RESUMO
About a thousand lactic acid bacteria (LAB) isolated from dairy products, especially cheeses, were identified and typed by species-specific PCR and RAPD-PCR, respectively. RAPD-PCR profiles, which were obtained by using the M13 sequence as a primer, allowed us to implement a large database of different fingerprints, which were analysed by BioNumerics software. Cluster analysis of the combined RAPD-PCR fingerprinting profiles enabled us to implement a library, which is a collection of library units, which in turn is a selection of representative database entries. A library unit, in this case, can be considered to be a definable taxon. The strains belonged to 11 main RAPD-PCR fingerprinting library units identified as Lactobacillus casei/paracasei, Lactobacillus plantarum, Lactobacillus rhamnosus, Lactobacillus helveticus, Lactobacillus delbrueckii, Lactobacillus fermentum, Lactobacillus brevis, Enterococcus faecium, Enterococcus faecalis, Streptococcus thermophilus and Lactococcus lactis. The possibility to routinely identify newly typed, bacterial isolates by consulting the library of the software was valued. The proposed method could be suggested to refine previous strain identifications, eliminate redundancy and dispose of a technologically useful LAB strain collection. The same approach could also be applied to identify LAB strains isolated from other food ecosystems.
Assuntos
Técnicas de Tipagem Bacteriana , Bacteriófago M13/genética , Queijo/microbiologia , Lactobacillus/classificação , Leite/microbiologia , Técnica de Amplificação ao Acaso de DNA Polimórfico/métodos , Streptococcaceae/classificação , Animais , Impressões Digitais de DNA/métodos , Primers do DNA , DNA Bacteriano/análise , DNA Bacteriano/isolamento & purificação , Biblioteca Gênica , Lactobacillus/genética , Lactobacillus/virologia , Reação em Cadeia da Polimerase , Análise de Sequência de DNA , Software , Especificidade da Espécie , Streptococcaceae/genética , Streptococcaceae/virologia , Fatores de TempoRESUMO
Lactic acid bacteria play an important role in many food and feed fermentations. In recent years major advances have been made in unravelling the genetic and molecular basis of significant industrial traits of lactic acid bacteria. Bacteriophages which can infect and destroy lactic acid bacteria pose a particularly serious threat to dairy fermentations that can result in serious economic losses. Consequently, these organisms and the mechanisms by which they interact with their hosts have received much research attention. This paper reviews some of the key discoveries over the years that have led us to our current understanding of bacteriophages themselves and the means by which their disruptive influence may be minimized.
Assuntos
Bacteriófagos/fisiologia , Indústria de Laticínios , Microbiologia Industrial , Ácido Láctico/metabolismo , Lactobacillus/virologia , Streptococcaceae/virologia , Fermentação , Lactobacillus/genética , Lactobacillus/fisiologia , Streptococcaceae/genética , Streptococcaceae/fisiologiaRESUMO
Lytic systems of lactic acid bacteria and their bacteriophages are reviewed with an emphasis on molecular characterization. Details of enzyme biochemistry and the cloning and analysis of lytic genes are presented, with coverage of lactococcal prolate headed bacteriophages, lactococcal isometric bacteriophages, Lactobacillus bacteriophages and lactococcal autolysins. Some comments on the importance of autolysis in cheese ripening are included and the biotechnological exploitation of cloned and characterized lytic genes is presented.
