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.

The Carbon Source Controls the Secretion and Yield of Polysaccharide-Hydrolyzing Enzymes of Basidiomycetes.

In the present study, the polysaccharide-hydrolyzing secretomes of Irpex lacteus (Fr.) Fr. (1828) BCC104, Pycnoporus coccineus (Fr.) Bondartsev and Singer (1941) BCC310, and Schizophyllum commune Fr. (1815) BCC632 were analyzed in submerged fermentation conditions to elucidate the effect of chemically and structurally different carbon sources on the expression of cellulases and xylanase. Among polymeric substrates, crystalline cellulose appeared to be the best carbon source providing the highest endoglucanase, total cellulase, and xylanase activities. Mandarin pomace as a growth substrate for S. commune allowed to achieve comparatively high volumetric activities of all target enzymes while wheat straw induced a significant secretion of cellulase and xylanase activities of I. lacteus and P. coccineus. An additive effect on the secretion of cellulases and xylanases by the tested fungi was observed when crystalline cellulose was combined with mandarin pomace. In I. lacteus the cellulase and xylanase production is inducible in the presence of cellulose-rich substrates but is suppressed in the presence of an excess of easily metabolizable carbon source. These enzymes are expressed in a coordinated manner under all conditions studied. It was shown that the substitution of glucose in the inoculum medium with Avicel provides accelerated enzyme production by I. lacteus and higher cellulase and xylanase activities of the fungus. These results add new knowledge to the physiology of basidiomycetes to improve cellulase production.

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).

Alteration of white-rot basidiomycetes cellulase and xylanase activities in the submerged co-cultivation and optimization of enzyme production by Irpex lacteus and Schizophyllum commune.

Mono and dual cultures of four white-rot basidiomycete species were evaluated for cellulase and xylanase activity under submerged fermentation conditions. Co-cultivation of Pycnoporus coccineus or Trametes hirsuta with Schizophyllum commune displayed antagonistic interactions resulting in the decrease of endoglucanase and total cellulase activities. In contrast, increases in cellulase and xylanase activity were revealed through the compatible interactions of Irpex lacteus with S. commune. Co-cultivation conditions were optimized for maximum enzyme production by I. lacteus and S. commune, the best producers of cellulase/xylanase and ß-glucosidase, respectively. An optimized medium for the target enzyme production by the mixed culture was established in a laboratory fermenter yielding 7U/mL total cellulase, 142U/mL endoglucanase, 104U/mL xylanase, and 5.2U/mL ß-glucosidase. The dual culture approach resulted in an enzymatic mixture with 11% improved lignocellulose saccharification potential compared to enzymes from a monoculture of I. lacteus.

Modulation of Cerrena unicolor laccase and manganese peroxidase production.

Among seven carbon sources tested, glycerol and glucose favored the Cerrena unicolor laccase production (18.8-20.3 U/mL); in addition, glycerol ensured the highest manganese peroxidase (MnP) activity (2 U/mL). Substitution of glycerol with the ethanol production residue (EPR) gave the highest laccase (90.1 U/mL) activity, while the walnut pericarp provided the highest MnP activity (7.4 U/mL). Supplementation of medium with 1 mM copper and 1 mM xylidine at appropriate time caused significant additive effect on laccase expression (333.2 U/mL) in shake-flask experiments. Overproduction of laccase activity (507 U/mL) and secretion of MnP activity was obtained when C. unicolor was cultivated in stirred-tank fermenter. C. unicolor showed several distinctive and attractive technological features: it is capable to synthesize high levels of oxidases under high carbon and high nitrogen conditions and it secretes high laccase activity during trophophase.

Lentinus edodes and Pleurotus species lignocellulolytic enzymes activity in submerged and solid-state fermentation of lignocellulosic wastes of different composition.

Lentinus edodes and Pleurotus species from various origins were compared for the first time for their ability to produce lignocellulolytic enzyme in solid-state (SSF) and submerged (SF) fermentation of various plant raw material. Fungi cultivation in identical culture conditions revealed wide differences among both species and strains of the same species. The yields of CMCase (62.3Uml(-1)), xylanase (84.1 U ml(-1)), FPA (5.9 U ml(-1)), and laccase (4103 Ul(-1)) are the best so far obtained with the strains of oyster mushrooms. The study pointed out that the nature of lignocellulosic material and the method of fungi cultivation are factors determining the expression of lignocellulolytic potential of fungi as well as the ratio of individual enzymes in enzyme complex. SSF of tree leaves is favorable for laccase and MnP secretion by the majority L. edodes and Pleurotus strains, whereas SF provides better production of hydrolytic enzymes.