ИСТИНА

Fungal extracellular proteases (especially from Aspergillus genus) are widely used in biotechnology, however, selection of optimal conditions for an efficient protease production still remains a time-consuming step. In this research, we tried to understand how fermentation conditions affect diversity of proteolytic activities and protease production for Aspergillus ochraceus L-1. For submerged fermentation, media containing various carbon and nitrogen sources were used. Collagenolytic, caseinolytic, fibrinolytic and elastinolytic activities were measured spectrophotometrically. Total DNA and mRNA were isolated and sequenced. The genome was annotated with AUGUSTUS. Putative extracellular proteases were predicted with HMMER and SignalP 6.0. Combination of glycerol and glucose was found to be the optimal carbon source for production of proteases with specific activities. The highest non-specific activity was observed in the sucrose-containing medium, when glycerol as the only carbon source in the medium completely depressed protease production. Maximal collagenolytic and fibrinolytic activities were observed when cultivating with fish meal hydrolysate and bovine collagen. Highest general and elastinolytic activities were detected in the medium with elastin and NaNO3. Genome mining suggested the presence of a wide range of serine, metallo- and aspartic peptidases. The RNA-sequencing will be used to evaluate expression level of predicted proteases.