title: Proteins causing membrane fouling in membrane bioreactors.
abstract: In this study, the details of proteins causing membrane fouling in membrane bioreactors (MBRs) treating real municipal wastewater were investigated. Two separate pilot-scale MBRs were continuously operated under significantly different operating conditions; one MBR was a submerged type whereas the other was a side-stream type. The submerged and side-stream MBRs were operated for 20 and 10 days, respectively. At the end of continuous operation, the foulants were extracted from the fouled membranes. The proteins contained in the extracted foulants were enriched by using the combination of crude concentration with an ultrafiltration membrane and trichloroacetic acid precipitation, and then separated by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). The N-terminal amino acid sequencing analysis of the proteins which formed intensive spots on the 2D-PAGE gels allowed us to partially identify one protein (OmpA family protein originated from genus Brevundimonas or Riemerella anatipestifer) from the foulant obtained from the submerged MBR, and two proteins (OprD and OprF originated from genus Pseudomonas) from that obtained from the side-stream MBR. Despite the significant difference in operating conditions of the two MBRs, all proteins identified in this study belong to β-barrel protein. These findings strongly suggest the importance of β-barrel proteins in developing membrane fouling in MBRs.
authors.affiliation: Research Center for Environmental Nano and Bio Engineering in Hokkaido University, N13W8, Kita-ku, Sapporo 060-8628, Japan E-mail: t-miyoshi@pegasus.kobe-u.ac.jp; Department of Chemical Science and Engineering, Center for Membrane and Film Technology, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan.
authors.forename: Taro
authors.initials: T
authors.lastname: Miyoshi
authors.affiliation: Division of Built Environment, Hokkaido University, N13W8, Kita-ku, Sapporo 060-8628, Japan.
authors.forename: Yuhei
authors.initials: Y
authors.lastname: Nagai
authors.affiliation: Division of Biological Sciences, Hokkaido University, N10W8, Kita-ku, Sapporo 060-0810, Japan.
authors.forename: Tomoyasu
authors.initials: T
authors.lastname: Aizawa
authors.affiliation: Division of Built Environment, Hokkaido University, N13W8, Kita-ku, Sapporo 060-8628, Japan.
authors.forename: Katsuki
authors.initials: K
authors.lastname: Kimura
authors.affiliation: Research Center for Environmental Nano and Bio Engineering in Hokkaido University, N13W8, Kita-ku, Sapporo 060-8628, Japan E-mail: t-miyoshi@pegasus.kobe-u.ac.jp.
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Watanabe
mesh_terms: D057219:Biofouling; D019149:Bioreactors; D008567:Membranes, Artificial; D011506:Proteins / Q000737:chemistry*; D014865:Waste Disposal, Fluid; D062065:Wastewater / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D008567:Membranes, Artificial; D011506:Proteins; D062065:Wastewater; D014874:Water Pollutants, Chemical