tailieunhanh - Sources of clostridia in raw milk on farms

Tài liệu tham khảo Sources of clostridia in raw milk on farms | Applied and Environmental Microbiology Oct. 2008 p. 6348-6357 Vol. 74 No. 20 0099-2240 08 0 doi Copyright 2008 American Society for Microbiology. All Rights Reserved. Sources of Clostridia in Raw Milk on Farmsvf Marie-Claude Julien 1 Patrice Dion 1 Carole Lafrenière 2 Hani Antoun 3 and Pascal Drouin4 Departement de phytologie Pavillon Charles-Eugene Marchand 1030 avenue de la médecine Université Laval Québec Quebec Canada G1V 0A61 Agriculture et Agroalimentaire Canada Ferme de recherche sur les bovins de boucherie de Kapuskasing 445 boulevard de l Universite Rouyn-Noranda Quebec Canada J9X 5E42 Departement des sols et de genie agroalimentaire Pavillon Paul-Comtois 2425 rue de l agriculture Universite Laval Quebec Quebec Canada G1V 0A63 and Unite de recherche en agroalimentaire Université du Quebec en Abitibi-Temiscamingue 445 boulevard de l Université Rouyn-Noranda Quebec Canada J9X 5E44 Received 22 April 2008 Accepted 19 August 2008 A PCR-denaturing gradient gel electrophoresis DGGE method was used to examine on-farm sources of Clostridium cluster I strains in four dairy farms over 2 years. Conventional microbiological analysis was used in parallel to monitor size of clostridial populations present in various components of the milk production chain soil forage grass silage maize silage dry hay and raw milk . PCR amplification with Clostridium cluster I-specific 16S rRNA gene primers followed by DGGE separation yielded a total of 47 operational taxonomic units OTUs which varied greatly with respect to frequency of occurrence. Some OTUs were found only in forage and forage profiles differed according to farm location southern or northern Quebec . More clostridial contamination was found in maize silage than in grass silage. Milk represented a potential environment for certain OTUs. No OTU was milk specific indicating that OTUs originated from other environments. Most 83 of the OTUs detected in raw milk were also found in grass or maize .