Correction: Pickering nano-emulsions stabilized by solid lipid nanoparticles as a temperature sensitive drug delivery system.

Correction for 'Pickering nano-emulsions stabilized by solid lipid nanoparticles as a temperature sensitive drug delivery system' by Sidy Mouhamed Dieng et al., Soft Matter, 2019, DOI: 10.1039/c9sm01283d.

Beneficial effects of cherry consumption as a dietary intervention for metabolic, hepatic and vascular complications in type 2 diabetic rats.

BACKGROUND: Oxidative stress (OS) plays an important role in type 2 diabetes (T2D) pathogenesis and its complications. New therapies target natural antioxidants as an alternative and/or supplemental strategy to prevent and control them. Our previous chemical and biological studies highlighted the important antioxidant activities of cherries, among other fruits and vegetables, thus we aimed to determine in vivo effects of 2-month long cherry consumption using a high-fat/high-fructose (HFHF) model of diabetic-rats (Lozano et al. in Nutr Metab 13:15, 2016). METHODS: After 2 months of HFHF, male Wistar rats were divided into: HFHF and HFHF enriched in cherry (nutritional approach) or standard diet ND (lifestyle measures) and ND plus cherry during 2 months. Metabolic, lipidic, oxidative parameters were quantified. Tissues (liver, pancreas and vessels) OS were assessed and hepatic (steatosis, fibrosis, inflammation) and vascular (endothelial dysfunction) complications were characterized. RESULTS: T2D was induced after 2 months of HFHF diet, characterized by systemic hyperglycaemia, hyperinsulinemia, glucose intolerance, dyslipidaemia, hyperleptinemia, and oxidative stress associated with endothelial dysfunction and hepatic complications. Cherry consumption for 2 months, in addition to lifestyle measures, in T2D-rats decreased and normalized the systemic disturbances, including oxidative stress complications. Moreover, in the vessel, cherry consumption decreased oxidative stress and increased endothelial nitric oxide (NO) synthase levels, thus increasing NO bioavailability, ensuring vascular homeostasis. In the liver, cherry consumption decreased oxidative stress by inhibiting NADPH oxidase subunit p22phox expression, nuclear factor erythroid-2 related factor 2 (Nrf2) degradation and the formation of reactive oxygen species. It inhibited the activation of sterol regulatory element-binding proteins (1c and 2) and carbohydrate-responsive element-binding protein, and thus decreased steatosis as observed in T2D rats. This led to the improvement of metabolic profiles, together with endothelial and hepatic function improvements. CONCLUSION: Cherry consumption normalized vascular function and controlled hepatic complications, thus reduced the risk of diabetic metabolic disorders. These results demonstrate that a nutritional intervention with a focus on OS could prevent and/or delay the onset of vascular and hepatic complications related to T2D.

Proteomic analysis of Lactobacillus pentosus for the identification of potential markers involved in acid resistance and their influence on other probiotic features.

Acidity often prevents the undesirable microbial colonization both in fermented foods and under gastric conditions. Thus, the acid resistance of Lactobacillus pentosus strains used as starter cultures and/or probiotics requires further understanding. This was investigated by means of comparative proteomic approach using three strains representing the phenotypes: resistant (AP2-15), intermediate (AP2-18) and sensitive (LP-1) to acidic conditions. Proteomic analysis of constitutive phenotypes revealed that the intrinsic resistance of L. pentosus is associated with the over-production of three principal proteins: 2,3-bisphosphoglycerate-dependent phosphoglycerate mutase 2 (PGAM-d), elongation factor G and 50S ribosomal protein L10, and additionally on ATP synthase subunit beta and chaperone protein DnaK; they are associated with metabolic pathways of proteins and carbohydrates, energy production and stress responses. Suggested protein biomarkers for acid resistance in L. pentosus include elongation factor G and PGAM-d, both being abundantly found in the constitutive proteome of the resistant phenotype under standard and acidic conditions. Furthermore, L. pentosus strains pre-exposed to acids displayed enhanced probiotic function such as auto-aggregation ability via surface proteins. We conclude that pre-exposure of probiotic L. pentosus strains to acid may strategically enhance their performance as starter cultures and probiotics.

TiO2 photocatalysis damages lipids and proteins in Escherichia coli.

This study investigates the mechanisms of UV-A (315 to 400 nm) photocatalysis with titanium dioxide (TiO2) applied to the degradation of Escherichia coli and their effects on two key cellular components: lipids and proteins. The impact of TiO2 photocatalysis on E. coli survival was monitored by counting on agar plate and by assessing lipid peroxidation and performing proteomic analysis. We observed through malondialdehyde quantification that lipid peroxidation occurred during the photocatalytic process, and the addition of superoxide dismutase, which acts as a scavenger of the superoxide anion radical (O2·(-)), inhibited this effect by half, showing us that O2·(-) radicals participate in the photocatalytic antimicrobial effect. Qualitative analysis using two-dimensional electrophoresis allowed selection of proteins for which spot modifications were observed during the applied treatments. Two-dimensional electrophoresis highlighted that among the selected protein spots, 7 and 19 spots had already disappeared in the dark in the presence of 0.1 g/liter and 0.4 g/liter TiO2, respectively, which is accounted for by the cytotoxic effect of TiO2. Exposure to 30 min of UV-A radiation in the presence of 0.1 g/liter and 0.4 g/liter TiO2 increased the numbers of missing spots to 14 and 22, respectively. The proteins affected by photocatalytic oxidation were strongly heterogeneous in terms of location and functional category. We identified several porins, proteins implicated in stress response, in transport, and in bacterial metabolism. This study reveals the simultaneous effects of O2·(-) on lipid peroxidation and on the proteome during photocatalytic treatment and therefore contributes to a better understanding of molecular mechanisms in antibacterial photocatalytic treatment.

Investigation of biomarkers of bile tolerance in Lactobacillus casei using comparative proteomics.

The identification of cell determinants involved in probiotic features is a challenge in current probiotic research. In this work, markers of bile tolerance in Lactobacillus casei were investigated using comparative proteomics. Six L. casei strains were classified on the basis of their ability to grow in the presence of bile salts in vitro. Constitutive differences between whole cell proteomes of the most tolerant strain (L. casei Rosell-215), the most sensitive one (L. casei ATCC 334), and a moderately tolerant strain (L. casei DN-114 001) were investigated. The ascertained subproteome was further studied for the six strains in both standard and bile stressing conditions. Focus was on proteins whose expression levels were correlated with observed levels of bile tolerance in vitro, particularly those previously reported to be involved in the bile tolerance process of lactobacilli. Analysis revealed that 12 proteins involved in membrane modification (NagA, NagB, and RmlC), cell protection and detoxification (ClpL and OpuA), as well as central metabolism (Eno, GndA, Pgm, Pta, Pyk, Rp1l, and ThRS) were likely to be key determinants of bile tolerance in L. casei and may serve as potential biomarkers for phenotyping or screening purposes. The approach used enabled the correlation of expression levels of particular proteins with a specific probiotic trait.

Determination of phosphatidylethanolamine molecular species in various food matrices by liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS2).

A liquid chromatographic-electrospray ionization-tandem mass spectrometric (LC-ESI-MS(2)) method has been developed for determination of the molecular species of phosphatidylethanolamine (PE) in four food matrices (soy, egg yolk, ox liver, and krill oil). The extraction and purification method consisted of a pressurized liquid extraction procedure for total lipid (TL) extraction, purification of phospholipids (PLs) by adsorption on a silica gel column, and separation of PL classes by semi-preparative normal-phase HPLC. Separation and identification of PE molecular species were performed by reversed-phase HPLC coupled with electrospray ionization tandem mass spectrometry (ESI-MS(2)). Methanol containing 5 mmol L(-1) ammonium formate was used as the mobile phase. A variety of PE molecular species were detected in the four food matrices. (C16:0-C18:2)PE, (C18:2-C18:2)PE, and (C16:0-C18:1)PE were the major PE molecular species in soy. Egg yolk PE contained (C16:0-C18:1)PE, (C18:0-C18:1)PE, (C18:0-C18:2)PE, and (C16:0-C18:2)PE as the major molecular species. Ox liver PE was rich in the species (C18:0-C18:1)PE, (C18:0-C20:4)PE, and (C18:0-C18:2)PE. Finally, krill oil which was particularly rich in (C16:0(alkyl)-C22:6(acyl))plasmanylethanolamine (PakE), (C16:0-C22:6)PE, and (C16:0-C20:5)PE, seemed to be an interesting potential source for supplementation of food with eicosapentaenoic acid and docosahexaenoic acid.

Improvement in determination of isothiocyanates using high-temperature reversed-phase HPLC.

The largely adopted reversed-phase HPLC analysis of the molecular species of isothiocyanates (ITCs) was performed and showed losses during the chromatographic run with eight ITCs. These losses, which obviously impact the accuracy of quantitative determinations, were due to precipitation in the chromatographic system. At 22°C, they ranged from 5.4% for sulforaphane (SFN) to 11.0% for benzyl-ITC when ITCs were injected at 80 µg mL(-1) , but they were up to three times higher at 1 mg mL(-1) reaching 31.9% for benzyl-ITC. The water solubility of the ITCs was a key determinant of the extent of the measured loss. When the column was heated at 60°C, losses in injected ITCs were reduced, in comparison with 22, 40, and 50°C, by two to ten times depending on the ITC considered. A reversed-phase HPLC method based on column heating was suggested and its quantitative performance was determined. It was then applied to the separation of methylene chloride extracts of various cruciferous vegetables. Ally-ITC, SFN, and iberin in cabbage; SFN and iberin in cauliflower; and allyl-ITC and phenylethyl-ITC in horseradish could be identified and quantified. The obtained results cast doubt on quantitative determinations of ITCs that are carried out at room temperature using reversed-phase HPLC.

SPE for the simultaneous determination of various isothiocyanates.

Several SPE sorbents were investigated for the extraction of a group of chemically diverse isothiocyanates (ITCs). They included bonded silica, carbon-based, and polymer-based sorbents with various functional groups. Results showed large differences in the ability of these sorbents to simultaneously extract ITCs from standard solutions. Recovery rates were on average the highest with divinylbenzene (DVB) based polymeric sorbents, especially with a DVB/N-vinylpyrrolidone copolymer that had recovery rates ranging between 86.7 and 95.6%. These sorbents achieved the most balanced extraction efficiency between aliphatic and aromatic, polar, and nonpolar ITCs. With graphitized carbon, C(18)-bonded silica, and amide-containing sorbent, recovery levels were higher for the two least polar aromatic ITCs (benzyl ITC and phenylethyl ITC), whereas for the polar aliphatic ITCs levels were the lowest. The least retained one, was methyl ITC that is the most polar with recoveries between 0 and 31.5%. The presence of amide groups, especially in a polyamide sorbent, appeared to be particularly unsuitable for the extraction of aliphatic ITCs. A copolymer made up of DVB and N-vinylpyrrolidone was therefore shown to be the most suited for the extraction of both aliphatic and aromatic ITCs.

Hyphenated LC-ABTS·+ and LC-DAD-HRMS for simultaneous analysis and identification of antioxidant compounds in Astragalus emarginatus Labill. extracts.

The compounds in leaf and stem extracts of Astragalus emarginatus Labill. (AEL), a plant species used in traditional Lebanese medicine, were investigated for antioxidant properties. First, the activity of various extracts was assessed using the Trolox equivalent antioxidant capacity, oxygen radical absorption capacity, and 2,2-diphenyl-1-picryl-hydrazyl-hydrate assays. The extract obtained using 30% ethanol showed the greatest activity. The antioxidant compounds in this extract were screened using a hyphenated high-performance liquid chromatography-2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonate) radical (ABTS·+) system before being separated by ultra-high-performance liquid chromatography and identified using high-resolution mass spectrometry and ultra-violet-visible diode array detection. Approximately 40 compounds were identified. Hydroxycinnamates (caffeic, ferulic, and p-coumaric acid derivatives) and flavonoids (quercetin, luteolin, apigenin, and isorhamnetin derivatives) were the two main categories of the identified compounds. The active compounds were identified as caffeic acid derivatives and quercetin glycosides. In addition, the catechol moiety was shown to be key to antioxidant activity. This study showed that AEL is a source of natural antioxidants, which may explain its medicinal use.

Comparative proteomic analysis of Lactobacillus plantarum for the identification of key proteins in bile tolerance.

BACKGROUND: Lactic acid bacteria are commonly marketed as probiotics based on their putative or proven health-promoting effects. These effects are known to be strain specific but the underlying molecular mechanisms remain poorly understood. Therefore, unravelling the determinants behind probiotic features is of particular interest since it would help select strains that stand the best chance of success in clinical trials. Bile tolerance is one of the most crucial properties as it determines the ability of bacteria to survive in the small intestine, and consequently their capacity to play their functional role as probiotics. In this context, the objective of this study was to investigate the natural protein diversity within the Lactobacillus plantarum species with relation to bile tolerance, using comparative proteomics. RESULTS: Bile tolerance properties of nine L. plantarum strains were studied in vitro. Three of them presenting different bile tolerance levels were selected for comparative proteomic analysis: L. plantarum 299 V (resistant), L. plantarum LC 804 (intermediate) and L. plantarum LC 56 (sensitive). Qualitative and quantitative differences in proteomes were analyzed using two-dimensional electrophoresis (2-DE), tryptic digestion, liquid chromatography-mass spectrometry analysis and database search for protein identification. Among the proteins correlated with differences in the 2-DE patterns of the bacterial strains, 15 have previously been reported to be involved in bile tolerance processes. The effect of a bile exposure on these patterns was investigated, which led to the identification of six proteins that may be key in the bile salt response and adaptation in L. plantarum: two glutathione reductases involved in protection against oxidative injury caused by bile salts, a cyclopropane-fatty-acyl-phospholipid synthase implicated in maintenance of cell envelope integrity, a bile salt hydrolase, an ABC transporter and a F0F1-ATP synthase which participate in the active removal of bile-related stress factors. CONCLUSIONS: These results showed that comparative proteomic analysis can help understand the differential bacterial properties of lactobacilli. In the field of probiotic studies, characteristic proteomic profiles can be identified for individual properties that may serve as bacterial biomarkers for the preliminary selection of strains with the best probiotic potential.

Icacina senegalensis (Icacinaceae), traditionally used for the treatment of malaria, inhibits in vitro Plasmodium falciparum growth without host cell toxicity.

BACKGROUND: With the aim of discovering new natural active extracts against malaria parasites, Icacina senegalensis was selected after an ethnopharmacological survey conducted on plants used in traditional malaria treatment in Senegal. METHODS: Different concentrations of the plant extract and fractions were tested on synchronized Plasmodium falciparum cultures at the ring stage using the parasite lactate dehydrogenase assay. Their haemolytic activity and in vitro cytoxicity were evaluated. The chromatographic profiles of active fractions were also established. RESULTS: The plant extract and fractions revealed anti-plasmodial activity (IC50 < 5 µg/mL) with no toxicity (Selectivity indexes >10). The dichloromethane fraction showed stronger anti-plasmodial activity than the total extract. CONCLUSION: Anti-plasmodial activity and toxicity of I. senegalensis are reported for the first time and showed promising results in malaria field research.

Simultaneous Determination of Various Isothiocyanates by RP-LC Following Precolumn Derivatization with Mercaptoethanol.

Numerous isothiocyanates (ITCs) are poorly soluble in water which causes their precipitation in aqueous mobile phases used in reversed phase liquid chromatography (RP-LC), thus impacting the accuracy of the quantification. By comparing the amounts of ITCs injected and released from the column, losses could be estimated at 5-32% depending on polarities and concentrations. Results could be dramatically improved in terms of separation and quantification using RP-LC with a mercaptoethanol precolumn derivatization aimed at avoiding ITCs precipitation. The cancer chemoprotective allyl-ITC and sulforaphane were found in cabbage extracts at 1.2 and 2.7 µg g(-1) fresh weight, respectively.

Identification of punicalagin as the bioactive compound behind the antimicrobial activity of pomegranate (Punica granatum L.) peels.

Extracts from 'Zhéri' and 'Hicaznar' varieties of pomegranate, Punica granatum L., were obtained by subjecting powdered peels to extraction using water, water/ethanol (1:1; v/v), ethanol, acetone and heptane. Using the agar diffusion assay, extracts with water and/or ethanol were shown to display significant antimicrobial activity with diameters of inhibition zones up to 20 mm. Ethanolic extracts, which were the most active, were fractionated using SPE, HPLC and UHPLC, and the active compounds they contain were identified by mass spectrometry. Punicalagin, under its α and ß anomeric forms, was identified as the antibacterial compound in pomegranate peel extracts. Both forms were active with MIC values between 0.3 and 1.2 µg.ml-1, and they easily converted from one to the other with an α/ß equilibrium ratio of 3/7. Their spectrum of activity targeted 10 out of 13 Gram positive and two out of three Gram negative bacteria as well as a yeast strain.

Online acetylcholinesterase inhibition evaluation by high-performance liquid chromatography-mass spectrometry hyphenated with an immobilized enzyme reactor.

A high-performance liquid chromatography-mass spectrometry technique hyphenated on-line with an immobilized enzyme reactor (IMER) was developed by the use of 3 known acetylcholinesterase (AChE) inhibitors (galanthamine, huperzine A and tacrine). This bioanalytical device allows qualitative comparison of the inhibitory strengths of AChE inhibitors. The AChE inhibitory strengths were evaluated and compared by the corresponding acetylcholine peak areas (mass signal) obtained after a chromatographic separation and the elution through the IMER. Only one injection of the analytes is needed to get this comparative analysis. This bioanalytical device was then applied to the extract of a natural plant, Lycoris radiata, which is known to contain AChE inhibitors such as galanthamine and lycoramine. Aside from the demonstration of the inhibitory activity of the two known AChE inhibitors, the AChE inhibitory activity of another compound (dihydro-latifaliumin C) was revealed. This is the first report describing the AChE inhibitory activity of this compound.

Pickering nano-emulsions stabilized by Eudragit RL100 nanoparticles as oral drug delivery system for poorly soluble drugs.

The purpose of this study was to develop Pickering water-in-oil nano-emulsions only stabilized by Eudragit RL100 nanoparticles (NPs), in order to increase the nano-emulsion stability and create a barrier to improve the drug encapsulation and better control the drug release. The first part of this study was dedicated to investigating the nano-emulsion formulation by ultrasonication and understanding the interfacial behavior and role of NPs in the stabilization of the water/oil interface. The focus was on the surface coverage in the function of the formulation parameters (volume fractions) to disclose the extents and limitations of the process. The main physicochemical analysis of the Pickering nano-emulsions was performed by dynamic light scattering and transmission electron microscopy. On the other hand, the second experimental approach was dedicated to understanding the interfacial behavior of the Eudragit RL100 NPs toward a model water/oil interface, using a dynamic tensiometer with axisymmetric drop shape analysis. The study investigated the NPs' adsorption, as well as their rheological behavior. The aim of this part was to reveal the main phenomena that govern the interactions between NPs and the interface in order to understand the origin of Pickering nano-emulsions' stability. The last part of the study was concerned with the stability and in vitro release of a model encapsulated drug (ketoprofen) in a gastric and simulated intestinal environment. The results showed that Pickering nano-emulsions significantly improved the resistance to gastric pH, inducing a significantly slower drug release compared to classical nano-emulsions' stabilized surfactants. These Pickering nano-emulsions appear as a promising technology to modify the delivery of a therapeutic agent, in the function of the pH, and can be, for instance, applied to the oral drug delivery of poorly soluble drugs.

Genetic identification of the bacteriocins produced by Enterococcus faecium IT62 and evidence that bacteriocin 32 is identical to enterocin IT.

Enterococcus faecium IT62, a strain isolated from ryegrass in Japan, produces three bacteriocins (enterocins L50A, L50B, and IT) that have been previously purified and the primary structures of which have been determined by amino acid sequencing (E. Izquierdo, A. Bednarczyk, C. Schaeffer, Y. Cai, E. Marchioni, A. Van Dorsselaer, and S. Ennahar, Antimicrob. Agents Chemother., 52:1917-1923, 2008). Genetic analysis showed that the bacteriocins of E. faecium IT62 are plasmid encoded, but with the structural genes specifying enterocin L50A and enterocin L50B being carried by a plasmid (pTAB1) that is separate from the one (pTIT1) carrying the structural gene of enterocin IT. Sequencing analysis of a 1,475-bp region from pTAB1 identified two consecutive open reading frames corresponding, with the exception of 2 bp, to the genes entL50A and entL50B, encoding EntL50A and EntL50B, respectively. Both bacteriocins are synthesized without N-terminal leader sequences. Genetic analysis of a sequenced 1,380-bp pTIT1 fragment showed that the genes entIT and entIM, encoding enterocin IT and its immunity protein, respectively, were both found in E. faecium VRE200 for bacteriocin 32. Enterocin IT, a 6,390-Da peptide made up of 54 amino acids, has been previously shown to be identical to the C-terminal part of bacteriocin 32, a 7,998-Da bacteriocin produced by E. faecium VRE200 whose structure was deduced from its structural gene (T. Inoue, H. Tomita, and Y. Ike, Antimicrob. Agents Chemother., 50:1202-1212, 2006). By combining the biochemical and genetic data on enterocin IT, it was concluded that bacteriocin 32 is in fact identical to enterocin IT, both being encoded by the same plasmid-borne gene, and that the N-terminal leader peptide for this bacteriocin is 35 amino acids long and not 19 amino acids long as previously reported.

Enterocin 96, a novel class II bacteriocin produced by Enterococcus faecalis WHE 96, isolated from Munster cheese.

Enterococcus faecalis WHE 96, a strain isolated from soft cheese based on its anti-Listeria activity, produced a 5,494-Da bacteriocin that was purified to homogeneity by ultrafiltration and cation-exchange and reversed-phase chromatographies. The amino acid sequence of this bacteriocin, named enterocin 96, was determined by Edman degradation, and its structural gene was sequenced, revealing a double-glycine leader peptide. After a comparison with other bacteriocins, it was shown that enterocin 96 was a new class II bacteriocin that showed very little similarity with known structures. Enterocin 96 was indeed a new bacteriocin belonging to class II bacteriocins. The activity spectrum of enterocin 96 covered a wide range of bacteria, with strong activity against most gram-positive strains but very little or no activity against gram-negative strains.

2-DE and MS analysis of key proteins in the adhesion of Lactobacillus plantarum, a first step toward early selection of probiotics based on bacterial biomarkers.

The identification of cell components involved in probiotic activities is a challenge in current probiotic research. In this work, a new approach based on proteomics as an analytical tool for the identification of characteristic protein profiles related to adhesion to mucin as a model probiotic property was used. Three Lactobacillus plantarum strains with different adhesion rates were used for proteomic analysis: L. plantarum WHE 92 (15.9%), L. plantarum 299 v (9.1%) and L. plantarum CECT 4185 (1.4%). Cell wall extracts were subjected to proteomic analysis of differential protein expression using 2-DE, tryptic digestion, chip-LC-QTOF mass analysis and protein identification using database search. Several proteins, previously reported to be involved in bacterial adhesion: elongation factor EF-Tu, GroEL chaperonin, molecular chaperone DnaK and glyceraldehyde-3-phosphate dehydrogenase were found to be overexpressed in the cell wall proteome of the highly adhesive strain L. plantarum WHE 92. The overexpression of two spots containing GroES co-chaperonin in the most adhesive strain also suggested the involvement of this protein in the adhesion process. The association of proteomic profiles and proteins with particular probiotic properties opens the way for the use of such profiles and proteins as bacterial biomarkers for the properties of bacteria but probably also for their potential health effects.

Microencapsulation of Lactobacillus plantarum spp in an alginate matrix coated with whey proteins.

Whey proteins were used as a coating material to improve encapsulation of Lactobacillus plantarum strains in calcium alginate beads. L. plantarum 299v, L. plantarum 800 and L. plantarum CIP A159 were used in this study. Inactivation experiments were carried out in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF). Cross-sections of freeze-dried beads revealed the random distribution of bacteria throughout the alginate network. From an initial count of 10.04+/-0.01 log(10) CFU g(-1) for L. plantarum 299v, 10.12+/-0.04 for L. plantarum CIP A159 and 10.03+/-0.01 for L. plantarum 800, bacteria in coated beads and incubated in SGF (37 degrees C, 60 min) showed a better survival for L. plantarum 299v, L. plantarum CIP A159 and L. plantarum 800 (respectively 7.76+/-0.12, 6.67+/-0.08 and 5.81+/-0.25 log(10) CFU g(-1)) when compared to uncoated beads (2.19+/-0.09, 1.89+/-0.09 and 1.65+/-0.10 log(10) CFU g(-1)) (p<0.05). Only bacteria in the coated beads survived in the SIF medium (37 degrees C, 180 min) after SGF treatment. This preliminary work showed that whey proteins are a convenient, cheap and efficient material for coating alginate beads loaded with bacteria.

Smearing of soft cheese with Enterococcus faecium WHE 81, a multi-bacteriocin producer, against Listeria monocytogenes.

Enterococcus faecium WHE 81, a multi-bacteriocin producer, was tested for its antimicrobial activity on Listeria monocytogenes in Munster cheese, a red smear soft cheese. The naturally delayed and superficial contamination of this type of cheese allowed the use of E. faecium WHE 81 at the beginning of the ripening as a surface culture. A brine solution inoculated at 10(5)CFU of E. faecium WHE 81 per mL was sprayed on the cheese surface during the first smearing operation. On day 7, smearing of cheese samples with a brine solution at 10(2)CFU of L. monocytogenes per mL yielded initial cell counts of approximately 50 CFU g(-1) of the pathogen on the cheese surface. Although, in some instances, L. monocytogenes could survive (<50 CFU g(-1)) in the presence of E. faecium WHE 81, it was unable to initiate growth. In control samples however, L. monocytogenes counts often exceeded 10(4) CFU g(-1). In other respects, E. faecium WHE 81, which naturally existed in Munster cheese, did not adversely impact on the ripening process.