Vertical distribution of methanogens in the anoxic sediment of Rotsee (Switzerland)

Article Abstract:

Anoxic sediments from Rotsee, Switzerland, were analyzed for the presence and diversity of methanogens by using molecular tools and for methanogenic activity by using radiotracer techniques, in addition to the measurement of chemical profiles. Discriminative oligonucleotide probes were used for the analysis of indigenous methanogens in a core of the anoxic sediment, in addition to domain-specific probes against members of the domains Bacteria and Archaea. Significant hydrogenotrophic methanogenesis was found in the organically enriched upper 2 centimeters of the sediment.

Analysis, Usage, Switzerland, Natural history, Nucleic acid probes, Sediments (Geology)

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Influence of pH on ammonia accumulation and toxicity in halophilic, methylotrophic methanogens

Article Abstract:

Negative membrane pH gradients during growth of three types of halophilic, methylotrophic methanogens cause accumulation of ammonium (NH4+) ions. Concentrations of two to five mM of un-ionized ammonia is toxic for Methanolobus bombayensis and M. taylorii, and reduce their growth by 50% regardless of external pH. Methanohalophilus zhilinaeae exhibits the highest resistance to un-ionized ammonia among all known organisms, the 50% inhibitory concentration for un-ionized ammonia being 13 mM at pH 8.5 and 45 mM at pH 9.5.

Physiological aspects, Observations, Ammonium, Bioaccumulation, Hydrogen-ion concentration

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Methanotrophs and methanogens in masonry

Article Abstract:

Measurements of biogenic methane production in samples of stone masonry from 19 historical buildings in Germany and Italy, indicated the presence of methanotrophic bacteria in 48 of the 225 samples. The strains of methane-oxidizing bacteria isolated from the stone samples are members of the type II methanotrophs of the genera Methylocystiis, Methylosinus and Methylobacterium. Findings showed that methanotrophs in building stones use the methane produced by methane-producing bacteria as a carbon and energy source.

Masonry, Building stones, Building stone

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