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

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 mu mol per day for the co-culture and 10.1 +/- 0.3 mu mol per day for the tri-culture) compared with DE195 grown alone (3.8 +/- 0.1 mu mol per day). Cell yield of DE195 was enhanced in the co-culture (9.0 +/- 0.5 x 10(7) cells per mu mol Cl- released, compared with 6.8 +/- 0.9 x 10(7) cells per mu mol Cl- released for the pure culture), whereas no further enhancement was observed in the tri-culture (7.3 +/- 1.8 x 10(7) cells per mu mol Cl- released). The transcriptome of DE195 grown in the co-culture was analyzed using a whole-genome 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. The ISME Journal (2012) 6, 410-421; doi: 10.1038/ismej. 2011.111; published online 1 September 2011