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Purk L, Kitsiou M, Ioannou C, El Kadri H, Costello KM, Gutierrez Merino J, Klymenko O, Velliou EG. Unravelling the impact of fat content on the microbial dynamics and spatial distribution of foodborne bacteria in tri-phasic viscoelastic 3D models. Sci Rep 2023; 13:21811. [PMID: 38071223 PMCID: PMC10710490 DOI: 10.1038/s41598-023-48968-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 12/02/2023] [Indexed: 12/18/2023] Open
Abstract
The aim of the current study is to develop and characterise novel complex multi-phase in vitro 3D models, for advanced microbiological studies. More specifically, we enriched our previously developed bi-phasic polysaccharide (Xanthan Gum)/protein (Whey Protein) 3D model with a fat phase (Sunflower Oil) at various concentrations, i.e., 10%, 20%, 40% and 60% (v/v), for better mimicry of the structural and biochemical composition of real food products. Rheological, textural, and physicochemical analysis as well as advanced microscopy imaging (including spatial mapping of the fat droplet distribution) of the new tri-phasic 3D models revealed their similarity to industrial food products (especially cheese products). Furthermore, microbial growth experiments of foodborne bacteria, i.e., Listeria monocytogenes, Escherichia coli, Pseudomonas aeruginosa and Lactococcus lactis on the surface of the 3D models revealed very interesting results, regarding the growth dynamics and distribution of cells at colony level. More specifically, the size of the colonies formed on the surface of the 3D models, increased substantially for increasing fat concentrations, especially in mid- and late-exponential growth phases. Furthermore, colonies formed in proximity to fat were substantially larger as compared to the ones that were located far from the fat phase of the models. In terms of growth location, the majority of colonies were located on the protein/polysaccharide phase of the 3D models. All those differences at microscopic level, that can directly affect the bacterial response to decontamination treatments, were not captured by the macroscopic kinetics (growth dynamics), which were unaffected from changes in fat concentration. Our findings demonstrate the importance of developing structurally and biochemically complex 3D in vitro models (for closer proximity to industrial products), as well as the necessity of conducting multi-level microbial analyses, to better understand and predict the bacterial behaviour in relation to their biochemical and structural environment. Such studies in advanced 3D environments can assist a better/more accurate design of industrial antimicrobial processes, ultimately, improving food safety.
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Affiliation(s)
- Lisa Purk
- Bioprocess and Biochemical Engineering Group (BioProChem), Department of Chemical and Process Engineering, University of Surrey, Guildford, GU2 7XH, UK
- Centre for 3D Models of Health and Disease, Division of Surgery and Interventional Science, University College London, Charles Bell House, 43-45 Foley Street, Fitzrovia, London, W1W 7TY, UK
| | - Melina Kitsiou
- Bioprocess and Biochemical Engineering Group (BioProChem), Department of Chemical and Process Engineering, University of Surrey, Guildford, GU2 7XH, UK
- Centre for 3D Models of Health and Disease, Division of Surgery and Interventional Science, University College London, Charles Bell House, 43-45 Foley Street, Fitzrovia, London, W1W 7TY, UK
| | - Christina Ioannou
- Bioprocess and Biochemical Engineering Group (BioProChem), Department of Chemical and Process Engineering, University of Surrey, Guildford, GU2 7XH, UK
| | - Hani El Kadri
- Bioprocess and Biochemical Engineering Group (BioProChem), Department of Chemical and Process Engineering, University of Surrey, Guildford, GU2 7XH, UK
| | - Katherine M Costello
- Bioprocess and Biochemical Engineering Group (BioProChem), Department of Chemical and Process Engineering, University of Surrey, Guildford, GU2 7XH, UK
| | | | - Oleksiy Klymenko
- Bioprocess and Biochemical Engineering Group (BioProChem), Department of Chemical and Process Engineering, University of Surrey, Guildford, GU2 7XH, UK
| | - Eirini G Velliou
- Bioprocess and Biochemical Engineering Group (BioProChem), Department of Chemical and Process Engineering, University of Surrey, Guildford, GU2 7XH, UK.
- Centre for 3D Models of Health and Disease, Division of Surgery and Interventional Science, University College London, Charles Bell House, 43-45 Foley Street, Fitzrovia, London, W1W 7TY, UK.
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2
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Saint Martin C, Caccia N, Darsonval M, Gregoire M, Combeau A, Jubelin G, Dubois-Brissonnet F, Leroy S, Briandet R, Desvaux M. Spatially localised expression of the glutamate decarboxylase gadB in Escherichia coli O157:H7 microcolonies in hydrogel matrices. NPJ Sci Food 2023; 7:55. [PMID: 37838796 PMCID: PMC10576782 DOI: 10.1038/s41538-023-00229-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 10/02/2023] [Indexed: 10/16/2023] Open
Abstract
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). Taking advantage of confocal laser scanning microscopy combined with a genetically-engineered dual fluorescent reporter system, it was possible to visualise the spatial patterns of bacterial gene expression from in-gel microcolonies. In E. coli O157:H7 microcolonies, gadB showed radically different expression patterns between neutral (pH 7) or acidic (pH 5) hydrogels. Differential spatial expression was determined in acidic hydrogels with a strong expression of gadB at the microcolony periphery. Strikingly, very similar spatial patterns of gadB expression were further observed for E. coli O157:H7 grown in the presence of L. lactis. Considering the ingestion of contaminated foodstuff, survival of E. coli O157:H7 to acidic stomachal stress (pH 2) was significantly increased for bacterial cells grown in microcolonies in acidic hydrogels compared to planktonic cells. These findings have significant implications for risk assessment and public health as they highlight inherent differences in bacterial physiology and virulence between liquid and structured food products. The contrasting characteristics observed underscore the need to consider the distinct challenges posed by these food types, thereby emphasising the importance of tailored risk mitigation strategies.
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Affiliation(s)
- Cédric Saint Martin
- Université Paris-Saclay, INRAE, AgroParisTech, MICALIS Institute, 78350, Jouy-en-Josas, France
- INRAE, UCA, UMR0454 MEDIS, 63000, Clermont-Ferrand, France
| | - Nelly Caccia
- INRAE, UCA, UMR0454 MEDIS, 63000, Clermont-Ferrand, France
| | - Maud Darsonval
- Université Paris-Saclay, INRAE, AgroParisTech, MICALIS Institute, 78350, Jouy-en-Josas, France
| | - Marina Gregoire
- Université Paris-Saclay, INRAE, AgroParisTech, MICALIS Institute, 78350, Jouy-en-Josas, France
| | - Arthur Combeau
- Université Paris-Saclay, INRAE, AgroParisTech, MICALIS Institute, 78350, Jouy-en-Josas, France
| | | | | | - Sabine Leroy
- INRAE, UCA, UMR0454 MEDIS, 63000, Clermont-Ferrand, France
| | - Romain Briandet
- Université Paris-Saclay, INRAE, AgroParisTech, MICALIS Institute, 78350, Jouy-en-Josas, France.
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3
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De Marchi S, García-Lojo D, Bodelón G, Pérez-Juste J, Pastoriza-Santos I. Plasmonic Au@Ag@mSiO 2 Nanorattles for In Situ Imaging of Bacterial Metabolism by Surface-Enhanced Raman Scattering Spectroscopy. ACS Appl Mater Interfaces 2021; 13:61587-61597. [PMID: 34927427 PMCID: PMC8719315 DOI: 10.1021/acsami.1c21812] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
It is well known that microbial populations and their interactions are largely influenced by their secreted metabolites. Noninvasive and spatiotemporal monitoring and imaging of such extracellular metabolic byproducts can be correlated with biological phenotypes of interest and provide new insights into the structure and development of microbial communities. Herein, we report a surface-enhanced Raman scattering (SERS) hybrid substrate consisting of plasmonic Au@Ag@mSiO2 nanorattles for optophysiological monitoring of extracellular metabolism in microbial populations. A key element of the SERS substrate is the mesoporous silica shell encapsulating single plasmonic nanoparticles, which furnishes colloidal stability and molecular sieving capabilities to the engineered nanostructures, thereby realizing robust, sensitive, and reliable measurements. The reported SERS-based approach may be used as a powerful tool for deciphering the role of extracellular metabolites and physicochemical factors in microbial community dynamics and interactions.
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Affiliation(s)
- Sarah De Marchi
- CINBIO,
Universidade de Vigo, Departamento de Química Física, Campus Universitario As Lagoas, Marcosende, 36310 Vigo, Spain
- Galicia
Sur Health Research Institute (IIS Galicia Sur), SERGAS-UVIGO, 36310 Vigo, Spain
| | - Daniel García-Lojo
- CINBIO,
Universidade de Vigo, Departamento de Química Física, Campus Universitario As Lagoas, Marcosende, 36310 Vigo, Spain
- Galicia
Sur Health Research Institute (IIS Galicia Sur), SERGAS-UVIGO, 36310 Vigo, Spain
| | - Gustavo Bodelón
- CINBIO,
Universidade de Vigo, Departamento de Química Física, Campus Universitario As Lagoas, Marcosende, 36310 Vigo, Spain
- Galicia
Sur Health Research Institute (IIS Galicia Sur), SERGAS-UVIGO, 36310 Vigo, Spain
| | - Jorge Pérez-Juste
- CINBIO,
Universidade de Vigo, Departamento de Química Física, Campus Universitario As Lagoas, Marcosende, 36310 Vigo, Spain
- Galicia
Sur Health Research Institute (IIS Galicia Sur), SERGAS-UVIGO, 36310 Vigo, Spain
| | - Isabel Pastoriza-Santos
- CINBIO,
Universidade de Vigo, Departamento de Química Física, Campus Universitario As Lagoas, Marcosende, 36310 Vigo, Spain
- Galicia
Sur Health Research Institute (IIS Galicia Sur), SERGAS-UVIGO, 36310 Vigo, Spain
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4
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Kapoore RV, Padmaperuma G, Maneein S, Vaidyanathan S. Co-culturing microbial consortia: approaches for applications in biomanufacturing and bioprocessing. Crit Rev Biotechnol 2021; 42:46-72. [PMID: 33980092 DOI: 10.1080/07388551.2021.1921691] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The application of microbial co-cultures is now recognized in the fields of biotechnology, ecology, and medicine. Understanding the biological interactions that govern the association of microorganisms would shape the way in which artificial/synthetic co-cultures or consortia are developed. The ability to accurately predict and control cell-to-cell interactions fully would be a significant enabler in synthetic biology. Co-culturing method development holds the key to strategically engineer environments in which the co-cultured microorganism can be monitored. Various approaches have been employed which aim to emulate the natural environment and gain access to the untapped natural resources emerging from cross-talk between partners. Amongst these methods are the use of a communal liquid medium for growth, use of a solid-liquid interface, membrane separation, spatial separation, and use of microfluidics systems. Maximizing the information content of interactions monitored is one of the major challenges that needs to be addressed by these designs. This review critically evaluates the significance and drawbacks of the co-culturing approaches used to this day in biotechnological applications, relevant to biomanufacturing. It is recommended that experimental results for a co-cultured species should be validated with different co-culture approaches due to variations in interactions that could exist as a result of the culturing method selected.
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Affiliation(s)
- Rahul Vijay Kapoore
- Department of Chemical and Biological Engineering, The University of Sheffield, Sheffield, UK.,Department of Biosciences, College of Science, Swansea University, Swansea, UK
| | - Gloria Padmaperuma
- Department of Chemical and Biological Engineering, The University of Sheffield, Sheffield, UK
| | - Supattra Maneein
- Department of Chemical and Biological Engineering, The University of Sheffield, Sheffield, UK.,Department of Pharmaceutical, Chemical & Environmental Sciences, The University of Greenwich, Kent, UK
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Haktanir I, Masoura M, Mantzouridou FT, Gkatzionis K. Mechanism of antimicrobial activity of honeybee (Apis mellifera) venom on Gram-negative bacteria: Escherichia coli and Pseudomonas spp. AMB Express 2021; 11:54. [PMID: 33835274 PMCID: PMC8035396 DOI: 10.1186/s13568-021-01214-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 03/29/2021] [Indexed: 11/17/2022] Open
Abstract
Honeybee venom (Apitoxin, BV), a secretion substance expelled from the venom gland of bees, has being reported as antimicrobial against various bacterial species; however, the mechanism of action remains uncharacterized. In this study, the antibacterial activity of BV was investigated on hygiene indicator Escherichia coli and the environmental pathogen and spoilage bacterial species, Pseudomonas putida and Pseudomonas fluorescens. An array of methods was combined to elucidate the mode of action of BV. Viability by culture on media was combined with assessing cell injury with flow cytometry analysis. ATP depletion was monitored as an indicator to metabolic activity of cells, by varying BV concentration (75, 225and 500 µg/mL), temperature (25 \documentclass[12pt]{minimal}
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\begin{document}$$^\circ \complement $$\end{document}∘∁), and time of exposure (0 to 24 h). Venom presented moderate inhibitory effect on E. coli by viability assay, caused high membrane permeability and significant ATP loss where the effect was increased by increased concentration. The viability of P. putida was reduced to a greater extent than other tested bacteria at comparable venom concentrations and was dictated by exposure time. On the contrary, P. fluorescens appeared less affected by venom based on viability; however, flow cytometry and ATP analysis highlighted concentration- and time-dependent effect of venom. According to Transmission Electron Microscopy results, the deformation of the cell wall was evident for all species. This implies a common mechanism of action of the BV which is as follows: the cell wall destruction, change of membrane permeability, leakage of cell contents, inactivation of metabolic activity and finally cell death.
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Verheyen D, Bolívar A, Pérez-Rodríguez F, Baka M, Skåra T, Van Impe JF. Isolating the effect of fat content on Listeria monocytogenes growth dynamics in fish-based emulsion and gelled emulsion systems. Food Control 2020. [DOI: 10.1016/j.foodcont.2019.106874] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Mohammadi S, Nadaraja AV, Luckasavitch K, Jain MC, June Roberts D, Zarifi MH. A Label-Free, Non-Intrusive, and Rapid Monitoring of Bacterial Growth on Solid Medium Using Microwave Biosensor. IEEE Trans Biomed Circuits Syst 2020; 14:2-11. [PMID: 31715571 DOI: 10.1109/tbcas.2019.2952841] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Microwave resonator sensors are attractive for their contactless and label-free capability of monitoring bacterial growth in liquid media. This paper outlines a new label-free microwave biosensor based on a pair of planar split ring resonators for non-invasive monitoring of bacterial growth on a solid agar media. The sensor is comprised of two split ring resonators with slightly different resonant frequencies for differential operation. The transmission coefficient (S21) of the sensor is considered as the sensor's response with a designed and measured quality factor above 200 to ensure a high-resolution operation of the biosensor. Two resonant frequencies of 1.95 and 2.11 GHz represent the sensing signal and the reference signal, respectively. The developed sensor demonstrates high performance in monitoring the growth dynamics of Escherichia coli (E. coli) on Luria-Bertani (LB) agar with 4 mm thickness. The sensor's resonant amplitude response demonstrated 0.5 dB variation corresponding to the bacterial growth over 48 hours when bacteria were spread on LB agar starting with initial OD600 = 1.5. Moreover, 0.6 dB change in the sensor's response was observed over 96 hours of bacterial growth starting with an initial OD600 = 1.17 spotted on LB agar. The measured results fit well to the curves created using Richards' bacterial growth model, showing the strength of the sensor as a potential candidate for use in predictive food microbiology systems.
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Wang L, He Y, Swanson CS, He Q, Mintah BK, Gao E, Zheng X, He M. Optimization of Medium Composition and Culture Conditions for Cell Multiplication of a High Quality Milk Beer Fermentation Yeast (<i>Kluyveromyces marxianus</i>). FSTR 2020. [DOI: 10.3136/fstr.26.351] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Liang Wang
- School of Food and Biological Engineering, Jiangsu University
| | - Yuting He
- School of Food and Biological Engineering, Jiangsu University
| | | | - Qiang He
- Department of Civil and Environmental Engineering, University of Tennessee
| | | | - Enyan Gao
- School of Food and Biological Engineering, Jiangsu University
| | - Xiaoyan Zheng
- School of Food and Biological Engineering, Jiangsu University
| | - Mingying He
- School of Food and Biological Engineering, Jiangsu University
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Stavropoulou E, Bezirtzoglou E. Predictive Modeling of Microbial Behavior in Food. Foods 2019; 8:E654. [PMID: 31817788 DOI: 10.3390/foods8120654] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 12/02/2019] [Accepted: 12/03/2019] [Indexed: 01/23/2023] Open
Abstract
Microorganisms can contaminate food, thus causing food spoilage and health risks when the food is consumed. Foods are not sterile; they have a natural flora and a transient flora reflecting their environment. To ensure food is safe, we must destroy these microorganisms or prevent their growth. Recurring hazards due to lapses in the handling, processing, and distribution of foods cannot be solved by obsolete methods and inadequate proposals. They require positive approach and resolution through the pooling of accumulated knowledge. As the industrial domain evolves rapidly and we are faced with pressures to continually improve both products and processes, a considerable competitive advantage can be gained by the introduction of predictive modeling in the food industry. Research and development capital concerns of the industry have been preserved by investigating the plethora of factors able to react on the final product. The presence of microorganisms in foods is critical for the quality of the food. However, microbial behavior is closely related to the properties of food itself such as water activity, pH, storage conditions, temperature, and relative humidity. The effect of these factors together contributing to permitting growth of microorganisms in foods can be predicted by mathematical modeling issued from quantitative studies on microbial populations. The use of predictive models permits us to evaluate shifts in microbial numbers in foods from harvesting to production, thus having a permanent and objective evaluation of the involving parameters. In this vein, predictive microbiology is the study of the microbial behavior in relation to certain environmental conditions, which assure food quality and safety. Microbial responses are evaluated through developed mathematical models, which must be validated for the specific case. As a result, predictive microbiology modeling is a useful tool to be applied for quantitative risk assessment. Herein, we review the predictive models that have been adapted for improvement of the food industry chain through a built virtual prototype of the final product or a process reflecting real-world conditions. It is then expected that predictive models are, nowadays, a useful and valuable tool in research as well as in industrial food conservation processes.
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Nyhan L, Begley M, Mutel A, Qu Y, Johnson N, Callanan M. Predicting the combinatorial effects of water activity, pH and organic acids on Listeria growth in media and complex food matrices. Food Microbiol 2018; 74:75-85. [DOI: 10.1016/j.fm.2018.03.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 02/27/2018] [Accepted: 03/07/2018] [Indexed: 11/28/2022]
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Padmaperuma G, Kapoore RV, Gilmour DJ, Vaidyanathan S. Microbial consortia: a critical look at microalgae co-cultures for enhanced biomanufacturing. Crit Rev Biotechnol 2017; 38:690-703. [PMID: 29233009 DOI: 10.1080/07388551.2017.1390728] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Monocultures have been the preferred production route in the bio-industry, where contamination has been a major bottleneck. In nature, microorganisms usually exist as part of organized communities and consortia, gaining benefits from co-habitation, keeping invaders at bay. There is increasing interest in the use of co-cultures to tackle contamination issues, and simultaneously increase productivity and product diversity. The feasibility of extending the natural phenomenon of co-habitation to the biomanufacturing industry in the form of co-cultures requires careful and systematic consideration of several aspects. This article will critically examine and review current work on microbial co-cultures, with the intent of examining the concept and proposing a design pipeline that can be developed in a biomanufacturing context.
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Affiliation(s)
- Gloria Padmaperuma
- a ChELSI Institute, Advanced Biomanufacturing Centre, Department of Chemical and Biological Engineering , The University of Sheffield , Sheffield , UK
| | - Rahul Vijay Kapoore
- a ChELSI Institute, Advanced Biomanufacturing Centre, Department of Chemical and Biological Engineering , The University of Sheffield , Sheffield , UK
| | - Daniel James Gilmour
- b Department of Molecular Biology and Biotechnology , The University of Sheffield , Sheffield , UK
| | - Seetharaman Vaidyanathan
- a ChELSI Institute, Advanced Biomanufacturing Centre, Department of Chemical and Biological Engineering , The University of Sheffield , Sheffield , UK
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12
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Maia MRG, Marques S, Cabrita ARJ, Wallace RJ, Thompson G, Fonseca AJM, Oliveira HM. Simple and Versatile Turbidimetric Monitoring of Bacterial Growth in Liquid Cultures Using a Customized 3D Printed Culture Tube Holder and a Miniaturized Spectrophotometer: Application to Facultative and Strictly Anaerobic Bacteria. Front Microbiol 2016; 7:1381. [PMID: 27630632 PMCID: PMC5006086 DOI: 10.3389/fmicb.2016.01381] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 08/22/2016] [Indexed: 11/13/2022] Open
Abstract
Here we introduce a novel strategy for turbidimetric monitoring of bacterial growth in liquid culture. The instrumentation comprises a light source, a customized 3D printed culture tube holder and a miniaturized spectrophotometer, connected through optical cables. Due to its small footprint and the possibility to operate with external light, bacterial growth was directly monitored from culture tubes in a simple and versatile fashion. This new portable measurement technique was used to monitor the growth of facultative (Escherichia coli ATCC/25922, and Staphylococcus aureus ATCC/29213) and strictly (Butyrivibrio fibrisolvens JW11, Butyrivibrio proteoclasticus P18, and Propionibacterium acnes DSMZ 1897) anaerobic bacteria. For E. coli and S. aureus, the growth rates calculated from normalized optical density values were compared with those ones obtained using a benchtop spectrophotometer without significant differences (P = 0.256). For the strictly anaerobic species, a high precision (relative standard deviation < 3.5%) was observed between replicates up to 48 h. Regarding its potential for customization, this manifold could accommodate further developments for customized turbidimetric monitoring, such as the use of light-emitting diodes as a light source or flow cells.
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Affiliation(s)
- Margarida R G Maia
- REQUIMTE, LAQV, ICBAS, Instituto de Ciências Biomédicas de Abel Salazar, Universidade do PortoPorto, Portugal; REQUIMTE, LAQV, DGAOT, Faculdade de Ciências, Universidade do PortoPorto, Portugal
| | - Sara Marques
- CIBIO, InBIO-Research Network in Biodiversity and Evolutionary Biology, Universidade do PortoVairão, Portugal; Departamento Clinicas Veterinárias - ICBAS, Instituto de Ciências Biomédicas de Abel Salazar, Universidade do PortoPorto, Portugal
| | - Ana R J Cabrita
- REQUIMTE, LAQV, ICBAS, Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto Porto, Portugal
| | - R John Wallace
- Rowett Institute of Nutrition and Health, University of Aberdeen Aberdeen, UK
| | - Gertrude Thompson
- CIBIO, InBIO-Research Network in Biodiversity and Evolutionary Biology, Universidade do PortoVairão, Portugal; Departamento Clinicas Veterinárias - ICBAS, Instituto de Ciências Biomédicas de Abel Salazar, Universidade do PortoPorto, Portugal
| | - António J M Fonseca
- REQUIMTE, LAQV, ICBAS, Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto Porto, Portugal
| | - Hugo M Oliveira
- REQUIMTE, LAQV, ICBAS, Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto Porto, Portugal
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Jeanson S, Floury J, Gagnaire V, Lortal S, Thierry A. Bacterial Colonies in Solid Media and Foods: A Review on Their Growth and Interactions with the Micro-Environment. Front Microbiol 2015; 6:1284. [PMID: 26648910 PMCID: PMC4664638 DOI: 10.3389/fmicb.2015.01284] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 10/31/2015] [Indexed: 01/26/2023] Open
Abstract
Bacteria, either indigenous or added, are immobilized in solid foods where they grow as colonies. Since the 80's, relatively few research groups have explored the implications of bacteria growing as colonies and mostly focused on pathogens in large colonies on agar/gelatine media. It is only recently that high resolution imaging techniques and biophysical characterization techniques increased the understanding of the growth of bacterial colonies, for different sizes of colonies, at the microscopic level and even down to the molecular level. This review covers the studies on bacterial colony growth in agar or gelatine media mimicking the food environment and in model cheese. The following conclusions have been brought to light. Firstly, under unfavorable conditions, mimicking food conditions, the immobilization of bacteria always constrains their growth in comparison with planktonic growth and increases the sensibility of bacteria to environmental stresses. Secondly, the spatial distribution describes both the distance between colonies and the size of the colonies as a function of the initial level of population. By studying the literature, we concluded that there systematically exists a threshold that distinguishes micro-colonies (radius < 100-200 μm) from macro-colonies (radius >200 μm). Micro-colonies growth resembles planktonic growth and no pH microgradients could be observed. Macro-colonies growth is slower than planktonic growth and pH microgradients could be observed in and around them due to diffusion limitations which occur around, but also inside the macro-colonies. Diffusion limitations of milk proteins have been demonstrated in a model cheese around and in the bacterial colonies. In conclusion, the impact of immobilization is predominant for macro-colonies in comparison with micro-colonies. However, the interaction between the colonies and the food matrix itself remains to be further investigated at the microscopic scale.
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Affiliation(s)
- Sophie Jeanson
- INRA, UMR1253, Science and Technology of Milk and EggsRennes, France
- AGROCAMPUS OUEST, UMR1253, Science and Technology of Milk and EggsRennes, France
| | - Juliane Floury
- INRA, UMR1253, Science and Technology of Milk and EggsRennes, France
- AGROCAMPUS OUEST, UMR1253, Science and Technology of Milk and EggsRennes, France
| | - Valérie Gagnaire
- INRA, UMR1253, Science and Technology of Milk and EggsRennes, France
- AGROCAMPUS OUEST, UMR1253, Science and Technology of Milk and EggsRennes, France
| | - Sylvie Lortal
- INRA, UMR1253, Science and Technology of Milk and EggsRennes, France
- AGROCAMPUS OUEST, UMR1253, Science and Technology of Milk and EggsRennes, France
| | - Anne Thierry
- INRA, UMR1253, Science and Technology of Milk and EggsRennes, France
- AGROCAMPUS OUEST, UMR1253, Science and Technology of Milk and EggsRennes, France
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Skandamis PN, Jeanson S. Colonial vs. planktonic type of growth: mathematical modeling of microbial dynamics on surfaces and in liquid, semi-liquid and solid foods. Front Microbiol 2015; 6:1178. [PMID: 26579087 PMCID: PMC4625091 DOI: 10.3389/fmicb.2015.01178] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 10/12/2015] [Indexed: 01/09/2023] Open
Abstract
Predictive models are mathematical expressions that describe the growth, survival, inactivation, or biochemical processes of foodborne bacteria. During processing of contaminated raw materials and food preparation, bacteria are entrapped into the food residues, potentially transferred to the equipment surfaces (abiotic or inert surfaces) or cross-contaminate other foods (biotic surfaces). Growth of bacterial cells can either occur planktonically in liquid or immobilized as colonies. Colonies are on the surface or confined in the interior (submerged colonies) of structured foods. For low initial levels of bacterial population leading to large colonies, the immobilized growth differs from planktonic growth due to physical constrains and to diffusion limitations within the structured foods. Indeed, cells in colonies experience substrate starvation and/or stresses from the accumulation of toxic metabolites such as lactic acid. Furthermore, the micro-architecture of foods also influences the rate and extent of growth. The micro-architecture is determined by (i) the non-aqueous phase with the distribution and size of oil particles and the pore size of the network when proteins or gelling agent are solidified, and by (ii) the available aqueous phase within which bacteria may swarm or swim. As a consequence, the micro-environment of bacterial cells when they grow in colonies might greatly differs from that when they grow planktonically. The broth-based data used for modeling (lag time and generation time, the growth rate, and population level) are poorly transferable to solid foods. It may lead to an over-estimation or under-estimation of the predicted population compared to the observed population in food. If the growth prediction concerns pathogen bacteria, it is a major importance for the safety of foods to improve the knowledge on immobilized growth. In this review, the different types of models are presented taking into account the stochastic behavior of single cells in the growth of a bacterial population. Finally, the recent advances in the rules controlling different modes of growth, as well as the methodological approaches for monitoring and modeling such growth are detailed.
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Affiliation(s)
- Panagiotis N Skandamis
- Laboratory of Food Quality Control and Hygiene, Department of Food Science and Human Nutrition, University of Athens Athens, Greece
| | - Sophie Jeanson
- Institut National de la Recherche Agronomique, UMR1253 Science and Technology of Milk and Eggs Rennes, France ; AGROCAMPUS OUEST, UMR1253 Science and Technology of Milk and Eggs Rennes, France
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15
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Stulova I, Kabanova N, Kriščiunaite T, Adamberg K, Laht TM, Vilu R. Microcalorimetric study of the growth of Streptococcus thermophilus in renneted milk. Front Microbiol 2015; 6:79. [PMID: 25713570 PMCID: PMC4322847 DOI: 10.3389/fmicb.2015.00079] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 01/22/2015] [Indexed: 11/13/2022] Open
Abstract
The growth of Streptococcus thermophilus ST12 (ST12) in liquid milk, reconstituted from low-heat skim milk powder reconstituted skim milk (RSM) and in RSM with rennet addition (r-RSM) at 40°C was monitored by microcalorimetry. It was shown that the growth rate of bacteria decreased in renneted samples in comparison with liquid RSM starting from certain sizes of the colonies ("deviation moments"), which depended on the inoculation rates. The hydrolysis of lactose was delayed for about 1 h in the r-RSM in comparison with RSM but otherwise the metabolism of carbohydrates in the renneted and non-renneted milks was similar. The total free amino acids (TFAA) content by the end of fermentations was higher in r-RSM than in RSM presumably due to the enzymatic hydrolytic activity of rennet. The quantitatively dominating amino acids were remarkably different in the r-RSM and RSM indicating that the hydrolysis cascade of caseins and/or metabolism of amino acids by the bacteria functioned differently in the two cases. The data obtained showed potential of microcalorimetry to characterize quantitative differences of growth and metabolism of the bacteria in renneted and liquid samples of milk.
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Affiliation(s)
- Irina Stulova
- Department of Chemistry, Tallinn University of Technology Tallinn, Estonia ; Competence Centre of Food and Fermentation Technologies Tallinn, Estonia
| | - Natalja Kabanova
- Competence Centre of Food and Fermentation Technologies Tallinn, Estonia
| | - Tiina Kriščiunaite
- Competence Centre of Food and Fermentation Technologies Tallinn, Estonia
| | - Kaarel Adamberg
- Department of Chemistry, Tallinn University of Technology Tallinn, Estonia ; Competence Centre of Food and Fermentation Technologies Tallinn, Estonia
| | - Tiiu-Maie Laht
- Department of Chemistry, Tallinn University of Technology Tallinn, Estonia
| | - Raivo Vilu
- Department of Chemistry, Tallinn University of Technology Tallinn, Estonia ; Competence Centre of Food and Fermentation Technologies Tallinn, Estonia
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