Municipal Solid Waste Landfills Harbor Distinct Microbiomes.

Blake W Stamps,Bradley S Stevenson,Christopher N Lyles,Isabelle M Cozzarelli,Joseph M Suflita,Jason R Masoner,Dana W Kolpin

doi:10.3389/fmicb.2016.00534

Blake W Stamps, Bradley S Stevenson + Show 5 more

Open Access

https://doi.org/10.3389/fmicb.2016.00534

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Abstract

Landfills are the final repository for most of the discarded material from human society and its “built environments.” Microorganisms subsequently degrade this discarded material in the landfill, releasing gases (largely CH4 and CO2) and a complex mixture of soluble chemical compounds in leachate. Characterization of “landfill microbiomes” and their comparison across several landfills should allow the identification of environmental or operational properties that influence the composition of these microbiomes and potentially their biodegradation capabilities. To this end, the composition of landfill microbiomes was characterized as part of an ongoing USGS national survey studying the chemical composition of leachates from 19 non-hazardous landfills across 16 states in the continental U.S. The landfills varied in parameters such as size, waste composition, management strategy, geography, and climate zone. The diversity and composition of bacterial and archaeal populations in leachate samples were characterized by 16S rRNA gene sequence analysis, and compared against a variety of physical and chemical parameters in an attempt to identify their impact on selection. Members of the Epsilonproteobacteria, Gammaproteobacteria, Clostridia, and candidate division OP3 were the most abundant. The distribution of the observed phylogenetic diversity could best be explained by a combination of variables and was correlated most strongly with the concentrations of chloride and barium, rate of evapotranspiration, age of waste, and the number of detected household chemicals. This study illustrates how leachate microbiomes are distinct from those of other natural or built environments, and sheds light on the major selective forces responsible for this microbial diversity.

Highlights

The global upsurge in urbanization of the human population is associated with even greater increases in the generation of municipal solid waste (MSW)
We investigated the connection between microbial communities in landfill leachates and several operational and environmental variables, as part of a broader study (Masoner et al, 2014)
The landfill leachates from ME1, ME2, ME3, MN, VT, and IA contained the highest relative abundance of Epsilonproteobacteria (>15%), which were composed almost entirely of members of the order Campylobacterales (Figure 2B)

Summary

Introduction

The global upsurge in urbanization of the human population is associated with even greater increases in the generation of municipal solid waste (MSW). The degradation of organic matter in landfills is broadly characterized by a succession of phases that result in the conversion of the waste materials to mineralized end products like water, CO2, and CH4 (Palmisano and Barlaz, 1996). Complex assemblages of bacteria and archaea carry out the majority of MSW degradation These syntrophic consortia are far more capable of mineralizing the myriad of organic substances deposited in landfills than single microorganisms or populations. Both chemical profiles and microbial community composition change during the biodegradation of MSW, but the general patterns are consistent with the anaerobic cycling of organic matter (McInerney et al, 2009). The shifting, heterogeneous physical and chemical profiles of landfills are certainly a main reason why they are home to such a diverse assemblage of microorganisms exhibiting a broad range of metabolic activities (Mori et al, 2003; Gomez et al, 2011; Lu et al, 2012)

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