[Studies on the yeasts and yeast-like fungi degrading trinitrotoluene]

Seventeen strains of yeasts and yeast-like fungi were isolated from soil and waste water samples polluted by trinitrotoluene (TNT). These strains can degrade 71%-93% TNT when growing in the medium originally containing 70-80 mg/L TNT within 40 h. They were identified. Among them, six strains are Candida krusei, four are C. quercitrusa, one is C. famata, one is Hansenula beijerinckii, one is H. subpelliculosa, and four are Geotrichum candidum. Six strains were selected for further studies on the conditions effecting TNT degradation by them. The optimum pH and temperature are pH 7 and 37-40 degrees C, respectively. TNT Degradation ability of the strains can be promoted by adding 0.01%-0.05% glucose or 0.01%-0.1% yeast extract into the medium. Addition of 0.05% (NH4)2SO4 or NH4Cl to the medium can evidently inhibit the degradation of TNT by the strains.