Activity of Lignin-Modifying Enzyme of Selected Medicinal Mushrooms in Submerged Fermentation of Lignocellulosic Materials.

In the present study, wide diversity in the set and activity of lignin-modifying enzymes (LME) was revealed during submerged fermentation of mandarin peel with 15 strains of white rot Basidiomycetes. Among them, Trametes pubescens BCC153 was distinguished by the simultaneous production of laccase, manganese peroxidase (MnP), and lignin peroxidase (LiP). Supplementation of CuSO4 at a concentration of 1 mM in the media for the cultivation of four Trametes species manifold increased the production of laccase. The diverse effects of chemically different lignocellulosic growth substrates and nitrogen sources on the production of individual LME have been established. The maximum laccase activity of T. pubescens was observed when the fungus was cultivated on media containing mandarin peel and wheat bran, whereas the highest MnP and LiP activities were detected in the submerged fermentation of tobacco residue. Peptone and casein hydrolysate appeared to be the best sources of nitrogen to produce laccase and both peroxidases by T. pubescens BCC153 whereas KNO3 was the worst nitrogen-containing compound for the production of all enzymes.

Antifungal Activity of Medicinal Mushrooms and Optimization of Submerged Culture Conditions for Schizophyllum commune (Agaricomycetes).

The main goal of the present study was the exploration of the antifungal properties of Agaricomycetes mushrooms. Among twenty-three tested mushrooms against A. niger, B. cinerea, F. oxysporum, and G. bidwellii, Schizophyllum commune demonstrated highest inhibition rates and showed 35.7%, 6.5%, 50.4%, and 66.0% of growth inhibition, respectively. To reveal culture conditions enhancing the antifungal potential of Sch. commune, several carbon (lignocellulosic substrates among them) and nitrogen sources and their optimal concentrations were investigated. Presence of 6% mandarin juice production waste (MJPW) and 6% of peptone in nutrient medium promoted antifungal activity of selected mushroom. It was determined that, extracts obtained in the presence of MJPW effectively inhibited the grow of pathogenic fungi. Moreover, the content of phenolic compounds in the extracts obtained from Sch. commune grown on MJPW was several times higher (0.87 ± 0.05 GAE/g to 2.38 ± 0.08 GAE/g) than the extracts obtained from the mushroom grown on the synthetic (glycerol contained) nutrient medium (0.21 ± 0.03 GAE/g to 0.88 ± 0.05 GAE/g). Flavonoid contents in the extracts from Sch. commune varied from 0.58 ± 0.03 to 27.2 ± 0.8 mg QE/g. Identification of phenolic compounds composition in water and ethanol extracts were provided by mass spectrometry analysis. Extracts demonstrate considerable free radical scavenging activities and the IC50 values were generally low for the extracts, ranging from 1.9 mg/ml to 6.7 mg/ml. All the samples displayed a positive correlation between their concentration (0.05-15.0 mg/ml) and DPPH radical scavenging activity. This investigation revealed that Sch. commune mushroom has great potential to be used as a source of antifungal and antioxidant substances.

Chemical Composition and Antioxidant Properties of Different Combinations of Submerged Cultured Mycelia of Medicinal Mushrooms.

This research describes the investigation of submerged cultivated mycelial biomass and hot water extracts prepared from different combinations and ratios of medicinal mushroom (MM) dry powders, comprising various biologically active compounds/secondary metabolites. In particular, it was evaluated the proximate composition (moisture, ash, crude protein, fat, total carbohydrates, and total energy), γ-aminobutyric acid (GABA) and ergothioneine (ERG), amino acid content of mycelia of 16 higher Basidiomycetes MM species. The results obtained demonstrate that almost all tested combinations were found to be good sources of polysaccharides, with content varying in the ranges of 4.73 ± 1.33% and 58.46 ± 4.15%. Total protein contents varied in 1.97 ± 0.40% - 5.37 ± 0.40% range. ERG was detected in all tested samples, while GABA existed only in eight samples out of 15 and varied from 0.03 ± < 0.01 to 0.61 ± 0.03 mg/g, and from 0.16 ± 0.03 to 5.69 ± 0.41 mg/g respectively. Analyses of total phenolic and flavonoid contents demonstrate considerable content in all samples (15.53 ± 0.23 - 18.88 ± 0.34 mg gallic acid equivalents/g and 1.23 ± 0.04 - 4.34 ± 0.73 mg rutin equivalents/g respectively). In present research the complexity of samples/extracts were evaluated by multiple antioxidant assays to verify their antioxidant capacity. Determination of in vitro antioxidant activity was successfully carried out by several different methods such as 2,2-diphenyl-1-picrylhydrazyl scavenging activity, reducing power, chelating ability, hydroxyl radical scavenging activity, and 2,2'-azino-bis(3-ethylbenzothi-azoline-6-sulfonic acid scavenging activity. Therefore, all tested samples confirm the capable antioxidant activities of bioactive compounds extracted from MMs.

Screening of Georgian Medicinal Mushrooms for Their Antibacterial Activity and Optimization of Cultivation Conditions for the Split Gill Medicinal Mushroom, Schizophyllum commune BCC64 (Agaricomycetes).

The present study aimed to evaluate the antibacterial activity (ABA) of new mushroom strains collected from the mountain and plain forests of Georgia and belonging to different taxonomic groups. Of 30 Basidiomycetes strains tested on agar plates, Schizophyllum commune BCC64 exhibited the highest inhibitory activity against Escherichia coli and Staphylococcus aureus by the diameter of inhibition zones (17 ± 1 mm and 19 ± 1 mm, respectively). Moreover, this mushroom showed strong activity against Staphylococcus enteritidis (11 mm), Pseudomonas aeruginosa (19 mm), and Salmonella epidermitidis (12 mm). In the submerged cultivation in synthetic medium, xylose and glucose ensured the highest ABA toward S. aureus (70% inhibition in microplate rider tests) and E. coli (60%), respectively. Among lignocellulosic materials tested in the submerged and solid-state fermentation, mandarin marc was found to be an excellent growth substrate for ABA accumulation by Sch. commune 64. Of six nitrogen sources, KNO3 favored the mushroom ABA increase against both bacteria. The suitability of the developed nutrient medium has been proven in 7 L fermenter. After fermentation, ethyl acetate extract obtained from culture liquid and ethanol extract obtained from mycelial biomass of Sch. commune 64 showed the best minimum inhibitory concentration (MIC) against E. coli (0.5 and 2.5 mg/mL, respectively) and S. aureus (1 mg/mL for both extracts).

Elucidation of the Higher Basidiomycetes Enzyme Activity in Dependence on the Medicinal Mushroom Inoculum Form, Precultivation Medium, Age, and Size.

The impact of five mushroom inoculum form, age, size, and precultivation medium on the lignocellulose-deconstracting enzyme (LCDE) production was evaluated in the submerged fermentation of mandarin marc. The results obtained evidence that an adaptation of individual fungi to lignocellulose during maintenance in culture collection and inoculum cultivation may be useful for the production of individual LCDE. Homogenization of submerged mycelium was beneficial for all LCDE production by Cerrena unicolor 305 and Ganoderna lucidum 447 and for LME secretion by Coriolopsis gallica 142 and Trametes multicolor 511. Finely chopped mycelial agar favored CMCase and xylanase production by T. multicolor 511 and LiP secretion by C. unicolor 305 and G. lucidum 447 while homogenized mycelial agar proved to be the worst form of inoculum for the production of most enzymes. Four-days inoculum was the most appropriate for the laccase and MnP production by G. lucidum 447 and T. multicolor 511 while the 7-days mycelium provided the highest yields of these enzymes in the cultivation of C. unicolor 305. Use of the 12-days homogenized mycelium from the late stationary phase resulted in lowest laccase activity of all fungi but provided the highest cellulase activity. Overall, the study showed that the LCDE activity and their accumulation profiles in the cultures with different inoculum size was species dependent.

Comparison of Mono- and Dikaryotic Medicinal Mushrooms Lignocellulolytic Enzyme Activity.

Mono- and dikaryotic medicinal mushroom strains isolated from four wood-rotting basidiomycete fruiting bodies were comparatively evaluated for laccase, manganese peroxidase, cellulase, and xylanase activities in submerged cultivation in glucose or mandarin peel-containing media. Mandarin peels appeared to be the preferred growth substrate for laccase production by both mono- and dikaryotic Trametes multicolor 511 and T. versicolor 5 while glucose favored laccase activity secretion by Pleurotus ostreatus 2175. Lignocellulose-deconstructing enzyme profiles were highly variable between the studied monokaryotic and dikaryotic strains. A distinctive superiority of enzyme activity of the dikaryotic Trametes versicolor 5 and P. ostreatus 2175 over the same species monokaryotic isolates was revealed. By contrast, laccase, cellulase, and xylanase activities of the monokaryotic strain of T. multicolor 511 were rather higher than those in the dikaryotic culture. At the same time, hydrolases activity of Schizophyllum commune 632 was practically independent of the origin of the fungal culture. The results suggest that the monokaryotic isolates derived from the basidiomycetes fruiting bodies inherit parental properties but the capacity of individual monokaryotic cultures to produce lignocellulose-deconstructing enzymes can vary considerably.

Free-radical scavenging activity of submerged mycelium extracts from higher basidiomycetes mushrooms.

Twenty-four Basidiomycetes strains were evaluated to determine their free-radical scavenging capacity in submerged cultivation. The scavenging capacity of the extracts varied from 1 to 85% depending on the mushroom species, solvent used, and concentration. A calculation of EC(50) of extracts from several wood-rotting Basidiomycetes showed high scavenging abilities at low effective concentration.