All Publications

  • Phylogenetic diversity of NO reductases, new tools for nor monitoring, and insights into N2O production in natural and engineered environments FRONTIERS OF ENVIRONMENTAL SCIENCE & ENGINEERING Woo, S., Sewell, H. L., Criddle, C. S. 2022; 16 (10)
  • Homoacetogenesis in Deep-SeaChloroflexi, as Inferred by Single-Cell Genomics, Provides a Link to Reductive Dehalogenation in TerrestrialDehalococcoidetes. mBio Sewell, H. L., Kaster, A. K., Spormann, A. M. 2017; 8 (6)


    The deep marine subsurface is one of the largest unexplored biospheres on Earth and is widely inhabited by members of the phylumChloroflexiIn this report, we investigated genomes of single cells obtained from deep-sea sediments of the Peruvian Margin, which are enriched in suchChloroflexi16S rRNA gene sequence analysis placed two of these single-cell-derived genomes (DscP3 and Dsc4) in a clade of subphylum IChloroflexiwhich were previously recovered from deep-sea sediment in the Okinawa Trough and a third (DscP2-2) as a member of the previously reported DscP2 population from Peruvian Margin site 1230. The presence of genes encoding enzymes of a complete Wood-Ljungdahl pathway, glycolysis/gluconeogenesis, aRhodobacternitrogen fixation (Rnf) complex, glyosyltransferases, and formate dehydrogenases in the single-cell genomes of DscP3 and Dsc4 and the presence of an NADH-dependent reduced ferredoxin:NADP oxidoreductase (Nfn) and Rnf in the genome of DscP2-2 imply a homoacetogenic lifestyle of these abundant marineChloroflexiWe also report here the first complete pathway for anaerobic benzoate oxidation to acetyl coenzyme A (CoA) in the phylumChloroflexi(DscP3 and Dsc4), including a class I benzoyl-CoA reductase. Of remarkable evolutionary significance, we discovered a gene encoding a formate dehydrogenase (FdnI) with reciprocal closest identity to the formate dehydrogenase-like protein (complex iron-sulfur molybdoenzyme [CISM], DET0187) of terrestrialDehalococcoides/Dehalogenimonasspp. This formate dehydrogenase-like protein has been shown to lack formate dehydrogenase activity inDehalococcoides/Dehalogenimonasspp. and is instead hypothesized to couple HupL hydrogenase to a reductive dehalogenase in the catabolic reductive dehalogenation pathway. This finding of a close functional homologue provides an important missing link for understanding the origin and the metabolic core of terrestrialDehalococcoides/Dehalogenimonasspp. and of reductive dehalogenation, as well as the biology of abundant deep-seaChloroflexiIMPORTANCEThe deep marine subsurface is one of the largest unexplored biospheres on Earth and is widely inhabited by members of the phylumChloroflexiIn this report, we investigated genomes of single cells obtained from deep-sea sediments and provide evidence for a homacetogenic lifestyle of these abundant marineChloroflexiMoreover, genome signature and key metabolic genes indicate an evolutionary relationship between these deep-sea sediment microbes and terrestrial, reductively dehalogenatingDehalococcoides.

    View details for PubMedID 29259088

    View details for PubMedCentralID PMC5736913

  • 1,2-Dichloroethane Exposure Alters the Population Structure, Metabolism, and Kinetics of a Trichloroethene-Dechlorinating Dehalococcoides mccartyi Consortium. Environmental science & technology Mayer-Blackwell, K., Fincker, M., Molenda, O., Callahan, B., Sewell, H., Holmes, S., Edwards, E. A., Spormann, A. M. 2016: -?


    Bioremediation of groundwater contaminated with chlorinated aliphatic hydrocarbons such as perchloroethene and trichloroethene can result in the accumulation of the undesirable intermediate vinyl chloride. Such accumulation can either be due to the absence of specific vinyl chloride respiring Dehalococcoides mccartyi or to the inhibition of such strains by the metabolism of other microorganisms. The fitness of vinyl chloride respiring Dehalococcoides mccartyi subpopulations is particularly uncertain in the presence of chloroethene/chloroethane cocontaminant mixtures, which are commonly found in contaminated groundwater. Therefore, we investigated the structure of Dehalococcoides populations in a continuously fed reactor system under changing chloroethene/ethane influent conditions. We observed that increasing the influent ratio of 1,2-dichloroethane to trichloroethene was associated with ecological selection of a tceA-containing Dehalococcoides population relative to a vcrA-containing Dehalococcoides population. Although both vinyl chloride and 1,2-dichloroethane could be simultaneously transformed to ethene, prolonged exposure to 1,2-dichloroethane diminished the vinyl chloride transforming capacity of the culture. Kinetic tests revealed that dechlorination of 1,2-dichloroethane by the consortium was strongly inhibited by cis-dichloroethene but not vinyl chloride. Native polyacrylamide gel electrophoresis and mass spectrometry revealed that a trichloroethene reductive dehalogenase (TceA) homologue was the most consistently expressed of four detectable reductive dehalogenases during 1,2-dichloroethane exposure, suggesting that it catalyzes the reductive dihaloelimination of 1,2-dichloroethane to ethene.

    View details for PubMedID 27809491

  • Comparative Physiology of Organohalide-Respiring Bacteria Organohalide-Respiring Bacteria Mayer-Blackwell, K., Sewell, H., Fincker, M., Spormann, A. M. Springer-Verlag Berlin Heidelberg. 2016: 259-280
  • Characterization of the Assaying Methods in Polymerization-Based Amplification of Surface Biomarkers Australian Journal of Chemistry Johnson, L. M., Avens, H. J., Hansen, R. R., Sewell, H. L., Bowman, C. N. 2009; 62 (8): 877-884

    View details for DOI 10.1071/CH09095