Phytase produced on citric byproducts: purification and characterization.

Citric pulp is an agro-industrial residue from the citrus processing industry with low inorganic phosphorus content applied in animal feed. A new bioprocess was developed to produce and purify a new phytase generated on citric pulp fermentation by Aspergillus niger FS3. The phytase was purified by cationic-exchange, anionic-exchange chromatography and chromatofocusing steps. From SDS-PAGE analysis, the molecular weight of the purified phytase was calculated to be 108 kDa. The phytase had an optimum pH of 5.0-5.5 and an optimum temperature of 60°C. The phytase displayed high affinity for phytate, and the K was 0.52 mM. The purified phytase was sufficiently able to withstand pelleting temperatures, retaining sufficiently high phytate-degrading activity. [ABSTRACT FROM AUTHOR]