title: Hydrolytic activity of alpha-amylase in anaerobic digested sludge.
abstract: Hydrolysis is usually considered to be a rate-limiting step in anaerobic digestion. For improving anaerobic solid waste treatments, it is essential to elucidate the mechanism of hydrolysis. In this study, alpha-amylase, one of the hydrolytic enzymes, was investigated for the elucidation of more precise mechanism of hydrolysis. Alpha-amylase activity of solid starch-degrading bacteria (SDB) was estimated through batch experiments with several different substrates and with distinction between cell-bound and cell-free alpha-amylase. Monitoring of newly isolated strains of SDB was done by fluorescence in situ hybridization. Results indicated that cell-bound alpha-amylase is chiefly responsible for the hydrolysis in the digested sludge, providing very useful information that the contact between microbial cells and solids is significantly important. The activity of alpha-amylase of the digested sludge remained quite low when not required, but increased as they recognized appropriate substrates. Several-fold higher activity was obtained for starch or maltose as compared to glucose only.
authors.affiliation: Department of Environmental Systems Engineering, Nagaoka University of Technology, 1603-1 Kamitomioka-machi, Nagaoka, Niigata 940-2188, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Higuchi
authors.forename: A
authors.initials: A
authors.lastname: Ohashi
authors.forename: H
authors.initials: H
authors.lastname: Imachi
authors.forename: H
authors.initials: H
authors.lastname: Harada
mesh_terms: D000333:Aeromonas / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D001421:Bacteria, Anaerobic / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D015169:Colony Count, Microbial; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D005947:Glucose / Q000378:metabolism; D006868:Hydrolysis; D017404:In Situ Hybridization, Fluorescence; D008320:Maltose / Q000378:metabolism; D010802:Phylogeny; D012329:RNA, Bacterial / Q000032:analysis / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000032:analysis / Q000235:genetics; D017422:Sequence Analysis, DNA; D012722:Sewage / Q000382:microbiology*; D013213:Starch / Q000378:metabolism; D014865:Waste Disposal, Fluid; D000516:alpha-Amylases / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D012722:Sewage; D008320:Maltose; D013213:Starch; D000516:alpha-Amylases; D005947:Glucose