Survey of microorganism for the production of extracellular phytase.

A culture enrichment technique was used to isolate phytase-producing microorganisms. Also, microorganisms from various culture collections were tested for their phytase-producing ability. A number of the Aspergillus niger group produced extracellular phytase which dephosphorylated calcium phytate in acidic solution. A soil isolate, A. ficuum NRRL 3135, produced the most active phytase in a cornstarch-based medium. Production of phytase was strongly repressed by inorganic phosphates and required a high carbon to phosphorus ratio in the medium.