PMID- 19534134 OWN - NLM STAT- MEDLINE DCOM- 20090707 LR - 20190715 IS - 0013-936X (Print) IS - 0013-936X (Linking) VI - 43 IP - 9 DP - 2009 May 1 TI - Sampling natural biofilms: a new route to build efficient microbial anodes. PG - 3194-9 AB - Electrochemically active biofilms were constructed on graphite anodes under constant polarization at -0.1V vs saturated calomel reference (SCE) with 10 mM acetate as substrate. The reactors were inoculated with three different microbial samples that were drawn from exactly the same place in a French Atlantic coastal port (i) by scraping the biofilm that had formed naturally on the surface of a floating bridge, (ii) by taking marine sediments just under the floating bridge, and (iii) by taking nearby beach sand. Current densities of 2.0 A/m2 were reached using the biofilm sample as inoculum while only 0.4 A/m2 and 0.8 A/m2 were obtained using the underlying sediments and the beach sand, respectively. The structure of bacterial communities forming biofilms was characterized by denaturing gradient gel electrophoresis (DGGE) analysis, and revealed differences between samples with the increase in relative intensities of some bands and the appearance of others. Bacteria close related to Bacteroidetes, Halomonas, and Marinobacterium were retrieved only from the efficient EA-biofilms formed from natural biofilms, whereas, bacteria close related to Mesoflavibacter were predominant on biofilm formed from sediments. The marine biofilm was selected as the inoculum to further optimize the microbial anode. Epifluorescence microscopy and SEM confirmed that maintaining the electrode under constant polarization promoted rapid settlement of the electrode surface by a bacterial monolayer film. The microbial anode was progressively adapted to the consumption of acetate by three serial additions of substrate, thus improving the Coulombic efficiency of acetate consumption from 31 to 89%. The possible oxidation of sulfide played only a very small part in the current production and the biofilm was not able to oxidize hydrogen. Graphite proved to be more efficient than dimensionally stable anode (DSA) or stainless steel butthis result might be due to differences in the surface roughness rather than the intrinsic features of the materials. Finally, a maximal current density of 7.9 A/m2 was reached with 10 mM acetate after only 8 days of biofilm formation at -0.1 V/SCE. These results are among the best performance values reported in the literature. Using natural biofilms as inoculum should, consequently, be a new, very promising wayto rapidly build more efficient microbial electrodes than those produced when the inoculum is drawn from bulk environments. FAU - Erable, Benjamin AU - Erable B AD - Laboratoire de Genie Chimique CNRS, Universite de Toulouse, 5 rue Paulin Talabot BP1301, 31106 Toulouse, France. benjamin.erable@ensiacet.fr FAU - Roncato, Marie-Anne AU - Roncato MA FAU - Achouak, Wafa AU - Achouak W FAU - Bergel, Alain AU - Bergel A LA - eng PT - Journal Article PT - Research Support, Non-U.S. Gov't PL - United States TA - Environ Sci Technol JT - Environmental science & technology JID - 0213155 RN - 0 (Acetates) RN - 12597-68-1 (Stainless Steel) RN - 7782-42-5 (Graphite) SB - IM MH - Acetates/pharmacology MH - Adaptation, Physiological/drug effects MH - Bacteria/cytology/drug effects/*metabolism/ultrastructure MH - Bioelectric Energy Sources/*microbiology MH - Biofilms/drug effects/*growth & development MH - Electricity MH - Electrochemistry MH - Electrodes/microbiology MH - Electrophoresis MH - Graphite MH - Microscopy, Electron, Scanning MH - Microscopy, Fluorescence MH - Seawater/microbiology MH - Stainless Steel MH - Time Factors EDAT- 2009/06/19 09:00 MHDA- 2009/07/08 09:00 CRDT- 2009/06/19 09:00 PHST- 2009/06/19 09:00 [entrez] PHST- 2009/06/19 09:00 [pubmed] PHST- 2009/07/08 09:00 [medline] AID - 10.1021/es803549v [doi] PST - ppublish SO - Environ Sci Technol. 2009 May 1;43(9):3194-9. doi: 10.1021/es803549v.