[Show abstract][Hide abstract] ABSTRACT: Dairy products are important sources of biological active compounds that can be interesting for human health. This includes immunoglobulins, whey proteins and peptides, polar lipids, lactic acid bacteria and in particular, probiotics which include many types of lactic acid bacteria. Understanding the interactions between these bioactive components and their delivery matrix may improve the success of their transport to their target site of action. Pioneering research on probiotic lactic acid bacteria has mainly focused on their host effects. However, little was done about their interaction with dairy ingredients. Such knowledge could contribute to design of new and more efficient dairy food, and to understand the interplay between the various constituents. The purpose of this review is first to provide an overview of current knowledge about biomolecules encountered on bacterial surface and dairy components composition. In order to understand how bacteria can interact with dairy molecules, adhesion mechanisms are discussed with regards to the environmental conditions affecting the bacterial adhesion. Methods that can be used to investigate the bacterial surface and the ones that can probe bacterial interactions with other components are also detailed. Finally, the interest in studying bacterial interactions with milk components is illustrated by relevant industrial examples, as the influence of bacterial surface biomolecules on yogurt structure or the bacterial location in a dairy matrix.
Advances in Colloid and Interface Science 12/2014; · 8.64 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Biodegradable polymers with distinct composition can be used as antimicrobial carriers. To judge their relative efficiency as antimicrobial carriers, release rates of fluorescently labeled nisin Z from hydroxypropyl methylcellulose (HPMC), chitosan (CTS), sodium caseinate (SC) and polylactic acid (PLA) films were evaluated at 4 and 40 °C in water–ethanol solution. Nisin diffusion coefficient (D) indicated that DCTS < DPLA < DSC < DHPMC. Temperature increase significantly increased nisin release from SC and HPMC films due to glass transition and hydrophilic nature. Partition coefficients (K) followed the same trend but were below 1, except for HPMC at 40 °C, which implies that, at equilibrium, a lower amount of nisin was liberated in water–ethanol solution. A higher antibacterial effect against Listeria monocytogenes CIP 82110 and Staphylococcus aureus CIP 4.83 was observed with HPMC and SC films containing nisin due to strong interactions (hydratation) between the medium and the film. However, HPMC, CTS, SC packaging films could progressively release nisin to sustain an anti-bacterial effect and can be favorably used for prolonging shelf life of packed food.
Journal of Food Engineering 12/2014; 143:178–185. · 2.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Chitosan and its derivatives functionalized by laccase-catalyzed oxidation of ferulic acid (FA) and ethyl ferulate (EF) were characterised for their physico-chemical, antioxidant and antibacterial properties. The enzymatic grafting of oxidised phenols led to FA-coloured and EF-colourless chitosan derivatives with good stability of colour and grafted phenols towards the chemical treatment by organic solvents. The efficiency of FA-products grafting onto chitosan was higher than that of EF-products. Moreover, the enzymatic grafting of phenols onto chitosan changed its morphological surface, increased its molecular weight and its viscosity. Furthermore, the chitosan derivatives presented improved antioxidant properties especially for FA-chitosan derivative when compared with chitosan with good antioxidant stability towards thermal treatment (100°C/1h). Chitosan and its derivatives showed also similar antibacterial activities and more precisely bactericidal activities. This enzymatic procedure provided chitosan derivatives with improved properties such as antioxidant activity, thermal antioxidant stability as well as the preservation of initial antibacterial activity of chitosan.
[Show abstract][Hide abstract] ABSTRACT: Dairy products are colonized with three main classes of Lactic Acid Bacteria (LAB): opportunistic bacteria, traditional starters, and industrial starters. Most of the population structure studies were previously performed with LAB species belonging to those three classes, and give interesting knowledge about the population structure of LAB at the stage where they are already industrialized. However, they give little information about the population structure of LAB prior their use as industrial starter. Carnobacterium maltaromaticum is a lactic acid bacterium colonizing diverse environments including dairy products. Since this bacterium was discovered relatively recently, it is not yet commercialized as an industrial starter, which makes C. maltaromaticum an interesting model for the study of unindustrialized LAB population structure in dairy products. An MLST scheme based on the analysis of fragments of the genes dapE, ddlA, glpQ, ilvE, pyc, pyrE, and leuS was applied to a collection of 47 strains, including 28 strains isolated from dairy products. The scheme allowed detecting 36 Sequence Types (STs) with a discriminatory index of 0.98. The whole population was clustered in four deeply branched lineages, in which the dairy strains were spread. Moreover, the dairy strains could exhibit a high diversity within these lineages, leading to an overall dairy population with a diversity level as high as the non dairy population. These results are in agreement with the hypothesis according to which the industrialization of LAB leads to a diversity reduction in dairy products.
Applied and Environmental Microbiology 04/2014; · 3.95 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Biomolecules labeling by fluorescent markers has emerged as innovative methodology for bio-analytical purposes in food microbiology, medicine and pharmaceutics due to great advantages of this method such as precision, wide detection limits, and in vivo recognition. Fluorescent nisin Z was synthesized by linking carboxyl group and amino group of nisin Z and 5-aminoacetamido fluorescein (AAA-flu). This new structure was fully characterized by mass spectrometry with a molecular weight of 3717.3Da. Intracellular K(+) leakage and transmembrane electrical potential (Δψ) were used to evaluate the antibacterial action of the labeled molecule against three listerial strains and demonstrated that nisin Z endured the labeling process without any activity loss. In vivo activity of labeled nisin was observed by confocal laser microscope and revealed its localization at the septum of listerial cell division site where the membrane-bound cell wall precursor lipid II is maximal. Fluorescent nisin Z showed its high interest as a tool to study antibacterial mechanism of action of nisin in biological systems.
Journal of microbiological methods 07/2013; · 2.43 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Carnobacterium maltaromaticum is a non-starter lactic acid bacterium frequently isolated from food products. While this bacterium has been extensively studied in foods, very little is known about its fate once ingested. In this study the strain C. maltaromaticum LMA 28 was given to mice by intragastric gavage. Selective enumeration of C. maltaromaticum in the faeces showed that the bacterium is able to survive through transit of the gut. In addition, experiments showed that C. maltaromaticum is able to adhere to Caco-2, HT29, and T84 cell lines. Moreover, the measurement of four cytokines produced by human peripheral blood mononuclear cells after incubation with the bacterium suggested that C. maltaromaticum LMA 28 exhibit either a neutral or a slightly anti-inflammatory behaviour. The analysis of the genome of C. maltaromaticum LMA 28 revealed it contains genes for adaptation to the gastroin-testinal tract.
[Show abstract][Hide abstract] ABSTRACT: Within the lactic acid bacterium genus Carnobacterium, Carnobacterium maltaromaticum is one of the most frequently isolated species from natural environments and food. It potentially plays a major role in food product biopreservation. We report here on the 3.649-Mb chromosome sequence of C. maltaromaticum LMA 28, which was isolated from ripened soft cheese.
[Show abstract][Hide abstract] ABSTRACT: Carnobacterium maltaromaticum is a lactic acid bacterium isolated from soft cheese. The objective of this work was to study its potential positive impact when used in cheese technology. Phenotypic and genotypic characterization of six strains of C. maltaromaticum showed that they belong to different phylogenetic groups. Although these strains lacked the ability to coagulate milk quickly, they were acidotolerant. They did not affect the coagulation capacity of starter lactic acid bacteria, Lactococcus lactis and Streptococcus thermophilus, used in dairy industry. The impact of C. maltaromaticum LMA 28 on bacterial flora of cheese revealed a significant decrease of Psychrobacter sp. concentration, which might be responsible for cheese aging phenomena. An experimental plan was carried out to unravel the mechanism of inhibition of Psychrobacter sp. and Listeria monocytogenes and possible interaction between various factors (cell concentration, NaCl, pH and incubation time). Cellular concentration of C. maltaromaticum LMA 28 was found to be the main factor involved in the inhibition of Psychrobacter sp. and L. monocytogenes.
[Show abstract][Hide abstract] ABSTRACT: Customized application of antimicrobial peptide (AMP) ‘nisin’ directly into food (neither in active packaging nor encapsulated form) is expensive and associated with loss of activity due to deactivation in complex food systems. The purpose of the present study was to fusion the two concepts for improved bioavailability i.e. AMP nanoencapsulation and biopolymer immobilizing to formulate the next generation biodegradable films embedded with either active agent, nano-encapsulated active agent or both of them. Nanoliposomes were prepared using soy-lecithin by microfluidizer at 2000 bar with 5 cycles to generate an average size of 151 ± 4 nm with 50 ± 3% encapsulation efficiency. For active films, nisin had demonstrated no negative impact on transparency, thickness and water sorption behavior obtained by GAB model (25 °C, 0–0.95 aw). For nano-active films, the results clearly illustrated that different physico-chemical properties including barrier (oxygen and water vapor permeability), color and transparency (200–900 nm) remained comparable to native hydroxypropyl methylcellulose (HPMC) films and were significantly improved than using lecithin directly without nano-scale restructuring. The microstructure studies (topography and morphology) by scanning and transmission electron microscopes (SEM/TEM) revealed different (pore, lamellar, fusion) modes of nisin release from nanoliposomes embedded in HPMC matrix. As microbiological worth, nisin nano-emulsion (encapsulated and free nisin) films were effective against potential foodborne pathogen Listeria monocytogenes. This innovative concept of biodegradable nano-active films may thus be a preventive system toward improved food safety.
[Show abstract][Hide abstract] ABSTRACT: Carnobacterium maltaromaticum strains are widely found in food including fish, meat and some dairy products. Producing a malty/chocolate like aroma due to 3-methylbutanal from the catabolism of leucine is a general characteristic of this species. In this study, we investigated metabolic routes responsible for the biosynthesis of this flavor compound from the catabolism of leucine in C. maltaromaticum LMA 28, a strain isolated from mold ripened soft cheese. Depending on the lactic acid bacterium, leucine can be converted into 3-methylbutanal following two possible metabolic pathways: either directly by α-ketoacid decarboxylase (KADC) pathway or indirectly by α-ketoacid dehydrogenase (KADH) pathway. Both KADC (41.0±3.0 nmol/mg protein/min) and KADH (1.43±0.62 nmol/mg protein/min) activities were detected and determined in vitro in C. maltaromaticum LMA 28. C. maltaromaticum LMA 28 slightly reduced the production of 3-methylbutanal from leucine in the presence of a specific inhibitor of KADH enzyme complex, i.e. sodium meta-arsenite, suggesting that both pathways were involved in vivo in leucine catabolism. Moreover the presence of genes encoding aminotransferase, glutamate dehydrogenase, α-ketoacid decarboxylase, α-ketoacid dehydrogenase and aldehyde dehydrogenase was confirmed. C. maltaromaticum is then the first lactic acid bacterium in which presence of both metabolic routes responsible for the biosynthesis of 3-methylbutanal from leucine catabolism was confirmed in vitro and in vivo as well.
International journal of food microbiology 05/2012; 157(3):332-9. · 3.01 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Carnobacteriocin BM1 (Cbn BM1) is a class IIa bacteriocin produced by Carnobacterium maltaromaticum CP5 isolated from a French mold ripened cheese. Numerous studies highlight variations in numerous parameters, such as bacterial membrane composition and potential, according to physiological changes. In this work, the mechanism of action of an oxidized form of Cbn BM1 was studied on C. maltaromaticum DSM20730 in log and stationary growth phases. Membrane integrity assessment and high resolution imaging by atomic force microscopy confirmed the link between physiological state and bacterial sensitivity to Cbn BM1. Indeed, these approaches enable visualizing morphological damage of C. maltaromaticum DSM20730 only in an active dividing state. To specifically address the interaction between peptide and bacterial membrane, fluorescence anisotropy measurements were conducted. Results revealed strong modifications in membrane fluidity by Cbn BM1 only for C. maltaromaticum DSM20730 in log growth phase. In a similar way, the Δψ component, but not the ΔpH component of the proton-motive force, was perturbed only for bacteria in log growth phase. These results clearly show that a class IIa bacteriocin antimicrobial mechanism of action can be modulated by the physiological state of its target bacteria.
Research in Microbiology 05/2012; 163(5):323-31. · 2.89 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Predicting which attributes consumers are willing to pay extra for has become straightforward in recent years. The demands for the prime necessity of food of natural quality, elevated safety, minimally processed, ready-to-eat, and longer shelf-life have turned out to be matters of paramount importance. The increased awareness of environmental conservation and the escalating rate of foodborne illnesses have driven the food industry to implement a more innovative solution, i.e. bioactive packaging. Owing to nanotechnology application in eco-favorable coatings and encapsulation systems, the probabilities of enhancing food quality, safety, stability, and efficiency have been augmented. In this review article, the collective results highlight the food nanotechnology potentials with special focus on its application in active packaging, novel nano- and microencapsulation techniques, regulatory issues, and socio-ethical scepticism between nano-technophiles and nano-technophobes. No one has yet indicated the comparison of data concerning food nano- versus micro-technology; therefore noteworthy results of recent investigations are interpreted in the context of bioactive packaging. The next technological revolution in the domain of food science and nutrition would be the 3-BIOS concept enabling a controlled release of active agents through bioactive, biodegradable, and bionanocomposite combined strategy.
Critical reviews in food science and nutrition 10/2010; 50(9):799-821. · 3.73 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Carnobacterium species constitute a genus of Lactic Acid Bacteria (LAB) present in different ecological niches. The aim of this article is to summarize the knowledge about Carnobacterium maltaromaticum species at different microbiological levels such as taxonomy, isolation and identification, ecology, technological aspects and safety in dairy products. Works published during the last decade concerning C. maltaromaticum have shown that this non-starter LAB (NSLAB) could present major interests in dairy product technology. Four reasons can be mentioned: i) it can grow in milk during the ripening period with no competition with starter LAB, ii) this species synthesizes different flavouring compounds e.g., 3-methylbutanal, iii) it can inhibit the growth of foodborne pathogens as Listeria monocytogenes due to its ability to produce bacteriocins, iv) it has never been reported to be involved in human diseases as no cases of human infection have been directly linked to the consumption of dairy products containing this species.
[Show abstract][Hide abstract] ABSTRACT: Bioactive composite coatings based on hydroxypropyl methylcellulose (HPMC), broad-spectrum food preservative nisin (Nisaplin®), and hydrophilic plasticizer glycerol were evaluated for mechanical, barrier (O2, H2O), transparency and microbiological effectiveness. Incorporation of Nisaplin® into cellulose derivative, i.e. HPMC-based films strongly increased the film thickness due to salt crystallization while glycerol had normalized it by homogenous dispersibility. The tensile strength of composite films decreased, however ultimate elongation was increased significantly. The dynamic vapour sorption experimental data fitted by different models had shown lesser values of respective energy constants for composite films. The transparency and water permeability of HPMC films were negatively affected by the additives as an effect individual but conversely as combined effect for film transparency. Film bioactivity demonstrated efficacy against Listeria > Enterococcus > Staphylococcus > Bacillus spp. These cellulose derivative based active films may thus be a key approach towards eradicating post-process contamination of healthy foods.
[Show abstract][Hide abstract] ABSTRACT: In order to contribute to the preservation of the Lebanese dairy heritage, the aim of this study was to characterize the Darfiyeh cheese, a traditional variety made from raw goat's milk and ripened in goat's skin. Three independent batches of Darfiyeh production were analyzed after 20, 40 and 60 days of ripening. Mesophilic lactobacilli, thermophilic coccal-shaped lactic acid bacteria (LAB) and thermophilic lactobacilli were enumerated. In order to explore the Darfiyeh natural ecosystem, a combination of phenotypical and molecular approaches was applied. The latter included Polymerase Chain Reaction-temporal temperature gel electrophoresis (PCR-TTGE), classical PCR and quantitative PCR. These methods revealed the presence of Streptococcus thermophilus, Enterococcus faecium, Enterococcus durans, Enterococcus faecalis, Enterococcus malodoratus, group D Streptococcus sp., Lactococcus lactis subsp. lactis and L. lactis subsp. cremoris, Lactobacillus plantarum, Lactobacillus curvatus, Staphylococcus haemolyticus, Escherichia coli, Clostridium sp./Eubacterium tenue. Real-time PCR enabled quantification of E. faecium, with a detection of 10(7)-10(9) cfu g(-1) of product. The present molecular approaches combined with phenotypic method allowed describing the complex natural ecosystem of Darfiyeh, giving useful information for the preservation of Lebanese artisanal dairy products.
[Show abstract][Hide abstract] ABSTRACT: Two purified class IIa carnobacteriocins Cbn BM1 and Cbn B2, from Carnobacterium maltaromaticum CP5, were evaluated for antimicrobial activity against pathogenic, spoilage and lactic acid bacteria. Then, the presence of a synergistic mode of action of these two carnobacteriocins on Listeria sp., Enterococcus sp. and Carnobacterium sp. was investigated. A synergistic mode of action between Cbn BM1 and Cbn B2 on sensitive target bacteria was demonstrated using the FIC index method. Combinations of carnobacteriocins enhanced their anti-bacterial activities and MICs were significantly reduced, between 2 and 15 fold, by the addition of the second bacteriocin. To improve the safety of the bacteriocins as biopreservative agents, the cytotoxicity of the combination of theses two bacteriocins was determined on Caco-2 cell line. However, these two peptides used alone or in combination, at concentration 100-fold higher than those required for antimicrobial activity, were not cytotoxic. This suggests that the two carnobacteriocins produced by C. maltaromaticum CP5 could be potential natural agents for food preservation.
Food and chemical toxicology: an international journal published for the British Industrial Biological Research Association 02/2009; · 2.99 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Mesenterocin 52A (Mes 52A) is a class IIa bacteriocin produced by Leuconostoc mesenteroides ssp. mesenteroides FR52. The interaction of Mes 52A with bacterial membranes of sensitive, resistant and insensitive Leuconostoc strains has been investigated. The degree of insertion of Mes 52A on the phospholipid bilayer was studied by fluorescence anisotropy measurements using two probes, 1-(4-trimethylammonium)-6-phenyl-1,3,5-hexatriene (TMA-DPH) and DPH, located at different positions in the membrane, and the consequence for K(+) efflux and proton motive force was analyzed. Mes 52A caused an increase in the fluorescence of TMA-DPH and DPH in the membrane of the sensitive strain L. mesenteroides ssp. mesenteroides LMA 7, indicating that Mes 52A inserts into the cytoplasmic membrane of this sensitive strain. This insertion leads to K(+) efflux, without perturbation of DeltapH and a weak modification of DeltaPsi, and is consistent with pore formation. With the high-level resistant strain L. mesenteroides ssp. mesenteroides LMA 7AR, or with the insensitive strain Leuconostoc citreum CIP 103405, no modification of TMA-DPH or DPH anisotropy occurred, even in the presence of high Mes 52A levels. The membrane potential was not modified and no K(+) efflux was detected. There is a clear correlation between the physico-chemical characteristics of the membrane, the degree of Mes 52A penetration, the mechanism of action and the resistance or insensitivity characteristic of the target strains.
[Show abstract][Hide abstract] ABSTRACT: Mesenterocin 52A (Mes 52A) is a class IIa bacteriocin produced by Leuconostoc mesenteroides subsp. mesenteroides FR52, active against Listeria sp. The interaction of Mes 52A with bacterial membranes of two sensitive Listeria strains has been investigated. The Microbial Adhesion to Solvents test used to study the physico-chemical properties of the surface of the two strains indicated that both surfaces were rather hydrophilic and bipolar. The degree of insertion of Mes 52A in phospholipid bilayer was studied by fluorescence anisotropy measurements using two probes, 1-(4-trimethylammonium)-6-phenyl-1,3,5-hexatriene (TMA-DPH) and DPH, located at different positions in the membrane. TMA-DPH reflects the fluidity at the membrane surface and DPH of the heart. With Listeria ivanovii CIP 12510, Mes 52A induced an increase only in the TMA-DPH fluorescence anisotropy, indicating that this bacteriocin affects the membrane surface without penetration into the hydrophobic core of the membrane. No significant K(+) efflux was measured, whereas the Delta Psi component of the membrane potential was greatly affected. With Listeria innocua CIP 12511, Mes 52A caused an increase in the fluorescence of TMA-DPH and DPH, indicating that this peptide inserts deeply in the cytoplasmic membrane of this sensitive strain. This insertion led to K(+) efflux, without perturbation of Delta pH and a weak modification of Delta Psi, and is consistent with pore formation. These data indicate that Mes 52A interacts at different positions of the membrane, with or without pore formation, suggesting two different mechanisms of action for Mes 52A depending on the target strain.
Applied Microbiology and Biotechnology 10/2008; 81(2):339-47. · 3.81 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: An optimization of the production and purification processes of carnobacteriocins Cbn BM1 and Cbn B2 from Carnobacterium maltaromaticum CP5, by heterologous expression in Escherichia coli is described. The genes encoding mature bacteriocin were cloned into an E. coli expression system and expressed as a fusion protein with a thermostable thioredoxin. Recombinant E. coli were cultivated following a fed-batch fermentation process with pH, temperature and oxygenation regulation. The overexpression of the fusion proteins was improved by replacing IPTG by lactose. The fusion proteins were purified by thermal coagulation followed by affinity chromatography. The thioredoxin fusion protein was removed by using CNBr instead of enterokinase and the carnobacteriocins were recovered by reverse-phase chromatography. These optimizations led us to produce up to 320 mg of pure protein per liter of culture, which is four to ten fold higher than what is described for other heterologous expression systems.
Journal of Microbiological Methods 05/2008; 73(1):41-8. · 2.16 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A selective medium was proposed for isolating the species Carnobacterium maltaromaticum from cheeses. This medium, named CM, was elaborated using combinations of three antibiotics (gentamicin, nalidixic acid, vancomycin) and alkaline pH value (8.8). An experimental design (Doehlert matrix) was drawn up to optimize the experimental conditions of the preparation of the medium. Based on the TS-YE agar medium, it contained 3.5 mg L(-1) of vancomycin, 5.0 mg L(-1) of gentamicin, and 20 mg L(-1) of nalidixic acid. The incubation time was 36 to 48 h at 25 degrees C. The selectivity of this medium was tested against bacterial strains present in the dairy industry and controlled by the PCR method. Thanks to this medium, it was easy to detect C. maltaromaticum and to follow this species in the cheese-making process.
Journal of Microbiological Methods 04/2007; 68(3):516-21. · 2.16 Impact Factor