Catalina Landeta-Salgado

Seaweed biomass is globally underutilized as a source of proteins despite its nutritional potential, with much of its use focused on hydrocolloid extraction. This study evaluated the nutritional quality and digestibility of protein and amino acids from two brown seaweeds (Durvillaea spp. and Macrocystis pyrifera), one green seaweed (Ulva spp.), and a novel mycoprotein derived from Durvillaea spp. through fungal fermentation. Using an in vitro gastrointestinal digestion Megazyme assay kit, protein digestibility-corrected amino acid scores (PDCAASs) and digestible indispensable amino acid scores (DIASSs) were determined. Compared with seaweeds, seaweed-derived mycoprotein presented significantly greater protein contents (~33%) and amino acid profiles (2.2 times greater than those of Durvillaea spp. and M. pyrifera), with greater digestibility (~100%) than seaweeds (Ulva spp., Macrocystis pyrifera, Durvillaea spp., and mycoproteins, respectively. The DIASSs highlighted the superior nutritional quality of the mycoprotein, particularly for lysine (0.59) and histidine (0.67). SDS-PAGE revealed soluble peptides (Durvillaea spp., Macrocystis pyrifera, and mycoproteins, whereas Ulva spp. proteins exhibited limited solubility due to structural aggregation. These findings highlight the need to characterize the nutritional properties of edible seaweeds in Chile further and emphasize the importance of optimized processing techniques, such as fermentation or bioconversion, to improve the nutritional potential of seaweeds and develop high-quality food ingredients for diverse applications.

Natural compounds derived from microorganisms, especially those with antioxidant and anticancer properties, are gaining attention for their potential applications in biomedical, cosmetic, and food industries. Marine fungi, such as Asteromyces cruciatus, are particularly promising due to their ability to produce bioactive metabolites through the degradation of marine algal polysaccharides. This study investigates the metabolic diversity of A. cruciatus grown on different carbon sources: glucose, Durvillaea spp., and Macrocystis pyrifera. Crude extracts of fungal biomass were analyzed for total phenolic content (TPC), antioxidant capacity (TAC), toxicity, and phenolic compound identification using ultra-high-performance liquid chromatography coupled with high-resolution electrospray ionization mass spectrometry (UHPLC-MS/MS). The analysis revealed the presence of anthraquinone compounds, including emodin (0.36 ± 0.08 mg/g DW biomass) and citrereosein in glucose medium and citrereosein and endocrocin in M. pyrifera medium. No such compounds were detected in Durvillaea spp. medium. The glucose-grown extract exhibited the highest TPC (3.09 ± 0.04 mg GAE/g DW) and TAC (39.70 ± 1.0 µmol TEq/g biomass). Additionally, no detrimental effects were observed on a neuronal cell line. These findings highlight the influence of carbon sources on the production of bioactive metabolites and their functional properties, providing valuable insights into the biotechnological potential of A. cruciatus.

This study aimed, for the first time, to determine the nutritional composition, beta-glucan and ergosterol contents, phenolic compound composition, and biological and functional activities of a novel mycoprotein produced through a bioconversion process of Durvillaea spp., a brown seaweed. An untargeted metabolomics approach was employed to screen metabolites and annotate molecules with nutraceutical properties. Two products, each representing a distinct consortia of co-cultured fungi, named Myco 1 and Myco 2, were analysed in this study. These consortia demonstrated superior properties compared to those of Durvillaea spp., showing significant increases in total protein (~238%), amino acids (~219%), and β-D-glucans (~112%). The protein contains all essential amino acids, a low fatty acid content, and exhibits high antioxidant activity (21.5–25.5 µmol TE/g). Additionally, Myco 2 exhibited the highest anti-alpha-glucosidase activity (IC₅₀ = 16.5 mg/mL), and Myco 1 exhibited notable anti-lipase activity (IC₅₀ = 10.5 mg/mL). Among the 69 top differentially abundant metabolites screened, 8 nutraceutical compounds were present in relatively high concentrations among the identified mycoproteins. The proteins and polysaccharides in the mycoprotein may play a crucial role in the formation and stabilization of emulsions, identifying it as a potent bioemulsifier. In conclusion, the bioconversion of Durvillaea spp. results in a mycoprotein with high-quality protein, significant nutritional and functional value, and prebiotic and nutraceutical potential due to the production of unique bioactive compounds.