Immobilised Phytase Production from Aspergillus foetidus MTCC 11682 Using an Optimized Media

Aim: Immobilised fungal phytase production from the novel strain Aspergillus foetidus MTTC 11682 and optimisation of cultural conditions for a better and continuous economic yield.

Study Design: The study was designed based on the classical method of changing one independent variable while fixing all other at a certain level- one factor at a time, a close ended system for the optimisation of fermentation process.

Methodology: Physical and nutritional parameters were optimised for phytase production and subjected to statistical analysis. Adsorption and Entrapment techniques were employed to immobilise the production strain.

Results: The optimum physical conditions for augmenting the yield up to 6 days incubation period were as follows: pH of 3.5, 30ºC temperatures and 5% inoculum size. Amongst the nutritional parameters, lactose and sodium nitrate were found to be the best carbon and nitrogen sources. K++, Mg++, Mn++ and Fe++ ions supported the phytase production. TritonX 100 and tween 80 showed an inducing effect on the secretion of phytase enzyme. Immobilised fungal phytase production resulted in an increased yield of 32.5% with poly urethane foam (PUF) as the matrix. A scale up fermentation resulted in an activity of 52.7 FTU/mL for immobilised cells as compared to 25.5 FTU/mL by its free counterpart.

Conclusion: Phytase produced in an optimised media employing immobilised Aspergillus foetidus 11682 on poly urethane foam cubes exhibited better phytase activity, improved stability and long shelf life.