A strain capable of phenol degradation

heterotrophic nitrification and aerobic denitrification was isolated from activated sludge of coking-plant waste water ponds under aerobic condition. Based on its morphology

physiology

biochemical analysis and phylogenetic characteristics

the isolate was identified as Diaphorobacter sp. PD-7. Biodegradation tests of phenol showed that the maximum phenol degradation occurred at the late phase of exponential growth stages

with 1400 mg·L

-1

phenol completely degraded within 85 h. Diaphorobacter sp. PD-7 accumulated a vast quantity of phenol hydroxylase in this physiological phase

ensuring that the cells quickly utilize phenol as a sole carbon and energy source. The kinetic behavior of Diaphorobacter sp. PD-7 in batch cultures was investigated over a wide range of initial phenol concentrations (0-1400 mg·L

-1

) by using the Haldanemodel

which adequately describes the dynamic behavior of phenol biodegradation by strain Diaphorobacter sp. PD-7. At initial phenol concentration of 1400 mg·L

-1

batch experiments (0.25 L flask) of nitrogen removal under aerobic condition gave almost entirely removal of 120.69 mg·L

-1

ammonium nitrogen within 75 h

while nitrate nitrogen removal reached 91% within 65 h. Moreover

hydroxylamine oxidase

periplasmic nitrate reductase and nitrite reductase were successfully expressed in the isolate.