Novel Approach to the Improvement of Biphenyl and Polychlorinated Biphenyl Degradation Activity: Promoter Implantation by Homologous Recombination

RIKEN, Вако, Saitama, Japan
Applied and Environmental Microbiology (Impact Factor: 3.67). 02/2003; 69(1):146-53. DOI: 10.1128/AEM.69.1.146-153.2003
Source: PubMed


To improve the capabilities of microorganisms relevant for biodegradation, we developed a new genetic approach and applied
it to the bph operon (bphEGF[orf4]A1A2A3CD[orf1]A4R) of Pseudomonas sp. strain KKS102 to enhance its biphenyl- and polychlorinated biphenyl (PCB)-degrading activity. A native promoter of the
bph operon, which was under control, was replaced through homologous recombination by a series of promoters that had constitutive
activity. By testing a series of promoters with various strengths, we were able to obtain strains that have enhanced degradation
activity for biphenyl and PCBs. This strategy removes the rate-limiting factor associated with transcription and has the potential
to improve the degradation activity of a wide variety of microorganisms involved in biodegradation.

Download full-text


Available from: Yuji Nagata, Jan 19, 2015
    • "Approaches That Upregulate Unmodified Coding Regions Ohtsubo et al. (2003) "
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper presents a critical review of the literature on the application of genetically engineered microorganisms (GEMs) in bioremediation. The important aspects of using GEMs in bioremediation, such as development of novel strains with desirable properties through pathway construction and the modification of enzyme specificity and affinity, are discussed in detail. Particular attention is given to the genetic engineering of bacteria using bacterial hemoglobin (VHb) for the treatment of aromatic organic compounds under hypoxic conditions. The application of VHb technology may advance treatment of contaminated sites, where oxygen availability limits the growth of aerobic bioremediating bacteria, as well as the functioning of oxygenases required for mineralization of many organic pollutants. Despite the many advantages of GEMs, there are still concerns that their introduction into polluted sites to enhance bioremediation may have adverse environmental effects, such as gene transfer. The extent of horizontal gene transfer from GEMs in the environment, compared to that of native organisms including benefits regarding bacterial bioremediation that may occur as a result of such transfer, is discussed. Recent advances in tracking methods and containment strategies for GEMs, including several biological systems that have been developed to detect the fate of GEMs in the environment, are also summarized in this review. Critical research questions pertaining to the development and implementation of GEMs for enhanced bioremediation have been identified and posed for possible future research.
    No preview · Article · Sep 2006 · Critical Reviews in Biotechnology
  • Source
    • "Km Ohtsubo et al. (2003) KLZX04 A derivative of KKS102, carrying pEcoli promoter fused with lacZ. Km Ohtsubo et al. (2003) KLZPQ-2 A derivative of KKS102, carrying bphQ upstream region fused with lacZ. Km. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Acidovorax sp. (formally Pseudomonas sp.) strain KKS102 carries a bph operon for the degradation of PCB/biphenyl. Transcription from the pE promoter for the bph operon was found to be under catabolite control, i.e. the promoter activity was at a lower level when succinate, fumarate or acetate was added to the culture. Some mutations in the immediate upstream region of the pE promoter resulted in catabolite-insensitive and constitutively low promoter activity, suggesting that a transcriptional activator was involved in catabolite control. A genetic screen for a pE promoter activator identified two tandemly arranged genes, bphP and bphQ, that encoded proteins homologous to the sensor kinases and response regulators, respectively, of two-component regulatory system. In the bphPQ double mutant, pE promoter activity was weak and catabolite-insensitive, and a supply of the bphQ gene alone led to the restoration of the catabolite response. The mechanism of catabolite repression in KKS102 is explained in terms of inhibition of activation by BphQ. The genes highly similar to bphQ were found from several beta-proteobacteria, such as Burkholderia cenocepacia J2315, B. multivorans ATCC17616, B. xenovorans LB400 and Ralstonia solanacearum RS1085.
    Full-text · Article · Jul 2006 · Molecular Microbiology
  • [Show abstract] [Hide abstract]
    ABSTRACT: Polychlorinated biphenyls (PCBs) are serious environmental pollutants that threaten both the natural ecosystem and human health. For remediation of environments contaminated with PCBs, several approaches that exploit the potential of microbes to degrade PCBs have been developed. These approaches include improvement of PCB solubilization and entry into the cell, pathway and enzyme engineering, and control of enzyme expression. In this mini-review, we briefly summarize these strategies and provide potentially useful knowledge for the further improvement of the bacterial breakdown of PCBs.
    No preview · Article · Sep 2004 · Applied Microbiology and Biotechnology
Show more