Dehalococcoides-Containing Enrichment Cultures Transform Two Chlorinated Organophosphate Esters

Area of Science:

• Environmental Microbiology
• Bioremediation
• Organic Geochemistry

Background:

• Chlorinated organophosphate esters (Cl-OPEs) are widespread environmental contaminants found in anoxic settings.
• Limited knowledge exists regarding the microbial transformation pathways of Cl-OPEs under anoxic conditions.

Purpose of the Study:

• To investigate the microbial transformation of tris(2-chloroethyl) phosphate (TCEP) and tris(1-chloro-2-propyl) phosphate (TCPP) under anoxic conditions.
• To identify the microbial players and metabolic mechanisms involved in Cl-OPE degradation.

Main Methods:

• Utilized enrichment cultures containing Dehalococcoides species.
• Analyzed transformation products using mass spectrometry and deuteration experiments.
• Employed 16S rRNA gene sequencing and quantitative PCR for microbial community analysis.
• Assembled draft genomes and analyzed gene transcription of Dehalococcoides.

Main Results:

• Dehalococcoides-containing cultures transformed TCEP and TCPP within 10 days.
• Identified transformation pathways involving one-electron transfer, C-O bond cleavage, and subsequent reduction.
• Confirmed Dehalococcoides as the primary organisms responsible for Cl-OPE transformation.
• Discovered multiple putative reductive dehalogenase (rdh) genes in Dehalococcoides genomes, with active transcription.

Conclusions:

• Dehalococcoides plays a significant role in the anaerobic transformation of representative Cl-OPEs.
• Reductive dehalogenase enzymes encoded by Dehalococcoides are likely key players in Cl-OPE degradation.
• This research provides crucial insights into the fate of Cl-OPEs in anoxic environments.