Microbial structure and diversity in non-sanitary landfills and association with physicochemical parameters

Abstract

This study assessed the bacterial populations in a non-sanitary landfill around Guarani Aquifer recharge zone in Brazil. Samples from two different positions (sites 1 and 2) at three different depths were evaluated, totaling six solid waste samples; two samples from an impacted stream were also collected. 16S rRNA sequencing was performed using the Ion S5TM XL platform; 3113 operational taxonomic units (OTUs) and 52 phyla were identified. Proteobacteria (37%) and Firmicutes (28%) were the most abundant phyla in the landfill, whereas Proteobacteria (~50%) and Bacteroidetes (~10%) were more profuse in surface water samples. Canonical correlation analysis (CCA) enabled us to clearly separate the samples according to their spatial location (site 1 or 2) or environmental matrix (surface water or solid waste samples), showing that microbiological populations are strongly associated with site-specific conditions and the kind of environmental matrix they come from. Environmental factors that mostly influenced the microbial communities were organic matter, oxidation-reduction potential, moisture, alkalinity, nitrogen (TKN), sodium, potassium, and zinc. Exiguobacterium (phylum Firmicutes) was overwhelmingly dominant at site 1 and was associated with higher concentrations of organic matter and potassium. Differently, site 2 did not present such dominant genera and was more diverse having lower concentrations of organic matter and nutrients. Distinct environments co-exist inside the same waste deposit, including zones which are representative of active and closed landfills and the occurrence of considerable physicochemical and microbiological shifts within short distances. Those shifts indicate that microbial populations are well adapted to the heterogeneity typical of urban solid waste, which is possibly beneficial to contaminant degradation.

Effects of Capping on Microbial Populations and Contaminants Immobilization in an Old Unlined Landfill

“…Similarly, the genus Gelria has been reported as in the metabolism of fatty acids, in the nal stages of fermentation (Fitzgerald et al, 2019) and in reducing land ll zones with higher organic matter and K content (Morita et al, 2020c). This genus was more abundant in samples located in capped zones and in F12, showing its greater relevance in methanogenic conditions.…”

Metagenomics Analysis Reveals the Microbial Communities, Antimicrobial Resistance Gene Diversity and Potential Pathogen Transmission Risk of Two Different Landfills in China

“…Proteobacteria was the most abundant group in both landfill samples, and was overwhelmingly abundant in the SZ landfill (67.59%) (Figure 2a). A high abundance of Proteobacteria was previously found in landfills [28][29][30], which could play a vital role in organic matter degradation [28]. For instance, Zainun et al [29] found that Proteobacteria were predominant in both active and closed non-sanitary landfills, and within this phylum, Gammaproteobacteria were the most abundant class detected in the active landfill, indicating their potential role in the decomposition of organic matter.…”