A non-dechlorinating strain of Dehalospirillum multivorans : evidence for a key role of the corrinoid cofactor in the synthesis of an active tetrachloroethene dehalogenase

Abstract

A strain of Dehalosprillum multivorans, designated strain N, was isolated from the same source as the formerly described tetrachloroethene (PCE)-dechlorinating D. multivorans, herein after referred to as strain K. Neither growing cells nor cell extracts of strain N were able to dechlorinate PCE. The pceA and pceB genes encoding for the PCE-reductive dehalogenase were detected in cells of strain N; and they were 100% homologous to the corresponding genes of strain K. Since the PCE dehalogenase of D. multivorans strain K contains a corrinoid cofactor, the corrinoids of strain N cells were extracted. Analysis of the corrinoids revealed the absence of the specific corrinoid, which is the cofactor of the PCE dehalogenase of strain K cells. RT-PCR of mRNA indicated that the pceA gene was transcribed in strain N cells to a far lower extent than the pceA gene of strain K under the same experimental conditions. Western blot analysis of crude extracts of strain N showed that, if at all, an insignificant amount of the apoprotein of the PCE dehalogenase was present. The results indicate that the inability of strain N to dechlorinate is due to the absence of the corrinoid cofactor of the enzyme mediating PCE dechlorination.

Molecular Characterization of a Dechlorinating Community Resulting from In Situ Biostimulation in a Trichloroethene-Contaminated Deep, Fractured Basalt Aquifer and Comparison to a Derivative Laboratory Culture

“…Microorganisms with enzymes from the acetyl-coenzyme A pathway, including acetogens and acetoclastic methanogens, may play a role in this first stage of dechlorination due to an abundance of transition metal corrinoid cofactors (15,20,42). Corrinoid-dependent dechlorination has been demonstrated in methanogenic and acetogenic consortia and isolates (6,19,24,26,40,41,(79)(80)(81)(82)84), as well as dehalorespiratory isolates (1,27,41,44,52,59,67,70). Our knowledge of microorganisms that can participate in the second stage of dechlorination, namely, the reduction of cis-DCE and VC, is currently limited to the genus Dehalococcoides (11,33,56).…”

“…Briefly, lactate injection resulted in dramatic increases in chemical oxygen demand and organic acids, a subsequent decrease in oxidation-reduction potential, complete removal of sulfate, an increase in dissolved iron, generation of methane, and a reduction of all aqueous-phase TCE to ethene, which has VOL. 70,2004 TCE DECHLORINATION AT TEST AREA NORTH 7331 been maintained since 1999. The sample from 8 November 2001 was collected 1 week following a lactate injection.…”

Characterization of Two Tetrachloroethene-Reducing, Acetate-Oxidizing Anaerobic Bacteria and Their Description asDesulfuromonas michiganensissp. nov

“…Since growth under these conditions depended on reductive dechlorination, the most likely explanation is that strain BB1 PCEϪ spontaneously lost the ability to dechlorinate PCE when it was grown with fumarate. Interestingly, a nondechlorinating variant of Dehalospirillum multivorans was isolated from the same activated sludge material as the well-studied dechlorinating strain, suggesting that loss of dechlorinating activity might not be an uncommon event (42). Further investigations are necessary to elucidate the nature of this loss of physiological function and to explore its relevance for bioremediation approaches.…”

Overview of organohalide-respiring bacteria and a proposal for a classification system for reductive dehalogenases

“…Many, if not all, characterized RdhAs contain corrinoid co-factors (derivatives of vitamin B12), including the PCE dehalogenase from Sulfurospirillum multivorans (formerly Dehalospirillum), which was shown to contain the very specific, previously unknown corrinoid norpseudo-B 12 [47]. Involvement of a Co(I) corrinoid in the catalytic activity of reductive dehalogenases has been demonstrated by the reversible inactivation of corrinoid using propyl iodides for a number of enzymes, and by the fact that the lack of the corrinoid cofactor resulted in loss of the PCE-dechlorination ability in S. multivorans and Dehalobacter restrictus PER-K23 [38,48]. Six chlorophenol and four PCE/trichloroethene (TCE) reductive dehalogenases have been purified from different Desulfitobacterium strains, and the majority of reductive dehalogenases that have so far been tested for the presence of a corrinoid prosthetic group contained such a group [49].…”