Sustainable syntrophic growth of Dehalococcoides ethenogenes strain 195 with Desulfovibrio vulgaris Hildenborough and Methanobacterium congolense: global transcriptomic and proteomic analyses

Abstract

Dehalococcoides ethenogenes strain 195 (DE195) was grown in a sustainable syntrophic association with Desulfovibrio vulgaris Hildenborough (DVH) as a co-culture, as well as with DVH and the hydrogenotrophic methanogen Methanobacterium congolense (MC) as a tri-culture using lactate as the sole energy and carbon source. In the co-and tri-cultures, maximum dechlorination rates of DE195 were enhanced by approximately three times (11.0±0.01 lmol per day for the co-culture and 10.1 ± 0.3 lmol per day for the tri-culture) compared with DE195 grown alone (3.8 ± 0.1 lmol per day). Cell yield of DE195 was enhanced in the co-culture (9.0 ± 0.5 Â 10 7 cells per lmol Cl À released, compared with 6.8 ± 0.9 Â 10 7 cells per lmol Cl À released for the pure culture), whereas no further enhancement was observed in the tri-culture (7.3±1.8 Â 10 7 cells per lmol Cl À released). The transcriptome of DE195 grown in the co-culture was analyzed using a wholegenome microarray targeting DE195, which detected 102 significantly up-or down-regulated genes compared with DE195 grown in isolation, whereas no significant transcriptomic difference was observed between co-and tri-cultures. Proteomic analysis showed that 120 proteins were differentially expressed in the co-culture compared with DE195 grown in isolation. Physiological, transcriptomic and proteomic results indicate that the robust growth of DE195 in co-and tri-cultures is because of the advantages associated with the capabilities of DVH to ferment lactate to provide H 2 and acetate for growth, along with potential benefits from proton translocation, cobalamin-salvaging and amino acid biosynthesis, whereas MC in the tri-culture provided no significant additional benefits beyond those of DVH.

Unexpected Specificity of Interspecies Cobamide Transfer from Geobacter spp. to Organohalide-Respiring Dehalococcoides mccartyi Strains

“…These observations suggest that the other microbes provided some benefit to Dehalococcoides, and subsequent microarray studies found genes involved in cobamide salvage and lower ligand attachment downregulated in the co-or tri-cultures and in cultures amended with excess vitamin B 12 (i.e., 100 g liter Ϫ1 ) (14,24). Since all of these cocultures used medium amended with up to 100 g of vitamin B 12 liter Ϫ1 , the effects of the corrinoid producers on Dehalococcoides dechlorination activity remained speculative.…”

“…Previous co-or triculture studies of D. mccartyi strain 195 with corrinoid producers (e.g., Acetobacterium woodii, Desulfovibrio desulfuricans, and Desulfovibrio vulgaris Hildenborough, methanogens) demonstrated modest (i.e., up to 1-fold) increases of strain 195 cell numbers compared to pure culture growth yields (9,24). These observations suggest that the other microbes provided some benefit to Dehalococcoides, and subsequent microarray studies found genes involved in cobamide salvage and lower ligand attachment downregulated in the co-or tri-cultures and in cultures amended with excess vitamin B 12 (i.e., 100 g liter Ϫ1 ) (14,24).…”

Metagenomic analysis of a stable trichloroethene-degrading microbial community

“…Previously sequenced Dhc strains have genes encoding for enzymes in the second part of the cobalamin biosynthesis pathway, lower ligand attachment and rearrangement (Maymó -Gatell et al, 1997;Kube et al, 2005;McMurdie et al, 2009), but not for the first part of the pathway, corrin ring synthesis. Even when Dhc isolates are provided sufficient hydrogen, acetate and cobalamin, they do not grow or dechlorinate as robustly as when grown in mixed communities or defined consortia (He et al, 2007;Lee et al, 2011;Men et al, 2012).…”

Efficient Metabolic Exchange and Electron Transfer within a Syntrophic Trichloroethene-Degrading Coculture of Dehalococcoides mccartyi 195 and Syntrophomonas wolfei

“…Although dechlorinating microbial communities have been extensively studied over the past decades (4, 10, 12, 13), community assembly processes in the highly specialized ecological niche of Dehalococcoides and the network of interactions between D. mccartyi, its syntrophic partners and other coexisting community members have yet to be deciphered. The optimization of D. mccartyi-based bioremediation systems to treat TCE-contaminated groundwater would be facilitated by a system-level understanding of interspecies electron, energy and metabolite transfers that shape the structural and functional robustness of TCE-dechlorinating microbial communities.To date, only a few studies of D. mccartyi-containing constructed cocultures and tricultures have been published (5,7,(14)(15)(16). A study with D. mccartyi 195 (strain 195) revealed that its growth in defined medium could be optimized by providing high concentrations of vitamin B 12 and that, over the short term, the strain could be grown to higher densities in cocultures and tricul- …”

“…To date, only a few studies of D. mccartyi-containing constructed cocultures and tricultures have been published (5,7,(14)(15)(16). A study with D. mccartyi 195 (strain 195) revealed that its growth in defined medium could be optimized by providing high concentrations of vitamin B 12 and that, over the short term, the strain could be grown to higher densities in cocultures and tricul-tures with the fermenters Desulfovibrio desulfuricans and/or Acetobacterium woodii that convert lactate to generate the hydrogen and acetate required by D. mccartyi (5).…”