title: A biofilm microreactor system for simultaneous electrochemical and nuclear magnetic resonance techniques.
abstract: Nuclear magnetic resonance (NMR) techniques are ideally suited for the study of biofilms and for probing their microenvironments because these techniques allow for noninvasive interrogation and in situ monitoring with high resolution. By combining NMR with simultaneous electrochemical techniques, it is possible to sustain and study live biofilms respiring on electrodes. Here, we describe a biofilm microreactor system, including a reusable and a disposable reactor, that allows for simultaneous electrochemical and NMR techniques (EC-NMR) at the microscale. Microreactors were designed with custom radio frequency resonator coils, which allowed for NMR measurements of biofilms growing on polarized gold electrodes. For an example application of this system we grew Geobacter sulfurreducens biofilms on electrodes. EC-NMR was used to investigate growth medium flow velocities and depth-resolved acetate concentration inside the biofilm. As a novel contribution we used Monte Carlo error analysis to estimate the standard deviations of the acetate concentration measurements. Overall, we found that the disposable EC-NMR microreactor provided a 9.7 times better signal-to-noise ratio over the reusable reactor. The EC-NMR biofilm microreactor system can ultimately be used to correlate extracellular electron transfer rates with metabolic reactions and explore extracellular electron transfer mechanisms.
authors.affiliation: Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352, USA E-mail: ryan.renslow@pnnl.gov.
authors.forename: R S
authors.initials: RS
authors.lastname: Renslow
authors.affiliation: The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, Washington 99164, USA.
authors.forename: J T
authors.initials: JT
authors.lastname: Babauta
authors.affiliation: Bruker BioSpin Corporation, Billerica, Massachusetts 01821, USA.
authors.forename: P D
authors.initials: PD
authors.lastname: Majors
authors.affiliation: Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352, USA E-mail: ryan.renslow@pnnl.gov.
authors.forename: H S
authors.initials: HS
authors.lastname: Mehta
authors.affiliation: Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352, USA E-mail: ryan.renslow@pnnl.gov.
authors.forename: R J
authors.initials: RJ
authors.lastname: Ewing
authors.affiliation: The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, Washington 99164, USA.
authors.forename: T W
authors.initials: TW
authors.lastname: Ewing
authors.affiliation: Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352, USA E-mail: ryan.renslow@pnnl.gov; Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA.
authors.forename: K T
authors.initials: KT
authors.lastname: Mueller
authors.affiliation: The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, Washington 99164, USA.
authors.forename: H
authors.initials: H
authors.lastname: Beyenal
mesh_terms: D018441:Biofilms; D019149:Bioreactors; D055664:Electrochemical Techniques; D045302:Geobacter / Q000502:physiology*; D009682:Magnetic Resonance Spectroscopy; D044085:Microfluidics