1,2-Dichloroethane Exposure Alters the Population Structure, Metabolism, and Kinetics of a Trichloroethene-Dechlorinating Dehalococcoides mccartyi Consortium

Abstract

Bioremediation of groundwater contaminated with chlorinated aliphatic hydrocarbons such as perchloroethene and trichloroethene can result in the accumulation of the undesirable intermediate vinyl chloride. Such accumulation can either be due to the absence of specific vinyl chloride respiring Dehalococcoides mccartyi or to the inhibition of such strains by the metabolism of other microorganisms. The fitness of vinyl chloride respiring Dehalococcoides mccartyi subpopulations is particularly uncertain in the presence of chloroethene/chloroethane cocontaminant mixtures, which are commonly found in contaminated groundwater. Therefore, we investigated the structure of Dehalococcoides populations in a continuously fed reactor system under changing chloroethene/ethane influent conditions. We observed that increasing the influent ratio of 1,2-dichloroethane to trichloroethene was associated with ecological selection of a tceA-containing Dehalococcoides population relative to a vcrA-containing Dehalococcoides population. Although both vinyl chloride and 1,2-dichloroethane could be simultaneously transformed to ethene, prolonged exposure to 1,2-dichloroethane diminished the vinyl chloride transforming capacity of the culture. Kinetic tests revealed that dechlorination of 1,2-dichloroethane by the consortium was strongly inhibited by cis-dichloroethene but not vinyl chloride. Native polyacrylamide gel electrophoresis and mass spectrometry revealed that a trichloroethene reductive dehalogenase (TceA) homologue was the most consistently expressed of four detectable reductive dehalogenases during 1,2-dichloroethane exposure, suggesting that it catalyzes the reductive dihaloelimination of 1,2-dichloroethane to ethene.

Chlorinated electron acceptor availability selects for specificDehalococcoidespopulations in dechlorinating enrichment cultures and in groundwater

“…This data provides a timeframe (∼5 years) for a major shift to happen in the rdhA fingerprint of a mixed culture maintained consistently on the same electron acceptor. This is different to the wholesale changes observed when the electron acceptor is changed, where a shift in the dominant D. mccartyi population may happen much faster, as demonstrated in a recent studies by Mayer-Blackwell et al (57, 58) where the dominant D. mccartyi population in a bioreactor shifted over a period of 50-100 days when the electron acceptor was switched for 1,2-DCA from TCE. In the field, where conditions are more variable both in time and space than in the laboratory, changes in D. mccartyi populations may occur even faster.…”

Impact of dichloroethane on the microbicidal activity of neutrophils and mononuclear phagocytes

“…Одна из актуальных медико-биологических проблем -изучение повреждающего действия экотоксикантов на организм человека. К числу этих соединений относится и дихлорэтан (ДХЭ), широко применяемый в производстве хлорвинила и полихлорвиниловой продукции в качестве растворителя отравляющих веществ, для обезжиривания и чистки одежды [1][2][3].…”

“…Острые отравления ДХЭ при авариях на химических производствах характеризуются высокой смертностью [1]. При этом попадание ДХЭ в почву, воду и воздух, а также длительный контакт в процессе работы на производстве могут приводить к хронической интоксикации ДХЭ [1][2][3]. Проникая в организм человека через неповреждённые кожные покровы, дыхательные пути, пищеварительный тракт, ДХЭ оказывает плейотропное повреждающее действие [1,2,4,5].…”

“…При этом попадание ДХЭ в почву, воду и воздух, а также длительный контакт в процессе работы на производстве могут приводить к хронической интоксикации ДХЭ [1][2][3]. Проникая в организм человека через неповреждённые кожные покровы, дыхательные пути, пищеварительный тракт, ДХЭ оказывает плейотропное повреждающее действие [1,2,4,5]. Несмотря на многолетнее изучение негативного воздействия ДХЭ на иммунную систему, остаётся открытым вопрос повреждения токсикантом нейтрофилов и мононуклеарных фагоцитов, которым принадлежит ведущая роль в первой линии защиты организма [1,[6][7][8][9].…”

Microbial transformation of organic and inorganic halogen compounds

“…One of the challenges of bioremediation is the presence of mixtures of organohalogens at contaminated sites. During dechlorination of co-mingled organohalogens, bioattenuation of specific chlorinated solvents has been shown to be prone to inhibition due to the inhibitory effect of dechlorination intermediates on OHRB, their reductive dehalogenase enzymes, and their syntrophic partners (Chan et al 2011;Dillehay et al 2014;Mayer-Blackwell et al 2016). For instance, 1,1,1-trichloroethane (1,1,1-TCA) was shown to strongly inhibit chloroethene reductive dehalogenases of Dehalococcoides (Chan et al 2011).…”