title: Enzymatic manganese(II) oxidation by a marine alpha-proteobacterium.
abstract: A yellow-pigmented marine bacterium, designated strain SD-21, was isolated from surface sediments of San Diego Bay, San Diego, Calif., based on its ability to oxidize soluble Mn(II) to insoluble Mn(III, IV) oxides. 16S rRNA analysis revealed that this organism was most closely related to members of the genus Erythrobacter, aerobic anoxygenic phototrophic bacteria within the alpha-4 subgroup of the Proteobacteria (alpha-4 Proteobacteria). SD-21, however, has a number of distinguishing phenotypic features relative to Erythrobacter species, including the ability to oxidize Mn(II). During the logarithmic phase of growth, this organism produces Mn(II)-oxidizing factors of approximately 250 and 150 kDa that are heat labile and inhibited by both azide and o-phenanthroline, suggesting the involvement of a metalloenzyme. Although the expression of the Mn(II) oxidase was not dependent on the presence of Mn(II), higher overall growth yields were reached in cultures incubated with Mn(II) in the culture medium. In addition, the rate of Mn(II) oxidation appeared to be slower in cultures grown in the light. This is the first report of Mn(II) oxidation within the alpha-4 Proteobacteria as well as the first Mn(II)-oxidizing proteins identified in a marine gram-negative bacterium.
authors.affiliation: Marine Biology Research Division and Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093-0202, USA.
authors.forename: C A
authors.initials: CA
authors.lastname: Francis
authors.forename: E M
authors.initials: EM
authors.lastname: Co
authors.forename: B M
authors.initials: BM
authors.lastname: Tebo
mesh_terms: D020561:Alphaproteobacteria / Q000145:classification / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification*; D020459:Genes, rRNA; D008345:Manganese / Q000378:metabolism*; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000378:metabolism*; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012623:Seawater / Q000382:microbiology*; D017422:Sequence Analysis, DNA
chemical_list: D012336:RNA, Ribosomal, 16S; D008345:Manganese; D010088:Oxidoreductases