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Biofilm formation on abiotic surfaces has become a major public health concern because of the serious problems they can cause in various fields. Biofilm cells are extremely resistant to stressful conditions, because of their complex structure impedes antimicrobial penetration to deep-seated cells. The increased resistance of biofilm to currently applied control strategies underscores the urgent need for new alternative and/or supplemental eradication approaches. The combination of two or more methods, known as Hurdle technology, offers an excellent option for the highly effective control of biofilms. In this perspective, the use of functional enzymes combined with biosourced antimicrobial such as essential oil (EO) is a promising alternative anti-biofilm approach. However, these natural antibiofilm agents can be damaged by severe environmental conditions and lose their activity. The microencapsulation of enzymes and EOs is a promising new technology for enhancing their stability and improving their biological activity. This review article highlights the problems related to biofilm in various fields, and the use of encapsulated enzymes with essential oils as antibiofilm agents. KEY POINTS: • Problems associated with biofilms in the food and medical sectors and their subsequent risks on health and food quality. • Hurdle technology using enzymes and essential oils is a promising strategy for an efficient biofilms control. • The microencapsulation of enzymes and essential oils ensures their stability and improves their biological activities.

Environmental conditions in food and medical fields enable the bacteria to attach and grow on surfaces leading to resistant bacterial biofilm formation. Indeed, the first step in biofilm formation is the bacterial irreversible adhesion. Controlling and inhibiting this adhesion is a passive approach to fight against biofilm development. This strategy is an interesting path in the inhibition of biofilm formation since it targets the first step of biofilm development. Those pathogenic structures are responsible for several foodborne diseases and nosocomial infections. Therefore, to face this public health threat, researchers employed cold plasma technologies in coating development. In this review, the different factors influencing the bacterial adhesion to a substrate are outlined. The goal is to present the passive coating strategies aiming to prevent biofilm formation via cold plasma treatments, highlighting antiadhesive elaborated surfaces. General aspects of surface treatment, including physico-chemical modification and application of cold plasma technologies, were also presented. Key points • Factors surrounding pathogenic bacteria influence biofilm development. • Controlling bacterial adhesion prevents biofilm formation. • Materials can be coated via cold plasma to inhibit bacterial adhesion.

The biofilm lifestyle plays a major role in the resistance and virulence of

In food industries, microbial contaminations are difficult to control due to the recurrent formation of biofilms that hinders antimicrobials penetration and efficiency. An understanding of Salmonella Enteritidis biofilms behavior under flow conditions is a key to develop efficient preventive and control strategies. S. Enteritidis biofilms displayed 5.96, 6.28 and 6.80 log CFU cm

Made available in DSpace on 2021-06-25T10:56:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-04-01 In this study, we evaluated the effect of complexation and microencapsulation with pea protein on the antioxidant activity of protein hydrolysates from bycatch in Brazil. The zeta potential values of complexes changed from negative to positive with the increase of pea protein as a result of positively charged complexes formation. The increase in the ratio of pea protein/hydrolysates also resulted in increased turbidity in all samples. Particle size measurements indicated that the complexes tended to form larger aggregates (ranged from 61.5 ± 1.7 μm to 183 ± 2.8 μm). The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of the pea protein/fish protein hydrolysate complexes was higher than that of the protein hydrolysates alone. Moreover, increasing levels of pea protein did not affect the antioxidant activity of fish protein hydrolysates. The complexes of the Paralonchurus brasiliensis were chosen for the microencapsulation process by spray-drying. The results revealed that spray-drying did not have a significant effect (P > 0.05) on the protein hydrolysate antioxidant activity when they were complexed with pea protein. Thus, this work suggests that the complexation with pea protein and subsequent microencapsulation by spray-drying is an efficient way to protect the biological activity of protein hydrolysates obtained from bycatch. This study provides evidence for the potential use of bycatch from shrimp fisheries as functional ingredients or nutraceuticals. São Paulo State University (UNESP), Aquaculture Center, Campus Jaboticabal UMR 8207 - UMET - Unité Matériaux Et Transformations Univ Lille CNRS INRAE Centrale Lille LAGEPP UMR 5007 Univ Lyon Université Claude Bernard Lyon 1 CNRS, 43 Bd 11 Novembre 1918 São Paulo State University (UNESP), Aquaculture Center, Campus Jaboticabal

International audience; Nisin is a small peptide produced byLactococcus lactisssplactisthat is currently industrially produced. This preservative is often used for growth prevention of pathogenic bacteria contaminating the food products. However, the use of nisin as a food preservative is limited by its low production during fermentation. This low production is mainly attributed to the multitude of parameters influencing the fermentation progress such as bacterial cells activity, growth medium composition (namely carbon and nitrogen sources), pH, ionic strength, temperature, and aeration. This review article focuses on the main parameters that affect nisin production byLactococcus lactisbacteria. Moreover, nisin applications as a food preservative and the main strategies generally used are also discussed.

Essential oils active components emerged as captivating antimicrobials to control biofilms developed on food contact surfaces. Free and nanoencapsulated carvacrol (CAR) and thymol (THY) were assessed as antimicrobials against Salmonella Enteritidis biofilms adhered to stainless steel. The developed spherical nanocapsules using the spray-drying technique showed an average size ranged between 159.25 and 234.76 nm and zeta potential values ranged between 23.60 and 24.66 mV. The minimal inhibitory concentrations (MIC) of free THY and CAR were both 1.25 mg L-1. Nanoencapsulation reduced MIC values to 0.62 mg L-1 (THY) and 0.31 mg L-1 (CAR). Furthermore, the exposure to free and nanoencapsulated CAR and THY induced a destabilization of bacterial membranes with obvisous morphological deformations and a pronounced leakage of potassium ions and green fluorescent proteins. Eradication of S. Enteritidis biofilms developed on stainless steel was achieved following a 15 min treatment with nanoencapsulated CAR and THY at 2 MIC. Free antimicrobial exposures induced up to 4.27 log CFU cm(-2) reductions. Additionally, the ecotoxicity tests against Daphnia magna crustaceans reported a non-toxicity of both free and nanoencapsulated CAR and THY after 48 h exposure. Thereby, both CAR and THY antimicrobials proved to be promising natural surface disinfectants that require further exploration and incorporation in food industries.

Mycosubtilin belongs to the family of lipopeptides. Different isoforms with various antifungal activities can be obtained according to the length and the isomery of the fatty acid. In this work, the activities of the mycosubtilin isoforms were first studied against the pathogen

International audience; Pathogenic bacterial biofilms invading surfaces in food and medical fields are a challenge to overcome. Despite all the strategies applied to fight their formation, the microbiological risk associated to bacterial biofilms remains an important threat for at risk population and for food and healthcare sectors. The prevention of biofilm formation might be an effective approach to confront this problem. In this study, stainless steel surfaces were functionalized by nisin, a natural antimicrobial peptide. The mechanism of action of immobilized nisin against sensitive bacteria is not fully understood. Therefore, nisin was grafted onto the surface by either its carboxylic group or its amino group. The generated coating's chemical, topographical and antibacterial properties were studied to understand the nisin mode of action, when immobilized, and identify the section of the bacteriocin responsible for the antimicrobial activity. The antimicrobial activity of the elaborated coatings was tested against Listeria monocytogenes. Indeed, the surfaces coated with nisin linked by its amino group showed an efficient antibacterial activity while the surface with nisin linked by its carboxylic group showed less antimicrobial effect. The antimicrobial results showed almost 2 log reduction of colony forming units for efficient antibacterial coatings while the other showed no bacterial reduction. The surface properties analysis permitted to understand the chemical and topographical characteristics of treated surfaces including nisin conformation and quantification. A tight relation was concluded between the surface topography, the nisin conformation, and the antibacterial activity of the bacteriocin-coated surfaces.

Bioactive aminooxime ligands based on optically pure (R)-limonene have been synthesized in two steps. Their ruthenium (II) cationic water-soluble complex was prepared by a reaction between dichloro (para-cymene) ruthenium (II) dimers and aminooxime ligands in a 1:2 molar ratio. Antibacterial and antibiofilm activities of the synthetized complex were assessed against Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, and Enterococcus faecalis. The results revealed that the ruthenium (II) complex has higher antibacterial and antibiofilm activities in comparison with free ligands or the enantiopure (R)-limonene. Moreover, microencapsulation of this complex reduced its cytotoxicity and improved their minimum inhibitory concentration and antibiofilm activity toward the considered bacteria. The ruthenium (II) complex targets the bacterial cell membrane, which leads to rapid leakage of intracellular potassium. Our study suggests that the developed ruthenium (II) complexes could be useful as an alternative to conventional disinfectants.

International audience; Emerging technology regarding antimicrobial coatings contributes to fighting the challenge of pathogenic bacterial biofilms in medical and agri-food environments. Stainless steel is a material widely used in those fields since it has satisfying mechanical properties, but it, unfortunately, lacks the required bio-functionality, rendering it vulnerable to bacterial adhesion and biofilm formation. Therefore, this review aims to present the coatings developed by employing biocides grafted on stainless steel. It also highlights antimicrobial peptides (AMPs)used to coat stainless steel, particularly nisin, which is commonly accepted as a safe alternative to prevent pathogenic biofilm development.

International audience; The aim of this work is to characterize the potential probiotic properties of 14 antifungal Lactobacillus strains isolated from traditional fermenting Moroccan green olives. The molecular identification of strains indicated that they are composed of five Lactobacillus brevis, two Lactobacillus pentosus, and seven Lactobacillus plantarum. In combination with bile (0.3%), all the strains showed survival rates (SRs) of 83.19–56.51% at pH 3, while 10 strains showed SRs of 31.67–64.44% at pH 2.5. All the strains demonstrated high tolerance to phenol (0.6%) and produced exopolysaccharides. The autoaggregation, hydrophobicity, antioxidant activities, and surface tension value ranges of the strains were 10.29–41.34%, 15.07–34.67%, 43.11–52.99%, and 36.23–40.27 mN/m, respectively. Bacterial cultures exhibited high antifungal activity against Penicillium sp. The cell-free supernatant (CFS) of the cultures showed important inhibition zones against Candida pelliculosa (18.2–24.85 mm), as well as an antibacterial effect against some gram-positive and gram-negative bacteria (10.1–14.1 mm). The neutralized cell-free supernatant of the cultures displayed considerable inhibitory activity against C. pelliculosa (11.2–16.4 mm). None of the strains showed acquired or horizontally transferable antibiotic resistance or mucin degradation or DNase, hemolytic, or gelatinase activities. Lactobacillus brevis S82, Lactobacillus pentosus S75, and Lactobacillus plantarum S62 showed aminopeptidase, β-galactosidase, and β-glucosidase activities, while the other enzymes of API-ZYM were not detected. The results obtained revealed that the selected antifungal Lactobacillus strains are considered suitable candidates for use both as probiotic cultures for human consumption and for starters and as biopreservative cultures in agriculture, food, and pharmaceutical industries.

The persistence of

International audience; The persistence of Salmonella enterica on abiotic surfaces in hospitals and the agri-food industries leads to several infections worldwide. In this context, this work aimed to study the adhesion of S. Enteritidis on plasma-modified stainless steel to prevent biofilm-associated-infections. Surface modification was achieved by the elaboration of organosilicon coatings from the monomer 1,1,3,3-tetramethyldisiloxane, mixed with oxygen, using a flowing nitrogen microwave post-discharge plasma polymerization technique. The effect of cold plasma parameters on the properties of the coatings, the coated surface topography and S. Enteritidis cell adhesion was studied. The results showed that the surface topography influenced the bacterial adhesion rate. Indeed, rough surfaces did not repel S. Enteritidis since the number of attached cells on these coatings was between 30 ± 4 to 65 ± 4 bacteria per microscopic field. Otherwise, smoother surfaces demonstrated an anti-adhesive character since the number of attached cells was almost nil on these coatings.

Dodecyltrimethylammonium chloride (DTAC) was trapped into maltodextrins/pectin spray dried microcapsules to improve its activity against

International audience; The biofilm formation on food-contact-surfaces is a serious threat for public health and often results in huge human and economic losses. Thus, it is of importance to develop new strategies that allow the monitoring of the biofilm formation on food-contact-surfaces. Such strategies permit effective and timely countermeasures and, therefore, to avoid the microbiological risk and associated environmental impact due to cleaning processes. Therefore, this work investigated a non-invasive method for monitoring and detection of the biofilm formation using Coda Wave Interferometry (CWI) method. The principle of this method and the calculation of decorrelation coefficient based on the ultrasonic measurements were explained. The results underlined that our developed method is able to detect the early stage of the biofilm formation of Staphylococcus aureus on the stainless steel. Namely, it is shown that the bacterial cell kinetic is well captured by the evolution of the decorrelation coefficient as a function of incubation times. Overall, this work showed that this cost effective CWI method is a promising tool for the detection of early stage biofilm formation on food-contact-surfaces.

International audience; Dodecyltrimethylammonium chloride (DTAC) was trapped into maltodextrins/pectin spray dried microcapsules to improve its activity against Salmonella enteritidis and Staphylococcus aureus biofilms. Two different microcapsules were prepared: uncomplexed DTAC-microcapsules (UDM), containing DTAC and maltodextrins; and complexed DTAC-microcapsules (CDM) containing DTAC complexed with pectin and maltodextrins. The minimum inhibitory concentrations (MIC) of both free and microencapsulated DTAC were investigated against S. Enteritidis and S. aureus. The MICs of DTAC were significantly lower when encapsulated. CDM treatment resulted in a 2 and 3.2 log reduction in S. aureus and S. Enteritidis biofilm culturable biomass, respectively. Microencapsulation reduced the cytotoxicity of DTAC by up to 32-fold. Free DTAC and CDM targeted the cell membrane resulting in the leakage of the intracellular molecules and subsequent cell death. The development of DTAC microcapsules reduced the amount of DTAC required to maintain the high standards of cleanliness and hygiene required in the food processing industries.

International audience; Aims: In this study, benzalkonium chloride (BAC) microcapsules were developed for surface disinfection purpose and were evaluated against Listeria monocytogenes and Escherichia coli biofilms.Methods and Results: Microcapsules were prepared with two different strategies: uncomplexed BAC‐microcapsules (UBM), containing BAC and maltodextrins and complexed BAC‐microcapsules (CBM) containing BAC complexed by pectin and maltodextrins. The minimum inhibitory concentrations (MICs) of free and microencapsulated BAC was investigated against two food pathogens: L. monocytogenes and E. coli. The antibiofilm activities of UBM and CBM against L. monocytogenes and E. coli biofilms formed on stainless steel at 37°C were evaluated and compared to BAC used under its free form. MICs of encapsulated BAC were up to 4‐fold lower than those of free BAC. The UBM and CBM showed higher antibiofilm effect when compared to the free BAC.Conclusions: Overall, results demonstrated that microencapsulation enhanced the antibacterial activity of BAC against L. monocytogenes and E. coli biofilms.Significance and Impact of the Study: The application of such BAC microcapsule‐based delivery systems can improve surface disinfection procedures and reduce the required BAC concentrations and the related cytotoxicity of this antimicrobial compound.

International audience; Front-face fluorescence spectroscopy technique coupled with chemometric tools was used for predicting the freshness state of a Lebanese dairy product called Qishta, stored up to 20 days. Acid, peroxide and thiobarbituric acid reactive substances (TBARS) values reached no more than 0.93 mg NaOH g−1 fat, 6.22 meq O2 Kg−1 fat, and 0.0313 mg malonaldehyde (MA) kg−1 sample, respectively, throughout the investigated storage time. In parallel, fluorescence emission spectra of tryptophan and riboflavin, and fluorescence excitation spectra of vitamin A were recorded and showed the highest fluorescence intensity for the Qishta samples aged of 20 days and the lowest intensity for the fresh ones. The primary and secondary indicators of lipid oxidation showed that Qishta can be stored for 20 days without any alteration despite the increase in the TBARS after 16 days of storage. Principal component analysis (PCA) applied on riboflavin emission spectra allowed better discrimination between Qishta samples with a clear distinction of those aged 20 days while some overlapping was noticed between samples aged below 16 days. A high correlation (R2 = 0.923) was observed between the peroxide value and the intensity of the riboflavin fluorescence recorded at 460 nm.

International audience; The objective of this work is to study the oleuropein (OLP) biodegradation by a strain of Lactobacillus plantarum FSO175 under conditions (pH 4.5, NaCl 5% and glucose 1%), during 7 days of incubation at 30 °C, in modified MRS broth containing OLP as carbon source. The results obtained, by HPLC analyses, showed that the biodegradation of OLP by L. plantarum FSO175, is accompanied with increase of hydroxytyrosol (HT) content and acidity values. The yields of OLP degradation and HT accumulation are depending on carbon sources, stress conditions and time of incubation. So that, the drastic reduction in OLP biodegradation, obtained at pH 6.7 (trial B), decreased significantly (p

International audience; Protein–protein cross-linking and protein-fat interactions in the traditional Lebanese dairy product, Qishta, were investigated. Liquid chromatography coupled to mass spectrometry was used for the detection of lysinoalanine (LAL) and lanthionine (LAN) during the production of Qishta, which is made by heating whole milk in an open shallow vessel for more than 2 h and harvesting the surface aggregates formed. LAL and LAN cross-links were seen in Qishta at concentrations higher than those in milk, indicating their importance in the gel formation and therefore their impact on Qishta texture. Disulphide bridges were also involved in Qishta formation. The amino acid residues (cysteine, serine or threonine) involved in the β-elimination and in dehydroalanine formation were identified. Confocal scanning laser microscopy showed the role of fat globules in the gel structure.

Salmonella is a pathogen transmitted by foods and it is one of the most important target bacteria in food irradiation studies. Few works were carried out on the effectiveness of gamma radiation against biofilms formed by this bacterium. Salmonella can form a biofilm on different material surfaces. The physicochemical properties of surfaces and environmental factors influence the adhesion of this pathogen. The present study investigated the effect of gamma radiation (1 and 2 kGy) and temperature (28°C and 37°C) on the development of Salmonella Hadar biofilm on polyvinyl chloride (PVC), glass, cellophane paper (CELLO), and polystyrene (POLY). The obtained results indicated that biofilm production is surface and temperature dependent. In addition, biofilm formation decreased significantly after gamma irradiation at either 1 or 2 kGy doses. However, the agfD and adrA genes expression did not demonstrate significant decrease. This work highlighted that gamma radiation treatment could reduce the biofilm formation of Salmonella enterica serovar Hadar on different food contact surfaces.

International audience; Objective: This work aims to evaluate the impact of the use of ultrasound during essential oils extraction from garlic bulbs. Material and methods: The essential oils were extracted by Conventional Hydrodistillation method (HD), Ultrasound-Assisted hydro-distillation (US-HD) and Sono-hydrodistillation (SHD) and compared using yield profile, chemical composition and antioxidant activity. Results: Higher performances were obtained when the direct application of ultrasound were used. Indeed, SHD allowed a higher yield after only 30 min of extraction time against 70 min and 90 min for the US-HD and the HD respectively. Among the total identified compounds by GC/MS, Sulphur compounds were found to be the most abundant with qualitative similarities for the three processes. Essential oils showed a potential DPPH radical scavenging activity with IC50 values of 0.96, 1.17 and 1.23 respectively for the three HD, US-HD and SHD processes. Conclusion: The use of ultrasound for the extraction of essential oil from garlic reduced extraction time without causing significant changes in volatile composition and antioxidant activity.

Citral-in-water emulsions were prepared with two different essential oil concentrations of 2.5 and 5.0% (w/w), then spray-dried in the presence of the same amount of maltodextrins (20%). The microcapsules were prepared with two different emulsifier compositions: monolayer microcapsules (ML) stabilized by sodium caseinate alone and layer-by-layer microcapsules (LBL) stabilized by sodium caseinate and pectin. The encapsulation efficiency was higher for LBL microcapsules (e.g. 99.6 ± 0.4% for 2.5% citral) than that for ML ones (e.g. 78.6 ± 0.6% for 2.5% citral) which confirm that the additional pectin layer was able to protect citral during the spray-drying process whatever citral concentration. Furthermore, our results showed that the antibacterial activity of the obtained microcapsules significantly depends on both citral concentration and interfacial membrane composition. The presence of two layers surrounding the citral droplets may result in a progressive and controlled release of the encapsulated citral.

The aim of the present work was to study and compare the effect of growth temperature (20, 30, and 37 degrees C) and surface type (stainless steel and polycarbonate) on the production of virulence factors, such as proteases and siderophores, and the risk of surface contamination associated with Pseudomonas aeruginosa biofilm and planktonic cells. The increase of growth temperature from 20 to 37 degrees C increased (approximately twofold) the electronegative charge and the hydrophobicity of the P. aeruginosa biofilm cell surface. P. aeruginosa biofilm cell adhesion to stainless steel and polycarbonate was 5- and 1.5-fold higher than their planktonic counterparts at 20 and 30 degrees C, respectively. The increase of growth temperature from 20 to 37 degrees C increased the production of proteases (twofold) and siderophores (twofold) and the cytotoxicity (up to 30-fold) against the HeLa cell line in the supernatants of P. aeruginosa planktonic and biofilm cultures. This study also highlighted that biofilm and planktonic P. aeruginosa cells exhibited distinct physiological properties with respect to the production of virulence factors and the cytotoxicity against the Hela cell line. Therefore, effective disinfection procedures should be adapted to inactivate bacteria detached from biofilms.

The aim of the present work was to study and compare the effect of growth temperature (20, 30, and 37°C) and surface type (stainless steel and polycarbonate) on the production of virulence factors, such as proteases and siderophores, and the risk of surface contamination associated with

International audience; Bacteriocins from lactic acid bacteria (LAB) are successfully applied as natural alternatives to food preservation and to antibiotics; however, information on these antimicrobial peptides (AMPs) is scattered through the literature and databases. Therefore, we developed the LABiocin database, a specialized database on LAB bacteriocins. The database was stored and compiled using MySQL with NetBeans IDE as the platform. Important data are compiled, including bacteriocin name, class, amino acids and nucleic acid sequences, if available. Target microorganisms, origin, status of the producing strains and their culture conditions and extraction and purification methods are also included in this new database. A phylogenetic tree for the mature peptide bacteriocin sequences has also been created.LABiocin is an interactive database with a user-friendly interface that integrates several tools and services and comprises up to 517 LAB bacteriocins. Besides data searching tools, a BLAST tool was integrated into the database to enable the user to perform a homology search against mature peptide sequences. Users can be linked to other databases that contain additional information, particularly about predicted bacteriocin structure and mechanisms of action.The LABiocin database enables comprehensive functional analysis of this special group of AMPs. This would be useful in food preservation and food safety applications and would also have substantial implications for development of new drugs for medical use. LABiocin database is available at labiocin.net.

International audience; The present study investigated and compared the effect of growth temperature on the susceptibility of biofilm-detached andplanktonic Staphylococcus aureus cells, to benzalkonium chloride (BAC). This study also highlights the impact of BAC on the bacterial physiology and the role of membrane fluidity regulation as a bacterial resistance mechanism. The minimum inhibitory concentration of BAC was characterized with micro-dilution growth inhibition assay. The BAC treatment was performed on S. aureus cultured at 20 degrees C and 37 degrees C, for 24h. The morphology of S. aureus cells was examined using scanning electron microscopy. The loss of bacterial membrane integrity after BAC treatment was studied by monitoring the intracellular potassium ion leakage using the atomic absorption spectroscopy. The bacterial membrane total fatty acid composition, controlling the membrane fluidity, was analyzed by GC/MS. The results showed that the resistance of S. aureus cells to BAC increased with the increase of growth temperature. The planktonic cells were more susceptible to BAC than biofilm-detached ones. The rise of growth temperature resulted in an increase of S. aureus membrane rigidity. Furthermore, a higher membrane fluidity was observed in planktonic cells when compared to that in the biofilm-detached ones. The resistance of S. aureus seems to depend on the growth temperature. Compared to planktonic cells, biofilm-detached cells showed a greater resistance to BAC. The BAC targets and disturbs the bacterial membrane. Membrane fluidity modulation is likely a one of resistance mechanisms for S. aureus to BAC at the cellular scale. Therefore, disinfection procedures, in food sector, should be adapted for bacteria detached from biofilm.

International audience; This study investigated the effect of the growth temperature (20 and 37 degrees C) of Escherichia coli strains isolated from pigs on their adhesion to stainless steel and polycarbonate. This study also evaluated the ability of the DLVO and XDLVO mathematical models to predict this adhesion. The rise of growth temperature from 20 to 37 degrees C significantly influenced the adhesion of studied E. coli strains. The data also underlined that the mathematical prediction did not fully match with the experimental bacterial adhesion to surfaces. Furthermore, results showed that the colistin-resistant and sensitive E. coli strains adhesion depends on the type of abiotic surface. Based on these results, the mathematical models are limited in the prediction of the bacterial adhesion to abiotic surfaces. The surface roughness is a major parameter of the bacterial adhesion and should be included in the future mathematical models predicting the bacterial adhesion.

This study aims to describe interactions that may occur between nisin and bacterial exopolysaccharides (EPS) when they are present together in a model solution. For this purpose, two EPS, namely EPS-GM and EPS-BMS, produced by potential probiotic Bacillus tequilensis-GM and Leuconostoc citreum-BMS, respectively, were used. Results showed that maximal complexation occurred at pH 5.0 between anionic EPS (1.5 g/L) and cationic nisin (1 g/L) mainly through electrostatic interactions. Results provided by scanning electron microscopy, epifluorescence microscopy and turbidity measurements showed that EPS-GM was able to form bigger and higher amounts of complexes with nisin. The nisin antimicrobial activity was interestingly not affected and even improved after its complexation with EPS suggesting that these latter may act as protective agents of the nisin antimicrobial activity when applied in foods. The results of this study should help food technologists to optimize the physicochemical conditions for optimal formulation of food products containing EPS.

International audience; This work aims at studying the impact of silane-based coatings, generated by atmospheric pressure plasma spraying (APPS) of a liquid precursor (hexamethydisiloxane – HMDSO), on dairy antifouling and antibacterial properties of food-grade 316L stainless steel. The influence of the manufacturing parameters (precursor flow rate, nozzle-to-substrate distance and scanning speed) on the coatings properties was investigated using a wide range of characterization techniques (drop shape analysis, X-Ray Mappings, Scanning Electron Microscopy, Fourier-Transformed Infrared Spectroscopy, Atomic Force Microscopy). Coating’s roughness in particular was shown to strongly increase when precursor flow rate increases. A pilot pasteurizer, fed with a model foulant solution (whey protein and calcium), allowed performing two consecutive industrial-like isothermal dairy fouling tests, revealing the promising anti-fouling properties of the HMDSO-coated steel. A fouling reduction of up to 90% compared to bare stainless steel was achieved after first cycle for all samples. The second fouling run allowed to select the best-performing sample, which kept the same antifouling properties as in the first test. Its mechanism of action was investigated, which revealed that a nanostructured, Si-O-Si rich surface was efficient to prevent isothermal dairy fouling. The adhesion of the pathogenic bacterium Staphylococcus aureus also proved to be impacted by this plasma coating, with a significant decrease of adhered cells (−30% compared to native stainless steel).

International audience; Bacteriocins are antimicrobial peptides produced by bacteria Gram-negative and Gram-positive, including lactic acid bacteria (LAB), organisms that are traditionally used in food preservation practices. Bacteriocins have been shown to have an aptitude as biofilm controlling agents in Listeria monocytogenes biofilms, a major risk for consumers and the food industry. Biofilms protect pathogens from sanitization procedures, allowing them to survive and persist in processing facilities, resulting in the cross-contamination of the end products. Studies have been undertaken on bacteriocinogenic LAB, their bacteriocins, and bioengineered bacteriocin derivatives for controlling L. monocytogenes biofilms on different surfaces through inhibition, competition, exclusion, and displacement. These alternative strategies can be considered promising in preventing the development of resistance to conventional sanitizers and disinfectants. Bacteriocins are "friendly" antimicrobial agents, and with high prevalence in nature, they do not have any known associated public health risk. Most trials have been carried out in vitro, on food contact materials such as polystyrene and stainless steel, while there have been few studies performed in situ to consolidate the results observed in vitro. There are strategies that can be employed for prevention and eradication of L. monocytogenes biofilms (such as the establishment of standard cleaning procedures using the available agents at proper concentrations). However, commercial cocktails using alternatives compounds recognized as safe and environmental friendly can be an alternative approach to be applied by the industries in the future.

Background: Mycobacterium spp. are responsible for several diseases, particularly in immunocompromised populations. The spreading of the resistance to antimycobacterial drugs is a significant problem to the public health and requires to find out a new and innovative alternative for the treatment of drug resistant mycobacterial strains. In this study, the antimycobacterial activity of Micromeria barbata, Eucalyptus globulus and Juniperus excelsa essential oils extracted from Lebanese plants was investigated against selected Mycobacterium spp. strains. Methods: Several dilutions of the three aforementioned essential oils were studied for antimycobacterial activity against four Mycobacterium spp. strains: Mycobacterium tuberculosis subsp. tuberculosis (ATCC® 27294™), multidrug-resistant M. tuberculosis (CMUL 157), Mycobacterium kansasii Hauduroy (ATCC® 12478™) and Mycobacterium gordonae Bojalil et al. (ATCC® 14470™). Results: Even with high dilutions, all tested essential oils showed a high antimycobacterial activity against targeted strains. Our data showed that M. barbata, E. globulus and J. excelsa essential oils totally inhibit the mycobacterial growth whatever the tested strains for the dilution 1/250, 1/100 and 1/250, respectively. Conclusion: To our knowledge, this is the first study regarding the antimycobacterial activity of essential oils in Lebanon. Our data show promising results, and encourage to investigate more on these medicinal plants, especially M. barbata. Keywords: Essential oils, Antimycobacterial activity, Micromeria barbata, Eucalyptus globulus, Juniperus excelsa