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Phytase biosynthesis with Aspergillus niger micromycete during laboratory starch fermentation of corn starch hydrolysates

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The aim of this work was to investigate the phytase biosynthesis during cultivation of an industrial strain of Aspergillus niger L-4 micromycetic acid-forming agent on corn starch hydrolysates with various degrees of hydrolysis in laboratory conditions. Objects of study – the mycelial mass of the Aspergillus niger L-4 producer and native solutions obtained by fermentation of corn starch hydrolysates (State Standart 32159-2013) with a degree of hydrolysis characterized by DE = 20.9 ± 1.5% and DE = 31.8 ± 2,1%. Enzymatic activity was determined according to State Standart 31487-2012. The content of protein substances was determined by the Lowry method. Compared with the previously obtained results of studies of starch-containing raw materials – rye grain grinding hydrolyzate, intracellular (intracellular) phytase activity on the fifth day of fermentation when the producer was cultured under the conditions of the Multitron shaker-incubator was 10 times higher and amounted to 1.2 ± 0.1 u/g. Extracellular (extracellular) phytase activity at the end of the biotechnological process was at the level of 6.8 ± 0.5 units/cm3, which is 18 times more than the rye grain grinding hydrolyzate. Increased both intra- and extracellular phytase activity were achieved during the biotechnological process in the Biostat®Cplus–C20-3MO laboratory fermenter and amounted to 5.3 ± 0.3 units/g of mycelium and 12.1 ± 1.1 units/cm3 of native solution respectively. It has been proved that the most preferred substrate for the phytase biosynthesis by Aspergillus niger L-4 fungus-acid former is corn starch hydrolyzate with a dextrose equivalent (DE) of 31.8 ± 2.1%. Productive phytase biosynthesis occurs in the logarithmic phase of micromycete growth, and active excretion of the enzyme occurs in thestationary phase of its development. To increase the level of phytase activity it is advisable to carry out a biotechnological process in a fermenter that provides intensive air supply.

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