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SURVIVAL OF VINYL CHLORIDE RESPIRING DEHALOCOCCOIDES MCCARTYI UNDER LONG-TERM ELECTRON DONOR LIMITATION
Mayer-Blackwell, K., M.F. Azizian, J.K. Green, A.M. Spormann, and L. Semprini.
Environmental Science & Technology 51(3):1635-1642(2017)

Effects on Dehalococcoides mccartyi (dhc) population structure resulting from a change in the ratio of electron donor to chlorinated electron acceptor were investigated in continuously stirred tank reactors operated over 7 years. When the electron donor formate was supplied in stoichiometric excess to TCE, both tceA-containing and vcrA-containing dhc populations persisted, and near-complete dechlorination to ethene was stably maintained. When the electron donor formate was supplied at substoichiometric concentrations, the interactions between tceA-containing and vcrA-containing populations shifted toward direct competition for the same limiting catabolic electron donor substrate, with subsequent niche exclusion of the vcrA-containing population. After more than 2000 days of operation under electron donor limitation, increasing the electron donor to TCE ratio facilitated a recovery of the vcrA-containing dhc population to its original frequency. Results demonstrated that electron donor scarcity alone, in the absence of competing metabolic processes or inhibitory dechlorination intermediate products, is sufficient to alter the dhc population structure.



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