Abstract: 2.5kb DNA fragment from a standard strain of Candida albicans (C li) was labeled with E-AGA-Photobiotin and Biotin-psoralen, respectively, and used as probe to hybridize with DNA from various Candida species, Cry-ptococcus and bacteria. Colorimetric sensitivity of E-ACA-Photobiotin labeled probe with Avidin-Alkaline phosphatase (A-AP) is 1 pg. Detection of target DNA by labeled probe is less than 100pg, and that of whole cellular DNA is 125pg, being ten times higher than that of the probe labeled with biotin-psoralen. 7 strains of C. albicans DNA hybridized with the above two photohiotin labelled probes gave strong positive results,and C. parapsiiasis showed weak hybridization signal. DNA from other Candida species, Gryptococcus and bacteria did not hybridize with the probes. These results showed that the sensitivity and specificity of C. albicans Clin 2.5kb probe labeled with E-ACA-Photobiotin are in conformity with that of radioactive labelling one. Moreover, with the advantages of simplicity, safety, stability and rapidity, photobiotin labelling method can replace the isotope labelling method.

Key words: Candida albicans, Probe, Photahiotin