The enterocin P-producing Enterococcus lactis strain Q1 was directly added at 10(7) CFU/g in refrigerated raw beef to evaluate its effectiveness in the control of Listeria monocytogenes EGDe 107776 proliferation. Furthermore, sensorial evaluation of the quality of treated beef meat samples with the enterococcal protective culture was performed basing on color, odor, and appearance parameters for 14 days. As a result, it was demonstrated that the enterocin P-producing E. lactis Q1 strain led to a remarkable reduction (p < .05) of L. monocytogenes in beef meat by 6.47 +/- 0.30 log units after 7 days and 7.25 +/- 0.35 log units below the control after 14 days, then remained stable up to 28 days of cold storage. Also, E. lactis Q1 strain improved significantly (p < .05) the organoleptic quality of treated beef sample. Hence, E. lactis Q1 clearly indicates its efficiency to be used as protective agent in a wide range of meat products. Practical applications Preserving meat using new bacteriocinogenic lactic acid bacteria is an important agenda to ensure consumer safety. The present study showed the ability of an enterocin P-producing strain named E. lactis Q1, added in raw beef meat during cold storage, to inhibit L. monocytogenes and improve meat sensory properties. Hence, E. lactis Q1 can be used in the future to develop healthy meat products with better shelf life and quality.

This study deals with the genetic characterisation of two enterocin-producing Enterococcus lactis strains named Q1 and 4CP3 using Randomly Amplified Polymorphic DNA (RAPD) PCR and the effect of their separate additions in the control of Listeria monocytogenes in refrigerated chicken breast meat. These strains demonstrated interesting in vitro antimicrobial activity towards L. monocytogenes EGDe 107776 by agar assay. To evaluate the in situ effect of E. lcids strains against L. monocytogenes in white meat model, chicken breast were artificially contaminated with 10(5) CFU/g of L. monocytogenes and inoculated with E. lactis Q1 and 4CP3 of each at 10(7) CFU/g. The pathogen counts were monitored during cold storage for 28 days. The anti-listerial effect of the enterococcal cultures was examined using linear (ANOVA) and general (ANCOVA) models and it has been shown that both of them controlled L monocytogenes by decreasing (P < 0.05) and suppressing the pathogen growth in refrigerated chicken meats during 28 days of storage. The present study shows that our E. lactic strains have great potential as protective cultures and might be used for preventing the growth of pathogenic bacteria such as L. monocytogenes in meat products during their refrigerated storage.

The aims of this study are to isolate new bacteriocinogenic lactic acid bacterial strains from white (Penaeus vannamei) and pink (Palaemon serratus) raw shrimps and evaluate their technological and probiotic potentialities. Seven strains were selected, among fifty active isolates, as producing interesting antimicrobial activity. Identified as Enterococcus lactis, these isolates were able to produce enterocins A, B and/or P. The safety aspect, assessed by microbiological and molecular tests, demonstrated that the strains were susceptible to relevant antibiotics such as vancomycin, negative for haemolysin and gelatinase activities, and did not harbour virulence and antibiotic resistance genes. The assessment of potential probiotic and technological properties showed a low or no lipolytic activity, moderate milk-acidifying ability, high reducing power, proteolytic activity and tolerance to bile (P < 0.05) and good autoaggregation and coaggregation capacities. Two strains designated as CQ and C43 exhibiting high enzymatic activities and bile salt hydrolase activity were found to display high survival under simulated in vitro oral cavity and gastrointestinal tract conditions caused by presence of lysozyme, pepsin, pancreatin, bile salts and acidic pH. This study highlights safe Enterococcus lactis strains with great technological and probiotic potentials for future application as new starter, adjunct, protective or probiotic cultures in food industry.

Over the last 20 years, natural peptides playing a key role in defense mechanisms and innate immunity have been isolated from unicellular organisms. Amphibian skin secretes dermaseptins, 24-34 amino acids in length that have a wide antimicrobial spectrum incorporating yeast, fungi, protozoa, bacteria and enveloped viruses. The anti-rabies virus (RABV) activity of dermaseptins S3 (30aa) and S4 (28aa) from Phyllomedusa sauvagei has been investigated, and further dissected its molecular basis by comparing punctual mutation or deletion of S4 analogues. The results showed that: (1) S4 is more active than S3 against RABV infection, 89% versus 38% inhibition at 7.5 μM; (2) the 5 NH2-aa of S4 are crucial for its inhibitory potential (S46-28 lost any inhibition) but the COOH terminus stabilizes the inhibitory potential (S41-16 showed only 23% inhibition at 7.5 μM); (3) there is a correlation between viral inhibition and dermaseptin cytotoxicity, which remains however moderated for BSR cells (≤12% at 10 μM). A single mutation in position 4 (S4M4K) slightly reduced cytotoxicity while keeping its antiviral activity, 97% at 7.5 μM. S4 and S4M4K showed an antiviral activity in vitro when provided 1 h after infection. In vivo experiments in mice by intramuscular injection of non-toxic doses of dermaseptin S4M4K 1 h post-infection by a lethal dose of RABV at the same site allowed more than 50% improvement in mice survival. This study highlights the potential interest of dermaseptins as non-expansive alternatives to rabies immunoglobulins for the treatment of rabies that continues to claim about 60,000 human lives per year worldwide, almost exclusively in developing countries.

Eight lactic acid bacterial (LAB) strains were newly isolated from fresh shrimps (Penaeus vannamei and Palaemon serratus) and characterised by phenotypic and molecular tests. These isolates, identified as Enterococcus Was producing the enterocins A, B and/or P, displayed interesting antagonistic activities against pathogenic bacteria and fungi. Regarding biotechnological properties, lards strains had generally great redox potentials, good proteolytic activities (P < 0.05) and medium acidification rates. Evaluated by the API ZYM system, two strains named Q1 and 4CP3 exhibited good enzymatic activities: leucine, valine and cystine arymalidases, Naphthol-AS-BI-phosphohydrolase and beta-galactosidase. For probiotic assessment, the examined strains were found to resist low pH and bile salts with presence of gastric and digestive enzymes. Likewise, they indicated potentialities of adhesion and colonisation in the intestines. All strains were sensitive to clinically important antibiotics and no PCR signals were detected for any of the common antibiotic resistance genes such as vanA and van]) for vancomycin. Furthermore, virulence traits including the presence of virulence factors, haemolysin and gelatinase, were not detected. This work suggests that our E lads strains can be considered as promising candidates for future applications as a starter, adjunct or protective cultures or could constitute new potential probiotics.

Lactic acid bacteria produce various antibacterial peptides such as bacteriocins that are active against pathogenic and spoilage microorganisms. Very little attention has been paid to the production of lysozyme as an antimicrobial enzyme. The present work represents one of the few studies reporting lysozyme production by enterococci. Indeed, this study was first conducted to evaluate the antimicrobial activity of Enterococcus lactis Q1, an enterocin P-producing strain previously isolated from fresh shrimp (Penaeus vannamei), against multidrug-resistant clinical isolates. Results showed significant inhibitory activity (P < 0.05) towards diverse pathogens. The purification of the antimicrobial substances produced by Q1 strain leads to the isolation of two active fractions. The SDS-PAGE and mass spectrometry analyses of fraction number 2 (fraction 2) revealed the presence of a protein with molecular mass of 14.3 kDa. Additionally, the experimental results are consistent with mass spectra of industrial lysozyme (Fluka ref. 62970). The lysozyme produced by Enterococcus lactis Q1 strain was confirmed by a plate method against Micrococcus luteus ATCC 4698. Also, sensitivity of the Q1 strain to different concentrations of lysozyme was investigated. For the first time, this study shows that E. lactis Q1 produces lysozyme which could be an excellent candidate in food biopreservation or production of functional foods to promote health benefits.

This study aims to characterise a potential bacteriocinogenic lactic acid bacterial strain isolated from a raw pink shrimp (Palaemon serratus) and evaluate its safety aspect. The strain designated as 4CP3 was noted to display antibacterial activities (P < 0.05) against Gram-positive and Gram-negative foodbome pathogens (Listeria monocytogenes and Pseudomonas aeruginosa) and some filamentous fungi (e.g. Aspergillus niger A79). Phenotypic and molecular techniques as well as phylogenetic analysis identified the isolate 4CP3 as Enterococcus lactis. Its produced antimicrobial substance was determined as a bacteriocin that was stable over a wide range of pH (2-10) and after heating at 100 degrees C for 15 min. The maximum bacteriocin production was 1400 AU/ml recorded after 12 h of incubation in de Man, Rogosa and Sharpe (MRS) broth medium at 30 degrees C. The mode of action of the bacteriocin produced by 4CP3 strain was identified as bactericidal against L. monocytogenes EGDe 107776 and P. aeruginosa ATCC 27853. By specific PCR amplifications, E. lactis 4CP3 was shown to produce the enterocins A, B and P. To our knowledge, this feature is newly described for E. lactis strain isolated from raw shrimps. Regarding safety aspect of E. Incas 4CP3, it has been demonstrated that this strain was not haemolytic, gelatinase negative, sensitive to vancomycin, and free of common antibiotic resistance genes and virulence factors. Therefore, it may be useful as a safe natural agent in preservation of foods or as a new probiotic strain in food and feed.

In this manuscript, a multiple enterocin-producing Enterococcus lactis strain named 4CP3 was used to control the proliferation of Listeria monocytogenes in refrigerated raw beef meat model. Also, the intraspecific genetic differentiation of 4CP3 strain was assessed by Random Amplified Polymorphic DNA Polymerase Chain Reaction (RAPD-PCR) analysis. E. lactis 4CP3 strain was found to produce the enterocins A, B, and P. It displayed activity against L. monocytogenes EGDe 107776 by agar-well diffusion method. The application of E. lactis 4CP3 culture at 107 CFU/g in raw beef meat was evaluated using both ANOVA and ANCOVA linear models in order to examine its effect on the growth of the pathogen L. monocytogenes during refrigerated storage. Hence, a very interesting result in decreasing (P<0.05) and suppressing the growth of L. monocytogenes in refrigerated raw beef meat was shown during 28 days of storage. In conclusion, E. lactis 4CP3 strain might be useful for prevention of the proliferation and survival of L. monocytogenes in raw meat during refrigerated storage.

Screening for lactic acid bacteria (LAB) from fresh shrimp samples (Penaeus vannamei) collected from retail seafood markets in the Tunisian's coast, resulted in the isolation of an Enterococcus strain termed Q1. This strain was selected for its antagonistic activity against pathogenic bacteria such as Listeria monocytogenes, Pseudomonas aeruginosa, Lactococcus garvieae and against fungi (Aspergillus niger and Fusarium equiseti). The Q1 strain was characterised using standard morphological and biochemical tests, growth assays at different temperatures, pH and salinity. 16S rRNA, rpoA and pheS gene sequencing, as well as the 16S-23S rRNA intergenic spacer analyses, were combined to identify strain Q1 as a strain of Enterococcus lactis. The bacteriocin produced by E. lactis Q1 is thermostable, active in the pH range from 4.0 to 9.0 and has a bactericidal mode of action. The enterocin P structural gene was detected by specific PCR in strain E. lactis Q1, which is in good agreement with SDS-PAGE data of the purified bacteriocin. A lack of significant antibiotic resistance genes and virulence determinants was confirmed by specific PCRs. This work provides the first description of an enterocin P producer E. lactis strain isolated from a fresh shrimp. Based on its safety properties (absence of haemolytic activity, virulence factors and antibiotic resistance genes), this strain has the potential to be used as a natural additive or adjunct protective culture in food biopreservation and/or probiotic culture.

In our research on natural compounds efficient against human pathogen or opportunist microorganisms contracted by food or water, the antimicrobial activity of 19 essential oils (EOs) was investigated against 11 bacterial species (6 Gram positive, 5 Gram negative) and 7 fungal species (2 dermatophytes, 1 mould, 4 yeasts) using microdilution assays. Five essential oils were obtained from Tunisian plants (EOtun): Artemisia herba-alba Asso, Juniperus phoenicea L., Rosmarinus officinalis L., Ruta graveolens L. and Thymus vulgaris L., whereas others were commercial products (EOcom). Overall, T. vulgaris EOtun was the most efficient EO against both bacteria (Gram negative: MIC ≤ 0.34 mg/mL; Gram positive: MIC ≤ 0.70 mg/mL) and fungi (yeasts: MIC ≤ 0.55 mg/mL; mould: MIC = 0.30 mg/mL; dermatophytes: MIC ≤ 0.07 mg/mL). Two EOcom displayed both acceptable antibacterial and antifungal potency, although weaker than T. vulgaris EOtun activity: Origanum vulgare EOcom (bacteria: MIC ≤ 1.13 mg/mL, fungi: MIC ≤ 1.80 mg/mL), and Cymbopogon martinii var. motia EOcom (bacteria: MIC ≤ 1.00 mg/mL, fungi: MIC ≤ 0.80 mg/mL). Bacillus megaterium, Legionella pneumophila, Listeria monocytogenes and Trichophyton spp. were the most sensitive species to both EOcom and EOtun. This study demonstrated the noteworthy antimicrobial activity of two commercial EOs and points out the remarkable efficiency of T. vulgaris EOtun on all tested bacterial and fungal species, certainly associated with its high content in carvacrol (85 %). These three oils could thus represent promising candidates for applications in water and food protections.

Use of lactic acid bacteria (LAB) as probiotics may provide an alternative to the use of antibiotics in aquaculture. LAB strains isolated from wild fish viscera and skin were evaluated for bacteriocin production and safety aspects (lack of antibiotic resistance, production of virulence factors). 16S rRNA gene sequences revealed the presence of Enterococcus faecium (13 isolates) and Lactococcus lactis (3 isolates) from fish samples. Pulsed-field gel electrophoresis analyses of the 13 enterococci isolates showed that they were all clustered, with greater than 95% similarity. However, RAPD analysis revealed significant molecular diversity between enterococci strains. Six enterococci strains were chosen and evaluated for their antibacterial activities. These strains produced a bacteriocin-like substance and exhibited a broad spectrum of inhibition against pathogenic bacteria isolated from diseased fish, including Streptococcus parauberis, Vagococcus spp., and Carnobacterium maltaromaticum, and in particular against the Gram-negative bacteria Flavobacterium frigidarium, Vibrio pectenicida, V. penaeicida, and Photobacterium damselae. The inhibition activity towards bacterial indicator strains was at a maximum when bacteria were grown at 37°C. However, bacteriocin production was observed at 15°C after 12 h of incubation. Only structural genes of enterocins A and B were detected by PCR in the 6 enterococci strains, suggesting the production of these enterocins. In addition, these strains did not harbor any virulence factors or any significant antibiotic resistance, and they tolerated bile. Our results suggest that enterococci are an important part of the bacterial flora of fish and that some strains have the potential to be used as probiotics.

Pseudomonas strains isolated from hot spring water were tested for bacteriocin-like substance (BLS) production using a target panel of closely related microorganisms and other Gram-positive and Gram-negative bacteria. Molecular identification was carried out through specific PCR and 16S RNA sequence analysis. Isolates were identified as Brevundimonas diminuta and Pseudomonas putida , the latter exhibited antimicrobial activity. Pseudomonas putida strains produce an inhibitory substance against other Pseudomonas strains and other species including food-borne pathogens. The BLS was sensitive to the proteolytic action of proteinase K, pronase E and trypsin but resistant to α-amylase, RNase and lipase C, reflecting its proteinaceous nature. The BLS was stable at 100 °C and also after thermal treatment at 121 °C for 15 min. Additionally, it was stable within a wide range of pH (2–10). The substance from P. putida T01 strain was bactericidal to Escherichia coli . SDS-PAGE analysis of the partial purified supernatant of strain T01 revealed a BLS with an approximate molecular mass of 8 kDa. Therefore, the results of this study show that P. putida strain T01 produces a BLS with a higher activity spectrum, which may find application in human medicine and in minimally processed food preservation.

The aim of this study was to investigate the composition of six essential oils extracted from Tunisian plants, i.e., Artemisia herba-albaAsso, Citrus sinensis (L.) Osbeck, Juniperus phoenicea L., Rosmarinus officinalis L., Ruta graveolens L., and Thymus vulgaris L., and to evaluate their activity against Legionella pneumophila (microdilution assays). Eight Legionella pneumophila strains were studied, including the two well-known serogroup 1 Lens and Paris strains as controls and six environmental strains isolated from Tunisian spas belonging to serogroups 1, 4, 5, 6, and 8. The essential oils were generally active against L. pneumophila. The activities of the A. herba-alba, C. sinensis, and R. officinalis essential oils were strain-dependent, whereas those of the J. phoenicea and T. vulgaris oils, showing the highest anti-Legionella activities, with minimum inhibitory concentrations (MICs) lower than 0.03 and lower than or equal to 0.07mg/ml, respectively, were independent of the strains' serogroup. Moreover, the microorganisms treated with T. vulgaris essential oil were shorter, swollen, and less electron-dense compared to the untreated controls. Isoborneol (20.91%), (1S)--pinene (18.30%) -phellandrene (8.08%), -campholenal (7.91%), and -phellandrene (7.58%) were the major components isolated from the J. phoenicea oil, while carvacrol (88.50%) was the main compound of the T. vulgaris oil, followed by p-cymene (7.86%). This study highlighted the potential interest of some essential oils extracted from Tunisian plants as biocides to prevent the Legionella risk.

ABSTRACT The rising number of infections caused by biofilm formation and the difficulties associated with their treatment by conventional antimicrobial therapies have led to an intensive search for novel antibiofilm agents. Dermaseptins are antimicrobial peptides with a number of attractive properties that might offer alternative therapies against resistant microorganisms. In this study, we synthesized a set of dermaseptin-derived peptides and evaluated their activities against Gram-positive and Gram-negative bacterial biofilm formation. All dermaseptin-derived peptides demonstrated concentration-dependent antibiofilm activities at microgram concentrations, and their activities were dependent on the nature of the peptides, with the highest levels of activity being exhibited by highly charged molecules. Fluorescent binding and confocal microscopy demonstrated that dermaseptin K 4 S 4 , a substituted derivative of the native molecule S 4 , significantly decreased the viability of planktonic and surface-attached bacteria and stopped biofilm formation under dynamic flow conditions. Cytotoxicity assays with HeLa cells showed that some of the tested peptides were less cytotoxic than current antibiotics. Overall, these findings indicate that dermaseptin derivatives might constitute new lead structures for the development of potent antibiofilm agents.

Pseudomonas strains isolated from hot spring water were tested for bacteriocin-like substance (BLS) production using a target panel of closely related microorganisms and other Gram-positive and Gram-negative bacteria. Molecular identification was carried out through specific PCR and 16S RNA sequence analysis. Isolates were identified as Brevundimonas diminuta and Pseudomonas putida, the latter exhibited antimicrobial activity. Pseudomonas putida strains produce an inhibitory substance against other Pseudomonas strains and other species including food-borne pathogens. The BLS was sensitive to the proteolytic action of proteinase K, pronase E and trypsin but resistant to -amylase, RNase and lipase C, reflecting its proteinaceous nature. The BLS was stable at 100 degrees C and also after thermal treatment at 121 degrees C for 15min. Additionally, it was stable within a wide range of pH (2-10). The substance from P. putida T01 strain was bactericidal to Escherichia coli. SDS-PAGE analysis of the partial purified supernatant of strain T01 revealed a BLS with an approximate molecular mass of 8kDa. Therefore, the results of this study show that P. putida strain T01 produces a BLS with a higher activity spectrum, which may find application in human medicine and in minimally processed food preservation.

Screening of lactic acid bacteria (LAB) from Tunisian raw bovine milk has resulted in the isolation of an Enterococcus italicus strain designated as GGN10, which has demonstrated a bacteriocin-like activity against Listeria spp. Antibacterial activity in the culture supernatant was lost after treatment with proteolytic enzymes, whereas it was stable over a wide range of pH (2–10). The treatment of extracellular extract of this strain at 100C did not cause loss of antimicrobial activity. The bacteriocin yield reached a maximum of 67,677.1 AU/mL at the beginning of the exponential growth phase and remained stable during 24 h of incubation. Amplification of bacteriocin genes revealed entA and entB genes present in GGN10. In addition, this result was confirmed by the bacteriocin's reversed-phase high-performance liquid chromatography purification and mass spectrometry analysis. This is the first report on enterocins A and B production by this newly isolated strain. Safety elucidation and antibiotics susceptibility of E. italicus GGN10 was conducted using polymerase chain reaction analysis. No commonly associated pathogenicity islands were identified. An enzymatic study revealed GGN10 as a high producer of acid phosphatase and aminopeptidase, which are important features in flavor and texture development during fermentation. Thus, E. italicus GGN10 produces antimicrobial substances and other biologically active substances of importance for food preservation. Practical Applications The potential advantages of discovering new lactic acid bacteria strains offer new possibilities in terms of food application, which may have potent socioeconomic applications. Studies on the local microflora in raw milk contribute to the understanding of both the environment and how selected wild strains can be used with fermented foods. In this study, the strain Enterococcus italicus GGN10 isolated from raw milk was identified as a means of providing a powerful tool for inhibiting pathogenic organisms such as Listeria monocytogenes in dairy foods.

Nine lactic acid bacteria strains showing bacteriocin-like activity were isolated from various fresh fish viscera. The following species were identified based on 16S rDNA sequences: Enterococcus durans (7 isolates), Lactococcus lactis (1) and Enterococcus faecium (1). These strains were active against Listeria innocua and other LAB. Random amplified polymorphic DNA analyses showed four major patterns for the E. durans species. PCR analyses revealed a nisin gene in the genome of the Lc. lactis strain. Genes coding enterocins A, B and P were found in the genome of the E. faecium isolate. Enterocins A and B genes were also present in the genome of E. durans GM19. Hence, this is the first report describing E. durans strains producing enterocins A and B. Electrospray ionization mass spectrometry revealed that the purified bacteriocin produced by the E. durans GMT18 strain had an exact molecular mass of 6,316.89 Da. This bacteriocin was designated as durancin GMT18. Edman sequencing failed to proceed; suggesting that durancin GTM18 may contain terminal lanthionine residues. Overall, the results obtained revealed the presence of a variety of enterococci in Mediterranean fish viscera, as evidenced by their genetic profiles and abilities to produce different bacteriocins. These strains could be useful for food biopreservation or as probiotics.

Chlamydia trachomatis is an obligate intracellular bacterium responsible for a number of health problems, including sexually transmitted infection in humans. Efforts were made for the search of alternative therapies. Accordingly, the present study was undertaken to perform a systemic in vitro investigation on the anti-chlamydial potential of cationic peptides from frog’s skin, namely dermaseptin S 4 (S 4 ) and its derivatives. Several strains of Chlamydia trachomatis serovar E were used to detect the antimicrobial activity of the new compounds. The infections tests and the toxic effects of the new compounds were determined using McCoy cells monolayers. Our data show that S 4 exhibited a potent anti-chlamydial activity and found that these peptides blocked infection of McCoy cells and reduced the numbers of inclusion-forming units (81 %) after 48 h at low concentration (5 μg/ml). Besides, the finding revealed that increasing the number of positive charges of the peptide resulted in a reduced cytotoxicity without affecting the antimicrobial effect. Among all peptides, the derivative K 4 K 20 S 4 was the more potent to inhibit C. trachomatis growth with 96 % reduction in the number of chlamydial inclusions compared with an untreated control infection and, therefore, can be considered as potential agents for therapy of Chlamydia infectious diseases.

BACKGROUND AND OBJECTIVES:Sexually transmitted infections (STIs) and unplanned pregnancies have serious effects on the reproductive health of women. The present study was undertaken with a view to develop an effective means of prevention. The microbicidal and contraceptive potential of cationic peptides from frog's skin, namely, dermaseptin S4 and its derivatives were investigated in vitro.: STUDY DESIGN Different bacterial and fungal strains were resorted to for determining the antimicrobial activity of the new compounds. The spermicidal activities of the latter were assessed using normal human semen samples, and their toxic effects were identified in a HeLa culture.RESULTS:All S4 derivatives elicited concentration-dependent spermicidal and antimicrobial activities at microgram concentrations. The highest levels recorded for both types of activity were displayed by K4K20S4, and the lowest levels were exhibited by D4D20S4 and S4(5-28). Cytotoxicity assays revealed that some of these compounds were significantly safer than nonoxynol-9 (N-9).CONCLUSIONS:The ability of these peptides to instantaneously kill human sperm and STI pathogens at low concentrations indicates that their application as active ingredients in vaginal contraceptive preparations could induce considerably better effects than N-9.

The combined effects of enterocin A with Thymus vulgaris essential oils (EOs) against Listeria monocytogenes and Escherichia coli O157:H7 were investigated in vitro by enumeration of surviving populations of testing pathogens and minimal inhibitory concentration (MIC) determination. Enterocin A was purified to homogeneity by RP-HPLC from the culture fluid of Enterococcus strain and thyme EOs were extracted from local Thymus vulgaris plants. The major constituent of thyme EOs oils determined by GC-MS was thymol (78.4 %). Combination of enterocin A with thyme EOs showed an enhanced bactericidal effect against Listeria monocytogenes. Checkerboard assay and isobologram construction displayed a synergistic interaction between these compounds against Listeria (FIC index <0.5). Moreover, the MIC value of enterocin A has fallen fivefold (from 4.57 to 0.9 μg/ml), while the MIC of thyme EOs decreased threefold (from 3.6 to 1.2 μg/ml). Treatments with enterocin A alone did not affect the growth of the enteric pathogen E. coli O157:H7. However, the addition of thyme EOs and enterocin A yielded a synergistic antimicrobial effect against E. coli (MIC thyme EOs decrease from 2.2 to 0.71 μg/ml). This is the first report on the combined effect of enterocin A and thyme EOs against food pathogen bacteria. This combination could be useful in food bio-preservation.