Strain improvement of Aspergillus ficuum NRRL 3135 and optimization of fermentation conditions for phytase production

Abstract

Phytase activities of mycelial and spore colonies of Aspergillus ficuum NRRL 3135 irradiated with UV for 10 to 60 min were determined. Spore colonies exposed to UV for 30 min gave the highest phytase activity (74.81 U L -1), which is more than three-fold higher than that of the wild type. Among the fermentation media containing varying levels (1 - 4% w/v) of rice bran, cornstarch, cornmeal and soybean meal as substrates, the use of rice bran (3% and 4% levels) resulted in the highest phytase activity without significant differences between their values. Enzyme activities were measured when the following ingredients were added at different levels (w/v) to the medium containing 3% rice bran: glucose (0.5 to 3.0%), nitrogen as sodium nitrate (0.5 to 2.0%) and peptone (0.1 to 0.5%). Based on the results, the fermentation medium should contain 0.5% glucose, 0.5% sodium nitrate and 0.2% peptone. Its enzyme activity increased to 380.46 U mL-1. The initial pH of the medium optimum for enzyme production was 5.5.

Source or Periodical Title

Philippine Agricultural Scientist

ISSN

317454

Page

387-394

Document Type

Article

Subject

Aspergillus ficuum NRRL 3135, Enzyme activity, Phosphorus, Phytase

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