Aspergillus niger as a cell factory for the production of pyomelanin, a molecule with UV-C radiation shielding activity

Stella Marie Koch; Carsten Freidank-Pohl; Oliver Siontas; Marta Cortesao; Afonso Mota; Katharina Runzheimer; Sascha Jung; Katarina Rebrosova; Martin Siler; Ralf Moeller; Vera Meyer

doi:10.3389/fmicb.2023.1233740

Aspergillus niger as a cell factory for the production of pyomelanin, a molecule with UV-C radiation shielding activity

Front Microbiol. 2023 Jul 20:14:1233740. doi: 10.3389/fmicb.2023.1233740. eCollection 2023.

Affiliations

¹ Radiation Biology Department, Aerospace Microbiology Research Group, German Aerospace Center, Institute of Aerospace Medicine, Cologne, Germany.
² Applied and Molecular Microbiology, Institute of Biotechnology, Technische Universität Berlin, Berlin, Germany.
³ Department of Microbiology, Faculty of Medicine, Masaryk University (MUNI) and St. Anne's Faculty Hospital, Brno, Czechia.
⁴ Institute of Scientific Instruments of the Czech Academy of Sciences, Brno, Czechia.

^# Contributed equally.

Abstract

Melanins are complex pigments with various biological functions and potential applications in space exploration and biomedicine due to their radioprotective properties. Aspergillus niger, a fungus known for its high radiation resistance, is widely used in biotechnology and a candidate for melanin production. In this study, we investigated the production of fungal pyomelanin (Pyo_Fun) in A. niger by inducing overproduction of the pigment using L-tyrosine in a recombinant ΔhmgA mutant strain (OS4.3). The Pyo_Fun pigment was characterized using three spectroscopic methods, and its antioxidant properties were assessed using a DPPH-assay. Additionally, we evaluated the protective effect of Pyo_Fun against non-ionizing radiation (monochromatic UV-C) and compared its efficacy to a synthetically produced control pyomelanin (Pyo_Syn). The results confirmed successful production of Pyo_Fun in A. niger through inducible overproduction. Characterization using spectroscopic methods confirmed the presence of Pyo_Fun, and the DPPH-assay demonstrated its strong antioxidant properties. Moreover, Pyo_Fun exhibited a highly protective effect against radiation-induced stress, surpassing the protection provided by Pyo_Syn. The findings of this study suggest that Pyo_Fun has significant potential as a biological shield against harmful radiation. Notably, Pyo_Fun is synthesized extracellularly, differing it from other fungal melanins (such as L-DOPA- or DHN-melanin) that require cell lysis for pigment purification. This characteristic makes Pyo_Fun a valuable resource for biotechnology, biomedicine, and the space industry. However, further research is needed to evaluate its protective effect in a dried form and against ionizing radiation.

Keywords: Aspergillus niger; cosmic radiation; melanin; pyomelanin; radioprotection; space exploration.

Grants and funding

KRe, SK, AM, MC, and RM were supported by the DLR grant FuE-Projekt ISS LIFE (Programm RF-FuW, Teilprogramm 475). MC was supported by the DLR/DAAD Research Fellowship Doctoral Studies in Germany, 2017 (57370122). VM was supported by TU internal funding. KRe and RM were supported by ESA via the ESA Contract No. 4000137602/22/NL/GLC/my for the Co-sponsored Ph.D., project I-2021-01758 (BioProtect-Bioinspired Shielding Material for Radiation Protection Purposes). KRe was supported by the Grant Agency of Masaryk University (MUNI/A/1361/2022). KRe and MS were supported by the Czech Health Research Council (NU21-05-00341) grant and ISI CAS. Open access funding was enabled and organized by Projekt DEAL.