title: Change in surface properties of Microthrix parvicella upon addition of polyaluminium chloride as characterized by atomic force microscopy.
abstract: The filamentous bacterium Microthrix parvicella causes severe separation and foaming problems at wastewater treatment plants (WWTPs). An effective control of the bacterium in activated sludge WWTPs can be accomplished by dosage with polyaluminium chloride (PAX-14). The purpose of this study was to investigate whether addition of PAX-14 affects surface properties such as the hydrophobicity of the bacterium and to study the exopolymers of M. parvicella that host surface-associated enzymes. To this end, force measurements by atomic force microscopy were carried out to measure the interactions between hydrophilic and hydrophobized tips and the bacterium surface. Addition of PAX-14 caused no changes in the hydrophobicity of the bacterium surface but the data indicate that it collapsed the polymeric layer likely due to electrostatic screening. It is concluded that the collapse of the polymeric layer may affect the transport of substrates (eg free fatty acids) to the bacterium and hence the competitiveness of M. parvicella compared to the other bacteria present in activated sludge.
authors.affiliation: Faculty of Health and Society, Biomedical Laboratory Science and Technology, Malmo University, Malmo, Sweden. jildiz.hamit@mah.se
authors.forename: Jildiz
authors.initials: J
authors.lastname: Hamit-Eminovski
authors.forename: Krister
authors.initials: K
authors.lastname: Eskilsson
authors.forename: Thomas
authors.initials: T
authors.lastname: Arnebrant
mesh_terms: D039903:Actinobacteria / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D000536:Aluminum Hydroxide / Q000494:pharmacology*; D001422:Bacterial Adhesion / Q000187:drug effects; D057219:Biofouling / Q000517:prevention & control; D005227:Fatty Acids / Q000378:metabolism; D057927:Hydrophobic and Hydrophilic Interactions; D018625:Microscopy, Atomic Force / Q000379:methods; D014865:Waste Disposal, Fluid
chemical_list: D005227:Fatty Acids; C016213:aluminum oxychloride; D000536:Aluminum Hydroxide