Aquatic environment drives the emergence of cell wall-deficient dormant forms in Listeria.

Stressed bacteria can enter a dormant viable but non-culturable (VBNC) state. VBNC pathogens pose an increased health risk as they are undetectable by growth-based techniques and can wake up back into a virulent state. Although widespread in bacteria, the mechanisms governing this phenotypic switch remain elusive.

Deciphering the impact of exogenous fatty acids on at low temperature by transcriptome analysis.

is a ubiquitous and psychrotrophic foodborne pathogen commonly found in raw materials, ready-to-eat products, and food environments. We previously demonstrated that can grow faster at low temperature when unsaturated fatty acids (UFA) are present in its environment. This could question the maintenance of food safety for refrigerated foods, especially those reformulated with a higher ratio of UFA versus saturated fatty acids (SFA) to fit with nutritional recommendations.

Characterization of Bacterial Membrane Fatty Acid Profiles for Biofilm Cells.

When submitted to environmental stresses, bacteria can modulate its fatty acid composition of membrane phospholipids in order to optimize membrane fluidity. Characterization of bacterial membrane fatty acid profiles is thus an interesting indicator of cellular physiological state. The methodology described here aims to improve the recovering of biofilm cells for the characterization of their fatty acid profiles.

Spatially localised expression of the glutamate decarboxylase gadB in Escherichia coli O157:H7 microcolonies in hydrogel matrices.

Functional diversity within isogenic spatially organised bacterial populations has been shown to trigger emergent community properties such as stress tolerance. Considering gadB gene encoding a key glutamate decarboxylase involved in E. coli tolerance to acidic conditions, we investigated its expression in hydrogels mimicking the texture of some structured food matrices (such as minced meat or soft cheese).

Growth of Listeria monocytogenes is promoted at low temperature when exogenous unsaturated fatty acids are incorporated in its membrane.

Listeria monocytogenes is a psychrotrophic food-borne pathogen mostly associated with consumption of ready-to eat foods. Due to its high prevalence in raw materials, it is fundamental to control its growth at low temperature. In lipid-rich products, fatty acids can be heterogeneously distributed in the food matrix and can be present in the environment immediately surrounding the pathogen.

Spatial organisation of Listeria monocytogenes and Escherichia coli O157:H7 cultivated in gel matrices.

The spatial organisation of bacterial pathogens in food matrices remains poorly understood, but is important in improving risk assessment and preventing infection of consumers by contaminated foodstuff. By combining confocal laser scanning microscopy with genetic fluorescent labelling of Listeria monocytogenes and Escherichia coli O157:H7, it was possible to investigate the spatial patterns of colonisation of both foodborne pathogens in gel matrices, alone or in combination, in various environmental conditions. Increasing low melting point agarose (LMPA) concentrations triggers the transition between a motile single-cell lifestyle to a sessile population spatially organised as microcolonies.

Rapid assessment and prediction of the efficiency of two preservatives against S. aureus in cosmetic products using High Content Screening-Confocal Laser Scanning Microscopy.

Most cosmetic products are susceptible to microbiological spoilage due to contaminations that could happen during fabrication or by consumer's repetitive manipulation. The composition of cosmetic products must guarantee efficient bacterial inactivation all along with the product shelf life, which is usually assessed by challenge-tests. A challenge-test consists in inoculating specific bacteria, i.

The Role of Biofilms in the Development and Dissemination of Microbial Resistance within the Food Industry.

Biofilms are multicellular sessile microbial communities embedded in hydrated extracellular polymeric matrices. Their formation is common in microbial life in most environments, while those formed on food-processing surfaces are of considerable interest in the context of food hygiene. Biofilm cells express properties that are distinct from planktonic ones, in particular, notorious resistance to antimicrobial agents.

Ferulic Acid and Eugenol Have Different Abilities to Maintain Their Inhibitory Activity Against in Emulsified Systems.

Natural phenolic compounds are found in large quantities in plants and plant extracts and byproducts from agro-industries. They could be used to ensure food quality and safety due to their antimicrobial properties demonstrated in systems such as culture media. The aim of this study was to evaluate the ability of two natural phenolic compounds, ferulic acid and eugenol, to maintain their inhibitory activity against the growth of in an oil-in-water emulsion, simulating a complex food system.

Inhibitory activity of phenolic acids against Listeria monocytogenes: Deciphering the mechanisms of action using three different models.

Phenolic compounds are well known for their antimicrobial activity. They may provide an interesting solution to ensure food safety by preventing the growth of foodborne pathogens while addressing the wishes of consumers for the use of natural preservatives in food and favoring the reuse of agro-industry byproducts. However, their mechanism of action is still not very well understood.

Characterization of Bacterial Membrane Fatty Acid Profiles for Biofilm Cells.

When exposed to environmental stresses, bacteria can modulate its fatty acid composition of membrane phospholipids in order to optimize membrane fluidity. Characterization of bacterial membrane fatty acid profiles is thus an interesting indicator of cellular physiological state. The methodology described here aims to improve the recovering of biofilm cells for the characterization of their fatty acid profiles.

Impact of Bacterial Membrane Fatty Acid Composition on the Failure of Daptomycin To Kill Staphylococcus aureus.

Daptomycin is a last-resort membrane-targeting lipopeptide approved for the treatment of drug-resistant staphylococcal infections, such as bacteremia and implant-related infections. Although cases of resistance to this antibiotic are rare, increasing numbers of clinical, , and animal studies report treatment failure, notably against The aim of this study was to identify the features of daptomycin and its target bacteria that lead to daptomycin treatment failure. We show that daptomycin bactericidal activity against varies significantly with the growth state and strain, according to the membrane fatty acid composition.

Phenolic compounds can delay the oxidation of polyunsaturated fatty acids and the growth of Listeria monocytogenes: structure-activity relationships.

Background: Phenolic compounds present a potential solution to ensure food quality and safety. Indeed, they can limit oxidation reactions and bacterial growth in food products. Although their antioxidant mechanisms of action are well known, their antibacterial ones are less well understood, especially in light of their chemical structures.

Spatial Organization Plasticity as an Adaptive Driver of Surface Microbial Communities.

Biofilms are dynamic habitats which constantly evolve in response to environmental fluctuations and thereby constitute remarkable survival strategies for microorganisms. The modulation of biofilm functional properties is largely governed by the active remodeling of their three-dimensional structure and involves an arsenal of microbial self-produced components and interconnected mechanisms. The production of matrix components, the spatial reorganization of ecological interactions, the generation of physiological heterogeneity, the regulation of motility, the production of actives enzymes are for instance some of the processes enabling such spatial organization plasticity.

The Biofilm Lifestyle Involves an Increase in Bacterial Membrane Saturated Fatty Acids.

Biofilm formation on contact surfaces contributes to persistence of foodborne pathogens all along the food and feed chain. The specific physiological features of bacterial cells embedded in biofilms contribute to their high tolerance to environmental stresses, including the action of antimicrobial compounds. As membrane lipid adaptation is a vital facet of bacterial response when cells are submitted to harsh or unstable conditions, we focused here on membrane fatty acid composition of biofilm cells as compared to their free-growing counterparts.

Hydrosol of Thymbra capitata Is a Highly Efficient Biocide against Salmonella enterica Serovar Typhimurium Biofilms.

Unlabelled: Salmonella is recognized as one of the most significant enteric foodborne bacterial pathogens. In recent years, the resistance of pathogens to biocides and other environmental stresses, especially when they are embedded in biofilm structures, has led to the search for and development of novel antimicrobial strategies capable of displaying both high efficiency and safety. In this direction, the aims of the present work were to evaluate the antimicrobial activity of hydrosol of the Mediterranean spice Thymbra capitata against both planktonic and biofilm cells of Salmonella enterica serovar Typhimurium and to compare its action with that of benzalkonium chloride (BC), a commonly used industrial biocide.

Adaptation of the wine bacterium Oenococcus oeni to ethanol stress: role of the small heat shock protein Lo18 in membrane integrity.

Malolactic fermentation in wine is often carried out by Oenococcus oeni. Wine is a stressful environment for bacteria because ethanol is a toxic compound that impairs the integrity of bacterial membranes. The small heat shock protein (sHsp) Lo18 is an essential actor of the stress response in O.

Plant-derived compounds as natural antimicrobials to control paper mill biofilms.

Biofilms can cause severe problems in industrial paper mills, particularly of economic and technological types (clogging of filters, sheet breaks or holes in the paper, machine breakdowns, etc.). We present here some promising results on the use of essential oil compounds to control these biofilms.

Biofilms of a Bacillus subtilis hospital isolate protect Staphylococcus aureus from biocide action.

The development of a biofilm constitutes a survival strategy by providing bacteria a protective environment safe from stresses such as microbicide action and can thus lead to important health-care problems. In this study, biofilm resistance of a Bacillus subtilis strain (called hereafter ND(medical)) recently isolated from endoscope washer-disinfectors to peracetic acid was investigated and its ability to protect the pathogen Staphylococcus aureus in mixed biofilms was evaluated. Biocide action within Bacillus subtilis biofilms was visualised in real time using a non-invasive 4D confocal imaging method.

Resistance of bacterial biofilms to disinfectants: a review.

A biofilm can be defined as a community of microorganisms adhering to a surface and surrounded by a complex matrix of extrapolymeric substances. It is now generally accepted that the biofilm growth mode induces microbial resistance to disinfection that can lead to substantial economic and health concerns. Although the precise origin of such resistance remains unclear, different studies have shown that it is a multifactorial process involving the spatial organization of the biofilm.

Comparative biocidal activity of peracetic acid, benzalkonium chloride and ortho-phthalaldehyde on 77 bacterial strains.

Despite numerous reports on biocide activities, it is often difficult to have a reliable and relevant overview of bacterial resistance to disinfectants because each work challenges a limited number of strains and tested methods are often different. The aim of this study was to evaluate the bactericidal activity of three different disinfectants commonly used in industrial or medical environments (peracetic acid, benzalkonium chloride and ortho-phthalaldehyde) against 77 bacterial strains from different origins using one standard test method (NF EN 1040). Results highlight the existence of high interspecific variability of resistance to disinfectants and, contrary to widespread belief, Gram-positive strains generally appeared more resistant than Gram-negative strains.

Deciphering biofilm structure and reactivity by multiscale time-resolved fluorescence analysis.

In natural, industrial and medical environments, microorganisms mainly live as structured and organised matrix-encased communities known as biofilms. In these communities, microorganisms demonstrate coordinated behaviour and are able to perform specific functions such as dramatic resistance to antimicrobials, which potentially lead to major public health and industrial problems. It is now recognised that the appearance of such specific biofilm functions is intimately related to the three-dimensional organisation of the biological edifice, and results from multifactorial processes.

Dynamics of the action of biocides in Pseudomonas aeruginosa biofilms.

The biocidal activity of peracetic acid (PAA) and benzalkonium chloride (BAC) on Pseudomonas aeruginosa biofilms was investigated by using a recently developed confocal laser scanning microscopy (CLSM) method that enables the direct and real-time visualization of cell inactivation within the structure. This technique is based on monitoring the loss of fluorescence that corresponds to the leakage of a fluorophore out of cells due to membrane permeabilization by the biocides. Although this approach has previously been used with success with various Gram-positive species, it is not directly applicable to the visualization of Gram-negative strains such as P.

The spatial architecture of Bacillus subtilis biofilms deciphered using a surface-associated model and in situ imaging.

The formation of multicellular communities known as biofilms is the part of bacterial life cycle in which bacteria display cooperative behaviour and differentiated phenotypes leading to specific functions. Bacillus subtilis is a Gram-positive bacterium that has served for a decade as a model to study the molecular pathways that control biofilm formation. Most of the data on B.