title: Fate of Clostridium botulinum and incidence of pathogenic clostridia in biogas processes.
abstract: OBJECTIVE
  This study aimed to assess the sanitary situation in agricultural biogas plants (BP) regarding pathogenic Clostridium spp.
  
  
  RESULTS
  The incidence of Clostridium botulinum, Clostridium difficile, Clostridium novyi, Clostridium haemolyticum, Clostridium septicum and Clostridium chauvoei was investigated in 154 plant and animal substrates, digester sludges and digestates from full-scale BP using a method combining microbial enrichment with Real-Time PCR. The investigated clostridia were absent in the samples, except for Cl. novyi that was barely present (3·9%) and Cl. difficile that was more frequently detected (44·8%). Clostridium botulinum exposed to lab-scale digesters in sentinel chambers was reduced with D-values of 34·6 ± 11·2 days at 38°C and 1·0 ± 0·2 days at 55°C.
  
  
  CONCLUSIONS
  These findings indicate minor relevance of clostridial pathogens in BP and an improved sanitary quality of the digestion product compared to untreated substrates concerning Cl. botulinum. However, the frequent detection of Cl. difficile opens questions on the durability of this organism in manure digestion lines.
  
  
  CONCLUSIONS
  This is the first study providing data on the reduction of Cl. botulinum during biogas processes that scientifically invalidate contrary claims by some media in the public. Furthermore, the results improve the fragmentary knowledge on the prevalence of several clostridial pathogens in agricultural biogas production.
authors.affiliation: Department for Quality Assurance and Analytics, Bavarian State Research Center for Agriculture (LfL), Freising, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Fröschle
authors.affiliation: Bavarian Health and Food Safety Authority (LGL), Oberschleißheim, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Messelhäusser
authors.affiliation: Bavarian Health and Food Safety Authority (LGL), Oberschleißheim, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Höller
authors.affiliation: Department for Quality Assurance and Analytics, Bavarian State Research Center for Agriculture (LfL), Freising, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Lebuhn
mesh_terms: D000818:Animals; D056804:Biofuels / Q000382:microbiology*; D001905:Botulinum Toxins; D003013:Clostridium / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D008372:Manure / Q000382:microbiology*; D060888:Real-Time Polymerase Chain Reaction; D012722:Sewage / Q000382:microbiology*
chemical_list: D056804:Biofuels; D008372:Manure; D012722:Sewage; D001905:Botulinum Toxins
keywords: Clostridium difficile; anaerobic digestion; hygiene; manure; ntnh; sanitation; silage