PHYTASE PRODUCED BY ASPERGILLUS NIGER AS A POTENTIAL FOOD MICRO-INGREDIENT

Abstract

This research sets out to study the activity of the phytase enzyme synthesized by the Aspergillus niger L-4 fungus strain in sucrose-mineral medium and to determine optimal conditions for culturing this strain, under which the greatest amount of the phytase enzyme can be synthesized. The possibility of obtaining the phytase enzyme as an additional target product of microbiological synthesis is investigated. The activity of the phytase synthesized by the Aspergillus niger L-4 micromycete is studied by the colorimetric method. This method is based on the determination of inorganic phosphates (PO₄) that form as a result of the phytase enzyme action on the sodium phytate substrate (sodium salt of phytic acid): under standard conditions the phosphates react with the vanadium-molybdenum reagent to yield a phosphor vanadium molybdenum complex of yellow colour. As a result of the fermentation of the Aspergillus niger L-4 strain into citric acid in a sucrose-mineral medium, the maximum activity of phytase in native solution constituted 68.75 units/cm³ for the inoculated mycelium aged 24 and 48 hours, at different volumes of inoculated mycelium (15 and 20%, respectively) and a temperature of 29 ºC. The maximum activity of phytase in the mycelial mass reached 60.50 units/g for the inoculated mycelium aged 36 and 48 h, at different volumes of inoculated mycelium (15 and 20%, respectively) and a temperature of 29 ºC. The results can be used for the development of a method for obtaining two food micro-ingredients - citric acid and phytase - in a single biotechnological process.