Five microorganisms, three bacteria and two yeasts, capable of degradi
ng Tapis light crude oil were isolated from oil-contaminated soil in B
angkok, Thailand. Soil enrichment culture was done by inoculating the
soil in mineral salt medium with 0.5% v/v Tapis crude oil as the sole
carbon source. Crude oil biodegradation was measured by gas chromatogr
aphy method. Five strains of pure microorganisms with petroleum degrad
ing ability were isolated: three were bacteria and the other two were
yeasts. Candida tropicalis strains 7Y and 15Y were identified as effic
ient oil degraders. Strain 15Y was more efficient, it was able to redu
ce 87.3% of the total petroleum or 99.6% of n-alkanes within the 7-day
incubation period at room temperature of 25 +/- 2 degrees C.