Insights Gained from the 'Dehalococcoides ethenogenes' Strain 195's Transcriptome Responding to a Wide Range of Respiration Rates and Substrate Types.

摘要

Bacteria of the group 'Dehalococcoides' display the ability to respire recalcitrant chlorinated organic compounds. 'Dehalococcoides' strains' respiratory pathways and function of most genome-encoded enzymes responsible for dechlorination, reductive dehalogenases (RDases), remain incompletely annotated. To further the description of the biological organization of 'Dehalococcoides', this study monitored the trancriptomic response of 'Dehalococcoides ethenogenes' stain 195 using two-color microarrays. This study analyzed the transcriptome of 23 varied continuous feed (or pseudo-steady state (PSS)) conditions and two distinct batch fed conditions. The continuous feed experiments were comprised of 57 cultures with varying electron acceptor feed rates (0-504 micro-eeq/(L-hr)), electron acceptor types (tetrachloroethene (PCE), trichloroethene (TCE), dichloroethene (DCE), 2,3-dichlorophenol (DCP), and no electron acceptor), electron donor to acceptor ratios (0.7 to 17 on an electron equivalence (eeq) basis), and electron donor type (butyrate, lactate, yeast extract, fermented yeast, pure hydrogen, or endogenous biomass decay). When similarly respiring (approximately 120 micro-eeq PCE/(L-hr)) batch and PSS cultures were contrasted, the RDases DET1545 and DET0180 were up-regulated in the PSS cultures indicating activity at lower overall electron acceptor concentration. For all continuous fed chloroethene cultures, members of the RDase family and electron transport chain displayed unique clusters of transcripts responding either positively, negatively, or indifferently to the respiration rate. An RDase within the indifferent group, DET1171, was highly (31 + or - 15fold) up regulated in response to DCP being fed as the electron acceptor. DET1171 could potentially play a role with DET1559 (27 + or - 4.1 fold up-regulated during DCP growth) and DET0318 pceA in the dechlorination of chlorophenols.