Comparative Physiology of Organohalide-Respiring Bacteria

Subtle changes in the active site architecture untangled overlapping substrate ranges and mechanistic differences of two reductive dehalogenases

“…An alteration of the cobamide content in the cells was excluded by testing for the abiotic conversion of 1,2-DBA that was not affected in comparison to other strains tested. Several models exist for S. multivorans and Dehalococcoides spp., which all involve exoplasmic as well as integral membrane proteins in the electron transfer chain [53][54][55]. The DcaA amount in the crude extract was detected by immunoblot that showed a weaker band compared to the wild-type enzyme (Fig.…”

“…The physiological electron donor interacting with the RDases in the organohalide respiratory chain is not known so far. Several models exist for S. multivorans and Dehalococcoides spp., which all involve exoplasmic as well as integral membrane proteins in the electron transfer chain [53][54][55]. It is unclear, whether the electrons enter the RDase at the distal or the proximal [4Fe-4S] cluster.…”

Why Is the Biodegradation of Polyfluorinated Compounds So Rare?

“…For example, certain natural polyhalogenated aromatic compounds in the oceans look a lot like industrial polychlorinated biphenyls (PCBs) ( 10 ). The phylogeny of dechlorinating enzymes reconstructed from microbial genome mining suggests an ancient history, as would be expected given the availability of growth-selectable chlorinated substrates driving microbial evolution over millions of years ( 11 ). In contrast, no one has yet discovered polyfluorinated natural products, and only a few monofluorinated compounds are found in nature ( 12 ).…”

Anaerobic microbial processes for energy conservation and biotransformation of pollutants

“…They can be classified as facultative or obligate organohalide-respiring bacteria (OHRB) (Krzmarzick andNovak, 2014, Atashgahi et al, 2016). Halorespiring bacteria have been isolated from a wide range of environments and show great differences in their phylogeny (Mayer-Blackwell et al, 2016). Several studies showed that halorespiring bacteria have higher affinity for hydrogen than methanogens, giving them an advantage in environments where hydrogen concentrations are low (Dolfing, 2016).…”

“…Reductive dehalogenation can also be performed co-metabolically or facultatively (Holliger and Schumacher, 1994). For example, Desulfitobacterium can perform facultative dehalogenation, as well as some strains of Desulfuromonas or Geobacter (Krzmarzick and Novak, 2014;Mayer-Blackwell et al, 2016). The enzyme systems that were reported to be involved in the co-metabolic reductive dehalogenation include corrinoids, factor F 430 , ferredoxins, iron (II) porphyrins or flavoproteinflavin complexes (Middeldorp et al, 1999;Holliger et al, 2004).…”