Nabil Ben Omar

Universidad de Jaén, Jaén, Andalusia, Spain

Are you Nabil Ben Omar?

Claim your profile

Publications (81)176.15 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Members of the genus Bacillus are known to produce a wide arsenal of antimicrobial substances, including peptide and lipopeptide antibiotics, and bacteriocins. Many of the Bacillus bacteriocins belong to the lantibiotics, a category of post-translationally modified peptides widely disseminated among different bacterial clades. Lantibiotics are among the best-characterized antimicrobial peptides at the levels of peptide structure, genetic determinants and biosynthesis mechanisms. Members of the genus Bacillus also produce many other nonmodified bacteriocins, some of which resemble the pediocin-like bacteriocins of the lactic acid bacteria (LAB), while others show completely novel peptide sequences. Bacillus bacteriocins are increasingly becoming more important due to their sometimes broader spectra of inhibition (as compared with most LAB bacteriocins), which may include Gram-negative bacteria, yeasts or fungi, in addition to Gram-positive species, some of which are known to be pathogenic to humans and/or animals. The present review provides a general overview of Bacillus bacteriocins, including primary structure, biochemical and genetic characterization, classification and potential applications in food preservation as natural preservatives and in human and animal health as alternatives to conventional antibiotics. Furthermore, it addresses their environmental applications, such as bioprotection against the pre- and post-harvest decay of vegetables, or as plant growth promoters.
    FEMS microbiology reviews 01/2011; 35(1):201-32. · 10.96 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Enterocin AS-48 was tested against rope-forming Bacillus subtilis CECT 4002 and Bacillus licheniformis CECT 20, as well as on Bacillus cereus and Bacillus pumilus strains in broth and in experimental dough from wheat flour. Vegetative B. subtilis cells in liquid broth were rapidly inactivated by AS-48 (7 AU/ml). In wheat dough, higher bacteriocin concentrations of 14 and 23 AU/g were required for inactivation of B. subtilis vegetative cells and endospores activated to germinate, respectively. B. cereus LWL1 and B. licheniformis CECT 20 were inactivated by AS-48 (14 AU/g) in doughs stored at 22 °C much faster compared to doughs stored at 10 °C. Strains of Bacillus pumilus were partially inactivated in dough by bacteriocin addition (14 AU/g). Results from this study indicate that enterocin AS-48 can reduce the populations of spoilage and potentially-toxigenic bacilli in wheat dough, decreasing the risks for spoilage and food intoxication.
    Food Control. 01/2011; 22(5):756-761.
  • [Show abstract] [Hide abstract]
    ABSTRACT: This chapter deals with food applications of bacteriocins. Regulatory issues on the different possibilities for incorporating bacteriocins as bioprotectants are discussed. Specific applications of bacteriocins or bacteriocin-producing strains are described for main food categories, including milk and dairy products, raw meats, ready-to-eat meat and poultry products, fermented meats, fish and fish products or fermented fish. The last section of the chapter deals with applications in foods and beverages derived from plant materials, such as raw vegetable foods, fruits and fruit juices, cooked food products, fermented vegetable foods and ­fermented beverages. Results obtained for application of bacteriocins in combination with other hurdles are also discussed for each specific case, with a special emphasis on novel food packaging and food-processing technologies, such as irradiation, pulsed electric field treatments or high hydrostatic pressure treatment.
    12/2010: pages 353-390;
  • [Show abstract] [Hide abstract]
    ABSTRACT: Cereal doughs are an important part of human diet, but at the same time can act as vehicles for the transmission of human pathogenic bacteria. In the present study, four pathogenic or toxinogenic bacteria (Escherichia coli O157:H7, Salmonella enterica serovar Enteritidis, Bacillus cereus and Staphylococcus aureus) were inoculated in a dough made from corn flour in combination with the single antimicrobial compounds carvacrol and 2-Nitro-1-propanol (2NPOH). Survival of single and mixed populations in the treated doughs incubated at 37 degrees C was followed by culture-dependent and independent methods (TTGE). All strains were completely inactivated within 24 h by the tested compounds at 5% final concentration, but showed variable inhibition at lower concentrations of 0.5% and 2%. Sensitivity to antimicrobial compounds was in general modified when strains were tested in cocultures compared with single cultures. B. cereus was more sensitive to carvacrol (minimum bactericidal concentration, MBC, 0.5%) in coculture with S. aureus. It was also more sensitive to 2NPOH in cocultures with S. aureus and with S. enterica (MBC, 2% in both cases). S. aureus was more resistant to carvacrol (MBC, 5%) in cocultures with B. cereus, E. coli, as well as S. enterica. However, sensitivity to 2NPOH was not modified in any of the coculture experiments (MBC, 2%). E. coli was more resistant to carvacrol (MBC, 5%) in cocultures with S. aureus and with S. enterica. Resistance of E. coli to 2NPOH also increased in cocultures with B. cereus (MBC, 5%) and with S. aureus (MBC, 2%), but not with S. enterica (MBC, 0.5%). S. enterica was more resistant to carvacrol (MBC, 5%) in cocultures with E. coli, but it was more sensitive to 2NPOH in cocultures with B. cereus as well as with S. aureus (MBC, 2% in both cases). TTGE analysis of survivors from cocultures treated with 2NPOH or carvacrol allowed a good estimation of the identity of survivors according to their DNA band patterns. Results from this study indicate that the efficacy of antimicrobials such as carvacrol and 2NPOH is greatly influenced by the complexity of the microbial populations under target and the relationships between individual populations.
    Food Microbiology 04/2010; 27(2):274-9. · 3.41 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Quantitative real-time PCR may be a rapid and automated procedure for detection of bacterial pathogens from food samples. Nevertheless, when testing the effects of antimicrobials on the viability of bacterial pathogens in foods, we found that DNA from dead cells interfered greatly in the detection of viable Listeria monocytogenes after treatment with the broad-spectrum bacteriocin enterocin AS-48. To overcome this problem, a quantitative real-time PCR (qRT-PCR) assay based on bacterial mRNA was adapted to quantify viable L. monocytogenes in food after bacteriocin treatments. The procedure allowed a better and faster estimation of viable cells compared to PALCAM viable cell counts when the threshold level was 2 log units/g of food, while PALCAM viable count allowed detection of one log unit/g. This procedure may be useful to verify the efficacy of bacteriocins against L. monocytogenes in foods.
    Current Microbiology 04/2010; 61(6):515-9. · 1.52 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Geobacillusstearothermophilus is a thermophilic bacterium typically responsible for the flat-sour spoilage of low-acid canned food with high water activity. Control of vegetative cells and spores of G.stearothermophilus strains CECT 48 and CECT 49 by enterocin EJ97 produced by Enterococcusfaecalis EJ97 is described. Both strains were highly sensitive to EJ97 in a culture medium. In samples from canned foods inoculated with a cocktail of vegetative cells or endospores of the two strains and stored at 45°C for 30days, viable cell counts were reduced below detection levels. The time course of microbial inactivation depended on the food sample and bacteriocin concentration. Dormant endospores were resistant to EJ97 short-time treatments (5min), but endospores activated to germinate by heat became bacteriocin sensitive. The simultaneous application of enterocin EJ97 and heat treatments (90 and 95°C) on dormant endospores had an increased antimicrobial effect that depended both on the bacteriocin concentration and the heat temperature. Results from this study strengthen the potential of enterocin EJ97 for biopreservation against G.stearothermophilus in canned vegetable foods and drinks.
    European Food Research and Technology 01/2010; 230(3):513-519. · 1.44 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Polythene films coated with the enterococcal bacteriocin enterocin EJ97 alone or in combination with EDTA were tested against Bacillus coagulans CECT 12. Bacteriocin activity was clearly enhanced by EDTA, as shown by viable staining and epifluorescence microscopy observation of treated cells. Activated films were tested in liquids from canned corn and canned peas inoculated with B. coagulans cell suspensions and stored at 4 °C and 20 °C for 24 h. The bacteriocin alone showed highest activity in samples stored at 4 °C, while the maximum performance of EDTA was observed at 20 °C. Films activated with a combination of both antimicrobials showed highest bactericidal activity at 4 °C. In liquid from canned corn and peas stored at 4 °C, the combined treatment reduced the concentrations of viable cells progressively over incubation time. Viable staining revealed an increase in the percentage of dead cells at 20 °C, avoiding proliferation of the bacilli. The bactericidal effect of the combined antimicrobial agents was higher in the liquid of canned peas than that of canned corn. The combined use of viable staining and classical viable cell counts allowed a better estimation of cell damage caused by the antimicrobial treatments.
    LWT - Food Science and Technology. 01/2010; 43(3):514-518.
  • [Show abstract] [Hide abstract]
    ABSTRACT: The cyclic peptide bacteriocin enterocin AS-48 was tested (at final concentrations of 0.175, 0.613, and 1.05 AU/ml) against the exopolysaccharide-producing cider spoilage strain Pediococcus parvulus 48 in apple juice in combination with high-intensity pulsed electric field (HIPEF) treatment (35 kV/cm and 150 Hz for 4 mus and bipolar mode). The effect of the combined treatments was studied by surface response methodology, with AS-48 concentration and HIPEF treatment time as process variables. A bacteriocin concentration of 0.613 AU/ml in combination with HIPEF treatment time of 1,000 micros reduced the population of pediococci by 6.6 log cycles in apple juice and yielded an apple juice that was free from pediococci during a 30-day storage period at 4 and 22 degrees Celsius. In contrast, application of HIPEF treatment alone had no effect on the surviving pediococci during storage of juice at 22 degrees Celsius. The combined treatment significantly improved the stability of the juice against spoilage by exopolysaccharide-producing P. parvulus.
    Journal of food protection 01/2010; 73(1):39-43. · 1.83 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In an ecological study, a collection of Gram-positive bacteria were isolated from Gueddid, an artisanal Tunisian fermented meat. From these, 24 strains showed antimicrobial activity and identified as Enterococcus faecium using molecular methods. The enterococci strains were further investigated regarding their safety aspects and functional properties. All the isolates produce bacteriocins with inhibitory activity against several food spoilage bacteria and food borne pathogens, including Listeria spp. Enterococcus spp. and Staphylococcus aureus. One isolate was active against Escherichia coli CECT 877. The majority of the isolates tested positive upon PCR amplification of structural genes for enterocins A, B and P. Investigation of virulence factors by PCR amplification revealed the presence of genes encoding for gelatinase (gelE), enterococcal antigen (efaAfm), sex pheromone (cpd and ccf) and expression of cytolysin (the haemolytic component cylB) whereas, other presumed virulence genes encoding for (agg, esp, cylM, cylA, and cob) were not detected. The isolates were mostly resistant to erythromycin, rifampicin, ciprofloxacin, lavofloxacin, and nitrofurantoin. All of them showed sensitivity to several antibiotics (ampicillin, penicillin, vancomycin, chloramphenicol, teicoplanin, gentamicin, streptomycin, and quinupristin/dalfopristin). Tyrosine, lysine, ornithine and histidine were not decarboxylated by any enterococcal isolate. Nine of the antagonistic enterococci tested did not show any virulence traits or produced biogenic amines, and still had important technological properties. The safety aspects of these selected strains should be studied in deeper details in order to evaluate their potential for biotechnological applications.
    Food Control. 01/2010; 21(4):462-470.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Seed sprouts may act as vehicles for foodborne pathogenic bacteria. In the present study, the effect of washing treatment with the enterococcal bacteriocin enterocin AS-48 on the microbiota of two batches of soybean sprouts was studied by culture-dependent and independent methods throughout storage at 10 degrees C. Viable cell counts of bacteriocin-treated samples revealed some modifications only for lactic acid bacteria and enterococci during storage. In the control samples from batch 1, the culture-independent DGGE analysis revealed species from genera Rahnella and Serratia as the predominant bacteria at early stages. Several bands corresponding to other genera (two Pantoea bands, one Escherichia band, and five Enterobacter bands) were also detected during storage of control samples, especially at days 3 and 5, while one Rahnella band disappeared. By contrast, some of the enterobacteria (Pantoea Escherichia and Enterobacter) were not detected or showed very faint bands in batch 1 bacteriocin-treated samples, in which two new and intense bands corresponding to genera Enterococcus and Leuconostoc were detected. Batch 2 showed a more homogeneous bacterial population, composed mainly by species of genus Enterobacter together with Pantoea. The major modifications detected in the bacteriocin-treated samples from batch 2 included the loss of one genus Enterobacter band at days 3, 5 and 7, and the detection of a new band corresponding to genus Leuconostoc at days 5 and 7. These results suggest that bacteriocin treatment disturbs the microbial balance in sprouts, producing changes in the microbial profile that cannot be detected by culture-dependent methods. The results also encourage the use of culture-independent methods to gain more insights into the global effects of bacteriocins in food systems.
    Food Microbiology 12/2009; 26(8):922-6. · 3.41 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The inhibitory effect of enterocin AS-48 against Staphylococcus aureus was investigated in various types of bakery ingredients. Antibacterial activity greatly depended on the food substrate, ranging from complete inactivation of S. aureus in liquid caramel (in which the bacterium survived poorly) to no significant inhibition (as in vanilla or chocolate creams). Significant reductions of viable counts in the range of 1.8 to 2.7 log units (P < 0.05) were achieved in substrates like pumpkin confiture or diluted almond cream stored at temperatures of 10 or 22 degrees C. Given the very low activity detected in chocolate substrates, enterocin AS-48 was tested in combination with other antimicrobials. Bactericidal activity increased markedly for the combinations of AS-48 and 0.1% eugenol (v/v), 0.5% 2-nitropropanol (v/v), or 3% Nisaplin (w/v). Enterocin AS-48 could be applied in combination with other antimicrobials for preservation of bakery ingredients against S. aureus.
    Journal of Food Science 09/2009; 74(7):M384-9. · 1.78 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Enterocin AS-48 was tested against Staphylococcus aureus, Bacillus cereus, and Listeria monocytogenes in different kinds of desserts. The highest activity against S. aureus was detected in baker cream. However, in yogurt-type soy-based desserts and in gelatin pudding, AS-48 (175 arbitrary units [AU]/g) reduced viable cell counts of S. aureus by only 1.5 to 1.8 log units at most. The efficacy of AS-48 in puddings greatly depended on inoculum size, and viable S. aureus counts decreased below detection levels within 24 h for inocula lower than 4 to 5.5 log CFU/g. For L. monocytogenes, bacteriocin concentrations of 52.5 to 87.5 AU/g reduced viable counts below detection levels and avoided regrowth of survivors. The lowest activity was detected in yogurt-type desserts. For B. cereus, viable cell counts were reduced below detection levels for bacteriocin concentrations of 52.5 AU/g in instant pudding without soy or by 175 AU/g in the soy pudding. In gelatin pudding, AS-48 (175 AU/g) reduced viable cell counts of B. cereus below detection levels after 8 h at 10 degrees C or after 48 h at 22 degrees C. Bacteriocin addition also inhibited gelatin liquefaction caused by the proteolytic activity of B. cereus.
    Journal of food protection 09/2009; 72(8):1654-9. · 1.83 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Enterocin AS-48 was tested in apple juice against the cider-spoilage, exopolysaccharide-producing strain Lactobacillus diolivorans 29 in combination with high-intensity pulsed-electric field (HIPEF) treatment (35 kV/cm, 150 Hz, 4 micros and bipolar mode). A response surface methodology was applied to study the bactericidal effects of the combined treatment, with AS-48 concentration and HIPEF treatment time as process variables. At subinhibitory bacteriocin concentrations, microbial inactivation by the combined treatment increased as the bacteriocin concentration and the HIPEF treatment time increased (from 0.5 to 2.0 microg/ml and from 100 to 1000 micros, respectively). Highest inactivation (4.87 logs) was achieved by 1000 micros HIPEF treatment in combination with 2.0 microg/ml AS-48. While application of treatments separately did not protect juice from survivors during storage, survivors to the combined treatment were inactivated within the following 24 h of storage, and the treated samples remained free from detectable lactobacilli for at least 15 days at temperatures of 4 degrees C as well as 22 degrees C. The combined treatment could be useful for inactivation of exopolysaccharide-producing L. diolivorans in apple juice.
    Food Microbiology 09/2009; 26(5):491-6. · 3.41 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Enterocin AS-48 (30-60 microg/g) significantly reduced viable counts of Listeria monocytogenes in Russian-type salad during one week storage at 10 degrees C. Antilisterial activity of AS-48 (30 microg/g) in salad was strongly enhanced by essential oils (thyme verbena, thyme red, Spanish oregano, ajowan, tea tree, clove, and sage oils tested at 1%, as well as with 2% rosemary oil). Antilisterial activity also increased in combination with bioactive components from essential oils and plant extracts, with other related antimicrobials of natural origin or derived from chemical synthesis (carvacrol, eugenol, thymol, terpineol, tyrosol, hydroxytyrosol, caffeic, ferulic and vanillic acid, luteolin, geranyl butyrate, geranyl phenylacetate, pyrocatechol, hydrocinnamic acid, tert butylhydroquinone, phenylphosphate, isopropyl methyl phenol, coumaric acid, and 2-nitropropanol), and with food preservatives (citric and lactic acid, sucrose palmitate, sucrose stearate, p-hydroxybenzoic methylester acid -- PHBME, and Nisaplin). AS-48 acted synergistically with citric, lactic acid, and PHBME. A mixed population of two L. monocytogenes strains was markedly reduced for one week in salads treated with AS-48 (30 microg/g) in combination with lactic acid, PHBME or Nisaplin. The increased bactericidal activity of these combinations is interesting to improve protection against L. monocytogenes during salad storage.
    Food and chemical toxicology: an international journal published for the British Industrial Biological Research Association 07/2009; 47(9):2216-23. · 2.99 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The cyclic bacteriocin enterocin AS-48 was tested on a cocktail of two Geobacillus stearothermophilus strains in canned food samples (corn and peas), and in coconut milk. AS-48 (7 microg/g) reduced viable cell counts below detection levels in samples from canned corn and peas stored at 45 degrees C for 30 days. In coconut milk, bacterial inactivation by AS-48 (1.75 microg/ml) was even faster. In all canned food and drink samples inoculated with intact G. stearothermophilus endospores, bacteriocin addition (1.75 microg per g or ml of food sample) rapidly reduced viable cell counts below detection levels and avoided regrowth during storage. After a short-time bacteriocin treatment of endospores, trypsin addition markedly increased G. stearothermophilus survival, supporting the effect of residual bacteriocin on the observed loss of viability for endospores. Results from this study support the potential of enterocin AS-48 as a biopreservative against G. stearothermophilus.
    Food Microbiology 06/2009; 26(3):289-93. · 3.41 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The low pH and acid content found in sports and energy drinks are a matter of concern in dental health. Raising the pH may solve this problem, but at the same time increase the risks of spoilage or presence of pathogenic bacteria. In the present study, commercial energy drinks were adjusted to pH 5.0 and challenged with Listeria monocytogenes (drinks A to F), Staphylococcus aureus, Bacillus cereus, and Bacillus licheniformis (drink A) during storage at 37 degrees C. L. monocytogenes was able to grow in drink A and survived in drinks D and F for at least 2 days. Addition of enterocin AS-48 (1 microg/ml final concentration) rapidly inactivated L. monocytogenes in all drinks tested. S. aureus and B. cereus also survived quite well in drink A, and were completely inactivated by 12.5 microg/ml enterocin AS-48 after 2 days of storage or by 25 microg/ml bacteriocin after 1 day. B. licheniformis was able to multiply in drink A, but it was completely inactivated by 5 microg/ml enterocin AS-48 after 2 days of storage or by 12.5 microg/ml bacteriocin after 1 day. Results from the present study suggest that enterocin AS-48 could be used as a natural preservative against these target bacteria in less acidic sport and energy drinks.
    Journal of food protection 05/2009; 72(4):881-4. · 1.83 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A collection of 16 isolates of Enterococcus faecalis from different vegetable foods were characterized by multilocus sequence typing (MLST). One isolate belonged to sequence type (ST) 9 of the previously described clonal complex 9, which is frequently associated with hospital environments. The rest of the isolates were grouped into two new STs named 168 and 169. ST168 represented a singleton clone that included 14 isolates and seemed to be the predominant type among E. faecalis from vegetable samples. ST168 was closely related to ST72, differing only by one allele type. Singleton ST169 was not related to any of the previously described STs.
    Foodborne Pathogens and Disease 05/2009; 6(3):321-7. · 2.28 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to determine the effect of enterocin AS-48 on Listeria monocytogenes CECT 4032 in fruits and fruit juice. Fruits were contaminated with a L. monocytogenes cell suspension, washed with enterocin AS-48 (25 microg/ml) or with sterile distilled water as control, and stored at different temperatures (-20, 6, 15, 22 degrees C). Washing treatments significantly inhibited or completely inactivated L. monocytogenes in strawberries, raspberries, and blackberries stored at 15 and 22 degrees C for up to 2 days and in blackberries and strawberries at 6 degrees C for up to 7 days. Washing treatments with enterocin AS-48 also reduced viable counts in sliced melon, watermelon, pear, and kiwi but did not avoid proliferation of survivors during storage at 15 and 22 degrees C. Added enterocin (25 microg/ml) completely inactivated L. monocytogenes in watermelon juice within 24 h. To enhance the antilisterial activity of treatments, enterocin AS-48 was tested in combination with other antimicrobial substances on sliced melon stored at 22 degrees C. The combinations of enterocin AS-48 and trisodium trimetaphosphate, sodium lactate, lactic acid, polyphosphoric acid, carvacrol, hydrocinnamic acid, p-hydroxybenzoic acid, n-propyl p-hydroxybenzoate, or 2-nitropropanol showed increased antilisterial activities compared with each antimicrobial tested separately. Washing treatments with enterocin AS-48 in combination with 12 mM carvacrol, as well as with 100 mM n-propyl p-hydroxybenzoate, avoided regrowth of Listeria during storage at 22 degrees C. Results from this study indicate that enterocin AS-48 alone or in combination with other preservatives could serve as an additional hurdle against L. monocytogenes in fruits and fruit juices.
    Journal of food protection 01/2009; 71(12):2460-7. · 1.83 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A collection of 25 isolates from foods of animal origin (including mainly milk and cheese, together with meat and ham) was studied. Enterococci were identified at species levels as E. faecalis (9 isolates) and E. faecium (16 isolates). Investigation of virulence factors by PCR amplification revealed incomplete sets of cytolysin genes both in E. faecalis and E. faecium isolates. Among E. faecalis, PCR amplification revealed a high incidence of genes encoding for enterococcal surface protein esp (7/9 isolates), enterococcal antigen efaAfs (6/9), aggregation substance agg (2/9) and sex-pheromone encoding genes ccf, cob, cpd (which were detected in 9, 5 and 3 out of 9 isolates, respectively). By contrast, only esp (7/16 isolates) and efaAfm (10/16) were detected among E. faecium. Antibiotic resistance detected at higher frequencies included rifampicin, nitrofurantoin, ciprofloxacin and levofloxacin. Vancomycin resistance was also detected among E. faecalis and E. faecium. E. faecalis isolates showed decarboxylating activity mostly for tyrosine (5/9 isolates), while E. faecium isolates showed a broader decarboxylating capacity, involving tyrosine (11/16 isolates) ornithine (6/16), lysine (4/16) and histidine (3/16). Six isolates produced bacteriocins, and genes encoding for enterocins A, B, P, L50, and 1071 were detected. Many isolates tested positive for several of the traits investigated, which raises concerns about their possible role as reservoirs for dissemination of antibiotic resistance and virulence traits in foods.
    Food Control. 01/2009;
  • [Show abstract] [Hide abstract]
    ABSTRACT: The effect of the broad spectrum cyclic antimicrobial peptide enterocin AS-48 combination with high-intensity pulsed-electric field (HIPEF) treatment (35 kV/cm, 150 Hz, 4 micros and bipolar mode) was tested on Salmonella enterica CECT 915 in apple juice. A response surface methodology was applied to study the bactericidal effects of the combined treatment. The process variables were AS-48 concentration, temperature, and HIPEF treatment time. While treatment with enterocin AS-48 alone up to 60 microg/ml had no effect on the viability of S. enterica in apple juice, an increased bactericidal activity was observed in combination with HIPEF treatments. Survival fraction was affected by treatment time, enterocin AS48 concentration and treatment temperature. The combination of 100 micros of HIPEF treatment, 30 microg/ml of AS-48, and temperature of 20 degrees C resulted in the lowest inactivation, with only a 1.2-log reduction. The maximum inactivation of 4.5-log cycles was achieved with HIPEF treatment for 1000 micros in combination with 60 microg/ml of AS-48 and a treatment temperature of 40 degrees C. Synergism between enterocin AS-48 and HIPEF treatment depended on the sequence order application, since it was observed only when HIPEF was applied in the presence of previously-added bacteriocin. The combined treatment could improve the safety of freshly-made apple juice against S. enterica transmission.
    International Journal of Food Microbiology 10/2008; 128(2):244-9. · 3.43 Impact Factor

Publication Stats

1k Citations
176.15 Total Impact Points

Institutions

  • 2001–2011
    • Universidad de Jaén
      • Department of Health Sciences
      Jaén, Andalusia, Spain
  • 1994–2006
    • University of Granada
      • Department of Microbiology
      Granata, Andalusia, Spain
  • 2000
    • Institute of Research for Development
      Marsiglia, Provence-Alpes-Côte d'Azur, France