title: Inhibitory effects of sulfur compounds on methane oxidation by a methane-oxidizing consortium.
abstract: Kinetic and enzymatic inhibition experiments were performed to investigate the effects of methanethiol (MT) and hydrogen sulfide (H2S) on methane oxidation by a methane-oxidizing consortium. In the coexistence of MT and H2S, the oxidation of methane was delayed until MT and H2S were completely degraded. MT and H2S could be degraded, both with and without methane. The kinetic analysis revealed that the methane-oxidizing consortium showed a maximum methane oxidation rate (Vmax) of 3.7 mmol g-dry cell weight (DCW)(-1) h(-1) and a saturation constant (Km) of 184.1 μM. MT and H2S show competitive inhibition on methane oxidation, with inhibition values (Ki) of 1504.8 and 359.8 μM, respectively. MT was primary removed by particulate methane monooxygenases (pMMO) of the consortium, while H2S was degraded by the other microorganisms or enzymes in the consortium. DNA and mRNA transcript levels of the pmoA gene expressions were decreased to ∼10(6) and 10(3)pmoA gene copy number g-DCW(-1) after MT and H2S degradation, respectively; however, both the amount of the DNA and mRNA transcript recovered their initial levels of ∼10(7) and 10(5)pmoA gene copy number g-DCW(-1) after methane oxidation, respectively. The gene expression results indicate that the pmoA gene could be rapidly reproducible after methane oxidation. This study provides comprehensive information of kinetic interactions between methane and sulfur compounds.
authors.affiliation: Department of Environmental Science and Engineering, Ewha Womans University, 52 Ewhayeodae-gil, Seodaemun-gu, Seoul 120-750, Republic of Korea.
authors.forename: Eun-Hee
authors.initials: EH
authors.lastname: Lee
authors.affiliation: Department of Environmental Science and Engineering, Ewha Womans University, 52 Ewhayeodae-gil, Seodaemun-gu, Seoul 120-750, Republic of Korea.
authors.forename: Kyung-Eun
authors.initials: KE
authors.lastname: Moon
authors.affiliation: Department of Environmental Science and Engineering, Ewha Womans University, 52 Ewhayeodae-gil, Seodaemun-gu, Seoul 120-750, Republic of Korea.
authors.forename: Tae Gwan
authors.initials: TG
authors.lastname: Kim
authors.affiliation: Department of Environmental Science and Engineering, Ewha Womans University, 52 Ewhayeodae-gil, Seodaemun-gu, Seoul 120-750, Republic of Korea.
authors.forename: Sang-Don
authors.initials: SD
authors.lastname: Lee
authors.affiliation: Department of Environmental Science and Engineering, Ewha Womans University, 52 Ewhayeodae-gil, Seodaemun-gu, Seoul 120-750, Republic of Korea. Electronic address: kscho@ewha.ac.kr.
authors.forename: Kyung-Suk
authors.initials: KS
authors.lastname: Cho
mesh_terms: D004247:DNA / Q000032:analysis / Q000096:biosynthesis; D018628:Gene Dosage; D006862:Hydrogen Sulfide / Q000378:metabolism / Q000494:pharmacology*; D007700:Kinetics; D008697:Methane / Q000378:metabolism*; D059013:Microbial Consortia / Q000187:drug effects* / Q000502:physiology*; D010084:Oxidation-Reduction / Q000187:drug effects; D010105:Oxygenases / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D013438:Sulfhydryl Compounds / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D012333:RNA, Messenger; D013438:Sulfhydryl Compounds; C005231:methylmercaptan; D004247:DNA; D010105:Oxygenases; C021555:methane monooxygenase; D008697:Methane; D006862:Hydrogen Sulfide
keywords: Hydrogen sulfide; Interaction; Methane; Methanethiol; Particulate methane monooxygenases