Denitrification Performance of a Culture of Thermophilic Aerobic Bacteria NBIMCC 3729

M. Natcheva and V. Beschkov

Abstract
In the present paper the reduction of nitrate to nitrogen under thermophilic conditions was studied. A culture developed from the thermophilic aerobic bacteria Geobacillus NBIMCC 3729 was used under non-aerated conditions. Instead of oxygen nitrates were used as an electron acceptor during the microorganisms’ growth. The study was accomplished under batch conditions with model aqueous solutions of nitrates and peptone and meat extract as a complex carbon source. The temperature range of the biochemical reduction process, was determined. A two-step consecutive reduction process was observed and the presence of nitrite in the broth as an intermediate product was found out. It is confirmed that the first step in nitrate reduction is strictly associated with the microbial growth. A clear effect of substrate inhibition of the denitrification process was revealed at higher nitrate concentrations, resulting mostly as considerable extension of the lag-phase in the microbial growth.

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Keywords
Thermophilic bacteria, denitrification, nitrite accumulation