Metagenomic Analysis of Bacterial Communities from a Nitrification–Denitrification Treatment of Landfill Leachates

Abstract

The efficiency of the biological removal of carbon and nitrogen from leachates is determined by the activity of microbial populations present in biological reactors. In this work, a complete characterization of bacterial communities revealed by personal genome machine sequencing (PGM) has been carried out from different points of a nitrification–denitrification process operated in an urban landfill. The leachate fed to the treatment is a mixture of young leachate, old leachate, and effluent from an anaerobic digestion process, in a volume ratio of 1:0.9:0.12, respectively. The anoxic and oxic reactors are followed by an ultrafiltration step. Samples are taken from different points of the process. Results reveal the microbial diversity of the samples, which include detection of minority populations that are difficult to explore by other methods. Bacteria belonging to Bacteroidetes and Proteobacteria are dominant in all the samples analyzed. Proteobacteria represents more than 50% of the total population in all cases. Samples taken after the biological treatment show a significant reduction in the relative abundance of Firmicutes, Tenericutes, and Lentisphaerae phyla in comparation with the initial leachate. The relative abundance of the classes is also studied and the most abundant in the samples are β‐Proteobacteria and Flavobacteria.

Potential Environmental and Human Health Risks Caused by Antibiotic-Resistant Bacteria (ARB), Antibiotic Resistance Genes (ARGs) and Emerging Contaminants (ECs) from Municipal Solid Waste (MSW) Landfill

“…The microbial taxa also play a major role in ARG distribution in the landfill and nearby environments [ 53 ]. Hence, several crucial factors like MGEs, heavy metals, landfill ages, antibiotics, and microbial diversity are important players in the abundance and dissemination of ARGs in landfill leachate associated with agro- and aquaculture [ 52 , 54 , 55 , 56 ]. Enterococcus faecalis isolated from a contaminated dumpsite showed 100% resistance to chloramphenicol, erythromycin, and tetracycline [ 57 ] and showed that the antibiotic and metal resistance genes are frequently carried on the MGEs.…”

Simultaneous Stripping of Ammonia from Leachate: Experimental Insights and Key Microbial Players

“…Additionally, Firmicutes are able to survive hyper-salinity conditions, by producing endospores in especially severe periods [2,34,35]. Díaz et al [53] studied bacterial communities in samples taken from different points of LFL treating Nitrification-Denitrification system. Bacteroidetes and Proteobacteria were dominant in all the samples analyzed.…”

Metagenomic Insights Into Functional and Taxonomic Compositions of an Activated Sludge Microbial Community Treating Leachate of a Completed Landfill: A Pathway-Based Analysis

“…Therefore, feasibility assessments based on the metagenome will help to establish innovative bioprocesses for valuable product biosynthesis. However, this approach has not been applied to a bioreactor for nitrification and denitrification in landfill leachate containing high concentrations of ammonia (e.g., several hundred mg N/L) and salt (above > 1%; Díaz et al, 2019;Shu et al, 2019). This study, therefore, advocates a rapid screening procedure based on the gene-centric analysis from metagenomic data in a simple manner.…”