Influence of hydrodynamic parameters on the synthesis of target metabolites and the degree of disintegration during the submerged cultivation of micromycetes

The effect of mechanical stirring rate on the yield of metabolites was investigated on the example of cultivation of mycelial fungi Aspergillus awamori – glucoamylase producer. It was found that the maximum yield of the enzyme was observed at the stirring speed of turbine impeller amounting to 60-120 rpm. As the stirring speed increased, the amount of synthesized metabolite decreased, which is a consequence of the destruction of the mycelial cells. The connection between the decrease in glucoamylase synthesis and the rejuvenation of the culture caused by its recovery from fragments of the destroyed mycelium and the subsequent increase in the amount of biomass was shown. At the same time, the degree of destruction was shown by the increase in the amount of nucleic acids in the filtrate.

The relationship between the degree of destruction of mycelial cells, determined by the amount of nucleic acids in the filtrate under extreme conditions of ultrasonic disintegration, and the viability of the culture was also demonstrated. The amount of viable cells increased at first (until the saturation of the culture fluid with nucleic acids), and then began to gradually decrease. The obtained results can serve as a starting point for further studies of the possibility of stimulating the primary accumulation of biomass of micromycetes by ultrasound.