Fungal Melanins and Applications in Healthcare, Bioremediation and Industry

Mattoon, Ellie Rose; Cordero, Radamés J. B.; Casadevall, Arturo

doi:10.3390/jof7060488

Cited by 38 publications

(26 citation statements)

References 83 publications

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“…The antioxidant properties of melanin are partially responsible for its protective properties [ 84 ]. Melanized C. auris yeast cells were partially protected against hydrogen peroxide, and this protection was stronger in the strain where melanization is more efficient (CDC 387).…”

Section: Discussionmentioning

confidence: 99%

Melanization of Candida auris Is Associated with Alteration of Extracellular pH

Smith

Mudrak

Zamith-Miranda

et al. 2022

JoF

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Candida auris is a recently emerged global fungal pathogen, which causes life-threatening infections, often in healthcare settings. C. auris infections are worrisome because the fungus is often resistant to multiple antifungal drug classes. Furthermore, C. auris forms durable and difficult to remove biofilms. Due to the relatively recent, resilient, and resistant nature of C. auris, we investigated whether it produces the common fungal virulence factor melanin. Melanin is a black-brown pigment typically produced following enzymatic oxidation of aromatic precursors, which promotes fungal virulence through oxidative stress resistance, mammalian immune response evasion, and antifungal peptide and pharmaceutical inactivation. We found that certain strains of C. auris oxidized L-DOPA and catecholamines into melanin. Melanization occurred extracellularly in a process mediated by alkalinization of the extracellular environment, resulting in granule-like structures that adhere to the fungus’ external surface. C. auris had relatively high cell surface hydrophobicity, but there was no correlation between hydrophobicity and melanization. Melanin protected the fungus from oxidative damage, but we did not observe a protective role during infection of macrophages or Galleria mellonella larvae. In summary, C. auris alkalinizes the extracellular medium, which promotes the non-enzymatic oxidation of L-DOPA to melanin that attaches to its surface, thus illustrating a novel mechanism for fungal melanization.

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Section: Discussionmentioning

confidence: 99%

Melanization of Candida auris Is Associated with Alteration of Extracellular pH

Smith

Mudrak

Zamith-Miranda

et al. 2022

JoF

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“…Diverse classes of melanins can be synthesized by different fungal species ( Mattoon et al, 2021 ). The black yeast Hortaea werneckii is the ultimate acknowledged halotolerant strain in fungi, capable of growing across a wide range of NaCl concentrations from 0 to saturation at 30% NaCl, and is well-known for its capacity to naturally synthesize melanin pigment ( Chung et al, 2019 ; Zalar et al, 2019 ).…”

Section: Introductionmentioning

confidence: 99%

“…Taking into account the unique physical and chemical properties of melanins in addition to their important biological functions, melanins can be utilized for various medical, environmental, and biotechnological applications ( Mattoon et al, 2021 ). Many diseases such as cancer, autoimmune diseases, and Alzheimer’s disease are caused by the destructive action of reactive oxygen species (ROS) to the structure and function of sensitive intracellular molecules ( Kurian et al, 2015 ; Cordero et al, 2017 ).…”

Section: Introductionmentioning

confidence: 99%

Suggested Sustainable Medical and Environmental Uses of Melanin Pigment From Halotolerant Black Yeast Hortaea werneckii AS1

et al. 2022

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The marine ecosystem is a complex niche with unique environmental circumstances. Microbial communities from the sea are one of the main origins of compounds with tremendous capabilities. Marine yeasts have the ability to produce secondary metabolites that are architecturally distinct from those found in terrestrial species. Melanin pigment synthesized by marine halotolerant black yeast Hortaea werneckii AS1 isolated from Mediterranean salt lakes in Alexandria, Egypt was found to exert a radical scavenging effect on 2,2-diphenyl-1-picrylhydrazyl (DPPH) with an IC50 of 61.38 μg/ml. Furthermore, it showed no cytotoxicity toward human skin fibroblast cell line (HSF) with an IC50 value above 0.1 mg/ml. The antimicrobial capability of the pigment was revealed against the tested number of bacterial and fungal strains with the highest inhibition zone of 25 mm against Aeromonas sp. and a growth inhibition percentage up to 63.6% against Aspergillus niger. From an environmental impact point of view, the pigment disclosed a heavy metal removal efficiency of 85.7, 84.8, and 81.5% for Pb2+, Cd2+, and Ni2+, respectively, at 100 mg/L metal concentration. The previously mentioned results suggested melanin from H. werneckii AS1 as a promising biocompatible candidate in various medical, cosmetics, pharmaceutical, and environmental applications.

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“…The antioxidant properties of melanin are partially responsible for its protective properties (63). Melanized C. auris yeast cells were partially protected against hydrogen peroxide, and this protection was stronger in the strain where melanization is more efficient (CDC 387).…”

Section: Discussionmentioning

confidence: 99%

Melanization ofCandida aurisis Associated with Alteration of Extracellular pH

Smith

Mudrak

Zamith-Miranda

et al. 2022

Preprint

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Candida auris is a recently emerged global fungal pathogen, which causes life threatening infections, often in healthcare settings and with immunocompromised patients. C. auris infections are particularly worrisome because the fungus is often resistant to multiple classes of antifungal drugs. Furthermore, the fungus forms durable biofilms that are difficult to remove from surfaces. Due to the relatively recent, resilient, and resistant nature of this fungal pathogen, we investigated whether C. auris made common fungal virulence factor melanin. Melanin is a black-brown pigment that enables microbes to evade the mammalian immune response due to its strong antioxidant properties, ability to inactivate antimicrobial peptides, shielding of pathogen-associated molecular patterns, and inactivation of antifungal drugs. We found that certain strains of C. auris , predominantly from Clade I and IV, oxidized catecholamines into melanin pigment. The formation of this melanin occurred extracellularly, resulting in granule-like melanin structures that are deposited on the surface of the fungus. This melanization was primarily chemically driven and mediated by alkalinization of the extracellular environment. The C. auris strains had relatively high cell surface hydrophobicity, but we did not find a correlation between hydrophobicity and ability to melanize. Melanin protected the fungus from oxidative damage but we did not observe a protective role in vitro or in vivo during infection of macrophages or Galleria mellonella, respectively. In summary, C. auris alkalinizes the extracellular medium, which promotes the chemical autooxidation of the L-DOPA to melanin that then attaches to its surface, thus illustrating a different mechanism for fungal melanization.

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Fungal Melanins and Applications in Healthcare, Bioremediation and Industry

Cited by 38 publications

References 83 publications

Melanization of Candida auris Is Associated with Alteration of Extracellular pH

Melanization of Candida auris Is Associated with Alteration of Extracellular pH

Suggested Sustainable Medical and Environmental Uses of Melanin Pigment From Halotolerant Black Yeast Hortaea werneckii AS1

Melanization ofCandida aurisis Associated with Alteration of Extracellular pH

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