these experiments, a set of triplicate 8 L glass reactors were constructed and filled with soil collected from Holcomb Creosote Superfund Site, a former wood treatment facility contaminated with high levels of creosote and heavy metals. Holcomb soil samples were analyzed for PAHs and metals and the microbial community was assessed through Illumina MiSeq sequencing. The samples present a gradient of PAH and metal co-contamination. Using Spearman correlation analysis, we correlated changes in taxonomic biodiversity to chemical variations to identify potential microbial targets for bioremediation. From this analysis, an engineered microbial consortium framework was developed for biostimulation ( with Geobacter), bioaugmentation (with Arthrobacter nitroguajacolicus and Pseudomonas xanthomarina (4M14)), and genetic bioaugmentation (with Sphingomonas aromaticivorans F199 and Sphingomonas sp. strain KS14). As the strains in the consortium harbor catabolic genes responsible for the degradation of PAHs, novel qPCR probes were developed to detect horizontal gene transfer events and quantify increases in gene abundance. This allows for the rapid and simple identification of an increase in catabolic genes normalized to an increased in microbial growth (i.e., an increase in overall biodegradation potential) in contaminated and complex soil matrices. Data on the biodegradation potential, prokaryotic population dynamics, and chemical degradation rates will be presented. Overall, we expect our experimental design to aid in the monitoring and implementation of field-level bioremediation strategies.

Enhanced bioremediation of PAH contaminated soils: Combining novel molecular techniques with targeted bioaugmentation strategies

253rd National Meeting (2017)

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