Distinct Microbiomes Identified in Landfills Throughout the United States

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A comprehensive study by U.S. Geological Survey (USGS) and scientists from the University of Oklahoma finds distinct microbial assemblages (microbiomes) in landfill leachate across the United States and investigates factors related to microbiome formation.

New section of a landfill under construction

New section of a landfill under construction. Photo Credit: Dana W. Kolpin, USGS.

Unlike previous studies investigating the microbiomes of landfills, the national study described here is the first to investigate microbiomes associated with leachate samples from 19 municipal landfills across 16 States using high-throughput sequencing of 16S ribosomal ribonucleic acid (rRNA) gene libraries. Species richness, evenness, and shared diversity in landfill leachate samples were used to understand differences between landfill microbiomes and those of other previously measured environments and to understand differences among landfills.

Scientists found that the municipal landfill leachate contained a diverse microbiome essentially distinct from any of the other ecosystems used for comparison (sediments, soils, fresh water, salt water, bogs, permafrost, humans, and canines) confirming that physical and chemical factors influencing microbiome composition are unique in landfills as compared to other environments.

USGS scientist sampling landfill leachate at the closed Norman Landfill, Norman, Oklahoma

USGS scientist sampling landfill leachate at the closed Norman Landfill, Norman, Oklahoma. Photo Credit: Jason R. Masoner, USGS.

Scientists also found that the landfills clustered into different groups based on microbiome composition prompting questions about the factors related to microbiome composition. Numerous factors were related to the microbial composition among the groups including the concentration of barium and chloride, the rate of evapotranspiration, the age of waste, and the number of household chemicals detected. This baseline information provides the necessary first step to more fully understand the factors that affect microbiome composition in landfills that is important for understanding biodegradation processes

Microorganisms have varying abilities to degrade incoming waste because of the complex mixture of chemicals present, shifting chemical profiles, toxicity associated with wastes, and succession of landfill phase changes. The microbiomes present in leachate could one day benefit bioremediation efforts, bio-industrial processes, and the discovery of new natural products though further research is needed.

This research follows and advances previous national-scale research on the characterization of contaminants of emerging concern (CECs) in leachate prior to treatment or storage processes (that is, fresh leachate) as well as leachate that have undergone treatment or storage process (that is, final leachate).

This research was funded by the USGS Ecosystems Mission Area’s Environmental Health Program (Contaminant Biology and Toxic Substances Hydrology).