Jean-Marie Perrier-Cornet

University of Burgundy | UB · Unité Mixte de Recherche Procédés Alimentaires et Microbiologiques (PAM)

Dipicolinic acid (DPA) is a specific molecule of bacterial spores which is essential to their resistance to various stresses such as ultraviolet (UV) exposure and to their germination. DPA has a particular photochemistry that remains imperfectly understood. In particular, due to its ability to absorb UVc radiation, it is likely to form in vitro a w...

In this study, we develop a characterization of bacterial spore resistance to NIR pulsed light under modalities traditionally used in multiphoton microscopy. Energy dose and laser power are both key parameters in spore and bacterial cell inactivation. Surprisingly, spores and vegetative cells seem to show a similar sensitivity to pulsed NIR, spores...

Bacterial spores can cause significant problems such as food poisoning (like neurotoxin or emetic toxin) or serious illnesses (like anthrax or botulism). This dormant form of bacteria, made of several layers of barriers which provide extreme resistance to many abiotic stresses (radiation, temperature, pressure, etc.), are difficult to investigate i...

In this study, stationary and time-resolved fluorescence signatures, were statistically and chemometrically analyzed among three typologies of Chardonnay wines (A, B and C) with the objectives to evaluate their sensitivity to acidic and polyphenolic changes. For that purpose, a dataset was built using Excitation Emission Matrices of fluorescence (N...

The advantage of using high pressure (HP) cycling treatment compared with continuous HP treatment was investigated for the inactivation of bacterial spores. The effects of parameters such as pulse number, pressure level, treatment temperature, compression and decompression rates, and time between pulses were evaluated. For this purpose, Bacillus su...

The sensitivity of Paenibacillus sp. and Terribacillus aidingensis spores to combined action of HP, nisin and moderate heating were investigated for the first time. The results showed that the effect of HP on spores varies with pressure level, treatment temperature, spore species and presence of nisin. T. aidingensis spores were more resistant than...

Bacterial spores are among the most resistant forms of life on Earth. Their exceptional resistance properties rely on various strategies, among them the core singular structure, organization and hydration. By using elastic incoherent neutron scattering, we probed the dynamics of Bacillus subtilis spores to determine whether core macromolecular moti...

Bacterial spores are extremely resistant life-forms that play an important role in food spoilage and foodborne disease. The return of spores to a vegetative cell state is a three-step process, these being activation, germination, and emergence. High-pressure (HP) processing is known to induce germination in part of the spore population and even to...

During slow freezing, spermatozoa undergo membrane alterations that compromise their ability of fertilizing. These alterations are cause either by cold shock or by the use of cryoprotectants known to be cytotoxic. However, little is known about the membrane changes that occurred during freezing. Here, we combined Generalized Polarization (GP), Time...

High hydrostatic pressure (HHP) treatments are trending as “green” stabilization and extraction process. The extraction of B-phycoerythrin from microalgae is getting more and more interest due to its numerous potentialities in foods, cosmetics and medicine. Thus, the effects of high pressure on the structural characteristics of B-phycoerythrin extr...

Today, there is no effective non-thermal method to inactivate unwanted bacterial spores in foods. High-Pressure (HP) process has been shown to act synergistically with moderate heating and the bacteriocin nisin to inactivate spores but the mechanisms have not been elucidated. The purpose of the present work was to investigate in depth the synergy o...

Specific treatments combining high temperatures of up to 150 °C and moderate pressure of up to 0.6 MPa have been applied to Bacillus subtilis 168 spores conditioned at different a w levels (between 0.10 and 0.70) corresponding to different residual water contents within the spore core. The spores were treated as a dry powder in a pressurized nitrog...

A multivariate image is an image stack in which each pixel contains several variables. Such images are common in many fields (medicine, imaging microscopy, satellite imaging...) and their analysis requires adapted multivariate statistical methods. In fluorescence imaging microscopy, different probes or different measurements such as intensity, fluo...

L’utilisation d’additifs conservateurs est souvent nécessaire pour assurer la sécurité microbiologique des produits carnés réfrigérés faiblement acides. Le projet ANR BLac HP (2014-2019) a étudié une nouvelle stratégie de stabilisation des produits carnés réfrigérés pour assurer le contrôle des flores indésirables à la fois végétatives et sporulées...

The aim of the study was to extract B-phycoerythrin from Porphyridium cruentum while preserving its structure. The high hydrostatic pressure treatments were chosen as extraction technology. Different methods have been used to observe the effects of the treatment: spectrophotometry and confocal laser scanning microscopy followed by image processing...

Blue light (400–430 nm) is known to induce lethal effects in some species of fungi by photo-oxidation caused by the excitation of porphyrins but the mechanisms involved remain poorly understood. In this work, we exposed the yeast Saccharomyces cerevisiae to a high density light flux with two-photon excitation (830 nm equivalent to a one-photon exci...

Evolution of fluorescence intensity in two excitation area (Region of interest: ROI) delimited by a red rectangle. The two ROI are exposed to light stimulation phases of 1.5.104 W/cm2. ROI 1 contains no any yeast cell. ROI 2 contains 1 yeast cell. (A) Photography of the initial photo-oxidation treatment induced by the production of 1O2 and labelled...

Cycle with acquisition phase (4 s, 400 W/cm2) and excitation phase (2 s) at different light powers (1.5.104; 1.7.104; 1.9.104; 2.3.104 and 2.6.104 W/cm2).

Visualization in video (accelerated 60X) of plasma membrane permeabilization and “photo-oxidative burst” for one cell exposed to a light power of 1.5.104 W/cm2 at 830 nm.

Visualization of plasma membrane permeabilization for six cells exposed to a light power of 1.5.104 W/cm2 at 830 nm in the plasma membrane area.

Because of the ability of foodborne pathogens to survive in low-moisture foods, their decontamination is an important issue in food protection. This study aimed to clarify some of the cellular mechanisms involved in inactivation of foodborne pathogens after drying and subsequent heating. Individual strains of Salmonella Typhimurium, Salmonella Senf...

Gating strategy for flow cytometry analysis. (∗) In the case of PI, the labeled cells were permeabilized cells. In the case of CTC, the labeled cells were the respiring cells.

Logarithmic inactivation corresponding to unculturable percentage for each bacterium and each treatment condition.

Effect of high pressure (HP) treatment on the antimicrobial properties and the structure of nisin was evaluated. Nisin solutions at pH 2.8 or 6.1 were treated by HP at 500 MPa – 10 min – 20 °C and their antimicrobial potency was determined. It appeared that HP clearly impacted the antimicrobial activity of nisin, with respective activity loss of 22...

Fluorescent Probes aimed at absorbing in the blue/green region of the spectrum and emitting in the green/red have been synthesized (as the form of dyads-pentads), studied by spectrofluorimetry, and used for cellular imaging. The synthesis of phthalocyanine-pyrene 1 was achieved by cyclotetramerization of pyrenyldicyanobenzene, whereas phthalocyanin...

Due to the ability of foodborne pathogens to survive in low moisture food, the decontamination of milk powder is an important issue in food protection. The safety of food products is, however, not always insured and the different steps in the processing of food involve physiological and metabolic changes in bacteria. Among these changes, virulence...

Due to the ability of foodborne pathogens to survive in low moisture foods, the decontamination of these products is an important issue in food hygiene. Up to now, such decontamination has mostly been achieved through empirical methods. The intention of this work is to establish a more rational use of heat treatment cycles. The effects of thermal t...

Salmonella Typhimurium and Cronobacter sakazakii are two foodborne pathogens involved in neonatal infections from milk powder and infant formula. Their ability to survive in low-moisture food and during processing from the decontamination to the dried state is a major issue in food protection. In this work, we studied the effects of the drying proc...

Drying is a common process which is used to preserve food products and technological microorganisms, but which is deleterious for the cells. The aim of this study is to differentiate the effects of drying alone from the effects of the successive and necessary rehydration. Rehydration of dried bacteria is a critical step already studied in starter c...

Logarithmic reduction of studied pathogens as function of instantaneous and rapid rehydration at four relative humidity levels (11%, 25%, 44% and 58% RH). (XLSX)

Logarithmic reduction of studied pathogens as function of four rehydration mods (instantaneous, rapid, slow, and very slow) after drying at 11% RH for 90 min. (XLSX)

In this work, we investigated how a combination of ethanol and high temperature (70 °C), affect the properties of the inner membrane of Bacillus subtilis spores. We observed membrane permeabilization for ethanol concentrations ≥ 50%, as indicated by the staining of the spores' DNA by the cell impermeable dye Propidium Iodide. The loss of membrane i...

An original high-pressure microscopy chamber has been designed for real-time visualization of biological cell growth during high isostatic (gas or liquid) pressure treatments up to 200 MPa. This new system is highly flexible allowing cell visualization under a wide range of pressure levels as the thickness and the material of the observation window...

Water crystallization and thawing has long been incriminated in cell death in cryopreservation protocols.We recently studied the role of cold-induced injuries in the occurrence of cell death during freezing of Escherichia coli K12TG1. We showed that extreme cold stress, arising under the supercooling step, is an important cause of cell death in cry...

N° d'article 201511121820

Hydrostatic pressure plays a significant role in the distribution of life in the biosphere. Knowledge of deep-sea piezotolerant and (hyper)piezophilic bacteria and archaea diversity has been well documented, along with their specific adaptations to cope with high hydrostatic pressure (HHP). Recent investigations of deep-sea microbial community comp...

Visualization of DNA and RNA quadruplex formation in human cells was demonstrated recently with different quadruplex-specific antibodies. Despite the significant interest in these immunodetection approaches, dynamic detection of quadruplex in live cells remains elusive. Here, we report on NaphthoTASQ (N-TASQ), a next-generation quadruplex ligand th...

Results from first neutron scattering experiments on bacterial spores are reported. The elastic intensities and mean square displacements have a non-linear behaviour as function of temperature, which is in agreement with a model presenting more pronounced variations at around 330 K (57 ◦C) and 400 K (127 ◦C). Based on the available literature on th...

Injuries in living cells caused by water freezing during a freeze-thaw process have been extensively reported. In particular, intracellular water freezing has long been incriminated in cell death caused by a high cooling rate, but this supposition could not always be demonstrated. This work aims to discriminate the role of water freezing, dehydrati...

Subphthalocyanine (SubPc), a putative fluorophore for optical imaging (OI), was conjugated to chelating ligands (DOTA, DTPA) affording water-soluble conjugates 1-2 complexed with (non radioactive) metals relevant to the following medical imaging techniques / therapies: MRI (Gd), PET (Cu, Ga), SPECT (In, Ga), RIT (Cu, Y), NCT (Gd). Magneto-optical p...

Water-soluble disulfonato-subphthalocyanines (SubPcs) or hydrophobic nano-encapsulated SubPcs are efficient probes for the fluorescence imaging of cells. 20 nm large liposomes (TEM and DLS) incorporated about 13% SubPc. Moreover, some of these fluorophores were found to be pH activatable.

Norovirus (NoV) is a main causative agent of acute gastroenteritis, worldwide. In temperate climates, outbreaks peak during the winter season. The mechanism by which climatic factors influence the occurrence of NoV outbreaks is unknown. We hypothesized that humidity is linked to NoV seasonality. Human NoV is not cultivatable, so we used cultivatabl...

Deep sea sediments constitute a considerable reserve of microorganisms belonging to different microbial communities. Our researches aimed to better understand cellular mechanisms related to cellular plasticity involved in resistance of such microbial communities to extreme conditions and more particularly to high level of pressure (> 50 MPa). Obvio...

L’imagerie cellulaire, dans le domaine des sciences du vivant, est essentielle à la compréhension des phénomènes cellulaires subcellulaires régulant le fonctionnement des cellules et tissus. En microscopie électronique, la mise en oeuvre de cryo-méthodes permet de préserver l’intégrité moléculaire et spatiale des protéines et lipides intracellulair...

Lipid mixtures within artificial membranes undergo a separation into liquid-disordered and liquid-ordered phases. However, the existence of this segregation into microscopic liquid-ordered phases has been difficult to prove in living cells, and the precise organization of the plasma membrane into such phases has not been elucidated in plant cells....

In this paper, emphasis has been put on the relationship between volume compression and cell inactivation for the Saccharomyces cerevisiae strain CBS 1171 submitted to high hydrostatic pressure treatments. The influence of cell dehydration on pressure inactivation was first investigated. Inactivation was found to be strongly limited, or even comple...

We utilize the fluorescent molecular rotor Bodipy-C12 to investigate the viscoelastic properties of hydrophobic layers of bacterial spores Bacillus subtilis. The molecular rotor shows a marked increase in fluorescence lifetime, from 0.3 to 4ns, upon viscosity increase from 1 to 1500cP and can be incorporated into the hydrophobic layers within the s...

Abstract The role of water, its distribution and its implication in the heat resistance of dried spores was investigated using DSC (Differential Scanning Calorimetry). Bacillus subtilis spores equilibrated at different water activity levels were heat treated under strictly controlled conditions. The temperature was increased linearly in pans with d...

In this article, an original non-thermal process to inactivate dehydrated bacterial spores is described. The use of gases such as nitrogen or argon as transmission media under high isostatic pressure led to an inactivation of over 2 logs CFU/g of Bacillus subtilis spores at 430 MPa, room temperature, for a 1 min treatment. A major requirement for t...

Advances in fundamental physical and optical principles applied to novel fluorescence methods are currently resulting in rapid progress in cell biology and physiology. Instrumentation devised in pioneering laboratories is becoming commercially available, and study findings are now becoming accessible. The first results have concerned mainly higher...

Contributions sur l'utilisation des hautes pressions dans les grands domaines de recherches. Les auteurs offrent un bilan décennal du domaine scientifique dont ils sont les principaux acteurs et montrent l'évolution des thèmes de recherches, les méthodes, les questions, les récentes réussites et les nouveaux enjeux propres à chaque discipline.

Bacillus subtilis(B. subtilis) cells were placed in various environmental conditions to study the effects of aeration, water activity of the medium, temperature, pH, and calcium content on spore formation and the resulting properties. Modification of the sporulation conditions lengthened the growth period of B. subtilis and its sporulation. In some...

In this study, we investigated the mechanisms of spore inactivation by high pressure at moderate temperatures to optimize the sterilization efficiency of high-pressure treatments. Bacillus subtilis spores were first subjected to different pressure treatments ranging from 90 to 550 MPa at 40°C, with holding times from 10 min to 4 h. These treatments...

The physicochemical properties of spores were studied in relationship of their structure, which was modulated by chemical or genetic methods. The Bacillus subtilis spores were equilibrated at different water activities (from 0.113 to ~1) and investigated by differential scanning calorimetry (DSC). The isothermal sorptions at 25°C of the native and...

The effects of water activity (a(w)) of diverse media i/ culture medium for sporogenesis, a(w sp) ii/ liquid spore suspension medium, a(w su) and iii/ medium for germination, a(w ge), on the germination time t(G) of Aspergillus carbonarius, Aspergillus flavus, Penicillium chrysogenum and Penicillium expansum were assessed according to a screening m...

IntroductionExample 1: Effects of Combined Hyperosmotic and Temperature PerturbationExample 2: Effects of Combined High Hydrostatic Pressure, Low Temperature, and Hyperosmotic PerturbationsConclusions References

We monitored the behavior of plasma membrane (PM) isolated from tobacco cells (BY-2) under hydrostatic pressures up to 3.5kbar at 30 degrees C, by steady-state fluorescence spectroscopy using the newly introduced environment-sensitive probe F2N12S and also Laurdan and di-4-ANEPPDHQ. The consequences of sterol depletion by methyl-beta-cyclodextrin w...

We investigated the influence of cell hydration on the ability of Saccharomyces cerevisiae CBS 1171 to withstand extreme hydrostatic pressure in order to determine the mechanisms involved in cell resistance. Hydration conditions were modified in two different ways. We first modulated the chemical potential of water by adding glycerol in cell suspen...

The survival of cells subjected to cooling at sub-zero temperature is of paramount concern in cryobiology. The susceptibility of cells to cryopreservation processes, especially freeze-thawing, stimulated considerable interest in better understanding the mechanisms leading to cell injury and inactivation. In this study, we assessed the viability of...

The effects of water activities for sporulation (a(wsp)) and germination (a(wge)) on the distributions of the growth rate of the germ tubes (mu) and the germination time (t(G)) of Penicillium chrysogenum conidia were determined by monitoring the length of the same germ tubes throughout the experiments automatically. No relationship between the indi...

Dried microorganisms are particularly resistant to high hydrostatic pressure effects. However, exposure to high pressures of nitrogen proved to be effective in inactivating dried yeasts. In this study, we tried to elucidate this mechanism on Saccharomyces cerevisiae. High-pressure treatments were performed using different inert gases at 150 MPa and...

Involvement of sterols in membrane structural properties has been extensively studied in model systems but rarely assessed in natural membranes and never investigated for the plant plasma membrane (PM). Here, we address the question of the role of phytosterols in the organization of the plant PM. The sterol composition of tobacco BY-2 cell PM was d...

The causes of Bacillus spore resistance remain unclear. Many structures including a highly compact envelope, low hydration of the protoplast, high concentrations of Ca-chelated dipicolinic acid, and the presence of small acid-soluble spore proteins seem to contribute to resistance. To evaluate the role of internal protoplast composition and hydrati...

Bacillus subtilis(B. subtilis) cells were placed in various environmental conditions to study the effects of aeration, water activity of the medium, temperature, pH, and calcium content on spore formation and the resulting properties. Modification of the sporulation conditions lengthened the growth period of B. subtilis and its sporulation. In some...

Dried microorganisms are particularly resistant to high hydrostatic pressure effects. In this study, the survival of Saccharomyces cerevisiae was studied under pressure applied in different ways. Original processes and devices were purposely developed in our laboratory for long-term pressurization. Dried and wet yeast powders were submitted to high...

The relationship between membrane permeability, changes in ultrastructure, and inactivation in Escherichia coli strain K-12TG1 cells subjected to high hydrostatic pressure treatment at room and subzero temperatures was studied. Propidium iodide staining performed before and after pressure treatment made it possible to distinguish between reversible...

The combined effects of subzero temperature and high pressure on the inactivation of Escherichia coli K12TG1 were investigated. Cells of this bacterial strain were exposed to high pressure (50 to 450 MPa, 10-min holding time) at two temperatures (−20°C without freezing and 25°C) and three water activity levels (aw) (0.850, 0.992, and ca. 1.000) ach...

Ce mémoire développe l'action des hautes pressions hydrostatiques sur les systèmes vivants qui constituent le cœur de mon travail de recherche. J'ai cependant participé activement à d'autres travaux de recherche qui ne seront pas développés dans ce mémoire comme la gélatinisation de l'amidon sous haute pression ou la production d'arôme par la levur...

High-pressure treatments necessary to reach high or complete microbial inactivation could be improved through the combination of high pressure with other physical parameters. This work was intended to study coupling effect of high pressure and subzero temperature on microbial inactivation. Escherichia coli LCB 320 was treated at different pressure...