Characterization of extracellular polymeric substances produced during nitrate removal by a thermophilic bacterium Chelatococcus daeguensis TAD1 in batch cultures

Abstract

Aerobic denitrification is a novel strategy for nitrogen removal in wastewater treatment. As an important functional component, extracellular polymeric substances (EPS) secreted by aerobic denitrifiers during the denitrification process are poorly understood. This paper presents the characteristics of EPS production by thermophilic bacterium Chelatococcus daeguensis TAD1 during aerobic denitrification in liquid cultures. Results indicated that strain TAD1 was capable of simultaneously accumulating EPS and reducing nitrate, with 245.1 mg g⁻¹ EPS obtained after aerobic denitrification. Polysaccharide and protein were determined to be the major components of EPS. Further single factor experiments showed that the EPS production was significantly affected by the carbon source, C/N ratio and pH value, rather than the incubation temperature. Moreover, good positive correlation (R² = 0.86) was observed between the EPS production and the nitrate removal efficiency, which implied that aerobic denitrification might prompt EPS production by strain TAD1.