Optimization of Melanin Production by Streptomyces antibioticus NRRL B-1701 Using Arthrospira (Spirulina) platensis Residues Hydrolysates as Low-Cost L-tyrosine Supplement

Photoprotection and antioxidant activity of eumelanin from Streptomyces lasalocidi NTB 42 and its photoprotective effects on Schizosaccharomyces pombe ARC039

This study evaluated the photoprotective and antioxidant properties of eumelanin derived from Streptomyces lasalocidi NTB 42 (eumelanin NTB 42). This study also investigated the cellular-level photoprotective effects of eumelanin using Schizosaccharomyces pombe ARC039 as a model organism and its ability to enhance the Sun Protection Factor (SPF) of commercial sunscreens. The thermal and light stability and total phenolic and flavonoid contents were analyzed. Antioxidant activity was assessed using hydroxyl radicals (OH), and superoxide anions (O2.-) radical-scavenging assays. The efficacy of photoprotection was determined using various in vitro methods, yeast cell viability assays, and enhanced SPF values of commercial sunscreen products. Eumelanin NTB 42 exhibited both thermal and photostabilities. The total phenolic and flavonoid contents were reported as 88.82 ± 0.68 mg gallic acid equivalent (GAE)/g and 53.24 ± 2.66 mg quercetin equivalent (QE)/g, respectively, representing the first report on microbial eumelanin. Eumelanin NTB 42 demonstrated significant scavenging activity against OH and O2.-. It also displays notable photoprotective effects against UV-B radiation, offering broad-spectrum coverage and optimal protection against UV-A radiation. It effectively acted as a sunblock against UV-A and UV-B radiation. Furthermore, eumelanin NTB 42 enhanced S. pombe ARC039 cell viability after exposure to UV-B and UV-C for 30-90 min. It also augmented the SPF value of commercial products at a minimum concentration of 0.0025 %. These findings highlight the potential antioxidant and photoprotective properties of eumelanin NTB 42, suggesting its applicability as a raw material for sunscreen formulations in the cosmetic industry.

Streptomycetes as Microbial Cell Factories for the Biotechnological Production of Melanin

Melanins are complex, polymeric pigments with interesting properties like UV-light absorbance ability, metal ion chelation capacity, antimicrobial action, redox behaviors, and scavenging properties. Based on these characteristics, melanins might be applied in different industrial fields like food packaging, environmental bioremediation, and bioelectronic fields. The actual melanin manufacturing process is not environmentally friendly as it is based on extraction and purification from cuttlefish. Synthetic melanin is available on the market, but it is more expensive than animal-sourced pigment and it requires long chemical procedures. The biotechnological production of microbial melanin, instead, might be a valid alternative. Streptomycetes synthesize melanins as pigments and as extracellular products. In this review, the melanin biotechnological production processes by different Streptomyces strains have been revised according to papers in the literature. The different fermentation strategies to increase melanin production such as the optimization of growth conditions and medium composition or the use of raw sources as growth substrates are here described. Diverse downstream purification processes are also reported as well as all the different analytical methods used to characterize the melanin produced by Streptomyces strains before its application in different fields.