RESUMO
Biopreservation is an alternative to prevent the growth of pathogens and reduce microbial spoilage in food based on the use of microorganisms and/or their metabolic products. The objective of this study was to determine the optimal mode of application and the effectiveness of cell-free supernatant (CFS) from Lactobacillus curvatus ACU-1, containing sakacin G, in Vienna-type sausages to control Listeria and spoilage flora. The functionality and the optimal dosage form between CFS, producing bacteria, a combination or concentrate of bacteriocin applied on Vienna-type sausages before and after stuffing the casings on an industrial scale were determined. Sakacin G was effective for the control of Listeria applied to the casing both before and after stuffing. The application of the antimicrobial on the ready sausages inhibits both lactic acid bacteria and mesophilic microorganisms from zero sampling time. The heat resistance of the bacteriocin in the food was verified under industrial manufacturing conditions. The antimicrobial activity of sakacin G was maintained throughout the period studied in all the conditions tested. In conclusion, the application of CFS containing bacteriocin is useful given both before and after casing stuffing; but the application prior to the stuffing is more practical for the process of elaboration.
Assuntos
Bacteriocinas , Listeria , Produtos da Carne , Bacteriocinas/farmacologia , Bacteriocinas/metabolismo , Lactobacillus/metabolismo , Listeria/metabolismo , Produtos da Carne/microbiologiaRESUMO
Whey, the main by-product of the dairy industry, is frequently disposed of in the environment without any treatment due to the high cost of this process. Alternatively, whey can be used as a medium to culture lactic acid bacteria and produce value-added products such as bacteriocins. In this work, we attempted to improve bacteriocin production by Lactobacillus plantarum ST16Pa in a whey powder formulation supplemented with additional sources of carbon, nitrogen, and vitamin B12 at different levels and varying the agitation intensity according to a Plackett-Burman experimental design. Only the addition of tryptone positively influenced the production of this bacteriocin. The results allowed us to identify a supplemented whey formulation, comprising 150 g/L of whey total solids plus 10 g/L of tryptone and soybean extract, whose fermentation by Lb. plantarum ST16Pa in shake flasks under agitation at 150 rpm led to a cell-free supernatant with an antimicrobial activity against Listeria innocua 6a CLIST 2865 (inhibition zone of 13.23 mm) close to that previously obtained in de Man, Rogosa and Sharpe medium by other authors. These results are significant considering that the same strain cultured in cheese whey did not previously display any antimicrobial activity.
Assuntos
Bacteriocinas/biossíntese , Lactobacillus plantarum/metabolismo , Soro do Leite/metabolismo , Animais , Bacteriocinas/isolamento & purificação , Bacteriocinas/farmacologia , Reatores Biológicos/normas , Queijo/microbiologia , Quimotripsina/metabolismo , Fermentação , Ácido Láctico/análise , Lactobacillus plantarum/efeitos dos fármacos , Lactobacillus plantarum/crescimento & desenvolvimento , Lactose/análise , Listeria/metabolismo , Pós , Pronase/metabolismo , Tripsina/metabolismo , Soro do Leite/química , Proteínas do Soro do Leite/metabolismoRESUMO
The hemolytic, lecithinase or phosphatidylinositol-specific phospholipase C activities of Listeria monocytogenes can be used to differentiate this pathogenic bacteria from L. innocua, apathogenic, frequently isolated from environmental sources and food. However, the interpretation of these characteristics is problematic because of the variation in the expression of virulence factors by L. monocytogenes, which can be influenced by environmental conditions. We used a cheap, simple plate assay to monitor this expression in strains obtained from various sources and grown under different culture conditions. The results were increasingly significant and were obtained adding activated charcoal and different salts to the culture media, and in some cases changing the culture temperature, all with a rigorous control on the process of media sterilization.
Assuntos
Técnicas de Tipagem Bacteriana , Listeria monocytogenes/crescimento & desenvolvimento , Listeria monocytogenes/patogenicidade , Fatores de Virulência/metabolismo , Toxinas Bacterianas/metabolismo , Carvão Vegetal , Meios de Cultura , Proteínas de Choque Térmico/metabolismo , Proteínas Hemolisinas , Humanos , Listeria/classificação , Listeria/crescimento & desenvolvimento , Listeria/metabolismo , Listeria/patogenicidade , Listeria monocytogenes/classificação , Listeria monocytogenes/metabolismo , Fosfatidilinositol Diacilglicerol-Liase/metabolismo , Fosfoinositídeo Fosfolipase C , Fosfolipases/metabolismo , TemperaturaRESUMO
AIM: The aim of this work was to study the influence of different cations on the enterocin CRL35 activity. METHODS AND RESULTS: The antilisterial activity of enterocin CRL35 was tested by performing viability curves and measuring the dissipation of the proton motive force by fluorescent methods upon the addition of Ca2+, Mg2+, Li+, K+ and Na+ chlorides. The peptide uptake by sensitive cells was studied in the different conditions as well. The addition of calcium and magnesium chlorides (0.5-2 mmol l(-1)) induced an inhibition of the peptide activity. Potassium, sodium and lithium chlorides have an inhibitory effect as well, but at different range of concentration compared with divalent cations (50-150 mmol l(-1)). Interestingly, we found a differential protection effect among monovalent ions, KCl being almost nonprotective, meanwhile LiCl shows the stronger effect and NaCl has an intermediate effect. The ion effect depends on the pH, being more efficient in acidic media. Both mono and divalent ions inhibited the ability of the peptide to dissipate the transmembrane electric potential and pH gradient. Furthermore, the peptide uptake was also inhibited. CONCLUSIONS: The enterocin CRL35 activity is strongly dependent on the pH and the nature of the salts present in the medium. SIGNIFICANCE AND IMPACT OF THE STUDY: These findings will allow definition of the best system in which this peptide can be applied as biopreservative.
Assuntos
Bacteriocinas/antagonistas & inibidores , Cátions Bivalentes/farmacologia , Listeria/efeitos dos fármacos , Bacteriocinas/farmacologia , Cálcio/farmacologia , Concentração de Íons de Hidrogênio , Listeria/metabolismo , Magnésio/farmacologia , Testes de Sensibilidade Microbiana , Potássio/farmacologia , Sódio/farmacologiaRESUMO
We studied the reciprocal antagonistic properties of 14 Listeria strains. Listeria innocua 29-CCM-A 819 (CIP 8011) produces a bacteriocin named Linnocuicina 819. This substance is mainly released in the exponential phase of growth and was isolated from the supernatant of TPB cultures. Thermal resistance and sensitivity to proteolytic enzymes was assayed. Linnocuicina 819 has a bactericidal mode of action producing a lytic effect.
Assuntos
Bacteriocinas/biossíntese , Listeria/crescimento & desenvolvimento , Bacteriocinas/antagonistas & inibidores , Bacteriocinas/isolamento & purificação , Bacteriocinas/farmacologia , Bacteriólise , Cromatografia em Gel , Temperatura Alta , Listeria/metabolismo , Peptídeo Hidrolases/farmacologia , Tripsina/farmacologiaRESUMO
La integración del género Listeria parece haberce resuelto con la inclusión de las especies Listeria monocytogenes (sensu stricto), L. Ivanovii (ex bulgárica), Linnocua, L. Welshimeri y L. Seeligeri. Se presenta una batería de resultados comparativos de varias cepas autóctonas y de colección, incluyendo las recientemente incorporadas al género. Se describe el hallazgo de dos nuevas especies moleculares de peso molecular 8.000 y 15.000 D, respectivamente con actividad hemolítica en L. monocytogenes y se analiza la importancia del estudio de actividad hemolítica en la identificación rápida de especies del género. Se enfatiza la necesidad de usar comparativamente hematíes de carnero y conejo, combinando la detección en medio gelificado y líquido, con o sin activación con 2 mercaptoetanol. Se reitera la importancia del estudio de ácidos grasos que en el caso de L. monocytogenes permite, por su riqueza en moléculas de C 15:Or y 17:Or, distinguirla fácilmente de otros géneros con fenotipos similares. Se analiza la crítica aplicación de serotipificación
Assuntos
Cobaias , Coelhos , Animais , Humanos , Listeria monocytogenes/isolamento & purificação , Listeria/metabolismoRESUMO
La integración del género Listeria parece haberce resuelto con la inclusión de las especies Listeria monocytogenes (sensu stricto), L. Ivanovii (ex bulgárica), Linnocua, L. Welshimeri y L. Seeligeri. Se presenta una batería de resultados comparativos de varias cepas autóctonas y de colección, incluyendo las recientemente incorporadas al género. Se describe el hallazgo de dos nuevas especies moleculares de peso molecular 8.000 y 15.000 D, respectivamente con actividad hemolítica en L. monocytogenes y se analiza la importancia del estudio de actividad hemolítica en la identificación rápida de especies del género. Se enfatiza la necesidad de usar comparativamente hematíes de carnero y conejo, combinando la detección en medio gelificado y líquido, con o sin activación con 2 mercaptoetanol. Se reitera la importancia del estudio de ácidos grasos que en el caso de L. monocytogenes permite, por su riqueza en moléculas de C 15:Or y 17:Or, distinguirla fácilmente de otros géneros con fenotipos similares. Se analiza la crítica aplicación de serotipificación (AU)