Revealing the stability of aerobic granular sludge in a membrane bioreactor under different DO values by proteomics analysis

Abstract The investigation revealed the effects of dissolved oxygen on the stability of aerobic granular sludge (AGS) in a membrane bioreactor. The results indicated that the variation of dissolved oxygen heavily influenced the characteristics of AGS, and a suitable DO range (1.5–2.0 mg/L) was an important guarantee to keep the stability of the structure of AGS, but under a low DO value (0–0.5 mg/L), the amount of Saprospiraceae increased which causes the reduction of protein content. Besides, the protein tag, a protein function secreted by Enterobacter hormaechei, was enriched, and they degraded the structural protein, which was an important reason causing the structure of AGS damaged. The results of proteomics analyses also showed that the number of proteins involved in extracellular structure and nuclear structure function is zero, which implied that the proteins in TB-EPS were mainly engaged in various functions but not in structural composition.