Pulsed-Field Gel Electrophoresis characterization of Listeria monocytogenes isolates from cheese manufacturing plants in São Paulo, Brazil

Made available in DSpace on 2015-06-17T12:05:20Z (GMT). No. of bitstreams: 2 license.txt: 1914 bytes, checksum: 7d48279ffeed55da8dfe2f8e81f3b81f (MD5) ernesto_hofer2etal_IOC-2014.pdf: 315557 bytes, checksum: 22e8e3c9c092e9a7e9653712008f087f (MD5) Previous issue date: 2014Universidade de São Paulo. Faculdade de Zootecnia e Engenharia de Alimentos. Departamento de Engenharia de Alimentos. Pirassinunga, SP, Brasil.Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz. Departamento de Agroindústria, Alimentos e Nutrição. Piracicaba, SP, Brasil.Universidade de São Paulo. Faculdade de Zootecnia e Engenharia de Alimentos. Departamento de Engenharia de Alimentos. Pirassinunga, SP, Brasil.Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz. Departamento de Agroindústria, Alimentos e Nutrição. Piracicaba, SP, Brasil.Universidade de São Paulo. Faculdade de Ciências Farmacêuticas de Ribeirão Preto. Departamento de Análises Clínicas, Toxicológicas e Bromatológicas. Ribeirão Preto. SP, Brasil.Universidade de São Paulo. Faculdade de Ciências Farmacêuticas de Ribeirão Preto. Departamento de Análises Clínicas, Toxicológicas e Bromatológicas. Ribeirão Preto. SP, Brasil.Universidade de São Paulo. Faculdade de Ciências Farmacêuticas de Ribeirão Preto. Departamento de Análises Clínicas, Toxicológicas e Bromatológicas. Ribeirão Preto. SP, Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Zoonoses Bacterianas, Rio de Janeiro, RJ, Brasil.Instituto Federal de Educação, Ciência e Tecnologia do Rio de Janeiro. Rio de Janeiro, RJ, Brasil.Universidade de São Paulo. Faculdade de Zootecnia e Engenharia de Alimentos. Departamento de Engenharia de Alimentos. Pirassinunga, SP, Brasil.This study aimed to evaluate the occurrence of Listeria monocytogenes in cheese and in the environment of three small-scale dairy plants (A, B, C) located in the Northern region state of São Paulo, Brazil, and to characterize the isolates using conventional serotyping and PFGE. A total of 393 samples were collected and analyzed from October 2008 to September 2009. From these, 136 came from dairy plant A, where only L. seeligeri was isolated. In dairy plant B, 136 samples were analyzed, and L. innocua, L. seeligeri and L. welshimeri were isolated together with L. monocytogenes. In dairy plant C, 121 samples were analyzed, and L. monocytogenes and L. innocua were isolated. Cheese from dairy plants B and C were contaminated with Listeria spp, with L. innocua being found in Minas frescal cheese from both dairy plants, and L. innocua and L. monocytogenes in Prato cheese from dairy plant C. A total of 85 L. monocytogenes isolates were classified in 3 serotypes: 1/2b, 1/2c, and 4b, with predominance of serotype 4b in both dairy plants. The 85 isolates found in the dairy plants were characterized by genomic macrorestriction using ApaI and AscI with Pulsed Field Gel Electrophoresis (PFGE). Macrorestriction yielded 30 different pulsotypes. The presence of indistinguishable profiles repeatedly isolated during a 12-month period indicated the persistence of L.monocytogenes in dairy plants B and C,which weremore than 100 km away from each other. Brine used in dairy plant C contained more than one L. monocytogenes lineage. The routes of contamination were identified in plants B and C, and highlighted the importance of using molecular techniques and serotyping to track L. monocytogenes sources of contamination, distribution, and routes of contamination in dairy plants, and to develop improved control strategies for L. monocytogenes in dairy plants and dairy products

Structure–Function Relationships of Microbial Communities

International audienceMicrobial community structure is the result of environmental conditions that vary significantly and frequently. In laboratory conditions, associations from two microorganisms to complex microbial communities are used to mimic real ecosystems and their functions. Nevertheless, the composition of individual members of complex ecosystems and their relationships, as well the environmental conditions needed to re-create microcosms and their associated activities, are hard to reproduce. The present chapter gives a laboratory-based methodological approach to study structure-function relationships. The results obtained from a systematic study of various ecosystems and the extent of environmental conditions that dictate the structure of communities and the link with ecosystem function are discussed. We also comment on, to what extent the results obtained in laboratory conditions are transposable to natural ecosystems. Finally, three specific case-studies related to cheese ripening are developed to illustrate how microbial ecology can be integrated into food microbiology for better quality and safety of smear cheeses