RESUMEN
Recently, probiotics has drawn much attention as an alternative of antibiotics because overuse use of antibiotics has caused widespread bacterial resistance. Given that prebiotics enhance the activity of probiotics, we prepared phthalyl dextran nanoparticles (PDNs) by conjugation of phthalic anhydride with dextran to form a prebiotic and checked its effects on the cellular and antimicrobial properties of the probiotics. First, we found that the internalization of PDNs by probiotics was dependent on temperature, time, and glucose transporters. Internalization of PDNs enhanced the production of antimicrobial peptides by probiotics through self-defense mechanism and resulted in higher antimicrobial activities against Gram-positive and -negative pathogens compared to probiotics themselves. Moreover, pediocin produced by PDN-internalized probiotics was able to suppress pathogenic gut infections and alter the population of gut microbiome in vivo. The enhanced antimicrobial property of Pediococcus acidilactidi internalized with PDNs could decrease the number of pathogens and increase beneficial bacteria species in mice. Furthermore, the composition of gut microbiome was changed, and resulted in preventing reduction of the diversity of the microflora. Our results indicate that PDNs as a new type of prebiotic can regulate probiotic bacterial metabolism, suggesting a new avenue for probiotic modulation and their use in addressing the challenge of bacterial resistance.
Asunto(s)
Antiinfecciosos/química , Dextranos/química , Nanopartículas/química , Prebióticos , Probióticos/química , Antiinfecciosos/farmacología , Pediococcus/efectos de los fármacos , Péptidos/químicaRESUMEN
The present study elucidates biopreservation potential of an antimicrobial protein; bacteriocin, producing Pediococcus spp. isolated from dairy sample and enhancement of their shelf life in comparison with two chemical preservatives. The antimicrobial protein producing Pediococcus spp. was isolated from selected diary samples and characterised by standard microbiology and molecular biology protocols. The cell free supernatant of Pediococcus spp. was applied on the selected food samples and monitored on daily basis. Antimicrobial potential of the partially purified protein from this bacterium was tested against clinical isolates by well diffusion assay. The preservation efficiency of bacteriocin producing isolate at various concentrations was tested against selected food samples and compared with two chemical preservatives such as sodium sulphite and sodium benzoate. The bacteriocin was partially purified and the microbiological qualities of the biopreservative treated food samples were assessed. The present study suggested that 100⯵g/l of bacteriocin extract demonstrated antimicrobial potential against E. coli and Shigella spp. The treatment with the Pediococcus spp. showed enhanced preservation at 15â¯mL/kg of selected samples for a period of 15â¯days in comparison with sodium sulphite and sodium benzoate. The microbiological quality of food samples treated with biopreservative showed lesser total bacterial count (CFU/g) in comparison with the food samples applied with chemicals (pâ¯≤â¯0.05). Thus, the present study suggests that bacteriocin producing Pediococcus probably provides enhanced shelf life to the selected food samples and can be used as biopreservatives.
Asunto(s)
Antiinfecciosos/farmacología , Conservantes de Alimentos/química , Pediococcus/efectos de los fármacos , Bacteriocinas/farmacología , Recuento de Colonia Microbiana , Productos Lácteos/microbiología , Contaminación de Alimentos/prevención & control , Microbiología de Alimentos , Almacenamiento de Alimentos , Pediococcus/aislamiento & purificación , ARN Ribosómico 16S/aislamiento & purificación , Análisis de Secuencia de ADNRESUMEN
This study aimed to investigate in vitro and in vivo the probiotic characteristics of lactic acid bacteria (LAB) isolated from Korean traditional fermented foods. Caenorhabditis elegans (C. elegans) was used for analytical assays of fertility, chemotaxis, life-span, worm-killing and bacterial colonization in the intestinal lumen of the worm. All 35 strains of LAB reduced fertility and slowed development in the worms. The worm-killing assay showed that LAB significantly increased the lifespan (P < 0.05) and reduced the susceptibility to virulent PA14; however, the heat-killed LAB did not. The bacterial colonization assay revealed that LAB proliferated and protected the gut of the worm against infection by Pseudomonas aeruginosa PA14. In addition, specific LAB Pediococcus acidilactici(P. acidilactici DM-9), Pediococcus brevis (L. brevis SDL1411), and Pediococcus pentosaceus (P. pentosaceus SDL1409) strains showed acid resistance (66-91%), resistance to pepsin (64-67%) and viability in simulated intestinal fluid (67-73%) based on in vitro probiotic analyses. Taken together, these results suggest that C. elegans may be a tractable model for screening efficient probiotics.
Asunto(s)
Caenorhabditis elegans/microbiología , Lactobacillales/fisiología , Probióticos , Pseudomonas aeruginosa/patogenicidad , Animales , Antibacterianos/farmacología , Quimiotaxis , Alimentos Fermentados/microbiología , Tracto Gastrointestinal/microbiología , Intestinos/microbiología , Longevidad , Interacciones Microbianas , Pediococcus/efectos de los fármacos , Pediococcus/fisiología , Pepsina A/farmacologíaRESUMEN
High level aminoglycoside resistance (HLAR) in the lactic acid bacteria (LAB) derived from food animals is detrimental. The aim of this study was to investigate the localization and conjugal transfer of aminoglycoside resistance genes, aac(6')Ie-aph(2â³)Ia and aph(3')IIIa in different Enterococcus species. The cross resistance patterns in Enterococcus faecalis MCC3063 to clinically important aminoglycosides by real time PCR were also studied. Southern hybridization experiments revealed the presence of aac(6')Ie-aph(2â³)Ia and aph(3')IIIa genes conferring HLAR in high molecular weight plasmids except in Lactobacillus plantarum. The plasmid encoded bifunctional aac(6')Ie-aph(2â³)Ia gene was transferable from Enterococcus avium (n = 2), E. cecorum (n = 1), E. faecalis (n = 1) and Pediococcus lolii (n = 1) species into the recipient strain; E. faecalis JH2-2 by filter mating experiments thus indicating the possible risks of gene transfer into pathogenic strains. Molecular analysis of cross resistance patterns in native isolate of E. faecalis MCC3063 carrying aac(6')Ie-aph(2â³)Ia and aph(3')IIIa gene was displayed by quantification of the mRNA levels in this study. For this, the culture was induced with increasing concentrations of gentamicin, kanamycin and streptomycin (2048, 4096, 8192, 16384 µg/mL) individually. The increasing concentrations of gentamicin and kanamycin induced the expression of the aac(6')Ie-aph(2â³)Ia and aph(3')IIIa resistance genes, respectively. Interestingly, it was observed that induction with streptomycin triggered a significant fold increase in the expression of the aph(3')IIIa gene which otherwise was not known to modify the aminoglycoside. This is noteworthy as streptomycin was found to confer cross resistance to structurally unrelated kanamycin. Also, expression of the aph(3')IIIa gene when induced with streptomycin, revealed that bacteria harbouring this gene will be able to overcome streptomycin bactericidal action at specific concentrations. HLAR in E. faecalis MCC3063 may be due to the combined expression of both the aac(6')Ie-aph(2â³)Ia and aph(3')IIIa genes which could be therapeutically challenging. A combined expression of both the genes in E. faecalis MCC3063 may yield HLAR which could be therapeutically challenging. The study highlights the significant alterations in the mRNA expression levels of aac(6')Ie-aph(2â³)Ia and aph(3')IIIa in resistant pathogens, upon exposure to clinically vital aminoglycosides.
Asunto(s)
Acetiltransferasas/genética , Conjugación Genética , Farmacorresistencia Bacteriana , Enterococcus/efectos de los fármacos , Transferencia de Gen Horizontal , Genes Bacterianos , Kanamicina Quinasa/genética , Aminoglicósidos/farmacología , Animales , Antibacterianos/farmacología , Southern Blotting , ADN Bacteriano/genética , Enterococcus/enzimología , Enterococcus/genética , Humanos , Lactobacillus plantarum/efectos de los fármacos , Lactobacillus plantarum/genética , Pediococcus/efectos de los fármacos , Pediococcus/genética , Plásmidos/análisis , Reacción en Cadena en Tiempo Real de la PolimerasaRESUMEN
We examined 10 lactic acid bacteria that have been previously characterized for commercial use as probiotic cultures, mostly for dairy products, including 1 Pediococcus and 9 Lactobacilli. Our objectives were to develop a rapid procedure for determining the long-term survivability of these cultures in acidified vegetable products and to identify suitable cultures for probiotic brined vegetable products. We therefore developed assays to measure acid resistance of these cultures to lactic and acetic acids, which are present in pickled vegetable products. We used relatively high acid concentrations (compared to commercial products) of 360 mM lactic acid and 420 mM acetic acid to determine acid resistance with a 1 h treatment. Growth rates were measured in a cucumber juice medium at pH 5.3, 4.2, and 3.8, at 30 °C and 0% to 2% NaCl. Significant differences in acid resistance and growth rates were found among the 10 cultures. In general, the acid resistant strains had slower growth rates than the acid sensitive strains. Based on the acid resistance data, selected cultures were tested for long-term survival in a simulated acidified refrigerated cucumber product. We found that one of the most acid resistant strains (Lactobacillus casei) could survive for up to 63 d at 4 °C without significant loss of viability at 108 CFU/mL. These data may aid in the development of commercial probiotic refrigerated pickle products.
Asunto(s)
Ácido Acético , Cucumis sativus/microbiología , Jugos de Frutas y Vegetales/microbiología , Ácido Láctico , Lactobacillus/crecimiento & desarrollo , Pediococcus/crecimiento & desarrollo , Probióticos , Ácido Acético/farmacología , Fermentación , Microbiología de Alimentos , Humanos , Concentración de Iones de Hidrógeno , Ácido Láctico/farmacología , Lactobacillus/efectos de los fármacos , Lacticaseibacillus casei , Pediococcus/efectos de los fármacos , Refrigeración , Sales (Química) , Cloruro de Sodio , Verduras/microbiologíaRESUMEN
BACKGROUND: Lactic acid bacteria (LAB) are important for the processing of various food products. Although genetically modified organisms have contributed to improvements in various food products, there are some limitations. Thus, the discovery of wild strains from natural sources must be considered as the most suitable approach for identifying new LAB. Therefore, we planned to isolate and characterise the LAB from Italian ryegrass forage and evaluate their biological potential. RESULTS: A total of 28 strains were isolated and screened for their anti-fungal and probiotic properties. A single strain was selected due to its antifungal and probiotic efficiency. The strain was identified as Pediococcus pentosaceus KCC-23. The strain KCC-23 showed effective inhibition against Aspergillus fumigatus, Pencillium chrysogenum, Pencillium roqueforti, Botrytis elliptica and Fusarium oxysporum. Further, it survived low pH, and the presence of bile salts and gastric juice. It exhibited significant aggregation and hydrophobicity properties. The KCC-23 effectively assimilated cholesterol and had the ability to utilise pre-biotics such as raffinose and inulin. Finally, KCC-23 exhibited significant free radical scavenging activity. CONCLUSION: P. pentosaceus KCC-23 showed effective anti-fungal, probiotic and anti-oxidant properties and would be a promising isolate for exploitation in the formulation of food for ruminants and humans.
Asunto(s)
Anticolesterolemiantes , Fungicidas Industriales , Lolium/microbiología , Pediococcus/fisiología , Probióticos , Antioxidantes , Ácidos y Sales Biliares/farmacología , Fermentación , Jugo Gástrico , Concentración de Iones de Hidrógeno , Inulina/metabolismo , Italia , Pediococcus/química , Pediococcus/efectos de los fármacos , Prebióticos , Rafinosa/metabolismoRESUMEN
OBJECTIVES: To qualitatively and quantitatively characterize a low molecular weight phenolic fraction (LMF) of Malbec wine from Cafayate, Argentina, and evaluate its effect on viability and exopolysaccharide production of Pediococcus pentosaceus 12p, a wine spoilage bacterium. RESULTS: The phenolic compounds detected were, in general, comparable to data previously reported but hydroxycinnamic acids were detected at higher concentrations than determined in other studies. Addition of LMF at identical concentrations present in wine or a four times concentrated LMF mixture to a synthetic wine-like medium produced a diminution in bacterial viability and exopolysaccharide production in the supernatant culture. Transmission electron microscopy revealed damage of bacterial cell integrity after 96 h of incubation only in the presence of four times concentrated LMF. CONCLUSION: This is the first time a low molecular weight phenolic fraction has been characterized in Cafayate wine and it has demonstrated a marked antimicrobial effect on an exopolysaccharide-producing wine spoilage bacterium.
Asunto(s)
Antibacterianos/toxicidad , Viabilidad Microbiana/efectos de los fármacos , Pediococcus/efectos de los fármacos , Fenoles/toxicidad , Polisacáridos/metabolismo , Vino/análisis , Antibacterianos/análisis , Microscopía Electrónica de Transmisión , Pediococcus/metabolismo , Pediococcus/fisiología , Pediococcus/ultraestructura , Fenoles/análisisRESUMEN
The present investigation deals with the optimization of cell growth rate of the candidate probiotic Pediococcus acidilactici in the presence of the specific prebiotic inulin. Three independent variables viz. concentration of inulin, concentration of glucose and pH have been selected for optimization study using response surface methodology. Theoretical analysis indicates that the maximum cell growth rate occurs at pH 7, 20 g/dm(3) concentration of inulin and 20 g/dm(3) concentration of glucose. Validation of these values has been done through a set of programmed experiments. Studies on cell dynamics in the presence of different concentrations of inulin have also been carried out to identify any limitation on the initial inulin concentration. Results clearly indicate that cell growth is enhanced with the increase in inulin concentration. However, there is a critical value of the prebiotic concentration (20 g/dm(3) inulin) beyond which the cell growth is inhibited. A summative type growth model has been proposed to explain the growth behaviour of P. acidilactici in the presence of the dual substrate, i.e. glucose and inulin. While growth on glucose follows Monod model, Haldane-type substrate-inhibited growth model holds good for growth on inulin. Intrinsic kinetic parameters for all the model equations have been determined experimentally.
Asunto(s)
Inulina/farmacología , Pediococcus/efectos de los fármacos , Pediococcus/crecimiento & desarrollo , Ambiente , Glucosa/metabolismo , Cinética , Modelos Biológicos , Prebióticos , ProbióticosRESUMEN
The suitable properties of potential probiotic lactic acid bacteria (LAB) strains (preselected among 153 strains on the basis of their potential technological properties) isolated from traditional Çubuk pickles were examined in vitro. For this purpose, these strains (21 Lactobacillus plantarum, 11 Pediococcus ethanolidurans, and 7 Lactobacillus brevis) were tested for the ability to survive at pH 2.5, resistance to bile salts, viability in the presence of pepsin-pancreatin, ability to deconjugate bile salts, cholesterol assimilation, and surface hydrophobicity properties. Most of the properties tested could be assumed to be strain-dependent. However, L. plantarum and L. brevis species were found to possess desirable probiotic properties to a greater extent compared to P. ethanolidurans. In contrast to P. ethanolidurans strains, the tested L. plantarum and L. brevis strains exhibited bile salt tolerance, albeit to different extent. All tested strains showed less resistance to intestinal conditions than gastric juice environment. Based on the survival under gastrointestinal conditions, 22 of the 39 strains were selected for further characterization. The eight strains having the highest cholesterol assimilation and surface hydrophobicity ratios could be taken as promising probiotic candidates for further in vivo studies, because of the strongest variations found among the tested strains with regard to these properties.
Asunto(s)
Microbiología de Alimentos , Viabilidad Microbiana/efectos de los fármacos , Probióticos/metabolismo , Ácidos y Sales Biliares/toxicidad , Jugo Gástrico/efectos de los fármacos , Concentración de Iones de Hidrógeno , Ácido Láctico/metabolismo , Levilactobacillus brevis/efectos de los fármacos , Levilactobacillus brevis/crecimiento & desarrollo , Lactobacillus plantarum/efectos de los fármacos , Pediococcus/efectos de los fármacos , Pediococcus/crecimiento & desarrollo , Pepsina A/metabolismo , Probióticos/aislamiento & purificaciónRESUMEN
3-Phenyllactic acid (PLA) is a broad-spectrum antimicrobial compound, produced by a wide range of lactic acid bacteria. A novel lactic acid bacteria strain with high PLA-producing ability, Pediococcus pentosaceus SK25, was isolated from traditional Chinese pickles. When grown in de Man, Rogosa, Sharpe broth at 30°C for 36h, this strain produced 135.6mg/L of PLA. Using this strain as starter for milk fermentation, 47.2mg/L of PLA was produced after fermentation for 12h. The PLA production was significantly improved by phenylalanine supplement, but was completely inhibited by tyrosine supplement.
Asunto(s)
Lactatos/metabolismo , Leche/química , Pediococcus/metabolismo , Animales , Antiinfecciosos/metabolismo , Femenino , Fermentación , Lactatos/antagonistas & inhibidores , Leche/metabolismo , Leche/microbiología , Pediococcus/química , Pediococcus/efectos de los fármacos , Fenilalanina/metabolismo , Análisis de Secuencia de ADN/veterinaria , Tirosina/metabolismoRESUMEN
The cationic, amphiphilic peptide nisin is an effective inhibitor of gram-positive bacteria whose mode of action does not encourage pathogenic resistance, and its proper incorporation into food packaging could enhance food stability, safety, and quality in a number of circumstances. Sufficiently small peptides have been shown to integrate into otherwise nonfouling polyethylene oxide (PEO) brush layers in accordance with their amphiphilicity and ordered structure, including nisin, and we have recently shown that nisin entrapment within a PEO layer does not compromise the nonfouling character of that layer. In this work we test the hypothesis that surface-bound, pendant PEO chains will inhibit displacement of entrapped nisin by competing proteins and, in this way, prolong retention of nisin activity at the interface. For this purpose, the antimicrobial activity of nisinloaded, PEO-coated surfaces was evaluated against the gram-positive indicator strain, Pediococcus pentosaceous. The retained antimicrobial activity of nisin layers was evaluated on uncoated and PEO-coated surfaces after incubation in the presence of bovine serum albumin for contact periods up to 1 week. Nisin-loaded, uncoated and PEO-coated samples were withdrawn at selected times and were incubated on plates inoculated with P. pentosaceous to quantify nisin activity by determination of kill zone radii. Our results indicate that nisin activity is retained at a higher level for a longer period of time after entrapment within PEO than after direct adsorption in the absence of PEO, owing to inhibition of nisin exchange with dissolved protein afforded by the pendant PEO chains.
Asunto(s)
Antibacterianos/química , Portadores de Fármacos/química , Nisina/química , Nisina/farmacología , Polietilenglicoles/química , Adsorción , Antibacterianos/farmacología , Pediococcus/efectos de los fármacosRESUMEN
Pediococcus pentosaceus SB83 is a bacteriocinogenic culture having potential use as a vaginal probiotic. The objective of this study was to evaluate the behaviour of P. pentosaceus SB83 incorporated in a liquid system for eventually formulating a gel for vaginal delivery. The vaginal probiotic incorporated into glycerol was able to survive in simulated vaginal fluid at normal vaginal pH (4.2) and at pH of vaginal infections (5.5 and 6.5). The probiotic can be stored at 4 °C for a longer period of time than at room temperature, however, after 13 weeks of storage at low temperature, there was a total loss of viable cells. The probiotic strain incorporated into glycerol showed bacteriocinogenic activity in simulated vaginal fluid, although the antimicrobial activity against Listeria monocytogenes declined during storage. This study showed the behaviour of P. pentosaceus SB83 in glycerol and in simulated vaginal fluid. However, it is necessary to optimise the formulation to produce an actively probiotic vaginal gel.
Asunto(s)
Bacteriocinas/metabolismo , Pediococcus/fisiología , Probióticos/administración & dosificación , Cremas, Espumas y Geles Vaginales/administración & dosificación , Administración Intravaginal , Estabilidad de Medicamentos , Almacenaje de Medicamentos , Femenino , Humanos , Concentración de Iones de Hidrógeno , Listeria monocytogenes/efectos de los fármacos , Viabilidad Microbiana/efectos de los fármacos , Viabilidad Microbiana/efectos de la radiación , Pediococcus/efectos de los fármacos , Pediococcus/metabolismo , Pediococcus/efectos de la radiación , Embarazo , TemperaturaRESUMEN
Three Pediococcus pentosaceus strains were isolated from jeotgals, salted and fermented Korean sea-foods, and their probiotic potentials were examined. After 2 h exposure to pH 3.0, P. pentosaceus F66 survived with the survival ratio of 32.6% followed by P. pentosaceus D56 (17.2%) and P. pentosaceus A24 (7.5%). P. pentosaceus F66 also survived better (26.6%) than P. pentosaceus A24 (13.7%) and P. pentosaceus D56 (5.8%) after 2 h exposure to 0.3% bile salts. Three strains grew slowly on MRS broth with 15% NaCl (w/v), reaching the OD600 values of 0.4-0.8 in 36 h. They adhered to Caco-2 cells (10.9-13.9 CFU/cell) with similar degree of adherence of a positive control, Lactobacillus rhamnosus GG (12.8 ± 0.5 CFU/cell). Three strains possess some desirable enzyme activities such as ß-galactosidase, α-glucosidase, ß-glucosidase, and N-acetyl-ß-glucosidase. From these results, P. pentosaceus F66 seems qualified as a probiotic and can be utilized for fermented foods including jeotgals.
Asunto(s)
Pediococcus/fisiología , Probióticos/farmacología , Alimentos Marinos/microbiología , Adhesión Bacteriana , Ácidos y Sales Biliares/metabolismo , Células CACO-2 , Enzimas/análisis , Células Epiteliales/microbiología , Humanos , Concentración de Iones de Hidrógeno , Corea (Geográfico) , Lacticaseibacillus rhamnosus , Viabilidad Microbiana/efectos de los fármacos , Pediococcus/efectos de los fármacos , Pediococcus/aislamiento & purificación , Cloruro de Sodio/metabolismoRESUMEN
Yerba mate (Ilex paraguariensis) is a tea known to have beneficial effects on human health and antimicrobial activity against some foodborne pathogens. Thus, the application of yerba mate as a feed additive for broiler chickens to reduce Salmonella colonization was evaluated. The first in vitro evaluation was conducted by suspending Salmonella Enteritidis and lactic acid bacteria (LAB) in yerba mate extract. The in vivo evaluations were conducted using preventative and horizontal transmission experiments. In all experiments, day-of-hatch chicks were treated with one of the following 1) no treatment (control); 2) ground yerba mate in feed; 3) probiotic treatment (Lactobacillus acidophilus and Pediococcus; 9:1 administered once on day of hatch by gavage); or 4) both yerba mate and probiotic treatments. At d 3, all chicks were challenged with Salmonella Enteritidis (preventative experiment) or 5 of 20 chicks (horizontal transmission experiment). At d 10, all birds were euthanized, weighed, and cecal contents enumerated for Salmonella. For the in vitro evaluation, antimicrobial activity was observed against Salmonella and the same treatment enhanced growth of LAB. For in vivo evaluations, none of the yerba mate treatments significantly reduced Salmonella Enteritidis colonization, whereas the probiotic treatment significantly reduced Salmonella colonization in the horizontal transmission experiment. Yerba mate decreased chicken BW and decreased the performance of the probiotic treatment when used in combination. In conclusion, yerba mate had antimicrobial activity against foodborne pathogens and enhanced the growth of LAB in vitro, but in vivo yerba mate did not decrease Salmonella Enteritidis colonization.
Asunto(s)
Bacterias/efectos de los fármacos , Pollos , Ilex paraguariensis/química , Enfermedades de las Aves de Corral/tratamiento farmacológico , Probióticos/farmacología , Salmonelosis Animal/tratamiento farmacológico , Alimentación Animal/análisis , Animales , Bacterias/crecimiento & desarrollo , Ciego/microbiología , Dieta/veterinaria , Suplementos Dietéticos/análisis , Lactobacillus/efectos de los fármacos , Lactobacillus/crecimiento & desarrollo , Pediococcus/efectos de los fármacos , Pediococcus/crecimiento & desarrollo , Extractos Vegetales/química , Hojas de la Planta/química , Enfermedades de las Aves de Corral/microbiología , Probióticos/administración & dosificación , Salmonelosis Animal/microbiología , Salmonella enteritidis/efectos de los fármacos , Salmonella enteritidis/crecimiento & desarrolloRESUMEN
AIMS: To examine the use of a natural antimicrobial peptide, human ß-defensin-3 (HBD3), as a means of preventing spoilage from bacterial contamination in brewery fermentations and in bottled beer. METHODS AND RESULTS: A chemically synthesised HBD3 peptide was tested for bactericidal activity against common Gram-positive and Gram-negative beer-spoiling bacteria, including species of Lactobacillus, Pediococcus and Pectinatus. The peptide was effective at the µmol l(-1) range in vitro, reducing bacterial counts by 95%. A gene construct encoding a secretable form of HBD3 was integrated into the genome of the lager yeast Saccharomyces pastorianus strain CMBS-33. The integrated gene was expressed under fermentation conditions and was secreted from the cell into the medium, but a significant amount remains associated with yeast cell surface. We demonstrate that under pilot-scale fermentation conditions, secreted HBD3 possesses bactericidal activity against beer-spoiling bacteria. Furthermore, when added to bottled beer, a synthetic form of HBD3 reduces the growth of beer-spoiling bacteria. CONCLUSIONS: Defensins provide prophylactic protection against beer-spoiling bacteria under brewing conditions and also in bottled beer. SIGNIFICANCE AND IMPACT OF THE STUDY: The results have direct application to the brewing industry where beer spoilage due to bacterial contamination continues to be a major problem in breweries around the world.
Asunto(s)
Antibacterianos/farmacología , Cerveza/microbiología , Lactobacillaceae/efectos de los fármacos , Pectinatus/efectos de los fármacos , Saccharomyces/metabolismo , beta-Defensinas/farmacología , Secuencia de Aminoácidos , Antibacterianos/biosíntesis , Secuencia de Bases , ADN de Hongos/química , Fermentación , Humanos , Lactobacillaceae/crecimiento & desarrollo , Lactobacillus/efectos de los fármacos , Lactobacillus/crecimiento & desarrollo , Datos de Secuencia Molecular , Pediococcus/efectos de los fármacos , Pediococcus/crecimiento & desarrollo , Proyectos Piloto , ARN de Hongos/genética , ARN de Hongos/aislamiento & purificación , Saccharomyces/genética , beta-Defensinas/biosíntesis , beta-Defensinas/química , beta-Defensinas/genéticaRESUMEN
The antimicrobial mechanism of a lactococcal bacteriocin, lacticin Q, can be described by the toroidal pore model without any receptor. However, lacticin Q showed different degrees of activity (selective antimicrobial activity) against Gram-positive bacteria even among related species. The ability of lacticin Q to induce pore formation in liposomes composed of lipids from different indicator strains indicated that its selective antimicrobial activity could not be attributed only to membrane lipid composition. We investigated the accumulation of deleterious hydroxyl radicals after exposure to lacticin Q as a contributing factor to cell death in the indicator strains. When lacticin Q of the same concentration as the MIC or minimum bactericidal concentration was added to the indicator cultures, high levels of hydroxyl radical accumulation were detected. Treatment with hydroxyl radical scavengers, thiourea and 2,2'-bipyridyl, decreased the levels of hydroxyl radical accumulation and recovered cell viability. These results suggest that, with or without pore formation, the final antimicrobial mechanism of lacticin Q is the accumulation of hydroxyl radicals, which varies by strain, resulting in the selective antimicrobial activity of lacticin Q.
Asunto(s)
Bacteriocinas/farmacología , Radical Hidroxilo/metabolismo , Lactococcus lactis/efectos de los fármacos , Lactococcus lactis/metabolismo , Antibacterianos/farmacología , Membrana Celular/efectos de los fármacos , Lípidos de la Membrana/metabolismo , Potenciales de la Membrana/efectos de los fármacos , Pruebas de Sensibilidad Microbiana , Viabilidad Microbiana/efectos de los fármacos , Pediococcus/efectos de los fármacos , Tiourea/farmacologíaRESUMEN
AIM: The current study aimed to visualize the damage caused by enterolysin A to the cells of sensitive strains and to find out cleavage site within the peptidoglycan moiety of bacterial cell walls. METHODS AND RESULTS: Enterolysin A produced by a local isolate, Enterococcus faecalis B9510 was found to rapidly kill cells of the sensitive strain Lactococcus lactis ssp. cremoris 2144 during 120 min of treatment as compared to the untreated control where no such effect was observed. Transmission electron microscopy of the enterolysin A-treated cells revealed leaking of the cytoplasmic contents ultimately resulting in complete lysis of cell walls. To find the cleavage site, purified cell walls of L. lactis ssp. cremoris 2144, Pediococcus pentosaceus 43201 and Lactobacillus delbrueckii ssp. bulgaricus ATCC 11842 were treated with enterolysin A, and liberated amino acids were derivatized for N and C terminals and analysed using thin layer chromatography on silica gel with isopropanol as solvent. The results showed that enterolysin A cleaves the peptide bonds at two locations within peptidoglycan subunits. The first location is between L-alanine and D-glutamic acid of the stem peptide and the other location is between L-lysine of the stem peptide and D-aspartic acid of the interpeptide bridge. CONCLUSIONS: Enterolysin A cleaves the peptide bonds within the stem peptide as well as in the interpeptide bridge of Gram-positive bacterial cell walls. This gives a possible reason for the broad spectrum of enterolysin A activity. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report identifying the cleavage site of enterolysin A within the cell walls of sensitive bacteria. This will help in identifying potential applications for enterolysin A.
Asunto(s)
Antibacterianos/farmacología , Bacteriocinas/farmacología , Secuencia de Aminoácidos , Antibacterianos/química , Antibacterianos/toxicidad , Bacteriocinas/química , Bacteriocinas/toxicidad , Pared Celular/efectos de los fármacos , Pared Celular/metabolismo , Enterococcus faecalis/metabolismo , Lactococcus lactis/efectos de los fármacos , Datos de Secuencia Molecular , Pediococcus/efectos de los fármacos , Peptidoglicano/química , Peptidoglicano/metabolismo , Homología de Secuencia de AminoácidoRESUMEN
A lactic acid bacterium with high tolerance of temperature and lignocellulose derived inhibitor was isolated and characterized as Pediococcus acidilactici DQ2. The strain used in the simultaneous saccharification and fermentation (SSF) for high titer lactic acid production at the high solids loading of corn stover. Corn stover was pretreated using the dry sulphuric acid pretreatment, followed by a biological detoxification to remove the inhibitors produced in the pretreatment. The bioreactor with a novel helical impeller was used to the SSF operation of the pretreated and biodetoxified corn stover. The results show that a typical SSF operation at 48 °C, pH 5.5, and near 30% (w/w) solids loading in both 5 and 50 L bioreactors was demonstrated. The lactic acid titer, yield, and productivity reached 101.9 g/L, 77.2%, and 1.06 g/L/h, respectively. The result provided a practical process option for cellulosic lactic acid production using virgin agriculture lignocellulose residues.
Asunto(s)
Biotecnología/métodos , Metabolismo de los Hidratos de Carbono , Fermentación , Ácido Láctico/metabolismo , Pediococcus/aislamiento & purificación , Residuos/análisis , Zea mays/metabolismo , Secuencia de Bases , Metabolismo de los Hidratos de Carbono/efectos de los fármacos , ADN Ribosómico/genética , Fermentación/efectos de los fármacos , Glucosa/farmacología , Lignina/metabolismo , Datos de Secuencia Molecular , Pediococcus/efectos de los fármacos , Pediococcus/genética , Pediococcus/metabolismo , Filogenia , Análisis de Secuencia de ADN , Temperatura , Volumetría , Xilosa/farmacología , Zea mays/efectos de los fármacosRESUMEN
Streptococcus thermophilus B59671 produces a bacteriocin with anti-pediococcal activity, but genes required for its production are not characterized. Genome sequencing of S. thermophilus has identified a genetic locus encoding a quorum sensing (QS) system that regulates production of class II bacteriocins. However, in strains possessing this gene cluster, production of bacteriocin like peptides (Blp) was only observed when excess pheromone was provided. PCR analysis revealed this strain possessed blpC, which encodes the 30-mer QS pheromone. To investigate if BlpC regulates bacteriocin production in S. thermophilus B59671, an integrative vector was used to replace blpC with a gene encoding for kanamycin resistance and the resulting mutant did not inhibit the growth of Pediococcus acidilactici. Constitutive expression of blpC from a shuttle vector restored the bacteriocin production, confirming the blp gene cluster is essential for bacteriocin activity in S. thermophilus B59671.
Asunto(s)
Bacteriocinas/metabolismo , Regulación Bacteriana de la Expresión Génica , Streptococcus thermophilus/genética , Streptococcus thermophilus/metabolismo , Eliminación de Gen , Prueba de Complementación Genética , Vectores Genéticos , Familia de Multigenes , Pediococcus/efectos de los fármacos , Feromonas/genética , Feromonas/metabolismoRESUMEN
This paper compares some important parameters and the free amino acid and biogenic amine contents of cured industrial and homemade meat products. To this aim, industrial and homemade "soppressata" and "salsiccia", typical dry fermented sausages produced in Southern Italy, were analyzed. The homemade sausages showed a higher level of free biogenic amines than that manufactured industrially, most likely because biogenic amine formation in industrial products is limited by the use of starter cultures. The industrial sausages are characterized by a higher total free amino acid content than the homemade products. Overall, free amino acid and biogenic amine contents demonstrated that appreciable differences exist between homemade and industrial sausages.