The acid soluble extracellular polymeric substance of aerobic granular sludge dominated by Defluviicoccus sp

• Published in: Water research (Oxford) 2017-10, Vol.122, p.148-158
• Main Authors: Pronk, M., Neu, T.R., van Loosdrecht, M.C.M., Lin, Y.M.
• Format: Article
• Language: English
• Subjects: Aerobic granular sludge; Aerobiosis; Biofilm; Defluviicoccus; EPS extraction; Extracellular polymeric substances; Polymers - chemistry; Polysaccharides - chemistry; Sewage; Spectroscopy, Fourier Transform Infrared
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2017.05.068

A new acid soluble extracellular polymeric substance (acid soluble EPS) was extracted from an acetate fed aerobic granular sludge reactor operated at 35 °C. Acid soluble EPS dominated granules exhibited a remarkable and distinctive tangled tubular morphology. These granules are dominated by Defluviicoccus Cluster II organisms. Acetic acid instead of the usually required alkaline extraction medium was needed to dissolve the granules and solubilise the polymeric matrix. The extracted acid soluble EPS was analysed and identified using various instrumental analysis including 1H and 13C Nuclear Magnetic Resonance, Fourier Transform Infrared Spectroscopy and Raman spectroscopy. In addition, the glycoconjugates were characterized by fluorescence lectin-binding analysis. The acid soluble EPS is α-(1 → 4) linked polysaccharide, containing both glucose and galactose as monomers. There are OCH3 groups connected to the glucose monomer. Transmission and scanning electron microscopy (TEM, SEM) as well as confocal laser scanning microscopy (CLSM) showed that the acid soluble EPS was present as a tightly bound capsular EPS around bacterial cells ordered into a sarcinae-like growth pattern. The special granule morphology is decided by the acid soluble EPS produced by Defluviicoccus Cluster II organisms. This work shows that no single one method can be used to extract all possible extracellular polymeric substances. Results obtained here can support the elucidation of biofilm formation and structure in future research. •Aerobic granular sludge dominated with Defluviicoccus II species exhibit a tubular growth pattern.•Acetic acid instead of the usually required alkaline extraction was needed to dissolve the granules.•The newly found acid soluble EPS extracted is responsible for the granule morphology.•The EPS consists of an α-(1 4) linked polysaccharide, containing glucose and galactose as monomers.•These results show that one cannot use a single extraction method for all possible structural EPSs.