title: Isolation of digested sludge-assimilating fungal strains and their potential applications.
abstract: OBJECTIVE
  Digested sludge (DS) is a major waste product of anaerobic digestion of sewage sludge and is resistant to biodegradation. In this study, we isolated and characterized DS-assimilating fungi from soil.
  
  
  RESULTS
  We tried to isolate DS-assimilating strains by enrichment culture using DS as the nutrient source, but microbial growth was not observed in any culture. To eliminate the inhibitory effect of metals in DS on microbial growth, acid-treated DS was subsequently used for enrichment, and eight fungal strains were isolated from the subcultures. At least 10-30% reduction in sludge was observed after 1-week cultivation, and prolonged cultivation led to further sludge reduction. All isolates produced xylanase, chitinase and keratinase. Phylogenetic analysis revealed that the isolates were Penicillium, Fusarium, Chaetomium, Cunninghamella, Neosartorya and Umbelopsis. Some isolates were suggested novel species.
  
  
  CONCLUSIONS
  To the best of our knowledge, our study is the first to report the isolation of DS-assimilating strains.
  
  
  CONCLUSIONS
  These isolates may be useful for commercial production of microbial enzymes using DS as the substrate. Because xylan, chitin and keratin in sludge-hyphae complexes are considered to be partially depolymerized, this material could also be utilized as a readily available fertilizer.
authors.affiliation: Faculty of Agriculture, Yamaguchi University, Yamaguchi, Japan. kfujii@yamaguchi-u.ac.jp
authors.forename: K
authors.initials: K
authors.lastname: Fujii
authors.forename: Y
authors.initials: Y
authors.lastname: Kai
authors.forename: S
authors.initials: S
authors.lastname: Matsunobu
authors.forename: H
authors.initials: H
authors.lastname: Sato
authors.forename: A
authors.initials: A
authors.lastname: Mikami
mesh_terms: D001673:Biodegradation, Environmental; D002688:Chitinases / Q000378:metabolism; D005308:Fertilizers; D005658:Fungi / Q000145:classification / Q000201:enzymology* / Q000302:isolation & purification*; D010447:Peptide Hydrolases / Q000378:metabolism; D010802:Phylogeny; D012722:Sewage / Q000737:chemistry / Q000382:microbiology*; D012988:Soil Microbiology; D014995:Xylosidases / Q000378:metabolism
chemical_list: D005308:Fertilizers; D012722:Sewage; D014995:Xylosidases; D002688:Chitinases; D010447:Peptide Hydrolases; C035855:keratinase
keywords: assimilation; chitinase; digested sludge; fungi; keratinase; xylanase