Phytase is commercially important enzyme. Phytate in food and feed makes it less nutritive as well as acts as anti-nutritional agent. Phytate make complexes with important mineral ions and proteins. Monogastric animals and human are not able to degrade the phytate from plant based food because they lack phytase. This leads to phosphorous deficiency. Addition of phytase into food and feed degrades the phytate. It makes, phosphorous and mineral ions become available for growth and development. There is need to evaluate these factors in vitro which in real affect the stability and activity of enzyme under feed production process and digestive system of monogastric animals.
Indigenous Aspergillus terreus isolate produce stable phytase to be used in poultry feed.Indigenous strains of Aspergillus terreus were identified by macroscopic and microscopic characteristics. These isolates were screened on Phytate Screening Medium (PSM) for phytase production. Phytase producing A. terreus was than analyzed for toxin production through TLC (Thin layer chromatography). Non toxigenic phytase producing A. terreus isolates were inoculated in phytate broth for phytase production through submerged fermentation (SmF) under optimum conditions (28°C for 8-10 days). After centrifugation and filtration supernatants were used as crude enzyme. Phytase enzyme was qualitatively analyzed through phytase assay. Phytases activity units observed for isolate PAST-16 was highest (271.49±8.14 FTU/mL) and lowest (79.00±8.05FTU/mL) of PAST-05. A. terreus phytase (PAST-16) was subjected to temperature, pH and metal ions treatment.
Thermostability of phytases was recorted at 35°C, 55°C, 75 °C and 90°C for 15, 30, 45, and 60 minutes treatments. Enzyme from A. terreus (PAST-16) was observed as thermostable at
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35°C, 55°C, 75 °C but not much stable at 95°C. Phytases showed 87.23±6.59, 198.34±4.47, 188.59±8.77 and 259.25±0.84 FTU/mL decreased in activity after 60 minutes of treatment at 35°C, 55°C, 75 °C and 95°C temperatures, respectively.
pH stability of phytases was found at pH of 2, 4, 6 and 8 for 15, 30, 45, and 60 minutes treatments. Enzyme from A. terreus (PAST-16) was observed as pH stable at 4, 6 and 8 but not much stable at 2 pH. Phytases showed 206.14±6.37, 169.59±6.37, 110.13±6.75 and 171.54±3.04 FTU/mL decreased in activity after 60 minutes of pH treatments at 2, 4, 6 and 8, respectively.
Metal ions effect on phytase activity was found with Ba2+, Ca2+, Cu2+, Fe3+, K+, Mg2+, Mn2+ and Na+ at the concentration of 1, 5 and 10mM. Enzyme from A. terreus (PAST-16) was observed as shows activity more with K+ less with Na+. Phytases showed 45.32±28.54 and 219.30±11.04 FTU/mL decreased in activity after 1mM conc. of K+ and 10mM conc of Na+, respectively.
Conclusion:
A.terreus isolate (PAST-16) produce stable phytase enzyme used in feed of poultry. In this way it tolerates condition under which feed process at commercial level and under digestive system monogastric animals.