title: Responses of soil microbial communities to weak electric fields.
abstract: Electrokinetically stimulated bioremediation of soils (electro-bioremediation) requires that the application of weak electric fields has no negative effect on the contaminant degrading microbial communities. This study evaluated the hypothesis that weak direct electric current (DC) fields per se do not negatively influence the physiology and composition of soil microbial communities given that secondary electrokinetic phenomena such as soil pH changes and temperatures are minimized. Mildly buffered, water-saturated laboratory mesocosms with agricultural soil were subjected for 34 days to a constant electric field (X=1.4 V cm(-1); J approximately 1.0 mA cm(-2)) and the spatiotemporal changes of soil microbial communities assessed by fingerprints of phospholipids fatty acids (PLFA) and terminal restriction fragment length polymorphisms (T-RFLP) of bacterial 16S rRNA genes. DC-induced electrolysis of the pore water led to pH changes (<1.5 pH units) in the immediate vicinity of the electrodes and concomitant distinct soil microbial community changes. By contrast, DC-treated bulk soil distant to the electrodes showed no pH changes and developed similar PLFA- and T-RFLP-fingerprints as control soil in the absence of DC. Our data suggest that the presence of an electric field, if suitably applied, will not influence the composition and physiology of soil microbial communities and hence not affect their potential to biodegrade contaminants.
authors.affiliation: UFZ, Helmholtz Centre for Environmental Research, Department of Environmental Microbiology, Permoserstrasse 15, 04318 Leipzig, Germany. lukas.wick@ufz.de
authors.forename: Lukas Y
authors.initials: LY
authors.lastname: Wick
authors.forename: Friederike
authors.initials: F
authors.lastname: Buchholz
authors.forename: Ingo
authors.initials: I
authors.lastname: Fetzer
authors.forename: Sabine
authors.initials: S
authors.lastname: Kleinsteuber
authors.forename: Claus
authors.initials: C
authors.lastname: Härtig
authors.forename: Lei
authors.initials: L
authors.lastname: Shi
authors.forename: Anja
authors.initials: A
authors.lastname: Miltner
authors.forename: Hauke
authors.initials: H
authors.lastname: Harms
authors.forename: Graciela N
authors.initials: GN
authors.lastname: Pucci
mesh_terms: D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D001673:Biodegradation, Environmental; D017753:Ecosystem; D004560:Electricity / Q000009:adverse effects*; D005227:Fatty Acids / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D016958:Pseudomonas putida / Q000378:metabolism; D012336:RNA, Ribosomal, 16S; D012988:Soil Microbiology
chemical_list: D005227:Fatty Acids; D012336:RNA, Ribosomal, 16S