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Analysis of methanotrophic bacteria in Movile cave by stable-Isotope Probing

Domenii publicaţii > Biologie + Tipuri publicaţii > Articol în revistã ştiinţificã

Autori: Hutchens, E., Radajewski, S., Dumont, M., McDonald, I. R., Murrell, J. C.

Editorial: Environmental Microbiology, 6(2), p.111-120, 2004.

Rezumat:

Movile Cave is an unusual groundwater ecosystem that is supported by in situ chemoautotrophic production. The cave atmosphere contains 1-2% methane (CH4), although much higher concentrations are found in gas bubbles which keep microbial mats afloat on the water surface. Since previous analyses of stable carbon isotope ratios have suggested that methane oxidation occurs in this environment, we hypothesised that aerobic methane oxidising bacteria (methanotrophs) are active in Movile Cave. To identify the active methanotrophs in the water and mat material from Movile Cave, a microcosm was incubated with a 10%13CH4 headspace in a DNA-based stable isotope probing (DNA-SIP) experiment. Using improved centrifugation conditions, a 13C-labelled DNA fraction was collected and used as a template for PCR amplification. Analysis of genes encoding the small-subunit rRNA and key enzymes in the methane oxidation pathway of methanotrophs identified that strains of Methylomonas, Methylococcus and Methylocystis/Methylosinus had assimilated the 13CH4, and that these methanotrophs contain genes encoding both known types of methane monooxygenase (MMO). Sequences of non-methanotrophic bacteria and an alga provided evidence for turnover of CH4 due to possible cross-feeding on 13C-labelled metabolites or biomass. Our results suggest that aerobic methanotrophs actively convert CH4 into complex organic compounds in Movile Cave, and thereby help to sustain a diverse community of microorganisms in this closed ecosystem

Cuvinte cheie: Pestera Movile, isotopi stabili, bacterii metanotrofe, metan monooxigenaxa, gena functionala, Methylomonas, // Movile Cave, stable isotope probing, methanotrophs, methane monooxygenase, functional gene, Methylomonas