title: Application of (13)C-stable isotope probing to identify RDX-degrading microorganisms in groundwater.
abstract: We employed stable isotope probing (SIP) with (13)C-labeled hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) to identify active microorganisms responsible for RDX biodegradation in groundwater microcosms. Sixteen different 16S rRNA gene sequences were derived from microcosms receiving (13)C-labeled RDX, suggesting the presence of microorganisms able to incorporate carbon from RDX or its breakdown products. The clones, residing in Bacteroidia, Clostridia, α-, β- and δ-Proteobacteria, and Spirochaetes, were different from previously described RDX degraders. A parallel set of microcosms was amended with cheese whey and RDX to evaluate the influence of this co-substrate on the RDX-degrading microbial community. Cheese whey stimulated RDX biotransformation, altered the types of RDX-degrading bacteria, and decreased microbial community diversity. Results of this study suggest that RDX-degrading microorganisms in groundwater are more phylogenetically diverse than what has been inferred from studies with RDX-degrading isolates.
authors.affiliation: Zachry Department of Civil Engineering, 3136 TAMU, 205G WERC, Texas A&M University, College Station, TX 77843-3136, USA.
authors.forename: Kun-Ching
authors.initials: KC
authors.lastname: Cho
authors.forename: Do Gyun
authors.initials: DG
authors.lastname: Lee
authors.forename: Hyungkeun
authors.initials: H
authors.lastname: Roh
authors.forename: Mark E
authors.initials: ME
authors.lastname: Fuller
authors.forename: Paul B
authors.initials: PB
authors.lastname: Hatzinger
authors.forename: Kung-Hui
authors.initials: KH
authors.lastname: Chu
mesh_terms: D001483:Base Sequence; D001673:Biodegradation, Environmental; D002247:Carbon Isotopes / Q000032:analysis; D004784:Environmental Monitoring; D060587:Groundwater / Q000737:chemistry / Q000382:microbiology*; D008969:Molecular Sequence Data; D014227:Triazines / Q000032:analysis / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism*
chemical_list: D002247:Carbon Isotopes; D014227:Triazines; D014874:Water Pollutants, Chemical; C009160:cyclonite