Mandana Karimi - Department of Soil Science, Khorasgan Branch, Islamic Azad University, Isfahan, Iran
Mehran Hoodaji - Department of Soil Science, Khorasgan Branch, Islamic Azad University, Isfahan, Iran
Arezoo Tahmurespour - Department of Microbiology, Khorasgan Branch, Islamic Azad University, Isfahan, Iran

Nitrification is an important biological process in soils which, ammonia convert to nitrite andsubsequently to nitrate, oxidation of ammonia accomplish by Autotrophic and Heterotrophic oxidizerbacteria. In this study, Heterotrophic oxidizer bacteria enumerated in two soil and wastewater sampleswith different characteristic and displayed that heterotrophic nitrifers in soil samples were higher thannumber of those in wastewater samples. Different pollutants have effects on nitrification process, oneof these are phenol that inhibitor for this process. Phenol is pertaining to poly aromatic hydrocarbonswhich are toxic chemical material for human and another organism. Add phenol with differentconcentrations to media of ammonia oxidizer bacteria and investigated decrease of ammonia removalpercentage and percentage of nitrite product in soil and wastewater samples. This decline in ammoniaremoval and nitrite product was surveyed in heterotrophic nitrification. The percentage of eliminationammonia in soil samples were about 67.9 % in the absence of phenol and decreased to about 47.5% in32 ppm phenol. The percentage of ammonia elimination in wastewater samples were about 91.3 % inthe absence of phenol and decreased to about 71.6% in 32 ppm phenol. In soil samples was separatedto two heterotrophic ammonia oxidizer bacteria, single and double rod with gram-positive test, thisseparation was because of vivid decreasing of ammonia removal percentage and in wastewatersamples separated bacteria were gram-positive double rod and gram-positive cocci. Heterotrophicammonia oxidizer bacteria in soil sample were had low resistance to phenol than heterotrophicammonia oxidizer bacteria in wastewater samples and decreased the ammonia removal percentage inlesser phenol concentration.

Nitrification, Phenol, Heterotrophic ammonia-oxidizing bacteria, Ammonia