title: Degradation of anaerobic reductive dechlorination products of Aroclor 1242 by four aerobic bacteria.
abstract: We studied the aerobic degradation of eight PCB congeners which comprise from 70 to 85% of the anaerobic dechlorination products from Aroclor 1242, including 2-, 4-, 2,4-, 2,6-, 2,2'-, 2,4'-, 2,2', 4-, and 2,4,4'-chlorobiphenyl (CB), and the biodegradation of their mixtures designed to simulate anaerobic dechlorination profiles M and C. Strains Comamonas testosteroni VP44 and Rhodococcus erythreus NY05 preferentially oxidized a para-substituted ring, while Rhodococcus sp. RHA1, similar to well known strain Burkholderia sp. LB400, preferably attacked an ortho-chlorinated ring. Strains with ortho-directed attack extensively degraded 2,4'- and 2,4,4'-CB into 4-chlorobenzoate, while bacteria with para-directed attack transformed these congeners mostly into potentially problematic meta-cleavage products. The strains that preferentially oxidized an ortho-substituted ring readily degraded seven of the eight congeners supplied individually; only 2,6-CB was poorly degraded. Degradation of 2,2'- and 2,4,4'-CB was reduced when present in mixtures M and C. Higher efficiencies of degradation of the individual congeners and defined PCB mixtures M and C and greater production of chlorobenzoates were observed with bacteria that preferentially attack an ortho-substituted ring. PCB congeners 2,4'-, 2,2',4-, and 2,4,4'-CB can be used to easily identify bacteria with ortho-directed attack which are advantageous for use in the aerobic stage of the two-phase (anaerobic/aerobic) PCB bioremediation scheme.
authors.affiliation: Center for Microbial Ecology, Michigan State University, East Lansing 48824, USA. maltseva@pilot.msu.edu
authors.forename: O V
authors.initials: OV
authors.lastname: Maltseva
authors.forename: T V
authors.initials: TV
authors.lastname: Tsoi
authors.forename: J F
authors.initials: JF
authors.lastname: Quensen
authors.forename: M
authors.initials: M
authors.lastname: Fukuda
authors.forename: J M
authors.initials: JM
authors.lastname: Tiedje
mesh_terms: D000693:Anaerobiosis; D001140:Aroclors / Q000378:metabolism*; D001420:Bacteria, Aerobic / Q000378:metabolism*; D001673:Biodegradation, Environmental; D001713:Biphenyl Compounds / Q000378:metabolism; D019117:Burkholderia / Q000378:metabolism; D002713:Chlorine / Q000378:metabolism*; D020585:Comamonas / Q000378:metabolism; D004785:Environmental Pollutants / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000378:metabolism; D010084:Oxidation-Reduction; D011078:Polychlorinated Biphenyls / Q000737:chemistry / Q000378:metabolism; D012240:Rhodococcus / Q000378:metabolism
chemical_list: D001140:Aroclors; D001713:Biphenyl Compounds; D004785:Environmental Pollutants; D005231:Fatty Acids, Unsaturated; C055142:2-chlorobiphenyl; D002713:Chlorine; C018971:2-hydroxy-6-oxo-6-phenyl-2,4-hexadienoic acid; C027423:aroclor 1242; D011078:Polychlorinated Biphenyls; C006983:4-chlorobiphenyl