title: Alternating Current Influences Anaerobic Electroactive Biofilm Activity.
abstract: Alternating current (AC) is known to inactivate microbial growth in suspension, but how AC influences anaerobic biofilm activities has not been systematically investigated. Using a Geobacter dominated anaerobic biofilm growing on the electrodes of microbial electrochemical reactors, we found that high frequency AC ranging from 1 MHz to 1 kHz (amplitude of 5 V, 30 min) showed only temporary inhibition to the biofilm activity. However, lower frequency (100 Hz, 1.2 or 5 V) treatment led to 47 ± 19% permanent decrease in limiting current on the same biofilm, which is attributed to the action of electrohydrodynamic force that caused biofilm damage and loss of intercellular electron transfer network. Confocal microscopy images show such inactivation mainly occurred at the interface between the biofilm and the electrode. Reducing the frequency further to 1 Hz led to water electrolysis, which generated gas bubbles that flushed all attached cells out of the electrode. These findings provide new references on understanding and regulating biofilm growth, which has broader implications in biofouling control, anaerobic waste treatment, energy and product recovery, and general understanding of microbial ecology and physiology.
authors.affiliation: MOE Key Laboratory of Pollution Processes and Environmental Criteria/Tianjin Engineering Center of Environmental Diagnosis and Contamination Remediation, Nankai University , No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.affiliation: MOE Key Laboratory of Pollution Processes and Environmental Criteria/Tianjin Engineering Center of Environmental Diagnosis and Contamination Remediation, Nankai University , No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China.
authors.forename: Lean
authors.initials: L
authors.lastname: Zhou
authors.affiliation: Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder , Boulder, Colorado 80309, United States.
authors.forename: Lu
authors.initials: L
authors.lastname: Lu
authors.affiliation: Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder , Boulder, Colorado 80309, United States.
authors.forename: Fernanda Leite
authors.initials: FL
authors.lastname: Lobo
authors.affiliation: Tianjin Key Lab of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University , No. 92 Weijin Road, Nankai District, Tianjin 300072, China.
authors.forename: Nan
authors.initials: N
authors.lastname: Li
authors.affiliation: Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder , Boulder, Colorado 80309, United States.
authors.forename: Heming
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Electrical Engineering, University of Colorado Denver , Denver, Colorado 80204, United States.
authors.forename: Jaedo
authors.initials: J
authors.lastname: Park
authors.affiliation: Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder , Boulder, Colorado 80309, United States.
authors.forename: Zhiyong Jason
authors.initials: ZJ
authors.lastname: Ren
mesh_terms: D001674:Bioelectric Energy Sources; D018441:Biofilms; D004560:Electricity; D004566:Electrodes; D004579:Electron Transport; D045302:Geobacter