Proteomics Supporting Information for Proteomics Metaproteomics: Evaluation of Protein Extraction from Activated Sludge C0141 Metaproteomic Analysis of Laboratory Scale Phosphorus Removal Reactors Reveals Functional Insights of Aerobic Granular Sludge

Enhanced biological phosphorus removal (EBPR) is a widely applied process for the removal of carbon and phosphorus from wastewater, which is achieved through the use of polyphosphate accumulating organisms (PAO). Conventional wastewater treatment plants utilise floccular sludge, which form small, suspended biofilm aggregates for the treatment of wastewater. A novel alternative to conventional floccular sludge is the use of aerobic granular sludge, which form large, dense, spherical biofilm aggregates, and offer numerous operational and economic advantages over conventional floccular systems. However, we still do not understand the fundamental microbial mechanisms associated with granular sludge formation and stability. This study monitored a granulating period in a laboratory scale reactor and present the first metaproteomic comparison of abundant proteins present in aerobic floccular and aerobic granular reactors to determine microbial functions important for granulation. We identified 403 unique proteins between floccular and granular sludge. Results indicate that proteins involved in signal transduction, cell motility, EPS formation and cell membrane biogenesis may play crucial roles in granulation.