Degradation of Aroclor 1242 Dechlorination Products in Sediments by Burkholderia xenovorans LB400( ohb ) and Rhodococcus sp. Strain RHA1( fcb )

Abstract

Burkholderia xenovorans strain LB400, which possesses the biphenyl pathway, was engineered to contain the oxygenolytic ortho dehalogenation (ohb) operon, allowing it to grow on 2-chlorobenzoate and to completely mineralize 2-chlorobiphenyl. A two-stage anaerobic/aerobic biotreatment process for Aroclor 1242-contaminated sediment was simulated, and the degradation activities and genetic stabilities of LB400(ohb) and the previously constructed strain RHA1(fcb), capable of growth on 4-chlorobenzoate, were monitored during the aerobic phase. The population dynamics of both strains were also followed by selective plating and real-time PCR, with comparable results; populations of both recombinants increased in the contaminated sediment. Inoculation at different cell densities (10 4 or 10 6 cells g ؊1 sediment) did not affect the extent of polychlorinated biphenyl (PCB) biodegradation. After 30 days, PCB removal rates for high and low inoculation densities were 57% and 54%, respectively, during the aerobic phase.

Characterization of multiple novel aerobic polychlorinated biphenyl (PCB)-utilizing bacterial strains indigenous to contaminated tropical African soils

“…LB400, have been reported to possess an exceptional ability to degrade even a larger range of congeners including penta-and hexachlorobiphenyl co-metabolically (Bopp 1986;Bedard et al 1987a, b;Commandeur et al 1996;Potrawfke et al 1998). These other micro-organisms, however, have not been shown to utilize the range of xenobiotics reported for SA-2 (or any of the SA strains) in this investigation for growth as sole carbon sources (McCullar et al 1994;Kim and Picardal 2001;Rodrigues et al 2006).…”

Bacterial Degradation and Bioremediation of Chlorinated Herbicides and Biphenyls

“…Additionally, the development of improved biocatalysts for the remediation of PCB-contaminated environments has been reported. Bacterial strains with enhanced PCB-degrading capabilities have been constructed by metabolic engineering (Rodriguez et al, 2006;Wittich and Wolff, 2007;Saavedra et al, 2010). The genetically modified bacterial strain C. necator JMS34, which has been constructed by the combination of the (chloro)biphenyl pathways, the CBA pathway and the chlorocatechol pathway, gained new catabolic abilities for mineralizing PCBs.…”

Coping with Polychlorinated Biphenyl (PCB) Toxicity: Physiological and Genome-Wide Responses of Burkholderia xenovorans LB400 to PCB-Mediated Stress

“…The burden of PCB degradation lies with aerobic cometabolism of the products of reductive dechlorination by biphenyland chlorobenzoate-degrading organisms (22,38). Recently a sequential anaerobic-aerobic process was shown at the laboratory scale to remove over 50% of Aroclor 1242 from river sediments (39).…”