Mineralization of PCBs by the genetically modified strain Cupriavidus necator JMS34 and its application for bioremediation of PCBs in soil

Abstract

Polychlorobiphenyls (PCBs) are classified as "high-priority pollutants." Diverse microorganisms are able to degrade PCBs. However, bacterial degradation of PCBs is generally incomplete, leading to the accumulation of chlorobenzoates (CBAs) as dead-end metabolites. To obtain a microorganism able to mineralize PCB congeners, the bph locus of Burkholderia xenovorans LB400, which encodes one of the most effective PCB degradation pathways, was incorporated into the genome of the CBA-degrading bacterium Cupriavidus necator JMP134-X3. The bph genes were transferred into strain JMP134-X3, using the mini-Tn5 transposon system and biparental mating. The genetically modified derivative, C. necator strain JMS34, had only one chromosomal insertion of bph locus, which was stable under nonselective conditions. This modified bacterium was able to grow on biphenyl, 3-CBA and 4-CBA, and degraded 3,5-CBA in the presence of m-toluate. The strain JMS34 mineralized 3-CB, 4-CB, 2,4'-CB, and 3,5-CB, without accumulation of CBAs. Bioaugmentation of PCB-polluted soils with C. necator strain JMS34 and with the native B. xenovorans LB400 was monitored. It is noteworthy that strain JMS34 degraded, in 1 week, 99% of 3-CB and 4-CB and approximately 80% of 2,4'-CB in nonsterile soil, as well as in sterile soil. Additionally, the bacterial count of strain JMS34 increased by almost two orders of magnitude in PCB-polluted nonsterile soil. In contrast, the presence of native microflora reduced the degradation of these PCBs by strain LB400 from 73% (sterile soil) to approximately 50% (nonsterile soil). This study contributes to the development of improved biocatalysts for remediation of PCB-contaminated environments.

The Homogentisate and Homoprotocatechuate Central Pathways Are Involved in 3- and 4-Hydroxyphenylacetate Degradation by Burkholderia xenovorans LB400

“…Central pathways involve the fission by a dioxygenase of the dihydroxylated aromatic metabolic intermediates at ortho - or meta -position and lead to the formation of Krebs cycle intermediates [1]–[4]. Bacterial metabolism of aromatic compounds has been extensively studied [3]–[11]. The metabolic reconstruction of aromatic compounds pathways in in model environmental bacteria has been achieved by genome sequence analyses [3], [12]–[14].…”

Characterization of the Metabolically Modified Heavy Metal-Resistant Cupriavidus metallidurans Strain MSR33 Generated for Mercury Bioremediation

“…In the present study, strain MSR33 showed a high mercury volatilization rate, 6 . Strain MSR33 was able to cleave the organic moiety from methylmercury and to reduce Hg 2+ into a less toxic Hg elemental form.…”

“…Bioremediation is an attractive technology for the clean-up of polluted waters and soils [1][2][3][4][5][6]. Mercury is one of the most toxic elements in the environment [7,8].…”

Association of Growth Substrates and Bacterial Genera with Benzo[a]pyrene Mineralization in Contaminated Soil

“…Many of the other groups enriched under the preincubation conditions have been associated with hydrocarbon degradation, but not necessarily PAH degradation ( Jeon et al, 2004;Kasai et al, 2006;Popp et al, 2006;Han et al, 2009;Saavedra et al, 2010).…”