Denitrification strategies of strain YSF15 in response to carbon scarcity: Based on organic nitrogen, soluble microbial products and extracellular polymeric substances.

This paper aims to determine the denitrification strategies of strain YSF15 in carbon scarcity condition from novel view of organic nitrogen, soluble microbial products (SMP) and extracellular polymeric substances (EPS). The batch tests demonstrated that strain YSF15 could achieve complete denitrification at C/N of 3.0. The conversion ratio of nitrogen gas accounted for 89.03%, 85.29% and 82.95% among total nitrogen in C/N systems from 3.0 to 5.0, respectively, indicating denitrification instead of assimilation was the major contribution to nitrogen removal. C/N could affect composition and content of organic nitrogen, SMP and EPS. The biodegradability of EPS was better than SMP, whereas polysaccharide (PS) likely correlated with nitrogen removal, predating the protein (PN). These results implied high biodegradability of EPS and more electron donors for denitrification both improved denitrification capacity of strain YSF15, which revealed the potential contribution of bacterium with production of biodegradable SMP or EPS in biological treatment process.