Taxonomic and functional diversity of the microbiome in a jet fuel contaminated site as revealed by combined application of in situ microcosms with metagenomic analysis

•Highly Moraxellaceae-enriched sediment suggest aerobic degradation at source-zone edge.•Metabolic potential for BTEX degradation in groundwater assessed by in situ microcosm.•Highly Peptococcaceae-enriched in situ microcosms confirm syntrophy.•Anaerobic degradation in groundwater occurs coupled to sulfate and/or iron reduction.•Fumarate addition, hydroxylation and carboxylation activation mechanisms presented.