Isolation and Biochemical Characterization of Acid Phytase from Aspergillus niger and Its Applications in Dephytinization of Phytic Acid in Poultry Feed Ingredients

Acidic phytase (PHY-B) was isolated from Aspergillus niger BIONCL8 strain, and assessed its application for the dephytinization of poultry feed ingredients. Aspergillus niger BIONCL8 strain was identified by precise molecular methods by targeting internal transcribed spacer (ITS) region of the fungi and molecular detection of PHY gene in the strain was confirmed by sequence analysis with respect to PHY production. The enzyme was isolated and purified by DEAE Sephadex A-50 and Bio-Gel P-60 Gel ion-exchange chromatography. The estimated molecular weight of the protein was 65 kDa on SDS-PAGE, it had a specific activity of 21.18 U/mg. The molecular weight of the protein was confirmed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The peptide sequence of PHY-B was identified using high resolution-mass spectrometry (LC-HR-MS), and its physicochemical parameters were studied. The PHY was stable at acidic pH 2.1, most active at 40°C and was stable up to 80°C, retaining 30% residual activity after 1 h of incubation. The PHY activity was enhanced in the presence of Mg 2+ and EDTA, and activity was inhibited in the presence of Hg 2+ and K + . The K m and V max of PHY were recorded as 3.35 mM and 1.27 U/mg, respectively. The PHY was shown to play a significant role in decreasing PA content in various poultry feed ingredients, ranging from 48.14 to 82.14%. The novel features of the enzyme can be used to decrease the PA content in feed ingredients and increase the bioavailability of nutrients to non-ruminant animals.