RESUMO
Listeria monocytogenes is a pathogen frequently found in dairy products. Its control in fresh cheeses is difficult, due to the psychrotrophic properties and salt tolerance. Bacteriocinogenic lactic acid bacteria (LAB) with proven in vitro antilisterial activity can be an innovative technological approach but their application needs to be evaluated by means of in situ tests. In this study, a novel bacteriocinogenic Lactococcus lactis strain ( Lc . lactis DF4Mi), isolated from raw goat milk, was tested for control of growth of L. monocytogenes in artificially contaminated fresh Minas type goat cheese during storage under refrigeration. A bacteriostatic effect was achieved, and counts after 10 days were 3 log lower than in control cheeses with no added LAB. However, this effect did not differ significantly from that obtained with a non-bacteriocinogenic Lc. lactis strain. Addition of nisin (12.5 mg/kg) caused a rapid decrease in the number of viable L. monocytogenes in the cheeses, suggesting that further studies with the purified bacteriocin DF4Mi may open new possibilities for this strain as biopreservative in dairy products.
Assuntos
Antibiose , Bacteriocinas/metabolismo , Queijo/microbiologia , Cabras , Lactococcus lactis/isolamento & purificação , Listeria monocytogenes/efeitos dos fármacos , Leite/microbiologia , Animais , Carga Bacteriana , Conservação de Alimentos/métodos , Inocuidade dos Alimentos/métodos , Lactococcus lactis/metabolismoRESUMO
Listeria monocytogenes is a pathogen frequently found in dairy products. Its control in fresh cheeses is difficult, due to the psychrotrophic properties and salt tolerance. Bacteriocinogenic lactic acid bacteria (LAB) with proven in vitro antilisterial activity can be an innovative technological approach but their application needs to be evaluated by means of in situ tests. In this study, a novel bacteriocinogenic Lactococcus lactis strain (Lc. lactis DF4Mi), isolated from raw goat milk, was tested for control of growth of L. monocytogenes in artificially contaminated fresh Minas type goat cheese during storage under refrigeration. A bacteriostatic effect was achieved, and counts after 10 days were 3 log lower than in control cheeses with no added LAB. However, this effect did not differ significantly from that obtained with a non-bacteriocinogenic Lc. lactis strain. Addition of nisin (12.5 mg/kg) caused a rapid decrease in the number of viable L. monocytogenes in the cheeses, suggesting that further studies with the purified bacteriocin DF4Mi may open new possibilities for this strain as biopreservative in dairy products.
Assuntos
Animais , Antibiose , Bacteriocinas/metabolismo , Queijo/microbiologia , Cabras , Lactococcus lactis/isolamento & purificação , Listeria monocytogenes/efeitos dos fármacos , Leite/microbiologia , Carga Bacteriana , Conservação de Alimentos/métodos , Inocuidade dos Alimentos/métodos , Lactococcus lactis/metabolismoRESUMO
Lactic acid bacteria capable of producing bacteriocins and presenting probiotic potential open innovative technological applications in the dairy industry. In this study, a bacteriocinogenic strain (Lactococcus lactis subsp. lactis DF4Mi) was isolated from goat milk, and studied for its probiotic potential. Lc. lactis DF4Mi was resistant to acidic pH and oxbile, presented co-aggregation with Listeria monocytogenes, and was not affected by several drugs from different generic groups, being sensitive to most tested antibiotics. These properties indicate that this Lc. lactis strain can be used for enhancement of dairy foods safety and quality, in combination with potential probiotic properties.
Assuntos
Bacteriocinas/metabolismo , Cabras , Lactococcus lactis/isolamento & purificação , Lactococcus lactis/metabolismo , Leite/microbiologia , Probióticos , Animais , Aderência Bacteriana , Bile/metabolismo , Inocuidade dos Alimentos/métodos , Concentração de Íons de Hidrogênio , Lactococcus lactis/efeitos dos fármacos , Listeria monocytogenes/fisiologia , Viabilidade Microbiana/efeitos dos fármacosRESUMO
Lactic acid bacteria capable of producing bacteriocins and presenting probiotic potential open innovative technological applications in the dairy industry. In this study, a bacteriocinogenic strain (Lactococcus lactis subsp. lactis DF4Mi) was isolated from goat milk, and studied for its antimicrobial activity. The bacteriocin presented a broad spectrum of activity, was sensitive to proteolytic enzymes, resistant to heat and pH extremes, and not affected by the presence of SDS, Tween 20, Tween 80, EDTA or NaCl. Bacteriocin production was dependent on the components of the culture media, especially nitrogen source and salts. When tested by PCR, the bacteriocin gene presented 100% homology to nisin Z gene. These properties indicate that this L. lactis subsp. lactis DF4Mi can be used for enhancement of dairy foods safety and quality.
Assuntos
Animais , Antibacterianos/metabolismo , Bacteriocinas/metabolismo , Lactococcus lactis/metabolismo , Leite/microbiologia , Sequência de Aminoácidos , Antibacterianos/química , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Bacteriocinas/química , Bacteriocinas/genética , Meios de Cultura/química , Detergentes , DNA Bacteriano/genética , Cabras , Concentração de Íons de Hidrogênio , Lactococcus lactis/crescimento & desenvolvimento , Dados de Sequência Molecular , Reação em Cadeia da Polimerase , Estabilidade Proteica , Análise de Sequência de DNA , Homologia de Sequência de Aminoácidos , Cloreto de Sódio/metabolismo , TemperaturaRESUMO
Lactic acid bacteria capable of producing bacteriocins and presenting probiotic potential open innovative technological applications in the dairy industry. In this study, a bacteriocinogenic strain (Lactococcus lactis subsp. lactis DF4Mi) was isolated from goat milk, and studied for its probiotic potential. Lc. lactis DF4Mi was resistant to acidic pH and oxbile, presented co-aggregation with Listeria monocytogenes, and was not affected by several drugs from different generic groups, being sensitive to most tested antibiotics. These properties indicate that this Lc. lactis strain can be used for enhancement of dairy foods safety and quality, in combination with potential probiotic properties.
Assuntos
Animais , Bacteriocinas/metabolismo , Cabras , Lactococcus lactis/isolamento & purificação , Lactococcus lactis/metabolismo , Leite/microbiologia , Probióticos , Aderência Bacteriana , Bile/metabolismo , Inocuidade dos Alimentos/métodos , Concentração de Íons de Hidrogênio , Lactococcus lactis/efeitos dos fármacos , Listeria monocytogenes/fisiologia , Viabilidade Microbiana/efeitos dos fármacosRESUMO
Lactic acid bacteria capable of producing bacteriocins and presenting probiotic potential open innovative technological applications in the dairy industry. In this study, a bacteriocinogenic strain (Lactococcus lactis subsp. lactis DF4Mi) was isolated from goat milk, and studied for its antimicrobial activity. The bacteriocin presented a broad spectrum of activity, was sensitive to proteolytic enzymes, resistant to heat and pH extremes, and not affected by the presence of SDS, Tween 20, Tween 80, EDTA or NaCl. Bacteriocin production was dependent on the components of the culture media, especially nitrogen source and salts. When tested by PCR, the bacteriocin gene presented 100% homology to nisin Z gene. These properties indicate that this L. lactis subsp. lactis DF4Mi can be used for enhancement of dairy foods safety and quality.
