The Alkali-Tolerant Bacterium of Bacillus thuringiensis EM-A1 Can Effectively Perform Heterotrophic Nitrification and Aerobic Denitrification
Tingjiang Wang, Mengping Chen, Xiwen Liang, Fali Chen, Tengxia He, Li Zhu
Abstract
Removal of nitrogen from hydroxylamine could effectively improve the wastewater treatment efficiency. In this work, Bacillus thuringiensis EM-A1 was obtained from a biogas digester with hydroxylamine as the only nitrogen source. Hydroxylamine (100%) and total nitrogen (71.86%) were efficiently removed under the following conditions: 30°C, sucrose as carbon source, carbon to nitrogen ratio 40, rotation speed 150 rpm, pH 9.58, and inoculant concentration of 0.58×10 8 colony-forming units. Ammonium was completely consumed by strain EM-A1, and 8.32 ± 0.08 mg/L of nitrate was produced during the ammonium removal process. During aerobic denitrification, the removal efficiencies of NO 2 − -N and NO 3 − -N by strain EM-A1 were 100 and 76.67%, respectively. There were about 29.34 ± 0.18%, 26.71 ± 0.36%, and 23.72 ± 0.88% initial total nitrogen lost as nitrogenous gas when NH 4 + , NO 3 − , and NO 2 − were separately used as the sole nitrogen source. The specific activities of ammonia monooxygenase, hydroxylamine oxidoreductase, nitrate reductase, and nitrite oxidoreductase were successfully detected as 0.37, 0.88, 0.45, and 0.70 U/mg protein, respectively. These results indicated that B . thuringiensis EM-A1 is a promising candidate for bioremediation of inorganic nitrogen from wastewater.