Nitrogen Removal by a Fungal Aerobic Denitrifier of Penicillium Strain

A kind of aerobic Penicillium that can remove ammonia, nitrite and nitrate was isolated through an improved bromothymol blue (BTB) selective culture medium method in this experiment and then the nitrogen removal by the strain was detailedly investigated. The results showed that this strain was able to make use of many kinds of organic carbon compounds as sole carbon source for the removal of the three types of inorganic nitrogen compounds but the way of removal was different. Ammonia was assimilated for forming cell components such as amino acid and protein, different from which, nitrite and nitrate were eliminated by the aid of dual assimilation and denitrification. When the three types of nitrogen coexist, the removal order was as follows: ammonia>nitrite>nitrate. Type of carbon source, initial nitrogen concentration and carbon nitrogen ratio (C/N) all had different effect on final solution pH, dry weight, nitrogen removal rate and removal ability of the strain. It was tested that non-polar organic carbon source containing -CH3 group like sucrose was inclined to be used by the strain. When sucrose was carbon source, the optimum C/N of ammonia, nitrite and nitrate removal were separate 4-6, 8-12 and 12-16. In addition, it was demonstrated with calculation that the removal abilities of the above mentioned three nitrogen of the strain were about 50, 60 and 90 mg g-1 respectively, showing its tremendous capability of nitrogen removal.