Volume 46, No. 03, Month MAY, Year 2019, Pages 431 - 443

Enhanced production of phytase, a feed enzyme, from pichia kudriavzevii using mutagenesis and improved culture conditions

Wanatchaporn Boontham, Natsuda Srivanichpoom, Pumin Nutaratat, Savitree Limtong, and Nantana Srisuk

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Pichia kudriavzevii WB17-1, a phytase-producing yeast isolated from duck excrement, was found to produce both cell-bound and extracellular phytases. To enhance extracellular phytase, P. kudriavzevii WB17-1 was subjected to induced mutation. Ethylmethane sulfonate (EMS) induced mutation resulted in 2,400 mutants. The mutant P. kudriavzevii WB17-1 EMS3 showed the highest extracellular phytase activity. This mutant possessed a 6.2-fold increase in enzyme activity compared to the wild type level. The wild type and mutant were subjected to characterization of PHYPk, a gene encoding P. kudriavzevii phytase. An open reading frame of 1,071 bp encoding 357 amino acids with a predicted protein molecular mass of 40.056 kDa was identified. To optimize the extracellular phytase activity of P. kudriavzevii WB17-1 EMS3, a response surface methodology (RSM) was employed. The highest extracellular phytase activity was obtained in the medium containing 2.95% dextrose and 0.58% peptone with an initial pH of 5.8. The optimized phytase activity was 2.3 times the level obtained under unoptimized conditions and was 14.4 times the wild type level. The results obtained here show successful yeast strain improvement and optimization of extracellular phytase by yeast using RSM.


phytase, optimisation, mutagenesis, Pichia kudriavzevii, yeast


Published by : Faculty of Science, Chiangmai University
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