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Somerton BT, Morgan BL. Comparison of plate counting with flow cytometry, using four different fluorescent dye techniques, for the enumeration of Bacillus cereus in milk. J Microbiol Methods 2024; 223:106978. [PMID: 38936432 DOI: 10.1016/j.mimet.2024.106978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2024] [Revised: 06/23/2024] [Accepted: 06/24/2024] [Indexed: 06/29/2024]
Abstract
This study aimed to compare the performance of flow cytometry methods with plate counting for the enumeration of bacteria, using Bacillus cereus as a model organism. It was found that the cFDA-propidium iodide, CellROX™ Green-propidium iodide, and DiOC2 dye techniques had similar accuracy to plate counting, while the SYTO 24-propidium iodide dye technique was not as accurate. The four dye techniques had comparable precision to plate counting, with the CellROX™ Green-propidium iodide dye having the greatest precision. The consistency of the position and shape of the cell clusters on the flow cytometry plots, and the extent of separation of the cell from background clusters, was greatest with the DiOC2 and CellROX™ Green-propidium iodide dyes. Furthermore, the DiOC2 and CellROX™ Green-propidium iodide dyes performed well, even when a sample was measured containing reconstituted whole milk powder at a 10-1 dilution, without the use of sample preparation to specifically remove the milk constituents prior to measurement. Given gating of only one cell cluster was required to be managed with the DiOC2 dye, to determine the viable number of cells, it was found that the DiOC2 dye had the greatest ease-of-use. Overall, results indicated that the DiOC2 dye is an ideal candidate for the enumeration of viable bacteria in dairy samples on a high-throughput, routine basis.
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Affiliation(s)
- Ben T Somerton
- Fonterra Research & Development Centre, Fonterra, Palmerston North, New Zealand.
| | - Brooke L Morgan
- Fonterra Research & Development Centre, Fonterra, Palmerston North, New Zealand
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2
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Marcos-Fernández R, Sánchez B, Ruiz L, Margolles A. Convergence of flow cytometry and bacteriology. Current and future applications: a focus on food and clinical microbiology. Crit Rev Microbiol 2023; 49:556-577. [PMID: 35749433 DOI: 10.1080/1040841x.2022.2086035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 05/12/2022] [Accepted: 05/31/2022] [Indexed: 11/03/2022]
Abstract
Since its development in the 1960s, flow cytometry (FCM) was quickly revealed a powerful tool to analyse cell populations in medical studies, yet, for many years, was almost exclusively used to analyse eukaryotic cells. Instrument and methodological limitations to distinguish genuine bacterial signals from the background, among other limitations, have hampered FCM applications in bacteriology. In recent years, thanks to the continuous development of FCM instruments and methods with a higher discriminatory capacity to detect low-size particles, FCM has emerged as an appealing technique to advance the study of microbes, with important applications in research, clinical and industrial settings. The capacity to rapidly enumerate and classify individual bacterial cells based on viability facilitates the monitoring of bacterial presence in foodstuffs or clinical samples, reducing the time needed to detect contamination or infectious processes. Besides, FCM has stood out as a valuable tool to advance the study of complex microbial communities, or microbiomes, that are very relevant in the context of human health, as well as to understand the interaction of bacterial and host cells. This review highlights current developments in, and future applications of, FCM in bacteriology, with a focus on those related to food and clinical microbiology.
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Affiliation(s)
- Raquel Marcos-Fernández
- Department of Microbiology and Biochemistry of Dairy Products, Dairy Research Institute of Asturias, Spanish National Research Council (IPLA-CSIC), Asturias, Spain
- Functionality and Ecology of Beneficial Microbes (MicroHealth) Group, Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), Asturias, Spain
| | - Borja Sánchez
- Department of Microbiology and Biochemistry of Dairy Products, Dairy Research Institute of Asturias, Spanish National Research Council (IPLA-CSIC), Asturias, Spain
- Functionality and Ecology of Beneficial Microbes (MicroHealth) Group, Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), Asturias, Spain
| | - Lorena Ruiz
- Department of Microbiology and Biochemistry of Dairy Products, Dairy Research Institute of Asturias, Spanish National Research Council (IPLA-CSIC), Asturias, Spain
- Functionality and Ecology of Beneficial Microbes (MicroHealth) Group, Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), Asturias, Spain
| | - Abelardo Margolles
- Department of Microbiology and Biochemistry of Dairy Products, Dairy Research Institute of Asturias, Spanish National Research Council (IPLA-CSIC), Asturias, Spain
- Functionality and Ecology of Beneficial Microbes (MicroHealth) Group, Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), Asturias, Spain
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Bellassi P, Fontana A, Morelli L. Application of flow cytometry for rapid bacterial enumeration and cells physiological state detection to predict acidification capacity of natural whey starters. Heliyon 2023; 9:e19146. [PMID: 37636441 PMCID: PMC10458327 DOI: 10.1016/j.heliyon.2023.e19146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 08/07/2023] [Accepted: 08/14/2023] [Indexed: 08/29/2023] Open
Abstract
Natural whey starter cultures are undefined microbial communities mainly consisting of thermophilic lactic acid bacteria (LAB). The technological pressure that shapes the natural whey starter community before and during the back-slopping procedure can impact the amount and viability of the different thermophilic LAB. Traditional culture-dependent analytical methods are useful for evaluating natural whey cultures based on plate enumeration with various culture media and are commonly used as self-control procedures in dairy items. These methods have high variability and require days to obtain results. As the dairy industry has been searching for a solution to this problem for a long time, researchers must explore alternative methods for the technological evaluation of natural whey and assessment of the health status of the thermophilic acidifying bacteria community in the cheesemaking process. The flow cytometry approach has been considered an alternative to classical methods in this work sector. This study compared bacterial enumeration by plate counting and flow cytometry on natural whey samples. Flow cytometry results showed positive agreement with a tendency to overestimate, linearity, and correlation with plate counting. Other parameters have also been introduced for evaluating a natural whey starter, measuring the physiological state of the cells. Specifically, cell-wall damage and metabolic activity were also evaluated, allowing us to quantify the number of cells even in sub-optimal physiological conditions.
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Affiliation(s)
- Paolo Bellassi
- Department for Sustainable Food Process (DISTAS), Università Cattolica Del Sacro Cuore, Italy
| | - Alessandra Fontana
- Department for Sustainable Food Process (DISTAS), Università Cattolica Del Sacro Cuore, Italy
| | - Lorenzo Morelli
- Department for Sustainable Food Process (DISTAS), Università Cattolica Del Sacro Cuore, Italy
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Shen X, Teo TW, Kong TF. A Technique for Rapid Bacterial-Density Enumeration through Membrane Filtration and Differential Pressure Measurements. MICROMACHINES 2022; 13:mi13081198. [PMID: 36014121 PMCID: PMC9415702 DOI: 10.3390/mi13081198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 07/25/2022] [Accepted: 07/26/2022] [Indexed: 02/01/2023]
Abstract
In this article, we present a microfluidic technique for the rapid enumeration of bacterial density with a syringe filter to trap bacteria and the quantification of the bacterial density through pressure difference measurement across the membrane. First, we established the baseline differential pressure and hydraulic resistance for a filtration membrane by fully wetting the filter with DI water. Subsequently, when bacteria were infused and trapped at the pores of the membrane, the differential pressure and hydraulic resistance also increased. We characterized the infusion time required for the bacterial sample to achieve a normalized hydraulic resistance of 1.5. An equivalent electric-circuit model and calibration data sets from parametric studies were used to determine the general form of a calibration curve for the prediction of the bacterial density of a bacterial sample. As a proof of concept, we demonstrated through blind tests with Escherichia coli that the device is capable of determining the bacterial density of a sample ranging from 7.3 × 106 to 2.2 × 108 CFU/mL with mean and median accuracies of 87.21% and 91.33%, respectively. The sample-to-result time is 19 min for a sample with lower detection threshold, while for higher-bacterial-density samples the measurement time is further shortened to merely 8 min.
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Affiliation(s)
- Xinhui Shen
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - Ting Wei Teo
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - Tian Fook Kong
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Singapore
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Nyhan L, Begley M, Johnson N, Callanan M. An evaluation of Lux technology as an alternative methodology to determine growth rates of Listeria in laboratory media and complex food matrices. Int J Food Microbiol 2020; 317:108442. [DOI: 10.1016/j.ijfoodmicro.2019.108442] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 09/04/2019] [Accepted: 11/10/2019] [Indexed: 11/16/2022]
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6
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Wilkinson MG. Flow cytometry as a potential method of measuring bacterial viability in probiotic products: A review. Trends Food Sci Technol 2018. [DOI: 10.1016/j.tifs.2018.05.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Guo R, McGoverin C, Swift S, Vanholsbeeck F. A rapid and low-cost estimation of bacteria counts in solution using fluorescence spectroscopy. Anal Bioanal Chem 2017; 409:3959-3967. [PMID: 28389919 PMCID: PMC5437196 DOI: 10.1007/s00216-017-0347-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 03/08/2017] [Accepted: 03/28/2017] [Indexed: 11/15/2022]
Abstract
The fluorescence spectrum of bacterially bound acridine orange (AO) was investigated to evaluate its use for the rapid enumeration of bacteria. Escherichia coli ATCC 25922 samples were stained with 2 × 10-2, 2 × 10-3 or 2 × 10-4% w/v AO, followed by 3, 2 or 0 washing cycles, respectively, and fluorescence spectra were recorded using a fibre-based spectroscopic system. Independent component analysis was used to analyse the spectral datasets for each staining method. Bacterial concentration order of magnitude classification models were calculated using independent component weights. The relationship between fluorescence intensity of bound AO and bacterial concentration was not linear. However, the spectral signals collected for AO stain concentration-bacterial concentration pairs were reproducible and unique enough to enable classification of samples. When above 105 CFU ml-1, it was possible to rapidly determine what the order of magnitude of bacterial concentration of a sample was using a combination of two of the sample preparation methods. A relatively inexpensive (around US$10 per test) rapid method (within 25 min of sampling) for enumeration of bacteria by order of magnitude will reduce the time and cost of microbiological tests requiring gross concentration information. Graphical Abstract Fluorescence spectra of bacterially bound acridine orange (AO) were used for the rapid enumeration of bacteria. Order of magnitude bacterial concentration classification models were calculated using independent components analysis of these fluorescence spectra. When above 105 CFU ml-1, it was possible to rapidly determine the order of magnitude of bacterial concentration of a sample using a combination of two sample preparation methods.
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Affiliation(s)
- Rachel Guo
- The Dodd-Walls Centre for Photonic and Quantum Technologies, Department of Physics, The University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand
| | - Cushla McGoverin
- The Dodd-Walls Centre for Photonic and Quantum Technologies, Department of Physics, The University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand
| | - Simon Swift
- Department of Molecular Medicine and Pathology, The University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand
| | - Frederique Vanholsbeeck
- The Dodd-Walls Centre for Photonic and Quantum Technologies, Department of Physics, The University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand.
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Bonomo M, Cafaro C, Guerrieri A, Crispo F, Milella L, Calabrone L, Salzano G. Flow cytometry and capillary electrophoresis analyses in ethanol-stressedOenococcus oenistrains and changes assessment of membrane fatty acid composition. J Appl Microbiol 2017; 122:1615-1626. [DOI: 10.1111/jam.13466] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 02/11/2017] [Accepted: 03/21/2017] [Indexed: 12/01/2022]
Affiliation(s)
- M.G. Bonomo
- Dipartimento di Scienze; Università degli Studi della Basilicata; Potenza Italy
| | - C. Cafaro
- Dipartimento di Scienze; Università degli Studi della Basilicata; Potenza Italy
| | - A. Guerrieri
- Dipartimento di Scienze; Università degli Studi della Basilicata; Potenza Italy
| | - F. Crispo
- Dipartimento di Scienze; Università degli Studi della Basilicata; Potenza Italy
| | - L. Milella
- Dipartimento di Scienze; Università degli Studi della Basilicata; Potenza Italy
| | - L. Calabrone
- Dipartimento di Scienze; Università degli Studi della Basilicata; Potenza Italy
| | - G. Salzano
- Dipartimento di Scienze; Università degli Studi della Basilicata; Potenza Italy
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9
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Self-assembled micro-structured sensors for food safety in paper based food packaging. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2015; 53:331-5. [DOI: 10.1016/j.msec.2015.04.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Revised: 01/10/2015] [Accepted: 04/21/2015] [Indexed: 11/21/2022]
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10
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Rapid and specific enumeration of viable Bifidobacteria in dairy products based on flow cytometry technology: A proof of concept study. Int Dairy J 2014. [DOI: 10.1016/j.idairyj.2014.02.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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11
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Winkelströter LK, Teixeira FBDR, Silva EP, Alves VF, De Martinis ECP. Unraveling microbial biofilms of importance for food microbiology. MICROBIAL ECOLOGY 2014; 68:35-46. [PMID: 24370864 DOI: 10.1007/s00248-013-0347-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Accepted: 12/06/2013] [Indexed: 06/03/2023]
Abstract
The presence of biofilms is a relevant risk factors in the food industry due to the potential contamination of food products with pathogenic and spoilage microorganisms. The majority of bacteria are able to adhere and to form biofilms, where they can persist and survive for days to weeks or even longer, depending on the microorganism and the environmental conditions. The biological cycle of biofilms includes several developmental phases such as: initial attachment, maturation, maintenance, and dispersal. Bacteria in biofilms are generally well protected against environmental stress, consequently, extremely difficult to eradicate and detect in food industry. In the present manuscript, some techniques and compounds used to control and to prevent the biofilm formation are presented and discussed. Moreover, a number of novel techniques have been recently employed to detect and evaluate bacteria attached to surfaces, including real-time polymerase chain reaction (PCR), DNA microarray and confocal laser scanning microscopy. Better knowledge on the architecture, physiology and molecular signaling in biofilms can contribute for preventing and controlling food-related spoilage and pathogenic bacteria. The present study highlights basic and applied concepts important for understanding the role of biofilms in bacterial survival, persistence and dissemination in food processing environments.
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Affiliation(s)
- Lizziane Kretli Winkelströter
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo (FCFRP-USP), Av. do Café s/n, 14040-903, Ribeirão Preto, São Paulo, Brazil
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12
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Huang X, Zou X, Zhao J, Shi J, Zhang X, Li Z, Shen L. Sensing the quality parameters of Chinese traditional Yao-meat by using a colorimetric sensor combined with genetic algorithm partial least squares regression. Meat Sci 2014; 98:203-10. [PMID: 24971808 DOI: 10.1016/j.meatsci.2014.05.033] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Revised: 03/19/2014] [Accepted: 05/30/2014] [Indexed: 10/25/2022]
Abstract
Yao-meat is a traditional Chinese salted meat. Total volatile basic nitrogen content (TVB-N), total viable bacterial count (TVC), and residual nitrite (RN) level are important indexes of freshness for Yao-meat. This paper attempted the feasibility to determine TVB-N content, TVC and RN level in Yao-meat by a colorimetric sensor array chip. A color change profile for each sample was obtained by differentiating the image of sensor array before and after exposure to Yao-meat's volatile organic compounds. Genetic algorithm partial least squares regression (GA-PLS) was proposed to build the relationship between the TVB-N content, TVC, RN and the color change profiles of sensor array, and to select informative chemically responsive dyes for the three quality parameters. The GA-PLS models were achieved with RTVB-N=0.812, RTVC=0.856, RRN=0.855, in prediction set. This study demonstrated that colorimetric sensory array with GA-PLS algorithm could be used successfully to analyze the quality of Chinese traditional Yao-meat.
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Affiliation(s)
- Xiaowei Huang
- School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Rd., 212013 Zhenjiang, Jiangsu, China
| | - Xiaobo Zou
- School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Rd., 212013 Zhenjiang, Jiangsu, China; Key Laboratory of Modern Agricultural Equipment and Technology, 301 Xuefu Rd., 212013 Zhenjiang, Jiangsu, China.
| | - Jiewen Zhao
- School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Rd., 212013 Zhenjiang, Jiangsu, China
| | - Jiyong Shi
- School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Rd., 212013 Zhenjiang, Jiangsu, China
| | - Xiaolei Zhang
- School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Rd., 212013 Zhenjiang, Jiangsu, China
| | - Zhihua Li
- School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Rd., 212013 Zhenjiang, Jiangsu, China
| | - Lecheng Shen
- School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Rd., 212013 Zhenjiang, Jiangsu, China
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Bonomo M, Milella L, Martelli G, Salzano G. Stress response assessment of Lactobacillus sakei
strains selected as potential autochthonous starter cultures by flow cytometry and nucleic acid double-staining analyses. J Appl Microbiol 2013; 115:786-95. [DOI: 10.1111/jam.12271] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Revised: 06/03/2013] [Accepted: 06/03/2013] [Indexed: 11/27/2022]
Affiliation(s)
- M.G. Bonomo
- Dipartimento di Scienze; Università degli Studi della Basilicata; Potenza Italy
| | - L. Milella
- Dipartimento di Scienze; Università degli Studi della Basilicata; Potenza Italy
| | - G. Martelli
- Dipartimento di Scienze; Università degli Studi della Basilicata; Potenza Italy
| | - G. Salzano
- Dipartimento di Scienze; Università degli Studi della Basilicata; Potenza Italy
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Nicolaou N, Xu Y, Goodacre R. Detection and Quantification of Bacterial Spoilage in Milk and Pork Meat Using MALDI-TOF-MS and Multivariate Analysis. Anal Chem 2012; 84:5951-8. [DOI: 10.1021/ac300582d] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Nicoletta Nicolaou
- School of Chemistry and Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street,
Manchester M1 7DN, United Kingdom
| | - Yun Xu
- School of Chemistry and Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street,
Manchester M1 7DN, United Kingdom
| | - Royston Goodacre
- School of Chemistry and Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street,
Manchester M1 7DN, United Kingdom
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Burgess SA, Lindsay D, Flint SH. Thermophilic bacilli and their importance in dairy processing. Int J Food Microbiol 2010; 144:215-25. [DOI: 10.1016/j.ijfoodmicro.2010.09.027] [Citation(s) in RCA: 206] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2010] [Revised: 08/15/2010] [Accepted: 09/25/2010] [Indexed: 11/24/2022]
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Jasson V, Jacxsens L, Luning P, Rajkovic A, Uyttendaele M. Alternative microbial methods: An overview and selection criteria. Food Microbiol 2010; 27:710-30. [DOI: 10.1016/j.fm.2010.04.008] [Citation(s) in RCA: 193] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2009] [Revised: 04/12/2010] [Accepted: 04/20/2010] [Indexed: 11/25/2022]
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17
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Díaz M, Herrero M, García LA, Quirós C. Application of flow cytometry to industrial microbial bioprocesses. Biochem Eng J 2010. [DOI: 10.1016/j.bej.2009.07.013] [Citation(s) in RCA: 132] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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18
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Cronin U, Wilkinson M. The potential of flow cytometry in the study of Bacillus cereus. J Appl Microbiol 2010; 108:1-16. [DOI: 10.1111/j.1365-2672.2009.04370.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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19
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Rajput IR, Khaskheli M, Rao S, Fazlani S, Shah Q, Khaskheli G. Microbial Quality of Formulated Infant Milk Powders. ACTA ACUST UNITED AC 2009. [DOI: 10.3923/pjn.2009.1665.1670] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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20
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Rajput IR, Khaskheli M, Soomro A, Rajput N, Khaskheli G. Enumeration of Thermoduric and Thermophilic Spores in Commercial Repacked Milk Powder. ACTA ACUST UNITED AC 2009. [DOI: 10.3923/pjn.2009.1196.1198] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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21
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Lavilla M, Marzo I, de Luis R, Perez MD, Calvo M, Sánchez L. Detection of Clostridium tyrobutyricum spores using polyclonal antibodies and flow cytometry. J Appl Microbiol 2009; 108:488-98. [PMID: 19659701 DOI: 10.1111/j.1365-2672.2009.04435.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIMS The present work investigates the feasibility of using flow cytometry (FCM) combined with fluorescent-labelled specific polyclonal antibodies for the detection and presumptive identification of Clostridium tyrobutyricum spores in bovine milk. METHODS AND RESULTS Two fluorescent molecules (fluorescein isothiocyanate and Alexa Fluor 488) were conjugated to antispores polyclonal antibodies. Side scatter and forward scatter profiles of the Cl. tyrobutyricum spores marked with fluorescent antibodies permitted the detection of spores and differentiated them from other related microbial species. The detection limit of this method was 10(3) spores per 100 ml of milk, and results could be achieved in 2 h. CONCLUSIONS FCM combined with fluorochrome-conjugated antibodies, especially Alexa Fluor, could be an efficacious means to detect and provide presumptive identification of Cl. tyrobutyricum spores, as well as differentiation from other Clostridium species that can also cause late blowing in cheese. SIGNIFICANCE AND IMPACT OF THE STUDY This study describes the basis for the development of a method suitable for analysis of milk destined for cheese manufacture that would permit the detection of Cl. tyrobutyricum spores in a short period. This would enable the industry to use contaminated milk for dairy products other than cheese where Cl. tyrobutyricum does not cause a problem.
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Affiliation(s)
- M Lavilla
- Tecnología de los Alimentos, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza, Spain
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22
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23
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Flint S, Walker K, Waters B, Crawford R. Description and validation of a rapid (1 h) flow cytometry test for enumerating thermophilic bacteria in milk powders. J Appl Microbiol 2006; 102:909-15. [PMID: 17381733 DOI: 10.1111/j.1365-2672.2006.03167.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIMS The aim of this study was to develop a rapid assay for enumerating thermophilic bacteria in milk powder. METHODS AND RESULTS The BactiFlow flow cytometer was used to count bacteria based on esterase activity in viable bacterial cells. A protocol for total viable bacteria was modified by heat-treating the sample to selectively label thermophilic bacteria. Samples of milk powder dissolved in 0.1% peptone were treated with 0.8% ethylenediaminetetraacetic acid to reduce background interference because of denatured milk proteins. Either thermophilic bacteria were added to the dissolved milk powder or milk powder solutions were incubated at 55 degrees C for 2-3 h to enrich the natural thermophile population for testing. Results from the BactiFlow were compared with traditional plate count results. CONCLUSIONS Thermophilic bacteria in milk powder can be enumerated within 1 h using the BactiFlow flow cytometer. SIGNIFICANCE AND IMPACT OF THE STUDY Microbiological test results obtained within 1 h can potentially be used to monitor manufacturing processes, effectively trace problems and provide confidence in the manufacture of product.
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Affiliation(s)
- S Flint
- Fonterra Research Centre, Palmerston North, New Zealand.
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