Abstract The Agaricomycetes fungi produce various compounds with pharmaceutical, medicinal, cosmetic, environmental and biotechnological properties. In addition, some polysaccharides extracted from the fungal cell wall have antitumor and immunomodulatory actions. The aim of this study was to use genetic modification to transform Schizophyllum commune and identify if the phenotype observed (different from the wild type) resulted in changes of the cell wall polysaccharides. The plasmid pUCHYG-GPDGLS, which contains the Pleurotus ostreatus glucan synthase gene, was used in S. commune transformations. Polysaccharides from cell wall of wild (ScW) and mutants were compared in this study. Polysaccharides from the biomass and culture broth were extracted with hot water. One of the mutants (ScT4) was selected for further studies and, after hydrolysis/acetylation, the GLC analysis showed galactose as the major component in polysaccharide fraction from the mutant and glucose as the major monomer in the wild type. Differences were also found in the elution profiles from HPSEC and NMR analyses. From the monosaccharide composition it was proposed that mannogalactans are components of S. commune cell wall for both, wild and mutant, but in different proportions. To our knowledge, this is the first time that mannogalactans are isolated from S. commune liquid culture.

ABSTRACT Fungi of Pleurotus genus have attracted a great interest due to their medicinal properties such as anti-inflammatory, antimicrobial and antitumor. These properties are attributed mainly to polysaccharides synthesized by Pleurotus. This work aimed to study the mycelial growth of P. ostreatus in submerged culture, evaluating the influence of the initial concentration of substrate (20 and 40 g/L of glucose) and the pH (4 and 6) on kinetic parameters of production of biomass. The effectiveness of different doses (10, 30 and 50 mg/kg) of a mycelium polysaccharide fraction extracted from P. ostreatus in reducing Sarcoma 180 development in mice was also verified. In the range of this study, maximum concentration of mycelial biomass (about 12.8 g/L) was obtained using 40.0 g/L of glucose, at pH 4.0. The total biomass productivity (Px) was not significantly affected by substrate concentration and pH, reaching values of 0.034 g/L.h. Sarcoma 180 tumor weight was reduced in 74.1, 75.5 and 53.7% when 10, 30 and 50 mg/kg were administered, respectively. These results show the high antitumor potential of intracellular polysaccharide fraction of mycelial biomass of P. ostreatus, particularly at lower doses of 10 and 30 mg/kg.