The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform

Yung-an Lee - One of the best experts on this subject based on the ideXlab platform.

  • microbial synthesis of cis cis Muconic Acid from benzoate by sphingobacterium sp mutants
    Biochemical Engineering Journal, 2006
    Co-Authors: Sung-nung Lee, Yung-an Lee
    Abstract:

    Abstract The mutants used in this study, Sphingobacterium sp. M4113/M4115, were originated from a wild-type strain GCG, which was isolated from the sewage of a styrene monomer-manufacturing factory. The culturing medium contains appropriate amounts of K2HPO4, (NH4)2SO4, MgSO4·7H2O, Na-succinate, yeast extract and EDTA–FeCl3 complex. The highest conversion yield was obtained with mutant strain M4115, in which more than 0.560 g of cis,cis-Muconic Acid was accumulated in 28 h from a Na-benzoate solution of 2.0 g/l (∼28% yield). Growth inhibition appeared as the concentration of Na-benzoate exceeded 3.0 g/l. In addition, an increase of 17% and 6% of cis,cis-Muconic Acid in yield were observed for M4115 and M4113, respectively, as EDTA–FeCl3 complex was employed. It's believed that this complex can enhance the yield of catechol 1,2-dioxygenase, and therefore, the yield of cis,cis-Muconic Acid according to β-ketoadipate biosynthesis pathway.

  • Microbial synthesis of cis,cis-Muconic Acid by Sphingobacterium sp GCG generated from effluent of a styrene monomer （SM） production plant
    Enzyme and Microbial Technology, 2004
    Co-Authors: Tsung-huei Lee, Sung-nung Lee, Yung-an Lee
    Abstract:

    Abstract Sphingobacterium sp. GCG was isolated from the sewage of a styrene monomer manufacturing factory in Taiwan. This bacterium could utilize benzoic Acid to synthesize cis,cis-Muconic Acid. Production of cis,cis-Muconic Acid by Sphingobacterium sp. strain is growth-associated. It was found that the strain through the BS-type (benzoic Acid/succinic Acid) culture medium with succinic Acid as a growth carbon source exhibits better growth rate than the other mediums. It was also found that glutamate used as a nitrogen source could optimize the production of cis,cis-Muconic Acid. In addition, an increment of ca. 75–100% of cis,cis-Muconic Acid could be obtained by adding EDTA–FeCl3 complex solution, since the enzyme catA, a necessary oxygenase to convert catechol to cis,cis-Muconic Acid, consists of 2 Fe(III) ions as the cofactor. On the other hand, a five-fold increase in the yield of cis,cis-Muconic Acid was observed when proceeded under fed-batch culture.

Jamsai Suwansaksri - One of the best experts on this subject based on the ideXlab platform.

  • Monitoring of urine trans, trans-Muconic Acid level among smokers and non-smokers
    Respiratory medicine, 2004
    Co-Authors: Viroj Wiwanitkit, Jamsai Suwansaksri, Suphan Soogarun
    Abstract:

    Summary Smoking has contributed to various neurological, cardiovascular, and pulmonary diseases. According to carcinogens found in cigarette smog, benzene is one of the important carcinogenic compounds. The urinary trans, trans-Muconic Acid (ttMA) levels among a sample of 10 Thai smokers and 35 Thai non-smokers were investigated, compared and reported. The average urinary ttMA level in smokers and non-smokers were 2.19±2.32 and 0.24±0.33 mg/gCr, respectively. A significant higher urinary ttMA level among the smokers was observed ( P 0.05 ). Since the higher urinary ttMA indicates the higher occult risk for cancer, the usage of urinary ttMA is recommended as a monitoring tool to follow up benzene exposure in the smokers.

  • A note on myeloperoxidation index and its correlation to the biomarker, urine trans, trans-Muconic Acid level, in the subjects occupationally exposed to benzene.
    Leukemia, 2003
    Co-Authors: Viroj Wiwanitkit, Suphan Soogarun, Jamsai Suwansaksri
    Abstract:

    A note on myeloperoxidation index and its correlation to the biomarker, urine trans, trans-Muconic Acid level, in the subjects occupationally exposed to benzene

  • Urine trans,trans-Muconic Acid determination for monitoring of benzene exposure in mechanics.
    The Southeast Asian journal of tropical medicine and public health, 2000
    Co-Authors: Jamsai Suwansaksri, Viroj Wiwanitkit
    Abstract:

    Benzene is an important carcinogenic substance used in many industrial processes. Inhalation of this substance can cause both acute and chronic toxicity. In this study, monitoring of benzene exposure by high-performance liquid chromatography for urine trans,trans-Muconic Acid (ttMA) determination in 94 subjects, (49 control subjects and 45 mechanics) was performed. The mean urine ttMA level in the control group was 0.116 +/- 0.027 mg/g creatinine. The mean urine ttMA level in the mechanics group was 0.280 +/- 0.131 mg/g creatinine. There was a significant difference between the groups (p < 0.05). Based on this study, we recommend the use of urine ttMA determination for monitoring of benzene exposure in high risk workers.

Jay D Keasling - One of the best experts on this subject based on the ideXlab platform.

  • An Orthogonal and pH-Tunable Sensor-Selector for Muconic Acid Biosynthesis in Yeast
    ACS Synthetic Biology, 2018
    Co-Authors: Tim Snoek, David Romero-suarez, Francesca Ambri, Mette L. Skjoedt, Suresh Sudarsan, Michael K. Jensen, Jie Zhang, Jay D Keasling
    Abstract:

    Microbes offer enormous potential for production of industrially relevant chemicals and therapeutics, yet the rapid identification of high-producing microbes from large genetic libraries is a major bottleneck in modern cell factory development. Here, we develop and apply a synthetic selection system in Saccharomyces cerevisiae that couples the concentration of Muconic Acid, a plastic precursor, to cell fitness by using the prokaryotic transcriptional regulator BenM driving an antibiotic resistance gene. We show that the sensor-selector does not affect production nor fitness, and find that tuning pH of the cultivation medium limits the rise of nonproducing cheaters. We apply the sensor-selector to selectively enrich for best-producing variants out of a large library of Muconic Acid production strains, and identify an isolate that produces more than 2 g/L Muconic Acid in a bioreactor. We expect that this sensor-selector can aid the development of other synthetic selection systems based on allosteric transcr...

  • An Orthogonal and pH-Tunable Sensor-Selector for Muconic Acid Biosynthesis in Yeast
    2018
    Co-Authors: Tim Snoek, David Romero-suarez, Francesca Ambri, Mette L. Skjoedt, Suresh Sudarsan, Michael K. Jensen, Jie Zhang, Jay D Keasling
    Abstract:

    Microbes offer enormous potential for production of industrially relevant chemicals and therapeutics, yet the rapid identification of high-producing microbes from large genetic libraries is a major bottleneck in modern cell factory development. Here, we develop and apply a synthetic selection system in Saccharomyces cerevisiae that couples the concentration of Muconic Acid, a plastic precursor, to cell fitness by using the prokaryotic transcriptional regulator BenM driving an antibiotic resistance gene. We show that the sensor-selector does not affect production nor fitness, and find that tuning pH of the cultivation medium limits the rise of nonproducing cheaters. We apply the sensor-selector to selectively enrich for best-producing variants out of a large library of Muconic Acid production strains, and identify an isolate that produces more than 2 g/L Muconic Acid in a bioreactor. We expect that this sensor-selector can aid the development of other synthetic selection systems based on allosteric transcription factors

  • An orthogonal and pH-tunable sensor-selector for Muconic Acid biosynthesis in yeast
    2017
    Co-Authors: Tim Snoek, David Romero-suarez, Mette L. Skjoedt, Suresh Sudarsan, Michael K. Jensen, Jie Zhang, Jay D Keasling
    Abstract:

    Microbes offer enormous potential for production of industrially relevant chemicals and therapeutics, yet the rapid identification of high-producing microbes from large genetic libraries is a major bottleneck in modern cell factory development. Here, we develop and apply a synthetic selection system in Saccharomyces cerevisiae that couples the concentration of Muconic Acid, a plastic precursor, to cell fitness by using the prokaryotic transcriptional regulator BenM driving an antibiotic resistance gene. We show the sensor-selector does not affect production, and find that tuning pH of the cultivation medium limits the rise of non-producing cheaters. We apply the sensor-selector to selectively enrich for best-producing variants out of a large library of Muconic Acid production strains, and identify an isolate that produced more than 2 g/L Muconic Acid in a bioreactor. We expect that this sensor-selector can aid the development of other synthetic selection systems based on allosteric transcription factors.

Jean-philippe Tessonnier - One of the best experts on this subject based on the ideXlab platform.

  • cis,cis-Muconic Acid isomerization and catalytic conversion to biobased cyclic-C6-1,4-diAcid monomers
    Green Chemistry, 2017
    Co-Authors: Jack M. Carraher, Toni Pfennig, Radhika G. Rao, Brent H. Shanks, Jean-philippe Tessonnier
    Abstract:

    Renewable terephthalic and 1,4-cyclohexanedicarboxylic Acids can be produced from biomass via Muconic Acid using a combination of biological and chemical processes. In this conversion scheme, cis,cis-mucononic Acid is first obtained by fermentation using either sugar or lignin monomers as a feedstock. The diunsaturated cis,cis-diAcid is then isomerized to trans,trans-Muconic Acid, reacted with biobased ethylene through Diels–Alder cycloaddition, and further hydrogenated or dehydrogenated to yield the desired 100% renewable cyclic dicarboxylic Acid. The isomerization of cis,cis- to trans,trans-Muconic Acid represents the main bottleneck in this process due to undesired side reactions that promote ring closing to form lactones. Therefore, new technologies for the selective isomerization of Muconic Acid are urgently needed. Here, we studied the corresponding reaction kinetics to elucidate the mechanisms involved in both the isomerization and cyclization reactions with the objective to identify conditions that favor the selective formation of trans,trans-Muconic Acid. We demonstrate that the reactivity of Muconic Acid in aqueous media strongly depends on pH. Under alkaline conditions, cis,cis-Muconic Acid is deprotonated to the corresponding muconate dianion. This species is stable for extended periods of time and does not isomerize. Conversely, cis,cis-Muconic Acid readily isomerizes to its cis,trans-isomer under Acidic conditions. Prolonged heating further triggers the intramolecular cyclizations through reaction of the carboxylic Acid and alkene functionalities. The formation of the muconolactone and its dilactone is kinetically favored over the isomerization to trans,trans-Muconic Acid over a broad range of conditions. However, strategies involving the chelation of the carboxylates with inorganic salts or their solvation using polar aprotic solvents were found to hamper the ring closing reactions and allow the isomerization to trans,trans-Muconic Acid to proceed with high selectivity (88%). The obtained compound was further reacted with ethylene and hydrogenated to 1,4-cyclohexanedicarboxylic Acid, an important monomer for the polyester and polyamide industries.

  • electrochemical conversion of Muconic Acid to biobased diAcid monomers
    ACS Sustainable Chemistry & Engineering, 2016
    Co-Authors: John E. Matthiesen, Jack M. Carraher, Monica Vasiliu, David A Dixon, Jean-philippe Tessonnier
    Abstract:

    Electrocatalysis is evolving as a competitive alternative to conventional heterogeneous catalysis for the conversion of platform chemicals from biomass. Here, we demonstrate the electrocatalytic conversion of cis,cis-Muconic Acid, a fermentation product, to trans,trans-Muconic Acid, trans-3-hexenedioic Acid, and adipic Acid used for the production of biobased polyamides and polyesters such as nylon, nylon derivatives, and polyethylene terephthalate (PET). The electrocatalytic hydrogenation in this work considers a wide range of early, late, and post-transition metals (Cu, Fe, Ni, Mo, Pb, Pd, Sn, and Zn) with low and high hydrogen overpotentials, and varying degrees of metal hydrogen binding strengths. The binding strength was determined to be an important factor for the conversion rate, faradaic efficiency, and product distribution. Selectivities are also discussed in relation to thermodynamic data, which suggests the possibility to tune the kinetics of the reaction to allow for the variable production of...

  • Comments on “Thermodynamics of cis,cis-Muconic Acid solubility in various polar solvents at low temperature range”
    Journal of Molecular Liquids, 2016
    Co-Authors: Jack M. Carraher, John E. Matthiesen, Jean-philippe Tessonnier
    Abstract:

    Abstract New light is shed on results published by Scelfo, Pirone, and Russo in “Thermodynamics of cis,cis-Muconic Acid solubility in various polar solvents at low temperature range”. We show that under the conditions described in their article, cis,cis-Muconic Acid isomerizes to cis,trans-Muconic Acid within minutes. This isomerization can be easily overlooked as both isomers present similar retention times during liquid chromatography analysis. Yet, the consequences are significant as the cis,trans isomer is five times more soluble at room temperature under Acidic conditions than cis,cis-Muconic Acid. pH should also be measured and taken into account as this parameter dramatically influences the species in solution, hence the solubility limit.

Viroj Wiwanitkit - One of the best experts on this subject based on the ideXlab platform.

  • Monitoring of urine trans, trans-Muconic Acid level among smokers and non-smokers
    Respiratory medicine, 2004
    Co-Authors: Viroj Wiwanitkit, Jamsai Suwansaksri, Suphan Soogarun
    Abstract:

    Summary Smoking has contributed to various neurological, cardiovascular, and pulmonary diseases. According to carcinogens found in cigarette smog, benzene is one of the important carcinogenic compounds. The urinary trans, trans-Muconic Acid (ttMA) levels among a sample of 10 Thai smokers and 35 Thai non-smokers were investigated, compared and reported. The average urinary ttMA level in smokers and non-smokers were 2.19±2.32 and 0.24±0.33 mg/gCr, respectively. A significant higher urinary ttMA level among the smokers was observed ( P 0.05 ). Since the higher urinary ttMA indicates the higher occult risk for cancer, the usage of urinary ttMA is recommended as a monitoring tool to follow up benzene exposure in the smokers.

  • A note on myeloperoxidation index and its correlation to the biomarker, urine trans, trans-Muconic Acid level, in the subjects occupationally exposed to benzene.
    Leukemia, 2003
    Co-Authors: Viroj Wiwanitkit, Suphan Soogarun, Jamsai Suwansaksri
    Abstract:

    A note on myeloperoxidation index and its correlation to the biomarker, urine trans, trans-Muconic Acid level, in the subjects occupationally exposed to benzene

  • Urine trans,trans-Muconic Acid determination for monitoring of benzene exposure in mechanics.
    The Southeast Asian journal of tropical medicine and public health, 2000
    Co-Authors: Jamsai Suwansaksri, Viroj Wiwanitkit
    Abstract:

    Benzene is an important carcinogenic substance used in many industrial processes. Inhalation of this substance can cause both acute and chronic toxicity. In this study, monitoring of benzene exposure by high-performance liquid chromatography for urine trans,trans-Muconic Acid (ttMA) determination in 94 subjects, (49 control subjects and 45 mechanics) was performed. The mean urine ttMA level in the control group was 0.116 +/- 0.027 mg/g creatinine. The mean urine ttMA level in the mechanics group was 0.280 +/- 0.131 mg/g creatinine. There was a significant difference between the groups (p < 0.05). Based on this study, we recommend the use of urine ttMA determination for monitoring of benzene exposure in high risk workers.