Microbial chain elongation (CE) has been shown at laboratory scale to drive reductive dehalogenation (RD) of chlorinated ethenes through both primary (oxidation of ethanol) and secondary (fermentation of medium chain carboxylates) hydrogen (H2) production. This process can offer engineers a sustainable in situ bioremediation alternative to address the challenges of conventional treatment technologies and processes. To aid in moving this process into field scale applications, a greater understanding of the specific microbiomes involved in both primary and secondary processes is needed. In this study, microbial community analysis was conducted on groundwater microcosms under various CE substrate combinations to quantify the extent of CE and the effect on RD of cis-1,2-dichloroethene (cis-DCE). Taxonomic classification of amplicon sequence variants obtained from DNA extracted from groundwater microcosms were used to characterize microbiomes using QIIME 2. Pielou’s eveness and beta diversity (via unweighted UniFrac distances) analyses were performed to assess the diversity of microbiomes. Overall, low concentration microcosms (excluding L-7:1 EtOH:Butyrate and L-9:1 EtOH:Acetate + Soil) underwent complete RD, as evidenced by significant ethene production. Alpha and beta diversity analyses confirm the findings of chemical data that the overall substrate concentrations played a major role in determining the extent of CE and RD.

Important antibiotics in human medicine have been used for many decades in animal agriculture for growth promotion and disease treatment. Several publications have linked antibiotic resistance development and spread with animal production. Aquaculture, the newest and fastest growing food production sector, may promote similar or new resistance mechanisms. This review of 650+ papers from diverse sources examines parallels and differences between land-based agriculture of swine, beef, and poultry and aquaculture. Among three key findings was, first, that of 51 antibiotics commonly used in aquaculture and agriculture, 39 (or 76%) are also of importance in human medicine; furthermore, six classes of antibiotics commonly used in both agriculture and aquaculture are also included on the World Health Organization’s (WHO) list of critically important/highly important/important antimicrobials. Second, various zoonotic pathogens isolated from meat and seafood were observed to feature resistance to multiple antibiotics on the WHO list, irrespective of their origin in either agriculture or aquaculture. Third, the data show that resistant bacteria isolated from both aquaculture and agriculture share the same resistance mechanisms, indicating that aquaculture is contributing to the same resistance issues established by terrestrial agriculture. More transparency in data collection and reporting is needed so the risks and benefits of antibiotic usage can be adequately assessed.

Processed municipal sewage sludges (MSS) are an abundant, unwanted by-product of wastewater treatment, increasingly applied to agriculture and forestry for inexpensive disposal and soil conditioning. Due to their high organic carbon and lipid contents, MSS not only is rich in carbon and nutrients but also represents a “sink” for recalcitrant, hydrophobic, and potentially bioaccumulative compounds. Indeed, many organics sequestered and concentrated in MSS meet the US Environmental Protection Agency’s definition of being persistent, bioaccumulative, and toxic (PBT). In a strategic effort, our research team at the Biodesign Institute has created the National Sewage Sludge Repository (NSSR), a large repository of digested MSSs from 164 wastewater treatment plants from across the USA, as part of the Human Health Observatory (H2O) at Arizona State University (ASU). The NSSR likely represents the largest archive of digested MSS specimens in the USA. The present study summarizes key findings gleaned thus far from analysis of NSSR samples. For example, we evaluated the content of toxicants in MSS and computed estimates of nationwide inventories of mass produced chemicals that become sequestrated in sludge and later are released into the environment during sludge disposal on land. Ongoing efforts document co-occurrence of a variety of PBT compounds in both MSS and human samples, while also identifying a large number of potentially harmful MSS constituents for which human exposure data are still lacking. Finally, we summarize future opportunities and invite collaborative use of the NSSR by the research community. The H2O at ASU represents a new resource and research tool for environmental scientists and the larger research community. As illustrated in this work, this repository can serve to (i) identify and prioritize emerging contaminants, (ii) provide spatial and temporal trends of contaminants, (iii) inform and evaluate the effectiveness of environmental policy-making and regulations, and (iv) approximate, ongoing exposures and body burdens of mass-produced chemicals in human society.