title: Oxygen Tension and Riboflavin Gradients Cooperatively Regulate the Migration ofShewanella oneidensisMR-1 Revealed by a Hydrogel-Based Microfluidic Device.
abstract: Shewanella oneidensisis a model bacterial strain for studies of bioelectrochemical systems (BESs). It has two extracellular electron transfer pathways: (1) shuttling electronsviaan excreted mediator riboflavin; and (2) direct contact between thec-type cytochromes at the cell membrane and the electrode. Despite the extensive use ofS. oneidensisin BESs such as microbial fuel cells and biosensors, many basic microbiology questions aboutS. oneidensisin the context of BES remain unanswered. Here, we present studies of motility and chemotaxis ofS. oneidensisunder well controlled concentration gradients of two electron acceptors, oxygen and oxidized form of riboflavin (flavin+), using a newly developed microfluidic platform. Experimental results demonstrate that either oxygen or flavin+ is a chemoattractant toS. oneidensis.The chemotactic tendency ofS. oneidensisin a flavin+ concentration gradient is significantly enhanced in an anaerobic in contrast to an aerobic condition. Furthermore, either a low oxygen tension or a high flavin+ concentration considerably enhances the speed ofS. oneidensis.This work presents a robust microfluidic platform for generating oxygen and/or flavin+ gradients in an aqueous environment, and demonstrates that two important electron acceptors, oxygen and oxidized riboflavin, cooperatively regulateS. oneidensismigration patterns. The microfluidic tools presented as well as the knowledge gained in this work can be used to guide the future design of BESs for efficient electron production.
authors.affiliation: Department of Biological and Environmental Engineering, Cornell University Ithaca, NY, USA.
authors.forename: Beum Jun
authors.initials: BJ
authors.lastname: Kim
authors.affiliation: School of Chemical and Biomolecular Engineering, Cornell University Ithaca, NY, USA.
authors.forename: Injun
authors.initials: I
authors.lastname: Chu
authors.affiliation: Department of Biological and Environmental Engineering, Cornell University Ithaca, NY, USA.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Jusuf
authors.affiliation: Department of Biological and Environmental Engineering, Cornell University Ithaca, NY, USA.
authors.forename: Tiffany
authors.initials: T
authors.lastname: Kuo
authors.affiliation: Department of Biological and Environmental Engineering, Cornell University Ithaca, NY, USA.
authors.forename: Michaela A
authors.initials: MA
authors.lastname: TerAvest
authors.affiliation: Department of Biological and Environmental Engineering, Cornell UniversityIthaca, NY, USA; Atkinson Center for a Sustainable Future, Cornell UniversityIthaca, NY, USA.
authors.forename: Largus T
authors.initials: LT
authors.lastname: Angenent
authors.affiliation: Department of Biological and Environmental Engineering, Cornell UniversityIthaca, NY, USA; Atkinson Center for a Sustainable Future, Cornell UniversityIthaca, NY, USA.
authors.forename: Mingming
authors.initials: M
authors.lastname: Wu
keywords: Shewanella; aerotaxis; bioelectrochemical system (BES); flavin; microfluidics; motility