Extracellular polymeric substances and structural stability of aerobic granule.

The contributions of individual components in extracellular polymeric substances (EPSs) on structural stability of phenol-fed, aerobic granules were examined. The roles of proteins, alpha- and beta-polysaccharides, and lipids were studied via their selective hydrolysis using enzymes, and the structural changes of granule were probed using in situ fluorescent staining and confocal laser scanning microscopy. Selective enzymatic hydrolysis of proteins, lipids, and alpha-polysaccharides had a minimal effect upon the three-dimensional structural integrity of the granules. Conversely, selective hydrolysis of beta-polysaccharides fragmented the granules. The beta-polysaccharides were expected to form the backbone of a network-like outer layer with embedded proteins, lipids, alpha-polysaccharides, and cells to support the mechanical stability of granules.