Shotgun metagenomics of indigenous bacteria collected from the banks of the San Jacinto River for biodegradation of aromatic waste

ABSTRACT Several Eastern Harris County communities lie near the now enclosed San Jacinto River (SJR) Waste Pit Superfund, a dumping ground for chlorinated dioxins and other paper mill waste products. Currently, no active monitoring of the SJR is conducted for these toxins with the exact concentration and health impact to the area unknown. As such, remediation and monitoring efforts outside of the Superfund itself could be necessary. To better understand the possible environmental fate of these aromatics, here we provide a shotgun metagenomic analysis of the structural and putative functional diversity of the SJR microbiome from two impacted Channelview, Texas communities bordering the Superfund. Results show that the underlying SJR microbiome possesses a core of metabolic enzymes related to the β-ketoadipate and benzoate degradation pathways. This suggests possible endpoints for many aromatics found deposited in the SJR including dioxin-like compounds. However, degradation biomarkers related to the priming and initial cleavage of chlorinated dioxin-like aromatics while present, are poorly concentrated across sampled sites. This may be due in part to decreased coverage of low abundance bacterial species, but also be a contributing factor leading to increased recalcitrance of these compounds in this environment compared to other aromatics.