Engineering TCE-degrading rhizobacteria for heavy metal accumulation and enhanced TCE degradation

Lee, Wonkyu; Wood, Thomas K.; Chen, Wilfred

doi:10.1002/bit.20950

Cited by 38 publications

(22 citation statements)

References 21 publications

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“…Microbes have been engineered for a diverse array of biotechnological applications (2,9,13,18,22,24,37). Within this context, metabolic engineering of E. coli has allowed the biosynthesis of high-value plant flavonoids (reviewed in reference 24).…”

Section: Discussionmentioning

confidence: 99%

Engineering Central Metabolic Pathways for High-Level Flavonoid Production in Escherichia coli

Leonard

Lim

Saw

et al. 2007

Appl Environ Microbiol

257

187

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The identification of optimal genotypes that result in improved production of recombinant metabolites remains an engineering conundrum. In the present work, various strategies to reengineer central metabolism in Escherichia coli were explored for robust synthesis of flavanones, the common precursors of plant flavonoid secondary metabolites. Augmentation of the intracellular malonyl coenzyme A (malonyl-CoA) pool through the coordinated overexpression of four acetyl-CoA carboxylase (ACC) subunits from Photorhabdus luminescens (PlACC) under a constitutive promoter resulted in an increase in flavanone production up to 576%. Exploration of macromolecule complexes to optimize metabolic efficiency demonstrated that auxiliary expression of PlACC with biotin ligase from the same species (BirA Pl ) further elevated flavanone synthesis up to 1,166%. However, the coexpression of PlACC with Escherichia coli BirA (BirA Ec ) caused a marked decrease in flavanone production. Activity improvement was reconstituted with the coexpression of PlACC with a chimeric BirA consisting of the N terminus of BirA Ec and the C terminus of BirA Pl . In another approach, high levels of flavanone synthesis were achieved through the amplification of acetate assimilation pathways combined with the overexpression of ACC. Overall, the metabolic engineering of central metabolic pathways described in the present work increased the production of pinocembrin, naringenin, and eriodictyol in 36 h up to 1,379%, 183%, and 373%, respectively, over production with the strains expressing only the flavonoid pathway, which corresponded to 429 mg/liter, 119 mg/liter, and 52 mg/liter, respectively.Many plant-derived natural products are important sources for the discovery of new drugs and nutraceuticals (3, 12). However, drug development from natural compounds faces important challenges that discourage the pursuit of such bioactive materials (33). One major limitation is the low concentration of these metabolites in the host organisms, which causes limited supply for rapid research, development, and clinical trials (6). Synthetic or semisynthetic routes are often employed to remedy this problem (30). However, the complicated structure of many natural molecules often results in lengthy chemical procedures that are impractical for large-scale production. Another approach to drug discovery relies on combinatorial chemistry (5). Even though this method can generate large libraries of compounds with common core structures, only a small fraction of bioactive molecules are identified through high-throughput bioassays (33). Biochemical synthesis presents a promising alternative not only for increasing the availability of important natural products but also for diversifying their chemistry. To serve this purpose, engineered microbes are often employed as living biocatalysts (24).Flavonoids are plant-derived drug candidates and nutraceuticals whose biosynthesis has recently been engineered in recombinant microorganisms (reviewed in references 11 and 24).In plants, flavonoi...

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Section: Discussionmentioning

confidence: 99%

Engineering Central Metabolic Pathways for High-Level Flavonoid Production in Escherichia coli

Leonard

Lim

Saw

et al. 2007

Appl Environ Microbiol

257

187

View full text Add to dashboard Cite

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“…In most cases these microorganisms will lower bioavailability of the metals by sequestering the ions on extracellular anionic polysaccharides (EPS) or on thiol-rich proteins (either intracellular or anchored to the cell surface). In some cases, such type of trait was deliberately engineered in microbial cells (Kuroda et al 2001;Lee et al 2006).…”

Section: Discussionmentioning

confidence: 99%

“…Many microorganisms are known to degrade a variety of organics, and likewise a number of metal-resistant microorganisms are known to detoxify metals such as lead, mercury or cadmium. Some works have analyzed the possibility of remediation of organic pollution in heavy metalcontaminated soils (Roane et al 2001;Lee et al 2006).…”

Section: Introductionmentioning

confidence: 99%

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Dual augmentation for aerobic bioremediation of MTBE and TCE pollution in heavy metal-contaminated soil

et al. 2008

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In this work we isolated from soil and characterized several bacterial strains capable of either resisting high concentrations of heavy metals (Cd 2? or Hg 2? or Pb 2? ) or degrading the common soil and groundwater pollutants MTBE (methyl-tertbutyl ether) or TCE (trichloroethylene). We then used soil microcosms exposed to MTBE (50 mg/l) or TCE (50 mg/l) in the presence of one heavy metal (Cd 10 ppm or Hg 5 ppm or Pb 50 or 100 ppm) and two bacterial isolates at a time, a degrader plus a metalresistant strain. Some of these two-membered consortia showed degradation efficiencies well higher (49-182% higher) than those expected under the conditions employed, demonstrating the occurrence of a synergetic relationship between the strains used. Our results show the efficacy of the dual augmentation strategy for MTBE and TCE bioremediation in the presence of heavy metals.

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“…This rhizoremediation strategy has been demonstrated using a wheat rhizosphere system for the detoxification of soil trichloroethylene (TCE) [26]. EC was shown to be resistant to elevated cadmium concentration and retained its TCE degrading activity [27]. The TCE degradation rate for cells without EC expression was reduced by 60% in the presence of cadmium.…”

Section: Surface-display For Organic Pollutant Remediationmentioning

confidence: 99%

Versatile microbial surface-display for environmental remediation and biofuels production

Wu¹,

Mulchandani²,

Chen³

2008

Trends in Microbiology

Self Cite

101

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Surface display is a powerful technique that utilizes natural microbial functional components to express proteins or peptides on the cell exterior. Since the reporting of the first surface-display system in the mid-1980s, a variety of new systems have been reported for yeast, Gram-positive and Gram-negative bacteria. Non-conventional display methods are emerging, eliminating the generation of genetically modified microorganisms. Cells with surface display are used as biocatalysts, biosorbents and biostimulants. Microbial cell-surface display has proven to be extremely important for numerous applications ranging from combinatorial library screening and protein engineering to bioremediation and biofuels production.3

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Engineering TCE-degrading rhizobacteria for heavy metal accumulation and enhanced TCE degradation

Cited by 38 publications

References 21 publications

Engineering Central Metabolic Pathways for High-Level Flavonoid Production in Escherichia coli

Engineering Central Metabolic Pathways for High-Level Flavonoid Production in Escherichia coli

Dual augmentation for aerobic bioremediation of MTBE and TCE pollution in heavy metal-contaminated soil

Versatile microbial surface-display for environmental remediation and biofuels production

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