Diferenciação genética e potencial bacteriocinogênico de Bactérias Láticas isoladas de leite de cabra

• Autor(a) principal: Cavicchioli, Valéria Quintana
• Data de Publicação: 2014
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5183
• topic: Leite de cabra; Bactérias láticas; Bacteriocinas; PFGE; Inibição; Goat milk; Lactic acid bacteria; Bacteriocins; PFGE; Inhibition; CNPQ::CIENCIAS AGRARIAS::MEDICINA VETERINARIA

Because of the diversity of its indigenous microbiota, goat milk is considered a good source of new strains of lactic acid bacteria (LAB) with potential for exploitation as alternatives to food biopreservation. The increasing consumer demand for these alternatives justifies studies to investigate the antimicrobial potential of these microorganisms. The present study aimed to evaluate the genetic diversity and the antimicrobial action range of autochthonous strains of BAL isolated from goat milk that can be potentially used as biopreservatives in food. The bacteriocinogenic activity against Listeria monocytogenes and stability in different environmental conditions were also the target of this study. Fifty-seven isolates of BAL (33 isolates of Enterococcus spp., and 24 isolates of Lactococcus spp.), previously characterized as bacteriocinogenic by genotypic and phenotypic methods, were subjected to macrorestriction with SmaI and PFGE and their profiles were compared with the results of bacteriocinogenic genes previously searched. High genetic diversity was observed for both genders. Although PFGE showed sufficient discriminatory power, isolates with different results for bacteriocinogenic genes were grouped as identical in both genders. Twelve isolates from Lactococcus spp. and eighteen isolates of Enterococcus spp., representing different pulsotypes, were selected for evaluation of the antimicrobial activity range against 46 target microorganisms (including BAL, pathogens and spoilage microorganisms). Lactococcus strains showed a wide spectrum against the targets, especially against L. monocytogenes and Clostridium spp.. Enterococcus spp., similarly, was able to inhibit various targets, acting mainly against Listeria spp. Gram- negative microorganisms also showed sensitivity to isolates of both genders. Six isolates (four Enterococcus spp., and two Lactococcus spp.) were evaluated for bacteriocinogenic potential against L. monocytogenes strains from different serotypes and all of them were inhibited by bacteriocins produced by these LAB. Additionally, bacteriocins produced by these isolates showed a wide range of stability at different pH values and temperatures. The data showed that goat milk can contain a diverse microbiota able to inhibit microorganisms of interest to the food industry and can be potentially employed in biopreservation of foods produced at different processing conditions.