title: Bioelectrochemical system accelerates microbial growth and degradation of filter paper.
abstract: Bioelectrochemical reactors (BERs) with a cathodic working potential of -0.6 or -0.8 V more efficiently degraded cellulosic material, i.e., filter paper (57.4-74.1% in 3 days and 95.9-96.3% in 7 days) than did control reactors without giving exogenous potential (15.4% in 3 days and 64.2% in 7 days). At the same time, resultant conversions to methane and carbon dioxide in cathodic working chamber of BERs by application of electrochemical reduction in 3 days of operation were larger than control reactors. However, cumulative methane production in cathodic BERs was similar to those in control reactors after 7 days of operation. Microscopic observation and 16S rRNA gene analysis showed that microbial growth in the entire consortium was higher after 2 days of operation of cathodic BERs as compared with the control reactors. In addition, the number of methanogenic 16S rRNA gene copies in cathodic BERs was higher than in control reactors. Moreover, archaeal community structures constructed in cathodic BERs consisted of hydrogenotrophic methanogen-related organisms and differed from those in control reactors after 2 days of operation. Specifically, the amount of Methanothermobacter species in cathodic BERs was higher within archaeal communities than in those control reactors after 2 days of operation. Electrochemical reduction may be effective for accelerating microbial growth in the start-up period and thereby increasing microbial treatment of cellulosic waste and methane production.
authors.affiliation: Biotechnology Sector, Environmental Science Research Laboratory, Central Research Institute of Electric Power Industry, 1646 Abiko, Abiko-shi, Chiba-ken, 270-1194, Japan.
authors.forename: Kengo
authors.initials: K
authors.lastname: Sasaki
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Hirano
authors.forename: Masahiko
authors.initials: M
authors.lastname: Morita
authors.forename: Daisuke
authors.initials: D
authors.lastname: Sasaki
authors.forename: Norio
authors.initials: N
authors.lastname: Matsumoto
authors.forename: Naoya
authors.initials: N
authors.lastname: Ohmura
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Igarashi
mesh_terms: D001105:Archaea / Q000235:genetics / Q000254:growth & development* / Q000302:isolation & purification / Q000378:metabolism*; D001419:Bacteria / Q000235:genetics / Q000254:growth & development* / Q000302:isolation & purification / Q000378:metabolism*; D001673:Biodegradation, Environmental; D001674:Bioelectric Energy Sources / Q000382:microbiology*; D019149:Bioreactors / Q000382:microbiology; D002482:Cellulose / Q000378:metabolism*; D004563:Electrochemistry; D008697:Methane / Q000378:metabolism; D008969:Molecular Sequence Data; D010209:Paper; D012037:Refuse Disposal
chemical_list: D002482:Cellulose; D008697:Methane