Sepedonium sp. and Phellinus sp. Novel Isolates: Growth Pattern and Production of Polysaccharide-Protein Complexes on Conventional and Grape Pomace Substrates

Abstract

Purpose The growth behavior of novel fungal isolates along with the production of bioactive compounds from mycelia mass during submerged fermentations were investigated using conventional synthetic media and agro-industrial residues as fermentation substrates. Methods Four novel isolated fungi, belonging to edible or medicinal species, were evaluated for their ex-situ growth on potato dextrose agar. Specific attention was designated to Sepedonium sp. and Phellinus sp. considering their high growth rate in solid state fermentations. Submerged fermentations were subsequently employed using synthetic carbon sources (glucose, fructose and lactose) to assess the fermentation behavior. Following the better growth pattern on glucose and fructose, compared to lactose, grape pomace extract (GPE) was applied as nutrient feedstock to assess the production of biomass and bioactive compounds. Aqueous extraction was performed to obtain crude intracellular polysaccharides (IPS), that were subsequently characterized in terms of antioxidant activity, protein and polysaccharide content. Results Sepedonium sp. demonstrated the highest biomass production; 11.4 and 10.5 g/L, using glucose and fructose, respectively, whereas Phellinus yielded up to 3.8 g/L. Lactose was also assimilated by both fungal strains, however biomass production was lower. Utilization of GPE affected biomass production; Sepedonium sp. biomass decreased, whereas biomass obtained from Phellinus sp. was enhanced, compared to synthetic sugars. Crude IPS extracts elicit high antioxidant activity (> 75% inhibition of DPPH• free radical). Conclusion The successful application of conventional and renewable substrates for Sepedonium and Phellinus fermentation was demonstrated, while the mycelia mass derived polysaccharide-protein complexes exhibited bioactive properties, and thus might be utilized as functional food components. Graphical Abstract

Valorization of Grape Pomace for Trametes versicolor Mycelial Mass and Polysaccharides Production

“…In our previous studies, GPE extract was evaluated as a substrate for the cultivation of Phellinus sp., Sepedonium sp. and Ganoderma lucidum strains [13,31]. A strain specificity was shown since, depending on the strain, biomass production increased or decreased compared with the synthetic media.…”

“…A previously described method was used to formulate grape pomace extract (GPE) using an aqueous extraction process. Briefly, the extraction of soluble, free sugars from grape pomace was performed at 40 • C for 2 h at a solid-to-liquid ratio of 1:10 (w/v) with deionized water [13]. The GPE contained ~5-6 g/L of glucose and ~5-6 g/L of fructose along with trace amounts of sucrose (0.4-0.5 g/L).…”

Ganoderma lucidum Mycelia Mass and Bioactive Compounds Production through Grape Pomace and Cheese Whey Valorization

“…and Sepedonium sp. isolates, TDW exhibited a decrease compared with glucose; however, that study implemented only static conditions [31]. In another study, Wei et al suggested that using an optimized ratio of glucose and sucrose improved the fungal mass of G. lucidum, along with polysaccharide and ganoderic acid production [26].…”

“…Subsequent steps employed replacing commercial media with a feedstock derived from renewable resources, following the results obtained from conventional carbon sources. A preliminary characterization of GPE was performed in our previous study [31], where the low concentration of total phenolic content and free amino nitrogen (FAN) was also reported. The experiments initiated by applying GPE as the sole substrate in static and shaking conditions, and the fermentation kinetics are shown in Figure 1.…”

“…using GPE, whereas a reduction in biomass was indicated for Sepedonium sp. [31]. In another study, eleven filamentous fungi, including G. lucidum, were grown on grape pomace under solid-state conditions to assess phenolic compound recovery and enzyme production as a biological pretreatment method [32].…”