Production of phytate-hydrolysing enzyme by some fungi

Abstract

Eighty-four fungi from twenty five species have been examined for the production of extracellular enzymes capable of hydrolysing phytate (3-phytase, myo-inositol hexakisphosphate 3-phosphohydrolase, EC 3.1.3.8, and 6-phytase, myo-inositol hexakisphosphate 6-phosphohydrolase, EC 3.1.3.26) when grown in: (1) rapeseed meal (RSM); (2) a semisynthetic medium containing phytate as the sole phosphorus source (PSM); (3) potato dextrose broth (PDB). Although 58 active strains showed substantial activity, results in either of the media were of no value in indicating activity in RSM. There was no relationship between the ability of a fungus to hydrolyse phytate and its taxonomic position. Aspergillus ficuum NRRL 3135 had the greatest activity in the synthetic medium, and was relatively active in RSM. The extracellular enzyme had maximum activity after 10 days growth in PSM and had a temperature optimum of 55°C. Two pH optima were noted at pH 2.0 and 5.5. Inorganic phosphate inhibited enzyme production; ammonia ions were a better nitrogen source than nitrate or urea.