Editor: Bernard Prior
Expression and characterization of Aspergillus thermostable phytases in Pichia pastoris
Article first published online: 19 NOV 2008
© 2008 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved
FEMS Microbiology Letters
Volume 290, Issue 1, pages 18–24, January 2009
How to Cite
Promdonkoy, P., Tang, K., Sornlake, W., Harnpicharnchai, P., Kobayashi, R. S., Ruanglek, V., Upathanpreecha, T., Vesaratchavest, M., Eurwilaichitr, L. and Tanapongpipat, S. (2009), Expression and characterization of Aspergillus thermostable phytases in Pichia pastoris. FEMS Microbiology Letters, 290: 18–24. doi: 10.1111/j.1574-6968.2008.01399.x
- Issue published online: 1 DEC 2008
- Article first published online: 19 NOV 2008
- Received 20 June 2008; accepted 24 September 2008.First published online 19 November 2008.
- Aspergillus japonicus;
- Aspergillus niger
Two thermostable phytases were identified from Thai isolates of Aspergillus japonicus BCC18313 (TR86) and Aspergillus niger BCC18081 (TR170). Both genes of 1404 bp length, coding for putative phytases of 468 amino acid residues, were cloned and transferred into Pichia pastoris. The recombinant phytases, r-PhyA86 and r-PhyA170, were expressed as active extracellular, glycosylated proteins with activities of 140 and 100 U mL−1, respectively. Both recombinant phytases exhibited high affinity for phytate but not for p-nitrophenyl phosphate. Optimal phytase activity was observed at 50 °C and pH 5.5. High thermostability, which is partly dependent on glycosylation, was demonstrated for both enzymes, as >50% activity was retained after heating at 100 °C for 10 min. The recombinant phytases also exhibited broad pH stability from 2.0 to 8.0 and are resistant to pepsin. In vitro digestibility tests suggested that r-PhyA86 and r-PhyA170 are at least as efficient as commercial phytase for hydrolyzing phytate in corn-based animal feed and are therefore suitable sources of phytase supplement.