title: Structural and Kinetic Characteristics of 1,4-Dioxane-Degrading Bacterial Consortia Containing the Phylum TM7.
abstract: 1,4-Dioxane-degrading bacterial consortia were enriched from forest soil (FS) and activated sludge (AS) using a defined medium containing 1,4-dioxane as the sole carbon source. These two enrichments cultures appeared to have inducible tetrahydrofuran/dioxane and propane degradation enzymes. According to qPCR results on the 16S rRNA and soluble di-iron monooxygenase genes, the relative abundances of 1,4-dioxane-degrading bacteria to total bacteria in FS and AS were 29.4% and 57.8%, respectively. For FS, the cell growth yields (Y), maximum specific degradation rate (Vmax), and half-saturation concentration (Km) were 0.58 mg-protein/mg-dioxane, 0.037 mg-dioxane/mg-protein∙h, and 93.9 mg/l, respectively. For AS, Y, Vmax, and Kmwere 0.34 mg-protein/mg-dioxane, 0.078 mg-dioxane/mg-protein∙h, and 181.3 mg/l, respectively. These kinetics data of FS and AS were similar to previously reported values. Based on bacterial community analysis on 16S rRNA gene sequences of the two enrichment cultures, the FS consortium was identified to contain 38.3% ofMycobacteriumand 10.6% ofAfipia, similar to previously reported literature. Meanwhile, 49.5% of the AS consortium belonged to the candidate division TM7, which has never been reported to be involved in 1,4-dioxane biodegradation. However, recent studies suggested that TM7 bacteria were associated with degradation of non-biodegradable and hazardous materials. Therefore, our results showed that previously unknown 1,4-dioxane-degrading bacteria might play an important role in enriched AS. Although the metabolic capability and ecophysiological significance of the predominant TM7 bacteria in AS enrichment culture remain unclear, our data reveal hidden characteristics of the TM7 phylum and provide a perspective for studying this previously uncultured phylotype.
authors.affiliation: Department of Environmental Engineering and Energy, Myongji University, Yongin 17058, Republic of Korea.
authors.forename: Ji-Hyun
authors.initials: JH
authors.lastname: Nam
authors.affiliation: Department of Engineering Science, College of Engineering and Agro-Industrial Technology, University of the Philippines, Los Baños, College, 4031 Laguna, Philippines.
authors.forename: Jey-R S
authors.initials: JS
authors.lastname: Ventura
authors.affiliation: Department of Civil and Environmental Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea.
authors.forename: Ick Tae
authors.initials: IT
authors.lastname: Yeom
authors.affiliation: Department of Chemistry and Applied Chemistry, College of Science and Technology, Hanyang University, Ansan 15588, Republic of Korea.
authors.forename: Yongwoo
authors.initials: Y
authors.lastname: Lee
authors.affiliation: Department of Environmental Engineering and Energy, Myongji University, Yongin 17058, Republic of Korea.
authors.forename: Deokjin
authors.initials: D
authors.lastname: Jahng
mesh_terms: D001419:Bacteria / Q000145:classification* / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001673:Biodegradation, Environmental; D004146:Dioxanes / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D059013:Microbial Consortia; D006899:Mixed Function Oxygenases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010802:Phylogeny; D012722:Sewage / Q000382:microbiology*; D012988:Soil Microbiology
chemical_list: D001426:Bacterial Proteins; D004146:Dioxanes; D012722:Sewage; D006899:Mixed Function Oxygenases; C025223:1,4-dioxane
keywords: 1,4-Dioxane degrading bacterial consortia; Afipia; Mycobacterium; candidate division TM7; kinetic parameters; soluble di-iron monooxygenase