title: Syntrophic degradation of proteinaceous materials by the thermophilic strains Coprothermobacter proteolyticus and Methanothermobacter thermautotrophicus.
abstract: Protein is a major component of organic solid wastes, and therefore, it is necessary to further elucidate thermophilic protein degradation process. The effects of hydrogenotrophic methanogens on protein degradation were investigated using the proteolytic bacterial strain CT-1 that was isolated from a methanogenic thermophilic (55°C) packed-bed reactor degrading artificial garbage slurry. Strain CT-1 was closely related to Coprothermobacter proteolyticus, which is frequently found in methanogenic reactors degrading organic solid wastes. Strain CT-1 was cultivated in the absence or presence of Methanothermobacter thermautotrophicus by using 3 kinds of proteinaceous substrates. Degradation rates of casein, gelatin, and bovine serum albumin were higher in co-cultures than in monocultures. Strain CT-1 showed faster growth in co-cultures than in monocultures. M. thermautotrophicus comprised 5.5-6.0% of the total cells in co-culture. Increased production of ammonia and acetate was observed in co-cultures than in monocultures, suggesting that addition of M. thermautotrophicus increases the products of protein degradation. Hydrogen produced in the monocultures was converted to methane in co-cultures. These results suggest that thermophilic proteolytic bacteria find it favorable to syntrophically degrade protein in a methanogenic environment, and that it is important to retain hydrogen-scavenging methanogens within the reactor.
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: Masahiko
authors.initials: M
authors.lastname: Morita
authors.forename: Daisuke
authors.initials: D
authors.lastname: Sasaki
authors.forename: Jun
authors.initials: J
authors.lastname: Nagaoka
authors.forename: Norio
authors.initials: N
authors.lastname: Matsumoto
authors.forename: Naoya
authors.initials: N
authors.lastname: Ohmura
authors.forename: Hiraku
authors.initials: H
authors.lastname: Shinozaki
mesh_terms: D000641:Ammonia / Q000378:metabolism; D001419:Bacteria / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism; D019149:Bioreactors / Q000382:microbiology; D004275:DNA, Ribosomal / Q000378:metabolism; D019605:Euryarchaeota / Q000378:metabolism*; D006859:Hydrogen / Q000378:metabolism; D008697:Methane / Q000378:metabolism*; D017013:Methanobacteriaceae / Q000378:metabolism*; D008969:Molecular Sequence Data; D059748:Proteolysis; D012336:RNA, Ribosomal, 16S / Q000378:metabolism
chemical_list: D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D000641:Ammonia; D006859:Hydrogen; D008697:Methane