title: Methanethiol accumulation exacerbates release of N2 O during denitrification in estuarine sediments and bacterial cultures.
abstract: Microbes play critical roles in the biogeochemical cycling of nitrogen and sulfur in aquatic environments. Here we investigated the interaction between the naturally occurring organic sulfur compound methanethiol (MeSH) and the final step of the denitrification pathway, the reduction of nitrous oxide (N2 O) to dinitrogen (N2 ) gas, in sediment slurries from the temperate Douro and Ave estuaries (NW Portugal) and in pure cultures of the marine bacterium Ruegeria pomeroyi. Sediment slurries and cell suspensions were amended with a range of concentrations of either MeSH (0-120 µM) or methionine (0-5 mM), a known precursor of MeSH. MeSH or methionine additions caused N2 O to accumulate and this accumulation was linearly related to MeSH concentrations in both coastal sediments (R(2)  = 0.7-0.9, P < 0.05) and R. pomeroyi cell suspensions (R(2)  = 0.9, P < 0.01). Our results suggest that MeSH inhibits the final step of denitrification resulting in N2 O accumulation.
authors.affiliation: CIMAR/CIIMAR - Centre of Marine and Environmental Research, University of Porto, Rua dos Bragas, n° 289, 4050-123 Porto, Portugal Department of Marine Sciences, University of South Alabama, LSCB 25 Mobile, AL 36688 USA Department of Microbiology, University of Tennessee, M409 Walters Life Sciences Knoxville, TN 37996-0845, USA Laboratory of Hydrobiology, Institute of Biomedical Sciences (ICBAS-UP), University of Porto, Largo Prof. Abel Salazar n° 2, 4099-003 Porto, Portugal Department of Marine Sciences, University of Georgia, Athens, GA 30602, USA.
authors.forename: C
authors.initials: C
authors.lastname: Magalhães
authors.forename: R P
authors.initials: RP
authors.lastname: Kiene
authors.forename: A
authors.initials: A
authors.lastname: Buchan
authors.forename: A
authors.initials: A
authors.lastname: Machado
authors.forename: W J
authors.initials: WJ
authors.lastname: Wiebe
authors.forename: A A
authors.initials: AA
authors.lastname: Bordalo