Heterotrophic aerobic denitrification by novel bacterium Georgenia daeguensis ARB2 for treatment of nitrate contaminated waters

Abstract

Denitrification is a potential strategy for nitrate removal from wastewater. This study reports the isolation of a novel bacterium Georgenia daeguensis ARB2 which has not been earlier reported for treatment of wastewater. ARB2 was isolated from pharmaceutical wastewater and optimized for growth and nitrate removal under conditions of 10 mM nitrate stress (140 mgL−1 $${{\text{NO}}_{3}^{ - }} - {\text{N}}$$ ). It can utilize nitrate as a sole source of nitrogen, exhibits highest growth and aerobic denitrification using glycogen + maltose as a carbon source at pH 7.0, carbon-to-nitrogen ratio of 34, temperature 30 °C, and shaking speed of 100 rpm. ARB2 removes 20% of the initial nitrate concentration of 10 mM in 56 h, and 40% of the initial nitrate concentration of 1 mM in 52 h. Further, the efficacy of strain ARB2 was tested on real contaminated waters and was found to successfully reduce nitrate levels in them. The findings suggest that Georgenia daeguensis ARB2 has a potential application for the alleviation of nitrate under aerobic conditions.