Molecular Analysis of Methanogen Richness in Landfill and Marshland Targeting 16S rDNA Sequences

Abstract

Methanogens, a key contributor in global carbon cycling, methane emission, and alternative energy production, generate methane gas via anaerobic digestion of organic matter. The methane emission potential depends upon methanogenic diversity and activity. Since they are anaerobes and difficult to isolate and culture, their diversity present in the landfill sites of Delhi and marshlands of Southern Assam, India, was analyzed using molecular techniques like 16S rDNA sequencing, DGGE, and qPCR. The sequencing results indicated the presence of methanogens belonging to the seventh order and also the order Methanomicrobiales in the Ghazipur and Bhalsawa landfill sites of Delhi. Sequences, related to the phyla Crenarchaeota (thermophilic) and Thaumarchaeota (mesophilic), were detected from marshland sites of Southern Assam, India. Jaccard analysis of DGGE gel using Gel2K showed three main clusters depending on the number and similarity of band patterns. The copy number analysis of hydrogenotrophic methanogens using qPCR indicates higher abundance in landfill sites of Delhi as compared to the marshlands of Southern Assam. The knowledge about “methanogenic archaea composition” and “abundance” in the contrasting ecosystems like “landfill” and “marshland” may reorient our understanding of the Archaea inhabitants. This study could shed light on the relationship between methane-dynamics and the global warming process.

Municipal Solid Waste Landfills Harbor Distinct Microbiomes

“…The landfill in VA, however, contained an OTU most closely related to the candidate genus “ Methanomethylophilus ,” within the order Thermoplasmatales. Interestingly, this candidate genus was also recently detected in a directed search for archaea within a landfill in India (Yadav et al, 2015 ). These close relatives of the genus “ Methanomethylophilus ” were the most abundant methanogens detected across any sample, with a relative abundance of 4.58–5.58% within the VA landfill.…”

Comparative Analysis of Methanogenic Communities in Different Laboratory-Scale Anaerobic Digesters

“…Interestingly, Methanobacterium with T-RF 464/465 negatively correlated with TAN level, pH, and CH 4 content ( p < 0.001), while Methanobacteriaceae with T-RF 471 only negatively correlated with temperature ( p < 0.001). Members of the family Methanobacteriaceae were detected in different anaerobic digesters (e.g., [23, 46]) as well as other environments [56] and in parallel with Methanomicrobiales representatives (e.g., Methanoculleus ) they were reported to be involved in the SAO process at high ammonia levels (>2.8 g TAN L −1 ) [49]. Therefore, SAO can also be assumed in reactors R4.19 and R4.20 fed with Jatropha biomass which operated at elevated levels of TAN (3.2–3.8 g L −1 ; Table S1, SI).…”

“…Methanosarcina spp. are found in various environments [56] and reported to achieve stable growth at high OLR and high levels of ammonium in biogas reactors, indicating their tolerance towards different process impairments [12], and therefore they are frequently found in various biogas reactors (e.g., [8, 14, 47, 55, 58]).…”

Molecular detection of Methylotrophs from an Indian landfill site and their potential for biofuel production

“…About 70-80% of generated MSW is collected, 9% of which is treated through composting and rest is disposed in uncontrolled open landfills. In absence of leachate and landfill gas collection systems, these landfills are a major source of groundwater contamination and generation of greenhouse gases like methane (Yadav et al, 2015). Methane is an important greenhouse gas, because it is 25 times more potent than CO2 in global warming (Yadav et al, 2014).…”

“…They are often found in low-lying open areas, where municipal waste is haphazardly and indiscriminately disposed. These sites neither have landfill lining to avoid percolation of leachate to groundwater table nor leachate collection facility (Yadav et al, 2015). The city of New Delhi generates about 9000 tons of solid waste per day (Gupta et al, 2007).…”