Enrichment and activity of methanotrophic microorganisms from municipal wastewater sludge

Abstract

In this study, methanotrophic microorganisms were enriched from a municipal wastewater sludge taken from an Upflow Anaerobic Sludge Blanket reactor. The enrichment was performed in a sequencing batch reactor (SBR) with an autotrophic medium containing nitrite and nitrate. The microbial community composition of the inoculum and of the enrichment culture after 100 days of SBR operation was investigated and compared with the help of data obtained from 454 pyrosequencing analyses. The nitrite and nitrate removal efficiencies were 68% and 53%, respectively, probably due to heterotrophic denitrification. Archaeal cells of the anaerobic methanotrophic Archaic (ANME)-I and ANME-II groups were detected by polymerase chain reaction throughout the whole cultivation period. Pyrosequencing analysis showed that community composition was different among the two samples analysed. The dominant phyla found in the inoculum were Synergistestes, Firmicutes and Euryarchaeota, while Planctomycetes, Verrucomicrobia, Chloroflexi and Proteobacteria prevailed in the enriched biomass. The cultivation conditions decreased Methanobacterium abundance from 8% to 1%, and enriched for methanotrophic bacteria such as Methylocaldum, Methylocistis and Methylosinus. Sequences of Methylocaldum sp. accounted for 2.5% of the total reads. The presence and high predominance of Verrucomicrobia in the enriched biomass suggested that other unknown methanotrophic species related to that phylum might also have occurred in the reactor. Anaerobic methane oxidation activity was measured for both samples, and showed that the activity of the enrichment culture was nearly three times higher than the activity of the inoculum. Taken together, these results showed that the inoculum type and cultivation conditions were properly suited for methanotrophic enrichment.

Enrichment of anaerobic nitrate-dependent methanotrophic ‘Candidatus Methanoperedens nitroreducens’ archaea from an Italian paddy field soil

“…Metagenome analysis revealed that only a few phyla other than ‘ Candidatus Methanoperedens nitroreducens’ and NC10 phylum bacteria were represented in greater than 5% abundance. Anaerolineales (8.5% abundance) belonging to Chloroflexi are obligate anaerobes that have previously been observed in anaerobic methanotrophic (Ettwig et al 2009a ; Siniscalchi et al 2015 ) and methanogenic enrichment cultures (Gray et al 2011 ; Liang et al 2015 ; Yamada et al 2005 ). Anaerolineales may be responsible for the degradation of n -alkanes and release formate, acetate, hydrogen, and carbon dioxide.…”

Removal performance and microbial communities in a sequencing batch reactor treating hypersaline phenol-laden wastewater

“…454 pyrosequencing is one of the popular high throughput sequencing analytical approaches which can sequence a certain number of DNA samples at the same time in one run (Ye and Zhang, 2013). The application of 454 pyrosequencing to evaluate microbial richness and 5 structure have been found in studies of SBR, membrane bioreactor (MBR), and many other biological wastewater treatment systems (Ng et al, 2015;Siniscalchi et al, 2015).…”

Diversity, enrichment, and genomic potential of anaerobic methane- and ammonium-oxidizing microorganisms from a brewery wastewater treatment plant

“…Further significant numbers of Chloroflexi were present. They are obligate anaerobes that have previously been found in both anaerobic methanotrophic (Ettwig et al 2009 ; Siniscalchi et al 2015 ) and methanogenic enrichment cultures (Yamada et al 2005 ; Gray et al 2011; Liang et al 2015). These Chloroflexi may degrade organic acids to formate, acetate, and hydrogen and feed the other community members (Hug et al 2013 ).…”