ИСТИНА

Proteases are widely used and demanded enzymes in industry, medicine, agriculture and waste management. Fungi of extreme environments represent the promising producers of new proteases. The significant progress in the application of proteases of extremophilic fungi is achieved, but practically nothing is known about their alkali active proteases. The proteolytic activity and spectrum of extracellular proteases of alkaliphilic and alkalitolerant fungi, isolated from soda soils, were assessed. 12 strains of 6 species, Sodiomyces alkalinus, Chordomyces antarcticum, Acrostalagmus luteoalbus, Verticillium zaregamsianum, Sodiomyces magadii, Gibellulopsis nigrescens were studied. They were grown in submerged conditions in alkaline medium (pH 10.2) with casein. Total proteolytic activity and spectrum of extracellular proteases were identified with azocasein and specific synthetic para-nitroanilide substrates for different classes of peptidases: GlpAALpNA, GlpFpNA, BzRpNA, GlpFApNA for endopeptidase; LpNA, L-Phenylalanine-4-nitroanilide, L-Glutamic acid 1-(4-nitroanilide) for aminopeptidase; EDTA for metalloprotease. The measurements were done at pH 9.5. 11 fungal strains demonstrated proteolytic activity. The greatest activity was indicated on the substrate with leucine residue – LpNA, it was significantly lower or absent on L-Phenylalanine-4-nitroanilide. Investigated strains did not hydrolyze L-Glutamic acid 1-(4-nitroanilide) or their activity was low. Trypsin and chymotrypsin activities of serine proteases were not detected. However, only 3 strains had low metalloprotease activity. 6 strains had active subtilisin serine proteases. Cysteine proteinases activities were discovered in 3 fungal strains of this ecological group. Perspective strains with high activities of subtilisin serine and cysteine proteases, amino peptidases, total proteolytic activity were detected. The work was supported by RSCF grant № 14-50-00029 (Kurakov).