Christine Faille

Christine Faille
French National Institute for Agriculture, Food, and Environment (INRAE) | INRAE · Department of Microbiology and the Food Chain

PhD

About

104
Publications
15,701
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3,274
Citations
Additional affiliations
January 1992 - present
French National Institute for Agriculture, Food, and Environment (INRAE)
Position
  • Research Director

Publications

Publications (104)
Article
In the food industry, the cleaning of contaminated surfaces requires new strategies to be adopted which can provide greater cleaning efficiency with minimal energy and water consumption. The use of wet foams was proposed to clean stainless steel surfaces contaminated by droplets containing Bacillus spores. Methods such as polarography, conductimetr...
Article
The formation of deposits by evaporation of droplets contaminated by Bacillus spores was investigated, focusing on the role of spore and material properties. Droplets containing hydrophilic to hydrophobic spores were deposited on materials (stainless steels, polypropylene, glass). The presence of spores within the droplets, as well as material hydr...
Article
Full-text available
In the food industry, the control of surface hygiene is a major issue. It is therefore essential to identify those parameters that can affect the bacterial contamination of surfaces and the effectiveness of hygiene procedures. Numerous studies have focused on the role of bacteria, flow arrangements or materials, but almost nothing has been reported...
Article
Full-text available
Mitigation of cross-contamination of fresh-cut food products at the washing step was studied by investigating how the vat design would affect the biofilm contamination surfaces. Hygienic design features such as no horizontal surfaces and only open angles exceeding 100° were proposed. The flow organisation (velocity streamlines, wall shear stresses,...
Article
Full-text available
Bacillus species are a major economic and food safety concern of the food industry because of their food spoilage-causing capability and persistence. Their persistence is mainly due to their ability to form highly resistant spores adhering to the surfaces of industrial equipment. Spores of the Bacillus subtilis group are surrounded by the crust, a...
Article
Food industry cleaning operations must efficiently mitigate any risk of remaining unwanted contamination without consuming large amounts of water, chemicals and energy. This study's originality was in analysing the capacity of flowing foams to remove Bacillus spores from stainless steel surfaces. A set-up was designed to allow the formation of wet...
Article
Interfaces between air, liquid and walls (ALW interfaces) are known to be conducive to the formation of biofilms, at least in some bacteria, yet little information is available on the influence of material properties on the amount of biofilms formed and their resistance to a cleaning procedure. In this study, we investigated the ability of four bac...
Article
The objectives of this study were 1) to evaluate the impact of two industrial disinfectants on the viability of Listeria monocytogenes populations in biofilm and 2) to investigate the viability state of L. monocytogenes cells present on contact surfaces in the smoked salmon processing environment. In the first step, we cultured mono species and mix...
Article
Aims The aim of this study was to evaluate the performance of sampling methods [contact plates, sponges, and swabs] in the recovery of biofilm Listeria monocytogenes populations considering the seafood environment conditions (nature of conditioning, of materials and bacterial species). Methods and results Different materials (stainless steel, poly...
Article
Surface contamination with droplets containing bacteria is of concern in the food industry and other environments where hygiene control is essential. Deposition patterns after the drying of contaminated droplets is affected by numerous parameters. The present study evaluated the rate of evaporation and the shape of deposition patterns after the dry...
Chapter
The origins of microbial contamination of processed food are diverse, occurring at different steps of the food value chain from the field to the plate. Equipment surfaces are often considered to be significant contaminant breeding grounds. This chapter first highlights the ways in which equipment geometries play a significant role in surface hygien...
Conference Paper
Aqueous foam is a non-Newtonian complex fluid. Its flow through the singularities presents many fundamental aspects. The rheological character of the foams flowing in this kind of geometries can create important disturbance on its behavior, according to the flow rate set and therefore a modification in its texture and in the nature of its establish...
Poster
Full-text available
Micro-organisms in agro-industries strongly attach on surfaces and their elimination demands the systematic establishment of cleaning and disinfection procedures. This study focuses on the mechanisms of detachment of bacterial spores adhered to the wall of a horizontal straight square pipe by flowing foam using two approaches: foam flow modeling an...
Article
Surface contamination by Pseudomonas fluorescens biofilms was studied using pilot scale washing tanks with standard design features encountered in the fresh-cut vegetable processing industry. Consequences on the biofilms'resistance to the shear stress and to enzymatic cleaning were analysed. It was found that biofilm structures depended on the loca...
Presentation
1 Déclaration de conflit d'intérêt Pour cette présentation, je déclare n'avoir aucun conflit d'intérêt. Les surfaces soumises à un séchage sont-elles des zones à risque en terme d'hygiène?
Conference Paper
In some industrial processes, aqueous foams flow presents an important phase of the process, whereas, they cause pressure drop when designing and dimensioning systems. Identifying the different rheological parameters of foam flow is an interest key to understanding the interfacial phenomena. Actually, the difficulty to model the rheological paramet...
Research
Full-text available
The INTERREG (France-Wallonie-Vlaanderen) project Veg-i-Tec is dedicated to the set up a cross-border network of technical centres and competencies for applied research and development of processing methods of vegetables and potatoes
Article
Full-text available
The wall teichoic acid (WTA) is the major carbohydrate found within the extracellular matrix of the Listeria monocytogenes biofilm. We first addressed the frequency of spontaneous mutations in two genes (lmo2549 and lmo2550) responsible for the GlcNAcylation in 93 serotype 1/2a strains that were mainly isolated from seafood industries. We studied t...
Article
Full-text available
Following publication of the original article (Khelissa et al. 2017), the authors reported that the legend for Fig. 3 contained an error. Instead of "Adhesion of planktonic and biofilm-detached Staphylococcus aureus cells on stainless steel and polycarbonate. Cell cultures were grown at 20, 30 and 37 °C, during 24 h (white square) and 48 h (white s...
Article
This study was designed to assess the efficiency of eight extraction methods regarding their ability to release superficial (exogenous) and intracellular (endogenous) DNA from B. cereus spores for subsequent analysis by quantitative PCR (qPCR). B. cereus spore suspensions were subjected to both commercial DNA extraction kits and mechanical DNA extr...
Article
Full-text available
The capacity of two primary growth models to describe Pseudomonas fluorescens and Pseudomonas grimontii biofilms’ development was assessed. The Baranyi and the ‘Logistic with Breaking Delay’ models were applied for biofilms grown in various laboratory and pilot-plant devices, including pipes or mock-ups mimicking vegetables washing tanks in the fre...
Article
Full-text available
The goal of this study was to investigate the effect of growth conditions such as the temperature (20, 30 and 37 °C), incubation duration (24 and 48 h) and surface type (stainless steel and polycarbonate) on the cell surface physicochemical properties and adhesion to abiotic surfaces of biofilm-detached and planktonic Staphylococcus aureus cells. T...
Article
Public authorities, chain stakeholders and consumers are all concerned by microbial food safety. Microbiological hazards are one of the most common causes of food poisoning that has been considered for many years but still on the track nowadays considering the recent foodborne disease outbreaks largely reported by the media. Microbial contamination...
Article
The objective of this study was to investigate the roles of mechanical and chemical actions on the detachment kinetics during CIP of biofilms of Pseudomonas fluorescens at a pilot-plant scale.Biofilms were grown 48 h at 20 °C in diluted milk. Shear stress conditions ranged from 0 (static) to 20 Pa and NaOH concentrations from 0.1 to 0.5% w/w. A sim...
Poster
Full-text available
Various types of surface are used in the food industry and are subject to contamination by microorganisms which can be organized into biofilm. Biofilm is a microorganism complex community that adhere on surface and embedded in an extracellular matrix. The objective of this study was therefore to evaluate the effectiveness of four recovery methods d...
Article
Full-text available
Abiotic surfaces are vulnerable to bacterial adhesion and to biofilm formation. Therefore, it is necessary to understand the parameters that influence bacterial adhesion to find out solutions against cell adhesion and biofilm formation. The ability of pathogenic bacteria to adhere and to form biofilms on abiotic surfaces represents a major health s...
Article
Full-text available
Bacillus cereus displays a high diversity of lifestyles and ecological niches and include beneficial as well as pathogenic strains. These strains are widespread in the environment, are found on inert as well as on living surfaces and contaminate persistently the production lines of the food industry. Biofilms are suspected to play a key role in thi...
Article
In various environments, including that of food processing, adherent bacteria are often subjected to drying conditions. These conditions have been shown to result in changes in the ability of biofilms to cross-contaminate food in contact with them. In this study, we investigated the consequences of a drying step on the further ability of adherent b...
Article
Full-text available
The spores of the Bacillus cereus group (B. cereus, Bacillus anthracis, and Bacillus thuringiensis) are surrounded by a paracrystalline flexible yet resistant layer called exosporium that plays a major role in spore adhesion and virulence. The major constituent of its hairlike surface, the trimerized glycoprotein BclA, is attached to the basal laye...
Article
Using air to displace a viscous fluid contained in Hele-Shaw cell can create a fingering pattern at the interface between the fluids, if the capillary number exceeds a critical value. This Saffman-Taylor instability is revisited for the inverse case of a viscous fluid displacing air, when partially wettable hydrophilic particles are lying on the wa...
Article
The aim of this study was to characterize the Listeria monocytogenes biofilm and particularly the nature of the carbohydrates in the biofilm extracellular matrix and culture supernatant versus to cell wall carbohydrates. L. monocytogenes serotype 1/2a and 4b strains were able to form complex biofilms embedded in an extracellular matrix. The soluble...
Article
This study was designed to establish the presence and function of the mucous layer surrounding spores of Bacillus subtilis. First, an external layer of variable thickness and regularity was often observed on B. subtilis spores. Further analyses were performed on B. subtilis 98/7 spores surrounded by a thick layer. The mechanical removal of the laye...
Article
The Hydrodynamic conditions as well as design and surface properties within fresh-cut food processing equipment create a complex environment for biofilms. A new experimental approach was thus proposed to identify those physical parameters impacting biofilm development in such conditions. A set-up comprising original mock-ups mimicking generic featu...
Article
Bacillus strains are often isolated from biofilms in the food industries. Previous works have demonstrated that sporulation could occur in biofilms, suggesting that biofilms would be a significant source of food contamination with spores. In this study, we investigated the properties of mono-species and mixed Bacillus biofilms and the ability of Ba...
Article
This study was designed to evaluate the respective roles of mechanical and chemical effects on the removal of Bacillus spores during cleaning-in-place. This analysis was performed on 12 strains belonging to the Bacillus cereus group (B. cereus, Bacillus anthracis, Bacillus thuringiensis) or to less related Bacillus species (Bacillus pumilus, Bacill...
Article
The purpose of this study was to quantify the extracellular matrix of Listeria monocytogenes biofilm. A preliminary study was carried out to establish a relationship between phylogenetic lineage of 27 strains and their ability to form biofilm in various conditions. Biofilm formation on microtitre plates of 27 strains of L. monocytogenes belonging t...
Article
Adhesion of microorganisms to the membrane surface is an important and critical first step in biofilm fouling. Fouling mechanisms governing the adhesion of Bacillus cereus spores on a 0.45μm tubular ceramic microfiltration membrane together with the relationship between hydraulic and microbiological cleanliness were investigated. Hydraulic cleanlin...
Article
The role of the BclA domains of B. cereus ATCC 14579 was investigated in order to understand the phenomena involved in the interfacial processes occurring between spores and inert surfaces. This was done by (i) creating deletions in the collagen-like region (CLR) and the C-terminal domain (CTD) of BclA, (ii) building BclA proteins with various leng...
Article
Full-text available
Bacillus cereus spores are surrounded by a loose-fitting layer called the exosporium, whose distal part is mainly formed from glycoproteins. The role played by the exosporium glycoproteins of B. cereus ATCC 14579 (BclA and ExsH) was investigated by considering hydrophobicity and charge, as well as the properties of spore adhesion to stainless steel...
Article
This study was designed to elucidate the influence of spore properties such as the presence of an exosporium, on their ability to adhere to materials. This analysis was performed on 17 strains belonging to the B. cereus group and to less related Bacillus species. We first demonstrated that spores of the B. cereus group, surrounded by an exosporium,...
Article
This study was designed to evaluate how conditions encountered by spores during cleaning-in-place (CIP) procedures affected their surface properties, their viability and ability to contaminate materials. Spores from five Bacillus cereus strains were treated with NaOH at high temperature. Results revealed that high temperatures (exceeding 60 degrees...
Article
Full-text available
The aim of this study was to analyze the cleaning efficiency of polysaccharidases and proteolytic enzymes against biofilms of bacterial species found in food industry processing lines and to study enzyme effects on the composition of extracellular polymeric substances (EPS) and biofilm removal in a Clean-in-Place (CIP) procedure. The screening of 7...
Article
Wall shear stress measurements and the distribution size of turbulent structures at the confined zone near the wall were used in order to investigate the cleanability of a part of a dairy processing line consisting in a manometer and a two-way valve. Geometry of equipment was discerned as an important factor governing the flow behavior and thereaft...
Article
The possible contamination of surfaces of food processing lines during cleaning in place (CIP) procedures was investigated. Experiments were focused on surface contamination of straight pipes and a two-way valve, chosen as an example of complex pieces of equipment. Pipes and a two-way valve were inserted into a CIP rig, at the same time as a series...
Article
The article reports on the selective adhesion of Bacillus cereus spores on patterned and heterogeneously wetted superhydrophobic silicon nanowires surfaces. Superhydrophilic patterns on superhydrophobic silicon nanowire (SiNW) surfaces were prepared by a standard optical lithography technique. Exposure of the patterned surface to a suspension of B....
Chapter
The ability of microorganisms to adhere to inert surfaces, to form biofilms and to resist further cleaning and disinfection procedures varies greatly according to the substratum composition. This chapter first presents materials (stainless steels, elastomers or plastics) used in food industry as well as regulation and requirements regarding food co...
Article
Full-text available
Biofilm formation by 102 Bacillus cereus and B. thuringiensis strains was determined. Strains isolated from soil or involved in digestive tract infections were efficient biofilm formers, whereas strains isolated from other diseases were poor biofilm formers. Cell surface hydrophobicity, the presence of an S layer, and adhesion to epithelial cells w...
Article
Full-text available
In membrane separation processes, biofouling of membranes is now well recognized as a major impediment to their efficient operation and overall performance. This study focuses on the first (attachment) phase of biofouling. We have investigated experimentally the cleanability of a ceramic microfiltration membrane fouled by Bacillus cereus spores in...
Article
Various lipopeptides produced by Bacillus subtilis were examined for their ability to modify the surface hydrophobicity of two substrata, stainless steel (SS) and Teflon. These modifications were evaluated by water contact angle measurements. The effects depended on the lipopeptide, its concentration, and the tested substratum. Treatment of SS with...
Article
The relative hygienic status of 16 stainless steel surfaces, characterised by topography and surface free energy was investigated. B. thuringiensis spores suspended in Bechamel sauce was chosen as the test fouling suspension. Surface topography was assessed using 10 standardised roughness parameters, along with scanning electron microscope observat...
Article
The effect of repeated conditioning procedures (25 runs), consisting of soiling (milk and meat products) and cleaning steps, on the hygienic status, physico-chemical properties and surface chemical composition of stainless steel (SS) surfaces, was investigated. Five SSs differing in grade and finish were used. Both soiling and surface cleaning/cond...
Article
This study was designed to evaluate the occurrence of Bacillus cereus spores with a damaged exosporium and the consequences of such damages on spore adhesion. The analysis of nine strains sporulated under optimal conditions (Spo8-agar, 30 degrees C) revealed that damaged exosporia were systematically found in one strain (B. cereus D17) and occasion...
Article
For the first time a purification process for small RuBisCO (ribulose-1,5-bisphosphate carboxylase/oxygenase) subunit (SRS) was developed from an industrial by-product of alfalfa, taking advantage of its solubility at low pH. Only one protein strip (14 kDa) was clearly detected in the sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-P...
Article
Seven strains of Bacillus cereus isolated from the environment and from patients with diarrheic symptoms were examined from two angles: their spore surface properties, and their ability to adhere to stainless steel and to resist a cleaning in place (CIP) procedure. Our results revealed significant differences in their morphology (size of exosporium...
Article
To analyse the cellular mechanisms that influence Listeria monocytogenes adhesion onto inert surfaces under acidic growth conditions. The adhesion capability of all the strains was significantly reduced after cultivation at constant pH 5 than at constant pH 7 and the cell surface was significantly less hydrophobic at pH 5 than at 7. At pH 5, the an...
Article
This paper investigates a methodology for the characterisation and location of a thin layer of irreversible fouling in a spiral-wound ultrafiltration membrane by using several physico-chemical techniques as SEM-EDX, SEMFEG, FTIR-ATR and AFM. Application to analysis of a spiral-wound PES membrane for UF of skimmed milk, after 4 years of production i...
Article
Coupons of fourteen different stainless steels were investigated in terms of surface chemistry and ease of cleaning. Steel surfaces were exposed to Bacillus cereus spores in static saline solution for 2 h. Surfaces were rinsed and then covered with whole milk and allowed to dry. Surfaces were then cleaned in an experimental flow system that mimics...
Article
Through a study of the effect of hydrodynamics on the cleanability of complex equipment, this work demonstrates the need for hygienic design to significantly improve food safety. A three-way valve was contaminated with Bacillus spores, isolated from a dairy production line and then suspended in custard. The valve was cleaned by a CIP procedure, inc...
Article
The effects of adhesion and of biofilm development on the efficiency of cleaning and disinfection procedures were investigated on three strains belonging to the E. coli, C. freundii and K. pneumoniae species, which were able to raise more or less complex biofilms. Resistance to a rinsing procedure was strain dependent but not related to the biofilm...
Article
The hygienic status of stainless steels used for food equipment was investigated by means of the number of residual adhering Bacillus cereus spores after a complete run of soiling and cleaning in place procedure. The 14 materials tested (304, 316 and 430 grades; pickling (2B), bright annealed (2R), and electropolished finishes) were shown to be hig...