RESEARCH OF INVERTASE ACTIVITY WHEN CHANGING THE PARAMETERS OF THE FERMENTATION PROCESS SUGAR-MINERAL MEDIUM AND HYDROLYSATE OF STARCH BY THE MICROMYCETE Aspergillus niger

The studies found that strains of micromycete Aspergillus niger L-4 and B-3, producers of citric acid, can synthesize hydrolytic enzymes with invertase activity with a deep cultivation method on a sugar-mineral medium and medium based on starch hydrolysate. The most preferred regimes for conducting the biotechnological process are: the age of the inoculated mycelium is 24 h, the fermentation temperature for the sugar-mineral medium is32 °C and for starch hydrolysate is29 °C. For the Aspergillus niger strain L-4, the extracellular invertase activity for 120 h of the biotechnological process as a result of the fermentation of the sugar-mineral medium was (0,847 ± 0,068) u/cm3 of the native solution, and for strain B-3 — (0,966 ± 0,077) u/cm3 of the native solution, respectively. During fermentation of the medium, based on starch hydrolysate, extracellular invertase activity for strain L-4 was (1,379 ± 0,097) u/cm3 of native solution, and for strain B-3 — (1,597 ± 0,144) u/cm3 of native solution, respectively. The strains of the fungus Aspergillus niger L-4 and B-3 when cultivated on a sugar-mineral medium and medium, based on starch hydrolysate, have the ability to synthesize enzymes with invertase activity, the invertase activity of strain B-3 at the end of the process higher. The obtained data can be applied in further researches to develop a technology for the production of citric acid and invertase in one biotechnological process.