ABSTRACT
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.
ABSTRACT
ABSTRACT Corn husks are the major wastes of corn industries with meagre economic significance. The present study was planned for value addition of corn husk through extraction of xylan, followed by its enzymatic hydrolysis into xylooligosaccharides, a pentose based prebiotic. Compositional analysis of corn husks revealed neutral detergent fibre 68.87%, acid detergent fibre 31.48%, hemicelluloses 37.39%, cellulose 29.07% and crude protein 2.68%. Irrespective of the extraction conditions, sodium hydroxide was found to be more effective in maximizing the yield of xylan from corn husks than potassium hydroxide (84% vs. 66%). Application of xylanase over the xylan of corn husks resulted into production of xylooligosaccharides with different degree of polymerization namely, xylobiose and xylotriose in addition to xylose monomer. On the basis of response surface model analysis, the maximum yield of xylobiose (1.9 mg/ml) was achieved with the enzymatic hydrolysis conditions of pH 5.8, temperature 44°C, enzyme dose 5.7U/ml and hydrolysis time of 17.5h. Therefore, the corn husks could be used as raw material for xylan extraction vis a vis its translation into prebiotic xylooligosaccharides.