Impacts of hydrophilic colanic acid on bacterial attachment to microfiltration membranes and subsequent membrane biofouling. (1st June 2015)

• Record Type: Journal Article
• Authors: Yoshida, Keitaro; Tashiro, Yosuke; May, Thithiwat; Okabe, Satoshi
• Is Part Of: Water research. Volume 76(2015)
• Page Start: 33
• Page End: 42
• Publication Date: 2015-06-01
• Subjects: Membrane fouling -- Bacterial attachment -- Colanic acid -- Extracellular polymeric substances (EPS); Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2015.02.045
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: In order to examine the interactions between physicochemical properties of specific extracellular polymeric substances (EPS) and membrane biofouling, we investigated the impacts of hydrophilic colanic acid, as a model extracellular polysaccharide component, on initial bacterial attachment to different microfiltration (MF) membranes and membrane biofouling by using Escherichia coli strains producing different amounts of colanic acid. In a newly designed microtiter plate assay, the bacterial attachment by an E. coli strain RcsF +, which produces massive amounts of colanic acid, decreased only to a hydrophobic membrane because the colanic acid made cell surfaces more hydrophilic, resulting in low cell attachment to hydrophobic membranes. The bench-scale cross-flow filtration tests followed by filtration resistance measurement revealed that RcsF + caused severe irreversible membrane fouling (i.e., pore-clogging), whereas less extracellular polysaccharide-producing strains caused moderate but reversible fouling to all membranes used in this study. Further cross-flow filtration tests indicated that colanic acid liberated in the bulk phase could rapidly penetrate pre-accumulated biomass layers (i.e., biofilms) and then directly clogged membrane pores. These results indicate that colanic acid, a hydrophilic extracellular polysaccharide, and possible polysaccharides with similar characteristics with colanic acid are considered as a major cause of severe irreversible membrane fouling (i.e., pore-clogging) regardless of biofilm formation (dynamic membrane). Graphical abstract: Highlights: Impact of colanic acid, a hydrophilic EPS, on MF membrane fouling was investigated. Colanic acid made cell surfaces hydrophilic and reduced cell attachment to hydrophobic membranes. Colanic acid caused severe irreversible membrane fouling (i.e., pore-clogging). Colanic acid penetrated pre-formed biofilms and clogged membrane pores.