Production of Phytase, Protease and Xylanase by Aspergillus niveus with Rice Husk as a Carbon Source and Application of the Enzymes in Animal Feed

Plant-based foods often contain antinutritional factors like phytic acid and non-starch polysaccharides, which hinder nutrient absorption in animals. To counter these effects, enzymes derived from filamentous fungi can mitigate antinutritional properties, benefiting gut health, nutrient availability, and digestibility in non-ruminant animals. Employing Aspergillus niveus, we investigated enzyme production using various alternative carbon sources, as well as biochemical factors including temperature and pH, in addition to the in vitro application of enzymes in animal feed. Notably, A. niveus achieved peak phytase production with rice husk (1.93 ± 0.01 U/mg), while the best protease production was with crushed brown rice (0.75 ± 0.03 U/mg) and xylanase with wheat bran (4.66 ± 1.38 U/mg). In the in vitro feed tests, A. niveus phytase displayed significant activity in WB and RB (2.21 ± 0.15 and 2.12 ± 0.37 µmol/mL, respectively), outperforming commercial phytase in RB (1.86 ± 0.04 µmol/mL). A. niveus protease hydrolysis was superior in RB (8.34 ± 0.76 µmol/mL) and the xylanase promoted hydrolysis of all feeds evaluated, surpassing commercial xylanase. After 8 h of incubation, A. niveus xylanase yielded optimal results in CN (38.63 ± 5.22 µmol/mL), while commercial enzyme exhibited activity in ADF (9.81 ± 1.75 µmol/mL) diet. Fungi producing pH-resistant enzymes and with potential for action in animal feed are important to be applied in the agroindustry.