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Research Article
Jean Lorquin
Aix-Marseille University
Corresponding Author
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Pyomelanin is a polymer of homogentisic acid synthesized by microorganisms. This work aimed to develop a production process and evaluate the quality of the pigment. Three procedures have been elaborated and optimized, (1) an HGA-Mn2+ chemical autoxidation (PyoCHEM yield 0.317 g/g substrate), (2) an induced bacterial culture of Halomonas titanicae through the 4-hydroxyphenylacetic acid-1-hydroxylase route (PyoBACT, 0.55 g/L), and (3) a process using a recombinant laccase with the highest level produced (PyoENZ, 1.25 g/g substrate) and all the criteria for a large-scale prototype. The chemical structures had been investigated by 13C solid-state NMR (CP-MAS) and FTIR. Car-Car bindings predominated in the three polymers, Car-O-Car (ether) linkages being absent, proposing mainly C3-C6 (β-bindings) and C4-C6 (α-bindings) configurations. This work highlighted a biological decarboxylation by the laccase or bacterial oxidase(s), leading to the partly formation of gentisyl alcohol and gentisaldehyde that are integral parts of the polymer. By comparison, PyoENZ exhibited an Mw of 5,700 Da, was hyperthermostable, non-cytotoxic even after irradiation, scavenged ROS induced by keratinocytes, and had a highly DPPH-antioxidant and Fe3+-reducing activity. As a representative pigment of living cells and an available standard, PyoENZ might also be useful for applications in extreme conditions and skin protection.
Keywords
pyomelanin, polymerization, laccase, Halomonas titanicae, solid-state CP-MAS NMR, antioxidant, electron transfer, cytotoxicity.
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View the published article at Scientific Reports.
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Editorial decision: Major revision
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See the published version of this preprint at Scientific Reports.
This is a preprint, a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice.
Learn more about In Review
Research Article
Jean Lorquin
Aix-Marseille University
Corresponding Author
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
Peer Review Timeline
CURRENT STATUS: Published
View the published article at Scientific Reports.
Version 1
Posted 30 Nov, 2020
No community comments so far
Editorial decision: Major revision
On 27 Jan, 2021
Reviews received
Received 14 Jan, 2021
Reviewers agreed
On 08 Jan, 2021
Reviewers invited
Invitations sent on 08 Jan, 2021
Editor assigned
On 07 Jan, 2021
Editor invited
On 24 Nov, 2020
Submission checks complete
On 24 Nov, 2020
First submitted
On 13 Nov, 2020
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
Subject Areas
Molecular Biology
License:
This work is licensed under a CC BY 4.0 License. Read Full License
View the published article at Scientific Reports.
Pyomelanin is a polymer of homogentisic acid synthesized by microorganisms. This work aimed to develop a production process and evaluate the quality of the pigment. Three procedures have been elaborated and optimized, (1) an HGA-Mn2+ chemical autoxidation (PyoCHEM yield 0.317 g/g substrate), (2) an induced bacterial culture of Halomonas titanicae through the 4-hydroxyphenylacetic acid-1-hydroxylase route (PyoBACT, 0.55 g/L), and (3) a process using a recombinant laccase with the highest level produced (PyoENZ, 1.25 g/g substrate) and all the criteria for a large-scale prototype. The chemical structures had been investigated by 13C solid-state NMR (CP-MAS) and FTIR. Car-Car bindings predominated in the three polymers, Car-O-Car (ether) linkages being absent, proposing mainly C3-C6 (β-bindings) and C4-C6 (α-bindings) configurations. This work highlighted a biological decarboxylation by the laccase or bacterial oxidase(s), leading to the partly formation of gentisyl alcohol and gentisaldehyde that are integral parts of the polymer. By comparison, PyoENZ exhibited an Mw of 5,700 Da, was hyperthermostable, non-cytotoxic even after irradiation, scavenged ROS induced by keratinocytes, and had a highly DPPH-antioxidant and Fe3+-reducing activity. As a representative pigment of living cells and an available standard, PyoENZ might also be useful for applications in extreme conditions and skin protection.
Figure 1
Figure 2
Figure 3
Figure 4
The full text of this article is available to read as a PDF.
This is a list of supplementary files associated with this preprint. Click to download.
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