Physiological, Ecological, and Phylogenetic Characterization of Stappia , a Marine CO-Oxidizing Bacterial Genus

Abstract

Bacteria play a major role in marine CO cycling, yet very little is known about the microbes involved. Thirteen CO-oxidizing Stappia isolates obtained from existing cultures, macroalgae, or surf samples representing geographically and ecologically diverse habitats were characterized using biochemical, physiological, and phylogenetic approaches. All isolates were aerobic chemoorganotrophs that oxidized CO at elevated (1,000 ppm) and ambient-to-subambient concentrations (<0.3 ppm). All contained the form I (OMP) coxL gene for aerobic CO dehydrogenase and also the form II (BMS) putative coxL gene. In addition, some strains possessed cbbL, the large subunit gene for ribulose-1,5-bisphosphate carboxylase/oxygenase, suggesting the possibility of lithotrophic or mixotrophic metabolism. All isolates used a wide range of sugars, organic acids, amino acids, and aromatics for growth and grew at salinities from 5 to 45 ppt. All but one isolate denitrified or respired nitrate. Phylogenetic analyses based on 16S rRNA gene sequences indicated that several isolates could not be distinguished from Stappia aggregata and contributed to a widely distributed species complex. Four isolates (of strains GA15, HI, MIO, and M4) were phylogenetically distinct from validly described Stappia species and closely related genera (e.g., Ahrensia, Pannonibacter, Pseudovibrio, and Roseibium). Substrate utilization profiles, enzymatic activity, and membrane lipid composition further distinguished these isolates and supported their designations as new Stappia species. The observed metabolic versatility of Stappia likely accounts for its cosmopolitan distribution and its ability to contribute to CO cycling as well as other important biogeochemical cycles.

Physiological and Metabolic Effects of Carbon Monoxide Oxidation in the Model Marine Bacterioplankton Ruegeria pomeroyi DSS-3

“…and Labrenzia aggregata have the potential to utilize CO as an energy source and as a carbon source, because some harbor the RuBisCO gene cbbL (16). Stappia and L. aggregata grown heterotrophically also rapidly oxidize CO at the same concentrations as those used in this study (16).…”

A Previously Uncharacterized, Nonphotosynthetic Member of the Chromatiaceae Is the Primary CO 2 -Fixing Constituent in a Self-Regenerating Biocathode

“…We identified expression of the coxL gene from the Labrenzia, Parvibaculum-1, and Gammaproteobacteria-1 cluster genomes. While not much is known about CO oxidation by Parvibaculum, L. aggregata is categorized as a carboxydovore, where only low concentrations of CO are oxidized during mixotrophic metabolism in the presence of other organic substrates (69). While it is not immediately apparent how CO oxidation is incorporated into the carbon cycle of the biofilm, we can imagine a scenario where CO is oxidized by members of Labrenzia, Parvibaculum-1, or Gammaproteobacteria-1 to CO 2 for fixation by Chromatiaceae.…”

“…Labrenzia spp. are among the bacteria known to oxidize CO via carbon monoxide dehydrogenase to CO 2 (69) and are estimated to make up ca. 5% of the biofilm composition, leading us to examine the genomic potential of the biocathode biofilm for CO oxidation.…”

Correlating carbon monoxide oxidation with cox genes in the abundant Marine Roseobacter Clade

“…Both R. pomeroyi DSS-3 (Moran et al, 2004) and the Stappia spp. studied by Weber and King (2007) depleted headspace CO concentrations in the culture to sub-ambient concentrations. In this study, the initial CO concentration used was higher than the CO concentration found in seawater and was only followed to B20 p.p.m.…”