title: Differential phytate utilization in Candida species.
abstract: The present study was undertaken to evaluate and characterize the phytase activity in different Candida species. A total of 113 Candida isolates representing eight species were examined for phytase activity by an agar plate assay using the calcium salt of phytic acid as the sole phosphorus source. A phytase-positive phenotype was identified by the formation of a clear halo around a fungal colony. Cell-bound differential phytase activity was observed in Candida isolates at inter- and intra-species levels. Although phytase activity was not affected by the supplementation of external phosphate in C. albicans, C. dubliniensis, C. glabrata, and C. kefyr, elevated phytase activity was evident in C. guilliermondii, C. krusei, C. parapsilosis, and C. tropicalis in phosphate-free medium. Further characterization showed that, in general, relatively higher phytase activity was observed at more acidic pHs, and the phytase activity increased with incubation temperature, reaching a maximum at 55 or 65°C. Taken together, the findings demonstrated, for the first time, differential phytase activities in different Candida species. Phytase activity may be a contributing factor to fungal survival and proliferation within the human gastrointestinal tract, where nutrients are usually scarce.
authors.affiliation: Oral BioSciences, Faculty of Dentistry, The University of Hong Kong, Prince Philip Dental Hospital, Sai Ying Pun, Hong Kong, China. pwktsang@hku.hk
authors.forename: Paul Wai-Kei
authors.initials: PW
authors.lastname: Tsang
mesh_terms: D010832:6-Phytase / Q000737:chemistry / Q000378:metabolism*; D000362:Agar; D002175:Candida / Q000145:classification / Q000201:enzymology* / Q000302:isolation & purification / Q000378:metabolism*; D003470:Culture Media / Q000737:chemistry; D004795:Enzyme Stability; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009055:Mouth / Q000382:microbiology; D010710:Phosphates / Q000378:metabolism; D010833:Phytic Acid / Q000378:metabolism*; D013696:Temperature
chemical_list: D003470:Culture Media; D010710:Phosphates; D010833:Phytic Acid; D000362:Agar; D010832:6-Phytase