Quantitative and qualitative characterization of extracellular polymeric substances from Anammox enrichment

Abstract

Abstract Extracellular polymeric substances (EPS) from different Anammox biomass were extracted and characterized by quantitative and qualitative analysis to investigate the link between their characteristics and the enrichment process in lab scale bioreactors. Quantitatively, a decrease of protein to polysaccharide ratio and an increase in total EPS extraction yield were observed during the enrichment process. In the three dimensional excitation emission matrixes, the spectra showed similar location of the fluorescence peaks for all of the samples. Whereas, samples extracted from sludge containing enriched Anammox bacteria possessed two distinct peaks in the low excitation wavelength range (220–230 nm). Multi-excitation peaks might occur as evidenced by the identical fluorescence chromatograms after size exclusion chromatography (SEC) separation at excitation/emission wavelength of 221/350 nm and 280/330 nm. With the process of Anammox enrichment, UV chromatogram at 210 nm after SEC, which is an indicator of polysaccharides, showed increase in both intensity and number of peaks. However, all fluorescence chromatograms, which reflect proteins and soluble microbial by-products, showed similar peak patterns with increased intensity. An increase of EPS hydrophobicity was observed during the enrichment process for both reactors.