Community Structure of Bacteria and Archaea Associated with Geotextile Filters in Anaerobic Bioreactor Landfills

Abstract

Landfills are an example of an environment that contains highly complex communities of microorganisms. To evaluate the microbial community structure, four stainless steel pilot-scale bioreactor landfills with single- and double-layered geotextile fabric were used. Two reactors (R-1 and R-2) contained municipal solid waste (MSW) and sewage sludge, while the other two reactors (R-3 and R-4) contained only MSW. A single layer of geotextile fabric (R2GT3 and R3GT3) was inserted in the drainage layers of the two reactors (R-2 and R-3), while a double layer of geotextile fabric (R4GT2 and R4GT1) was inserted in one of the reactors (R-4). Scanning electron microscopy demonstrated that biomass developed on the geotextile fabrics after 540 days of bioreactor operation. The metagenomics analyses of the geotextile samples by 16S rRNA gene sequencing indicated that the geotextile bacterial communities were dominated by the phyla Firmicutes, Bacteroidetes, and Thermotogeae, while Proteobacteria were detected as the rarest bacterial phylum in all the geotextile samples. Treponema, Caldicoprobacter, and Clostridium were the most dominant anaerobic and fermentative bacterial genera associated with the geotextile fabric in the bioreactors. Euryarchaeota was the predominant archaean phylum detected in all the geotextile samples. In the archaeal communities, Methanosarcina, and Vadin CA11 were identified as the predominant genera. The diversity of microorganisms in landfill bioreactors is addressed to reveal opportunities for landfill process modifications and associated operational optimization. Thus, this study provides insights into the population dynamics of microorganisms in geotextile fabrics used in bioreactor landfills.

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“…The amplification protocol included a 3 min incubation at 95 • C followed by 35 cycles of 95 • C for 30 s, 55 • C for 30 s, and 72 • C for 1 min, and a final 3 min extension at 72 • C. Targeted variable regions (V3-V5) of the archaeal 16S rRNA gene were amplified with the MiSeq primer pair 519F and 915R [51]. This set of primers (519F/915R) offers the highest resolution for archaebacterial diversity analysis [51,[53][54][55]. The mastermix was performed as mentioned above, and the protocol was as follows: The resulting amplicons were then separated in a 1.5% (w/v) agarose gel in TAE buffer (40 mM Tris-acetate, 1 mM EDTA), while the product, with a length of approximately 550 bp was visualized in Bio-Rad's Gel Doc XR+ system (Bio-Rad, Hercules, CA, USA).…”

“…Targeted variable regions (V3–V5) of the archaeal 16S rRNA gene were amplified with the MiSeq primer pair 519F and 915R [ 51 ]. This set of primers (519F/915R) offers the highest resolution for archaebacterial diversity analysis [ 51 , 53 , 54 , 55 ]. The mastermix was performed as mentioned above, and the protocol was as follows: 3 min denaturation at 95 °C; 35 cycles of 95 °C for 20 s, 57 °C for 15 s and 72 °C for 45 s, and 3 min of final elongation step at 72 °C.…”