Carbon and nitrogen source effects on basidiomycetes exopolysaccharide production.

The capability to synthesize the extracellular polysaccharide (EPS) is widespread among eight mushroom species which accumulated 0.6-2.2 g/l of EPS in submerged cultivation. Glucose, maltose, and mannitol were the most appropriate carbon sources for biomass and EPS production. Organic nitrogen sources appeared to be the most suitable nitrogen sources for biomass and EPS accumulation. The cultivation process in shake flasks was successfully reproduced in a laboratory fermentor with enhanced EPS production. The highest yield of EPS (3.8-4.0 g/l) was achieved in cultivation of Agaricus nevoi and Inonotus levis.

[Dependence of activities of polysaccharide hydrolases and oxidases from Cerrena unicolor on the source of carbon and aromatic acids in culture media]. / Zavisimost' aktivnosti polisakharidgidrolaz i oksidaz Cerrena unicolor ot istochnika ugleroda i aromaticheskikh soedinenii v srede.

The activities of carboxymethylcellulase and xylanase in the higher basidial fungus Cerrena unicolor grown in avicel-containing medium reached 1.95 and 1.50 units per mg protein, respectively, whereas in mannitol-containing medium they ranged from 0.02 to 0.05 units per mg protein. The activity of fungal beta-glucosidase depended on the carbon source in the culture medium and ranged from 2.1 units per mg protein in the presence of mannitol to 17.3 units per mg protein in the presence of avicel. In contrast to polysaccharides, easily metabolizable substrates (cellobiose, mannitol, and glucose) provided the highest rates of secretion of laccase (52.7-123.5 ncat per mg protein) and ligninase (22-106 units per mg protein). The addition of tangerine pomace, a substrate enriched with aromatic compounds, to the culture medium caused an increase in the rate of bio-synthesis of laccase and ligninase to 862 ncat per ml and 557 units per ml, respectively. Aromatic compounds such as p-xylidine and veratric aldehyde increased the laccase activity of C. unicolor IBB 62 from 7.9 to 23.6 and 18.3 ncat per mg protein, respectively. Veratryl alcohol caused a sevenfold increase in the activity of Mn-dependent peroxidase in the culture medium.

Cellulase and xylanase activities in higher basidiomycetes.

Extracellular carboxymethylcellulase, xylanase, beta-glucosidase, and beta-xylosidase activities of four cultures of higher basidial fungi were studied in relation to the source of carbon in the nutrient medium. It was shown that beta-glucosidases and beta-xylosidases of all basidiomycetes and cellulases and xylanases of Pholiota aurivella IBR437 and Gloeophyllum saepiarium IBR155, the causal agents of wood brown rot, are constitutive enzymes; however, their activities depend on the source of carbon in the growth medium. Cellulases and xylanases of Coriolus pubescens IBR663 and Lentinus tigrinus IBR100 degrading wood through white rot are inducible enzymes. The synthesis of cellulases and xylanases was induced upon fungal growth on media containing crystalline cellulose and plant raw materials; carboxymethylcellulose and xylan were less effective. The induction of C. pubescens IBR663 cellulase and xylanase was observed when avicel was added to the culture growing on a mannitol-containing medium. Glucose at a concentration of 0.2-0.8% caused catabolite repression of C. pubescens IBR663 cellulase and xylanase. After utilization of glucose, leading to a decrease in its concentration below 0.1%, the synthesis of enzymes was resumed. These data indicate that the synthesis of cellulases and xylanases in the examined macromycetes is under common regulatory control.