title: Possible practical utility of an enzyme cocktail produced by sludge-degrading microbes for methane and hydrogen production from digested sludge.
abstract: Digested sludge (DS) is a major waste product of anaerobic digestion of sewage sludge and is resistant to biodegradation. In this study, we examined suitability of the hydrolases produced by DS-degrading fungal strains (DS-hydrolases) for methane and hydrogen fermentation from DS. Although the strains are mesophilic, DS-hydrolases showed strong chitinase and keratinase activity at ∼50°C. SDS-PAGE analysis suggested that the strains possess a multienzyme system, which allows the hydrolases of some strains to be stable in a wide range of temperatures. Addition of the DS-hydrolases to a vial-scale anaerobic digester enhanced methane and hydrogen production from DS at pH 9.0 and 5.0, respectively. The hydrogen production was also enhanced by the use of methacrylate ester-precipitated DS as a substrate. Further improvement of culture and reaction conditions may make these hydrolases suitable for production of renewable fuels.
authors.affiliation: Graduate School of Agriculture, Yamaguchi University, Yoshida, Yamaguchi 7538515, Japan.
authors.forename: Hayato
authors.initials: H
authors.lastname: Sato
authors.affiliation: Faculty of Agriculture, Yamaguchi University, Yoshida, Yamaguchi 7538515, Japan.
authors.forename: Kyohei
authors.initials: K
authors.lastname: Kuribayashi
authors.affiliation: Graduate School of Agriculture, Yamaguchi University, Yoshida, Yamaguchi 7538515, Japan; Faculty of Agriculture, Yamaguchi University, Yoshida, Yamaguchi 7538515, Japan. Electronic address: kfujii@yamaguchi-u.ac.jp.
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Fujii
mesh_terms: D005591:Chemical Fractionation; D004952:Esters / Q000378:metabolism; D005285:Fermentation; D005427:Flocculation; D005658:Fungi / Q000201:enzymology* / Q000254:growth & development; D006859:Hydrogen / Q000378:metabolism*; D006867:Hydrolases / Q000378:metabolism*; D008697:Methane / Q000096:biosynthesis*; D012722:Sewage / Q000382:microbiology*; D014867:Water / Q000737:chemistry
chemical_list: D004952:Esters; D012722:Sewage; D014867:Water; D006859:Hydrogen; D006867:Hydrolases; D008697:Methane