Identification of specific corrinoids reveals corrinoid modification in dechlorinating microbial communities

Abstract

Cobalamin and other corrinoids are essential cofactors for many organisms. The majority of microbes with corrinoid-dependent enzymes do not produce corrinoids de novo, and instead must acquire corrinoids produced by other organisms in their environment. However, the profile of corrinoids produced in corrinoid-dependent microbial communities, as well as the exchange and modification of corrinoids among community members have not been well studied. In this study, we applied a newly developed LC/MS/MS–based corrinoid detection method to examine relationships between corrinoids, their lower ligand bases, and specific microbial groups in microbial communities containing Dehalococcoides mccartyi that has an obligate requirement for benzimidazole-containing corrinoids for trichloroethene-respiration. We found that p-cresolylcobamide ([p-Cre]Cba) and cobalamin were the most abundant corrinoids in the communities. It suggests that members of the family Veillonellaceae are associated with the production of [p-Cre]Cba. The decrease of supernatant-associated [p-Cre]Cba and the increase of biomass-associated cobalamin were correlated with the growth of D. mccartyi by dechlorination. This supports the hypothesis that D. mccartyi is capable of fulfilling its corrinoid requirements in community through corrinoid remodeling, in this case, by importing extracellular [p-Cre]Cba and 5,6-dimethylbenzimidazole (DMB) (the lower ligand of cobalamin), to produce cobalamin as a cofactor for dechlorination. This study also highlights the role of DMB, the lower ligand produced in all of the studied communities, in corrinoid remodeling. These findings provide novel insights on roles played by different phylogenetic groups in corrinoid production and corrinoid exchange within microbial communities. This study may also have implications for optimizing chlorinated solvent bioremediation.

Anaerobic biosynthesis of the lower ligand of vitamin B 12

“…15 N-ammonium chloride was purchased from Cambridge Isotopes Laboratories. 5-OHBza was synthesized as previously described (33 12 , and Factor A were purified as described (34).…”

“…The UV-Vis spectra were collected during HPLC analysis using Agilent ChemStation software. Samples were further characterized on an Agilent 6410 liquid chromatograph-triple quadrupole mass spectrometer using an Agilent Zorbax SB-Aq column to identify cobamides based on their characteristic transitions and retention times (34). For corrinoid extracts from strains grown in 15 NH 4 Cl, the MS method was modified to detect the Fig.…”

The corrinoid cofactor of reductive dehalogenases affects dechlorination rates and extents in organohalide-respiring Dehalococcoides mccartyi

“…Studies with Dhc strain 195 revealed that TCE reductive dechlorination was only sustained by DMB-cobamide (Cba), 5-MeBzaCba and 5-OMeBza-Cba, but not by Bza-Cba, 5-hydroxybenzimidazolyl-cobamide (5-OHBza-Cba or factor III) or phenolic cobamides (Phe-Cba and p-Cresol-Cba) (Yi et al, 2012;Men et al, 2014b). Apparently, the cobamide lower base (Figure 1) determines whether Dhc can or cannot use chlorinated hydrocarbons as electron acceptors.…”

An Amoebal Grazer of Cyanobacteria Requires Cobalamin Produced by Heterotrophic Bacteria

“…Corrinoids are a family of related molecules that include vitamin B 12 and are obligatorily or facultatively utilized by many organisms, including animals, algae, and bacteria (10,11). Corrinoids comprise a porphyrin ring that coordinates a central cobalt ion (12) with variable upper and lower axial ligands (13,14). The most well-studied corrinoid variants are cobalamins, with dimethylbenzimidazole (DMB) as the lower axial ligand, and which include vitamin B 12 (or cyanocobalamin, Cbl), which has a CN group as the upper axial ligand.…”