Oxidation of Trichloroethylene and Dimethyl Sulfide by a MarineMethylomicrobiumStrain Containing Soluble Methane Monooxygenase

Authors:
  • MOMisaki Ohta
    Misaki Ohta
  • OTOsamu Takimura
    Osamu Takimura
  • KMKatsuji Murakami
    Katsuji Murakami
  • HIHiroyuki Inoue
    Hiroyuki Inoue
  • YYYukiho Yamaoka
    Yukiho Yamaoka
  • JOJose M. Oclarit
    Jose M. Oclarit
  • TOToshio Omori
    Toshio Omori
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Abstract
Sixteen marine methanotrophic bacteria were isolated and 14 marine methanotrophic mixed cultures were obtained. They were assayed for soluble methane monooxygenase (sMMO) by naphthalene oxidation and only one isolate (strain NI) was positive. Strain NI degraded trichloroehylene (TCE) more efficiently than other methanotrophic isolates containing no sMMO only under copper limiting conditions. Dimethyl sulfide (DMS), one of the radiatively important trace gases released from the sea, was transformed to dimethyl sulfoxide (DMSO) by methanotrophs and the efficiency for the transformation of DMS to DMSO was not as much affected by the presence of sMMO as that of TCE. The taxonomical properties of strain NI and phylogenetic analysis based on 16S rDNA genes indicated that strain NI was a type I methanotroph belonging to the genus Methylomicrobium, and closely related to Methylomicrobium pelagicum. The partial mmoX gene of strain NI was amplified by the primers common to three other mmoX genes and its 270 bp were sequenced. 77 residues out of the 89 amino acids derived from the sequences were common among the four mmoX genes.
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