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Bagel A, Bouvier-Crozier M, Canizares M, Hamadou B, Courcol L, Lopez C, Michel V, Douellou T, Sergentet D. Surface proteins of Shiga toxin-producing Escherichia coli mediate association with milk fat globules in raw milk. Front Microbiol 2023; 14:1156374. [PMID: 37426002 PMCID: PMC10328742 DOI: 10.3389/fmicb.2023.1156374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 05/29/2023] [Indexed: 07/11/2023] Open
Abstract
Introduction By adhering to host cells and colonizing tissues, bacterial pathogens can successfully establish infection. Adhesion is considered the first step of the infection process and bacterial adhesion to anti-adhesive compounds is now seen as a promising strategy to prevent infectious diseases. Among the natural sources of anti-adhesive molecules, the membrane of milk fat globules (MFGs) is of interest because of its compositional diversity of proteins and glycoconjugates. However, few studies have focused on the bacterial molecules involved in MFG- mediated inhibition of bacterial adhesion to enterocytes. Methods We used three pathogenic Shiga toxin-producing Escherichia coli (STEC) strains (O26:H11 str. 21765, O157:H7 str. EDL933, and O103:H3 str. PMK5) as models to evaluate whether STEC surface proteins are involved in the affinity of STEC for MFG membrane proteins (MFGMPs). The affinity of STEC for MFGMPs was assessed both indirectly by a natural raw milk creaming test and directly by an adhesion test. Mass spectrometry was used to identify enriched STEC proteins within the protein fraction of MFGMs. Bacterial mutants were constructed and their affinity to MFGs were measured to confirm the role of the identified proteins. Results We found that free STEC surface proteins inhibit the concentration of the pathogen in the MFG-enriched cream in a strain-dependent manner. Moreover, the OmpA and FliC proteins were identified within the protein fraction of MFGMs. Our results suggest that FliC protein participates in STEC adhesion to MFGMPs but other STEC molecules may also participate. Discussion For the first time, this study highlighted, the involvement of STEC surface proteins in the affinity for MFGs. The mechanism of STEC-MFG association is still not fully understood but our results confirm the existence of receptor/ligand type interactions between the bacteria and MFGs. Further studies are needed to identify and specify the molecules involved in this interaction. These studies should consider the likely involvement of several factors, including adhesion molecules, and the diversity of each STEC strain.
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Affiliation(s)
- Arthur Bagel
- Bacterial Opportunistic Pathogens and Environment Research Group, UMR 5557 Ecologie Microbienne Lyon, CNRS, Université de Lyon, VetAgro Sup, INRAE, Marcy-l’Etoile, France
| | - Marion Bouvier-Crozier
- Bacterial Opportunistic Pathogens and Environment Research Group, UMR 5557 Ecologie Microbienne Lyon, CNRS, Université de Lyon, VetAgro Sup, INRAE, Marcy-l’Etoile, France
- Laboratoire d’Etudes des Microorganismes Alimentaires Pathogènes—French National Reference Laboratory for Escherichia coli Including Shiga Toxin-Producing E. coli (NRL-STEC), Université de Lyon, VetAgro Sup—Campus Vétérinaire, Marcy-l’Etoile, France
| | - Mélissa Canizares
- Laboratoire d’Etudes des Microorganismes Alimentaires Pathogènes—French National Reference Laboratory for Escherichia coli Including Shiga Toxin-Producing E. coli (NRL-STEC), Université de Lyon, VetAgro Sup—Campus Vétérinaire, Marcy-l’Etoile, France
| | - Badis Hamadou
- Laboratoire d’Etudes des Microorganismes Alimentaires Pathogènes—French National Reference Laboratory for Escherichia coli Including Shiga Toxin-Producing E. coli (NRL-STEC), Université de Lyon, VetAgro Sup—Campus Vétérinaire, Marcy-l’Etoile, France
| | - Louise Courcol
- Bacterial Opportunistic Pathogens and Environment Research Group, UMR 5557 Ecologie Microbienne Lyon, CNRS, Université de Lyon, VetAgro Sup, INRAE, Marcy-l’Etoile, France
| | | | | | - Thomas Douellou
- Bacterial Opportunistic Pathogens and Environment Research Group, UMR 5557 Ecologie Microbienne Lyon, CNRS, Université de Lyon, VetAgro Sup, INRAE, Marcy-l’Etoile, France
| | - Delphine Sergentet
- Bacterial Opportunistic Pathogens and Environment Research Group, UMR 5557 Ecologie Microbienne Lyon, CNRS, Université de Lyon, VetAgro Sup, INRAE, Marcy-l’Etoile, France
- Laboratoire d’Etudes des Microorganismes Alimentaires Pathogènes—French National Reference Laboratory for Escherichia coli Including Shiga Toxin-Producing E. coli (NRL-STEC), Université de Lyon, VetAgro Sup—Campus Vétérinaire, Marcy-l’Etoile, France
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Bagel A, Delignette-Muller ML, Lopez C, Michel V, Sergentet D, Douellou T. Strain- and serotype-dependent affinity of Shiga toxin-producing Escherichia coli for bovine milk fat globules. J Dairy Sci 2022; 105:8688-8704. [PMID: 36175225 DOI: 10.3168/jds.2022-21840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 07/01/2022] [Indexed: 11/19/2022]
Abstract
Shiga toxin-producing Escherichia coli (STEC) are widely detected in raw milk products intended for human consumption. Although STEC are a worldwide public health problem, the pathogenicity of STEC in cheese remains unclear. In fact, bacterial association with compounds in raw milk cheeses could reduce their pathogenicity. A previous study showed the association of 2 STEC strains with raw milk cream in a natural creaming assay. Different concentrations of each strain were required to saturate the cream. In this study, we hypothesized that all STEC strains could be associated with milk fat globules (MFG) in raw milk and that the bacterial load required for saturation of the cream is serotype dependent. We evaluated the affinity of STEC strains belonging to the O157:H7, O26:H11, and O103:H2 serotypes for bovine raw milk cream and analyzed saturation of the cream layer by natural creaming assay. We used 12 STEC strains and 3 strains belonging to another pathotype to assess the effects of serotypes on this phenomenon. We performed sucrose density gradient centrifugation assays with 2 STEC model strains to confirm the results obtained by natural creaming. The localization of STEC within MFG-enriched creams was observed by confocal and electron microscopy. We recovered approximately 10 times more STEC from the cream layer after natural creaming than from raw bovine milk. The concentration of STEC required to saturate the cream layer (the saturation concentration) was estimated for each strain by nonlinear regression, highlighting a strain and serotype effect. Moreover, the concentration of STEC in the cream was milk fat level dependent. However, even in nonsaturating conditions, a high level of STEC was still present in the aqueous phase, after fat separation. Thus, natural creaming should not be used as the sole preventive measure to remove STEC from naturally contaminated raw milk. The results of our study suggest that cream saturation is a complex mechanism, most likely involving specific interactions between STEC and raw MFG.
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Affiliation(s)
- A Bagel
- Bacterial Opportunistic Pathogens and Environment Research Group, Université de Lyon, UMR 5557 Ecologie Microbienne Lyon, National Center of Scientific Research, VetAgro Sup, 69280 Marcy-l'Etoile, France
| | - M-L Delignette-Muller
- Laboratoire de Biométrie et Biologie Evolutive, UMR 5558, Université de Lyon, VetAgro Sup, National Center of Scientific Research, 69622 Villeurbanne, France
| | - C Lopez
- INRAE, UR BIA, F-44316, Nantes, France
| | - V Michel
- Actalia, 74800 La Roche-sur-Foron, France
| | - D Sergentet
- Bacterial Opportunistic Pathogens and Environment Research Group, Université de Lyon, UMR 5557 Ecologie Microbienne Lyon, National Center of Scientific Research, VetAgro Sup, 69280 Marcy-l'Etoile, France; VetAgro Sup-Campus Vétérinaire, Laboratoire d'Etudes des Microorganismes Alimentaires Pathogènes-French National Reference Laboratory for Escherichia coli including Shiga toxin-producing E. coli (NRL-STEC), Université de Lyon, 69280, Marcy-l'Etoile, France.
| | - T Douellou
- Bacterial Opportunistic Pathogens and Environment Research Group, Université de Lyon, UMR 5557 Ecologie Microbienne Lyon, National Center of Scientific Research, VetAgro Sup, 69280 Marcy-l'Etoile, France
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High throughput screening of technological and biopreservation traits of a large set of wild lactic acid bacteria from Brazilian artisanal cheeses. Food Microbiol 2021; 100:103872. [PMID: 34416969 DOI: 10.1016/j.fm.2021.103872] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 07/15/2021] [Accepted: 07/16/2021] [Indexed: 11/21/2022]
Abstract
This study aimed to evaluate technological (acidification, proteolysis, lipolysis, resistance to low pH, NaCl, and bile salts) and biopreservation (antimicrobial activity against foodborne pathogens) features of 1002 LAB by high throughput screening (HTS) methods. The LAB was isolated from 11 types of Brazilian artisanal cheeses (BAC) marketed in the main 5 producing regions. Remarkable intra-species variability in acidification rates have been found, which was most pronounced between isolates from Mina's artisanal cheeses, Caipira and Coalho cheeses. Lacticaseibacillus paracasei and Levilactobacillus brevis showed the fastest acidification rate; however, all isolates showed slower acidification rates than a lactococcal control strain (4.3 × lower). When testing inhibitory effects, > 75% of LAB isolates could inhibit the growth of Staphylococcus aureus ATCC 19095 and Listeria monocytogenes ATCC 7644. Two of these isolates, identified as Lactiplantibacillus plantarum and Lentilactobacillus buchneri, the sterile and neutral supernatants alone, were sufficient to inhibit L. monocytogenes growth. Principal component analysis (PCA) allowed the identification of functional groups based on proteolytic and lipolytic activity, osmotic stress resistance, and inhibition of L. monocytogenes. The type of cheese the isolates were recovered from influenced properties such as anti-listerial compounds and lipolytic enzyme production. The use of HTS and multivariate statistics allowed insights into a diverse set of LAB technological and biopreservation properties. These findings allow a profound knowledge of the heterogeneity of a large set of isolates, which can be further used to design starter cultures with varied and combined properties, such as biopreservation and technological features. Besides that, HTS makes it possible to analyze a vast panel of LAB strains, reducing costs and time within laboratory analysis, while avoiding the loss of information once all LAB are tested at the same time (differently from the traditional labor-intensive approach, in which a few numbers of strains is tested per time).
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Impact of Lacticaseibacillus rhamnosus GG on the Emulsion Stability of Raw Milk. Foods 2021; 10:foods10050991. [PMID: 34062810 PMCID: PMC8147333 DOI: 10.3390/foods10050991] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 04/27/2021] [Accepted: 04/28/2021] [Indexed: 12/13/2022] Open
Abstract
Lactic acid bacteria (LAB) have been studied for several decades to understand and determine their mechanism and interaction within the matrix into which they are introduced. This study aimed to determine the spatial distribution of Lacticaseibacillus rhamnosus GG (LGG) in a dairy matrix and to decipher its behaviour towards milk components, especially fat globules. Two strains of this widely studied bacterium with expected probiotic effects were used: LGG WT with pili on the cell surface and its pili-depleted mutant—LGG ΔspaCBA—in order to determine the involvement of these filamentous proteins. In this work, it was shown that LGG ΔspaCBA was able to limit creaming with a greater impact than the wild-type counterpart. Moreover, confocal imaging evidenced a preferential microbial distribution as aggregates for LGG WT, while the pili-depleted strain tended to be homogenously distributed and found as individual chains. The observed differences in creaming are attributed to the indirect implication of SpaCBA pili. Indeed, the bacteria-to-bacteria interaction surpassed the bacteria-to-matrix interaction, reducing the bacterial surface exposed to raw milk. Conversely, LGG ΔspaCBA may form a physical barrier responsible for preventing milk fat globules from rising to the surface.
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Zhang L, García-Cano I, Jiménez-Flores R. Characterization of adhesion between Limosilactobacillus reuteri and milk phospholipids by density gradient and gene expression. ACTA ACUST UNITED AC 2020; 1:29-35. [PMID: 36341148 PMCID: PMC9623644 DOI: 10.3168/jdsc.2020-18939] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 08/08/2020] [Indexed: 01/02/2023]
Abstract
The interaction between lactic acid bacteria and milk phospholipids can be semi-quantified Binding and interaction between milk phospholipids and LAB is mediated by gene modulation Two of three genes for surface adhesion corresponded directly with binding results This method identifies LAB that adhere tightly to the intestinal membranes
The benefits of fermented dairy products, in particular the presence of lactic acid bacteria (LAB) and milk phospholipids (MPL), seem to correlate with positive effects on human health. We hypothesize that one aspect of this benefit is the adhesion of LAB to the milk fat globule membrane via the interaction of LAB and MPL. Our first objective was to present a method to characterize and quantify such adhesion and investigate its association with a physical test. Our second objective was to further analyze the mechanism of interaction by analyzing expression of 3 previously reported surface binding-promoting genes (MapA, Cnb, and CmbA). We categorized adhesion between MPL and LAB by observing the distribution of MPL in corresponding bacterial cultures. Our working hypothesis was that any interaction or adhesion between these 2 components would yield differences in the distribution of MPL. Out of 122 LAB tested, 27% showed what could be characterized as adhesion; 38% of these strains were Limosilactobacillus reuteri. Further characterization of adhesion was carried out using an reverse transcription quantitative-PCR experiment, which demonstrated that the relative expression level of CmbA was positively associated with that adhesion. In addition, supplementation of MPL caused overexpression of MapA and Cnb in L. reuteri OSU-PECh-37A and OSU-PECh-48. This study indicated strain-specific adhesion between MPL and LAB and suggested that CmbA, which encodes a surface protein, is a potential factor involved in that adhesion. A better understanding of interactions between MPL and LAB may contribute to the design of new functional products and improve the delivery of these bioactive ingredients to their target site of action.
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Gomand F, Mitchell WH, Burgain J, Petit J, Borges F, Spagnolie SE, Gaiani C. Shaving and breaking bacterial chains with a viscous flow. SOFT MATTER 2020; 16:9273-9291. [PMID: 32930313 DOI: 10.1039/d0sm00292e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Some food and ferment manufacturing steps such as spray-drying result in the application of viscous stresses to bacteria. This study explores how a viscous flow impacts both bacterial adhesion functionality and bacterial cell organization using a combined experimental and modeling approach. As a model organism we study Lactobacillus rhamnosus GG (LGG) "wild type" (WT), known to feature strong adhesive affinities towards beta-lactoglobulin thanks to pili produced by the bacteria on cell surfaces, along with three cell-surface mutant strains. Applying repeated flows with high shear-rates reduces bacterial adhesive abilities up to 20% for LGG WT. Bacterial chains are also broken by this process, into 2-cell chains at low industrial shear rates, and into single cells at very high shear rates. To rationalize the experimental observations we study numerically and analytically the Stokes equations describing viscous fluid flow around a chain of elastically connected spheroidal cell bodies. In this model setting we examine qualitatively the relationship between surface traction (force per unit area), a proxy for pili removal rate, and bacterial chain length (number of cells). Longer chains result in higher maximal surface tractions, particularly at the chain extremities, while inner cells enjoy a small protection from surface tractions due to hydrodynamic interactions with their neighbors. Chain rupture therefore may act as a mechanism to preserve surface adhesive functionality in bacteria.
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Affiliation(s)
- Faustine Gomand
- LIBio - Université de Lorraine, 2 avenue de la Forêt de Haye, 54500 Vandoeuvre-lès-Nancy, France. and Department of Mathematics, University of Wisconsin-Madison, 480 Lincoln Dr., Madison, WI 53706, USA.
| | - William H Mitchell
- Department of Mathematics, Statistics, and Computer Science, Macalester College, 1600 Grand Ave, St. Paul, MN 55105, USA.
| | - Jennifer Burgain
- LIBio - Université de Lorraine, 2 avenue de la Forêt de Haye, 54500 Vandoeuvre-lès-Nancy, France.
| | - Jérémy Petit
- LIBio - Université de Lorraine, 2 avenue de la Forêt de Haye, 54500 Vandoeuvre-lès-Nancy, France.
| | - Frédéric Borges
- LIBio - Université de Lorraine, 2 avenue de la Forêt de Haye, 54500 Vandoeuvre-lès-Nancy, France.
| | - Saverio E Spagnolie
- Department of Mathematics, University of Wisconsin-Madison, 480 Lincoln Dr., Madison, WI 53706, USA.
| | - Claire Gaiani
- LIBio - Université de Lorraine, 2 avenue de la Forêt de Haye, 54500 Vandoeuvre-lès-Nancy, France.
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Probing the surface ultrastructure of Brevibacillus laterosporus using atomic force microscopy. Micron 2020; 131:102827. [PMID: 31951938 DOI: 10.1016/j.micron.2020.102827] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Revised: 01/12/2020] [Accepted: 01/12/2020] [Indexed: 11/21/2022]
Abstract
One of the main obstacles to studying the surface ultrastructure of microbial cells by atomic force microscopy (AFM) is determining how to immobilize live cells on the AFM substrates. Each method has its own advantages and disadvantages. The aim of this study was to characterize a new simple and inexpensive method using two types of polyethersulfone (PES) membrane filters that differ in pore size (micropore and nanopore) to immobilize live and dead Brevibacillus laterosporus for AFM imaging. B. laterosporus was easily trapped by the microporous PES membrane, facilitating the successful AFM scanning of the bacterial surface ultrastructure. In addition, B. laterosporus strongly attached to the nanoporous membranes and withstood the pulling forces exerted by the AFM tip during scanning. These methods of immobilization did not affect the cell viability. The nanostructure and roughness of the bacterial surface were also observed for live, fixed, and air-dried cells. Live and dead bacteria displayed similar morphologies at low resolution, while at high resolution, live bacteria displayed a more convoluted surface ("brain-like structure").
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Gomand F, Borges F, Guerin J, El-Kirat-Chatel S, Francius G, Dumas D, Burgain J, Gaiani C. Adhesive Interactions Between Lactic Acid Bacteria and β-Lactoglobulin: Specificity and Impact on Bacterial Location in Whey Protein Isolate. Front Microbiol 2019; 10:1512. [PMID: 31333617 PMCID: PMC6617547 DOI: 10.3389/fmicb.2019.01512] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 06/17/2019] [Indexed: 12/11/2022] Open
Abstract
In the last decade, there has been an increasing interest in the potential health effects associated with the consumption of lactic acid bacteria (LAB) in foods. Some of these bacteria such as Lactobacillus rhamnosus GG (LGG) are known to adhere to milk components, which may impact their distribution and protection within dairy matrices and therefore is likely to modulate the efficiency of their delivery. However, the adhesive behavior of most LAB, as well as its effect on food structuration and on the final bacterial distribution within the food matrix remain very poorly studied. Using a recently developed high-throughput approach, we have screened a collection of 73 LAB strains for their adhesive behavior toward the major whey protein β-lactoglobulin. Adhesion was then studied by genomics in relation to common bacterial surface characteristics such as pili and adhesion-related domain containing proteins. Representative adhesive and non-adhesive strains have been studied in further depth through biophysical measurement using atomic force microscopy (AFM) and a relation with bacterial distribution in whey protein isolate (WPI) solution has been established. AFM measurements have revealed that bacterial adhesion to β-lactoglobulin is highly specific and cannot be predicted accurately using only genomic information. Non-adhesive strains were found to remain homogeneously distributed in solution whereas adhesive strains gathered in flocs. These findings show that several LAB strains are able to adhere to β-lactoglobulin, whereas this had only been previously observed on LGG. We also show that these adhesive interactions present similar characteristics and are likely to impact bacterial location and distribution in dairy matrices containing β-lactoglobulin. This may help with designing more efficient dairy food matrices for optimized LAB delivery.
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Affiliation(s)
- Faustine Gomand
- Laboratoire d'Ingénierie des Biomolécules, Université de Lorraine, Vandœuvre-lès-Nancy, France
| | - Frédéric Borges
- Laboratoire d'Ingénierie des Biomolécules, Université de Lorraine, Vandœuvre-lès-Nancy, France
| | - Justine Guerin
- Laboratoire d'Ingénierie des Biomolécules, Université de Lorraine, Vandœuvre-lès-Nancy, France
| | - Sofiane El-Kirat-Chatel
- CNRS, Laboratoire de Chimie Physique et Microbiologie pour les Matériaux et l'Environnement (LCPME), UMR 7564, Université de Lorraine, Villers-lès-Nancy, France
| | - Gregory Francius
- CNRS, Laboratoire de Chimie Physique et Microbiologie pour les Matériaux et l'Environnement (LCPME), UMR 7564, Université de Lorraine, Villers-lès-Nancy, France
| | - Dominique Dumas
- Plateforme d'Imagerie et de Biophysique Cellulaire de Nancy (PTIBC IBISA-NANCY), UMS 2008, IMOPA UMR 7365 - Université de Lorraine, Vandœuvre-lès-Nancy, France
| | - Jennifer Burgain
- Laboratoire d'Ingénierie des Biomolécules, Université de Lorraine, Vandœuvre-lès-Nancy, France
| | - Claire Gaiani
- Laboratoire d'Ingénierie des Biomolécules, Université de Lorraine, Vandœuvre-lès-Nancy, France
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