Isolamento e caracterização de bacteriófagos para biocontrole de Pseudomonas spp. em queijo Minas Frescal

• Autor(a) principal: Ramos, Michelle Silva
• Data de Publicação: 2013
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2932
• topic: Bacteriófago; Pseudomonas; Vida de prateleira; Controle de qualidade; Bacteriophage; Pseudomonas; Shelf life; Quality Control; CNPQ::CIENCIAS AGRARIAS::CIENCIA E TECNOLOGIA DE ALIMENTOS::CIENCIA DE ALIMENTOS

The aim of this study was to isolate, characterize and use the lytic bacteriophages in biocontrol Pseudomonas spp. in Minas Frescal cheese. Bacteriophages obtained from dairy wastewater and exudate of frozen chickens were isolated and characterized bacteriophages obtained from dairy wastewater and exudate of frozen chickens. After propagation, bacteriophages achieved counting between 10-10 and 10-11 PFU. mL-1 and were evaluated for specificity to different genera and species of microbial strains and in relation to bacterial strains isolated from Minas Frescal cheese obtained in retail stores in Viçosa region and from different periods and producers. They were then characterized for the morphology and genetic diversity. Bacteriophages presented a low spectrum of action between different genera of bacteria and wide spectrum of different species of the same genus. As to the lytic activity of the bacteriophage to the bacterial strains isolated from cheese Minas Frescal retail, the bacteriophage isolated of exudate chicken showed specificity against a larger number of strains in comparison to the bacteriophage isolated from dairy wastewater. The two bacteriophages showed no differences in genomic profiling, these exhibited similar morphologies, with icosahedral heads and short tails, indicating that they belong to the family Podoviridae and order Caudovirales. Through biochemical tests and PCR were performed and confirmed the identification of bacterial strains isolated from Minas Frescal cheese retail, demonstrating majority in the identification of the genus Pseudomonas spp. Frescal Minas cheeses were manufactured under laboratory conditions in order to verify the efficiency of the combined use of bacteriophages at concentrations 10-4, 10-6 and 10-8 PFU. mL-1 in the biocontrol of deteriorative microorganisms. The microbiological parameters have includedcounts of Pseudomonas spp. Proteolytic micro-organisms, bacteriophages in milk, whey, cheese and the in the exudate of the cheeses and the physicochemical were pH, chlorides and percentage of weight loss during 21 days under refrigeration. It was noted in this review that the effect of the combined use of bacteriophages on the count of Pseudomonas spp and proteolytic micro-organisms in Minas cheese Frescal showing dependence on concentration used. The largest reductions in the counts of Pseudomonas spp and proteolytic micro-organisms were observed in the concentration 10-4 PFU. mL-1. As for the concentrations of 10-6 and 10-8 PFU. mL-1 bacteriophages. showed no effect in controlling the growth of these micro-organisms during storage period. Similar results were observed when measured count proteolytic microorganisms to which the bacteriophage concentration of 10-4 PFU mL- 1 showed a higher efficiency in inhibiting the proliferation of these micro-organisms. It was observed a decrease in the count of bacteriophages, however, the presence of the cheeses continued during the storage time. No significant changes in relation to pH, mass of cheeses and percentage of chlorides during the storage period. Thus, it is concluded that the combined use of lytic bacteriophages isolated from different environments have potential use in the biocontrol of Pseudomonas spp. in Minas Frescal.