Inhibition of methanogenesis by ethylene and other unsaturated hydrocarbons : (Methanogenic degradation; selective inhibition; sulfate reduction; ethylene; acetylene; aromatic hydrocarbons)
نویسنده
چکیده
Ethylene (ethene) was found to inhibit methane formation in slurries from sewage sludge and sediment samples taken from freshwater and marine sources. Methane formation from sediment contents was inhibited by 50% at 0.07% ethylene concentration in the gas phase (approx. 5 #moll -1 in the aqueous phase) and by 94% at >i 0.5% ethylene in the gas phase (>1 36 #mol. 1-1 in the aqueous phase). Sulphate reduction was not impaired. Methane formation from added acetate, hydrogen or methanol was inhibited by >1 98%, from lactate by about 90%. The inhibition was reversible, and methanogenic activity recuperated completely after ethylene removal. Cyclopentadiene and cycloheptatriene led to strong inhibition; benzene, toluene, isoprene, and 1-hexine to moderate inhibition of methanogenesis; several unsaturated linear hydrocarbons were without effect. Pure cultures of Methanospirillum hungatei, Methanothrix soehngenii, and Methanosarcina barkeri were all inhibited by 50% at 0.05-0.1% ethylene concentration in the gas phase (3.6-7.2 /zmol. 1-1 in the aqueous phase). Pure cultures of Acetobacterium woodii, Halobacterium halobium and Sulfolobus acidocaldarius were not significantly inhibited by either ethylene or acetylene. Ethylene is recommended as a selective inhibitor of methanogenesis for physiological and enrichment experiments with sediment and sludge sampies.
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