Mineralization of Paraoxon and Its Use as a Sole C and P Source by a Rationally Designed Catabolic Pathway in
            <i>Pseudomonas putida</i>

Mattozzi, Matthew D.; Tehara, Sundiep K.; Hong, Thomas D.; Keasling, Jay D.

doi:10.1128/aem.00907-06

Cited by 54 publications

(25 citation statements)

References 32 publications

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“…No single microbe is known to completely mineralize paraoxon. Keasling and co-workers patched together enzymes from four organisms to construct a strain of P. putida that uses paraoxon as a sole source of carbon and phosphorus (Figure 6)47. This strain may be useful for destroying stockpiles of insecticides and toxic nerve agents such as soman and sarin, as well as for decontaminating equipment used in insecticide application.…”

Section: Strategies For Engineering Novel Pathwaysmentioning

confidence: 99%

Evolution of efficient pathways for degradation of anthropogenic chemicals

2009

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Anthropogenic compounds used as pesticides, solvents, and explosives often persist in the environment and can cause toxicity to humans and wildlife. The persistence of anthropogenic compounds is due to their recent introduction into the environment; microbes in soil and water have had relatively little time to evolve efficient mechanisms for degradation of these novel compounds. Some anthropogenic compounds are easily degraded, while others are degraded very slowly or only partially, leading to accumulation of toxic products. This review examines the factors that affect the ability of microbes to degrade anthropogenic compounds and the mechanisms by which novel pathways emerge in nature. New approaches for engineering microbes with enhanced degradative abilities include assembly of pathways using enzymes from multiple organisms, directed evolution of inefficient enzymes, and genome shuffling to improve microbial fitness under the challenging conditions posed by contaminated environments.Anthropogenic chemicals are widely used in agriculture, industry, medicine, and military operations. Examples include pesticides such as atrazine, pentachorophenol (PCP), 1,3-dichloropropene, and DDT, explosives such as trinitrotoluene (TNT), solvents such as trichloroethylene, and dielectric fluids such as PCBs. There was little concern over the fate of anthropogenic chemicals in the environment until the late 20 th century. Adverse effects on wildlife eventually focused attention on the fact that some anthropogenic chemicals persist in the environment because they are not readily degraded by microbes. However, some anthropogenic compounds, such as atrazine, are degraded remarkably quickly. Others, such as paraoxon, are efficiently detoxified, although not degraded. This review will examine how microbes assemble novel pathways for detoxification or degradation of anthropogenic compounds and how the efficiency of biodegradation can be enhanced by optimizing naturally occurring pathways and by patching together novel pathways using enzymes from different organisms.Microbial enzymes that act upon anthropogenic compounds arise from promiscuous activities of previously existing enzymes. Promiscuous enzymes can evolve to become more effective catalysts as a result of selective pressure for detoxification of a toxic compound or use of a novel source of carbon, nitrogen, or phosphorus. Detoxification often requires only a single step. For example, PCP is toxic because it dissipates trans-membrane proton gradients, and thereby uncouples oxidative phosphorylation 1,2 . Phanerochaete chrysosporium detoxifies PCP by methylating the hydroxyl group, thus eliminating its ability to transport protons across a lipid bilayer 3 . Figure 1. Atrazine is the most widely used pesticide in the world. Three steps that replace the substituents on the ring with hydroxyl groups convert atrazine into cyanuric acid, which is readily metabolized, either within the same microbe (e.g. Pseudomonas sp. strain ADP), or by other microbes. 4 PCP is used pri...

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Section: Strategies For Engineering Novel Pathwaysmentioning

confidence: 99%

Evolution of efficient pathways for degradation of anthropogenic chemicals

2009

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“…Such bacteria are capable of degrading the latter because of the presence of some enzymes, mainly related to the phosphotriesterase, which is capable of hydrolyzing OP pesticides through a nucleophilic attack on phosphorous central atom in the molecule. The hydrolysis is essential for complete degradation of OP pesticides and phosphotriesterase activity is the first and the most important step in the detoxification of OP waste or OP-contaminated sites (Yáñez-Ocampo et al 2009;Sorgob and Vilanova 2002;de la Peña et al 2006).…”

Section: Introductionmentioning

confidence: 99%

Removal of methyl parathion and tetrachlorvinphos by a bacterial consortium immobilized on tezontle-packed up-flow reactor

2011

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A tezontle-packed up-flow reactor (TPUFR) with an immobilized bacterial consortium for biological treatment of methyl-parathion and tetrachlorvinphos was evaluated. These organophosphate pesticides are widely used in Mexico for insect and mite control, respectively. With the aim of developing a tool for pesticide biodegradation, four flow rates (0.936, 1.41, 2.19, and 3.51 l/h) and four hydraulic residence times (0.313, 0.206, 0.133, and 0.083 h) were evaluated in a TPUFR. In the bioreactor, with an operating time of 8 h and a flow of 0.936 l/h, we obtained 75% efficiency in the removal of methyl-parathion and tetrachlorvinphos. Their adsorptions in the volcanic rock were 9% and 6%, respectively. It was demonstrated that the removal of pesticides was due to the biological activity of the immobilized bacterial consortium. We confirmed the decrease in toxicity in the treated effluent from the bioreactor through the application of acute toxicity tests on Eisenia foetida. Immobilization of a bacterial consortium using tezontle as a support is innovative and an economical tool for the treatment of mixtures of organophosphorus pesticide residues.

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“…Notable successes include the microbial syntheses of amorphadiene (8), a precursor of the antimalarial drug artemisinin, and taxadiene, the precursor of the potent anticancer drug Taxol (9). Assembly of a pathway that degrades the toxic insecticide paraoxon has also been reported (10).…”

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confidence: 99%

Inhibitory cross-talk upon introduction of a new metabolic pathway into an existing metabolic network

Kim

Copley

2012

Proc. Natl. Acad. Sci. U.S.A.

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Evolution or engineering of novel metabolic pathways can endow microbes with new abilities to degrade anthropogenic pollutants or synthesize valuable chemicals. Most studies of the evolution of new pathways have focused on the origins and quality of function of the enzymes involved. However, there is an additional layer of complexity that has received less attention. Introduction of a novel pathway into an existing metabolic network can result in inhibitory cross-talk due to adventitious interactions between metabolites and macromolecules that have not previously encountered one another. Here, we report a thorough examination of inhibitory cross-talk between a novel metabolic pathway for synthesis of pyridoxal 5′-phosphate and the existing metabolic network of Escherichia coli. We demonstrate multiple problematic interactions, including (i) interference by metabolites in the novel pathway with metabolic processes in the existing network, (ii) interference by metabolites in the existing network with the function of the novel pathway, and (iii) diversion of metabolites from the novel pathway by promiscuous activities of enzymes in the existing metabolic network. Identification of the mechanisms of inhibitory cross-talk can reveal the types of adaptations that must occur to enhance the performance of a novel metabolic pathway as well as the fitness of the microbial host. These findings have important implications for evolutionary studies of the emergence of novel pathways in nature as well as genetic engineering of microbes for "green" manufacturing processes. molecular evolution | metabolic engineering | serendipitous pathway | synthetic biology | biodegradation

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Mineralization of Paraoxon and Its Use as a Sole C and P Source by a Rationally Designed Catabolic Pathway in Pseudomonas putida

Cited by 54 publications

References 32 publications

Evolution of efficient pathways for degradation of anthropogenic chemicals

Evolution of efficient pathways for degradation of anthropogenic chemicals

Removal of methyl parathion and tetrachlorvinphos by a bacterial consortium immobilized on tezontle-packed up-flow reactor

Inhibitory cross-talk upon introduction of a new metabolic pathway into an existing metabolic network

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