Influence of different extraction methods on the compositions and structural characteristics of extracellular polymeric substances in biofilms from biological aerated filters

摘要

Extracellular polymeric substances (EPS) were extracted from biofilms in a continuously running biological aerated filter (BAF) reactor by five different methods, including heating treatment at 60 degrees C, cation exchange resin (CER), EDTA, sodium hydroxide (NaOH), and sulfuric acid (H2SO4). High-speed centrifugation was used as a control method. The results showed that the extraction method played a great role on EPS yields and chemical compositions, whereas no remarkable difference in their structural characteristics was observed. Heating treatment was determined as the most effective protocol with the highest EPS recovery and lowest cell damage. The total amount of the extracted EPS was 131.6 mg/g volatile suspended solids (VSS), while the DNA content only accounted for 7.0%. The intensity of absorption bands in the UV-visible (UV-vis) spectra was in agreement with chemical compositions of the extracted EPS. In addition, the Fourier transform infrared (FT-IR) results indicated that no noticeable effect was found on EPS structures extracted by different methods. However, both UV-vis and FT-IR spectroscopic analyses revealed that chemical reagents used during extraction processes might contaminate the extracted EPS, and then interfered with the determination of proteins in EPS.