Strain improvement of Aspergillus ficuum NRRL 3135 and optimization of fermentation conditions for phytase production
2002
Capitan, C.T. | Zamora, A.F. (Philippine Univ. Los Banos, College, Laguna (Philippines). Inst. of Biological Sciences)
The presence of high amount of phytic acid in feeds is undesirable because it binds irreversibly with calcium, zinc, iron and magnesium, making these elements unavailable to animals. Not surprisingly, phytic acid is considered an anti-nutritive factor. Its level in animal feed must be lowered by breaking it down to it's components, phosphoric acid and myo-inositol. The enzyme that can break down phytic acid is phytase. This enzyme is produced in high amounts by the mold Aspergillus ficuum NRRL 3135. In this study, a high-phytase producing mutant that yields 3 times more phytase was developed by exposing the original selection of mold to ultraviolet radiation for 30 minutes. The optimum fermentation medium (nutrient mixture for growing the mold) that best supports mold growth for high phytase production used rice bran as a basic ingredient and contained low amount of glucose, sodium nitrate and peptone at an acidity level or pH of 5.5-6.0. With these results, phytase can be easily produced for incorporation in animal feeds
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