Diversity and enrichment of nitrite-dependent anaerobic methane oxidizing bacteria from wastewater sludge.
Bottom Line: This enrichment was monitored using specific pmoA primers and M. oxyfera cells were visualized with fluorescence oligonucleotide probes.After 112 days, the enrichment consumed up to 0.4 mM NO(2)(-) per day.The results of this study show that appropriate sources of biomass, enrichment strategies, and diagnostic tools existed to start and monitor pilot scale tests for the implementation of nitrite-dependent methane oxidation in wastewater treatment at ambient temperature.
Affiliation: Department of Microbiology, Institute for Water and Wetland Research, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.Show MeSH
Mentions: In order to get an impression of the relative abundance of M. oxyfera cells compared to the other community members, fluorescence in situ hybridization (FISH) was performed using general and specific probes (Fig. 3). No M. oxyfera-type bacteria could be detected in the inoculum (Fig. 3a), probably because the number of cells was below detection level (Amann et al. 1995). This is consistent with the 16S rRNA and pmoA phylogenetic analysis (see above). Although PCR is a more sensitive technique compared to FISH, a nested PCR approach was necessary to detect M. oxyfera-type bacteria in the inoculum. After 64 days of cultivation in the 3-l bioreactor, approximately 2–3% of the microbial community hybridized with specific probes for M. oxyfera (Fig. 3b). After 308 days, the M. oxyfera population was enriched for approximately 60–70% (Fig. 3c). The enriched bacteria appeared to grow mainly in clusters, but some single cells were also visible as observed previously (Ettwig et al. 2009).Fig. 3
Affiliation: Department of Microbiology, Institute for Water and Wetland Research, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.