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Souza LV, Martins E, Moreira IMFB, de Carvalho AF. Strategies for the Development of Bioprotective Cultures in Food Preservation. Int J Microbiol 2022; 2022:6264170. [PMID: 37645592 PMCID: PMC10462446 DOI: 10.1155/2022/6264170] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 11/11/2022] [Accepted: 11/28/2022] [Indexed: 08/31/2023] Open
Abstract
Consumers worldwide are increasingly demanding food with fewer ingredients, preferably without chemical additives. The trend called "Clean Label" has stimulated the development and commercialization of new types of bioprotective bacterial cultures. These bacteria are not considered new, and several cultures have been available on the market. Additionally, new bioprotective bacteria are being identified to service the clean label trend, extend the shelf life, and, mainly, improve the food safety of food. In this context, the lactic acid bacteria (LAB) have been extensively prospected as a bioprotective culture, as they have a long history in food production and their antimicrobial activity against spoilage and pathogenic microorganisms is well established. However, to make LAB cultures available in the market is not that easy, the strains should be characterized phenotypically and genotypically, and studies of safety and technological application are necessary to validate their bioprotection performance. Thus, this review presents information on the bioprotection mechanisms developed by LAB in foods and describes the main strategies used to identify and characterize bioprotective LAB with potential application in the food industry.
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Affiliation(s)
- Luana Virgínia Souza
- Inovaleite—Department of Food Technology, Federal University of Viçosa (Universidade Federal de Viçosa) (UFV), Avenida Peter Henry Rolfs, s/n—Campus Universitário, Viçosa, MG 36570-900, Brazil
| | - Evandro Martins
- Inovaleite—Department of Food Technology, Federal University of Viçosa (Universidade Federal de Viçosa) (UFV), Avenida Peter Henry Rolfs, s/n—Campus Universitário, Viçosa, MG 36570-900, Brazil
| | - Isabella Maria Fernandes Botelho Moreira
- Inovaleite—Department of Food Technology, Federal University of Viçosa (Universidade Federal de Viçosa) (UFV), Avenida Peter Henry Rolfs, s/n—Campus Universitário, Viçosa, MG 36570-900, Brazil
| | - Antônio Fernandes de Carvalho
- Inovaleite—Department of Food Technology, Federal University of Viçosa (Universidade Federal de Viçosa) (UFV), Avenida Peter Henry Rolfs, s/n—Campus Universitário, Viçosa, MG 36570-900, Brazil
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Bangar SP, Chaudhary V, Singh TP, Özogul F. Retrospecting the concept and industrial significance of LAB bacteriocins. FOOD BIOSCI 2022. [DOI: 10.1016/j.fbio.2022.101607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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3
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Effect of Packaging and Portioning on the Dynamics of Water–Fat Serum Release from Fresh Pasta Filata Soft Cheese. Foods 2022; 11:foods11030296. [PMID: 35159448 PMCID: PMC8834549 DOI: 10.3390/foods11030296] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 01/19/2022] [Accepted: 01/20/2022] [Indexed: 12/04/2022] Open
Abstract
The aim of the present study was to analyze the impact of cheese fragmentation and packaging on the dynamics of water–fat serum released from pasta filata cheese made from cow’s milk and its mixture with sheep’s milk. The addition of sheep’s milk reduced the amount of leachate from the vacuum-packed cheeses and did not cause as much loss of gloss as in the case of cow’s milk cheeses. This was also reflected in the microscopic images of the cheese samples. Consumers showed less acceptance of cow’s milk pasta filata cheeses than cheeses made with a mixture of cow’s and sheep’s milk (they had the same fat content, acidity, hardness, and oiling-off, but better stretching). The data describing water–fat serum release from pasta filata cheese within 24 h of unpacking was modeled with the use of the feed-forward artificial neural networks, whose architecture is based on Multi-Layer Perceptron with a single hidden layer. The model inputs comprised four independent variables, including one quantitative (i.e., time) and the other qualitative ones, which had the following states: type of raw material (cow’s milk, cow-sheep’s milk), way of sample portioning (whole, quarters, slices), packing method (vacuum packed and packed in brine).
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CESA-LUNA CATHERINE, ALATORRE-CRUZ JULIAMARÍA, CARREÑO-LÓPEZ RICARDO, QUINTERO-HERNÁNDEZ VERÓNICA, BAEZ ANTONINO. Emerging Applications of Bacteriocins as Antimicrobials, Anticancer Drugs, and Modulators of The Gastrointestinal Microbiota. Pol J Microbiol 2021; 70:143-159. [PMID: 34349808 PMCID: PMC8326989 DOI: 10.33073/pjm-2021-020] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 04/06/2021] [Accepted: 04/25/2021] [Indexed: 02/06/2023] Open
Abstract
The use of bacteriocins holds great promise in different areas such as health, food, nutrition, veterinary, nanotechnology, among others. Many research groups worldwide continue to advance the knowledge to unravel a novel range of therapeutic agents and food preservatives. This review addresses the advances of bacteriocins and their producer organisms as biocontrol agents for applications in the medical industry and agriculture. Furthermore, the bacteriocin mechanism of action and structural characteristics will be reviewed. Finally, the potential role of bacteriocins to modulate the signaling in host-associated microbial communities will be discussed.
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Affiliation(s)
- CATHERINE CESA-LUNA
- Centro de Investigaciones en Ciencias Microbiológicas (CICM), Instituto de Ciencias (IC), Benemérita Universidad Autónoma de Puebla (BUAP), Puebla, México
| | | | - RICARDO CARREÑO-LÓPEZ
- Centro de Investigaciones en Ciencias Microbiológicas (CICM), Instituto de Ciencias (IC), Benemérita Universidad Autónoma de Puebla (BUAP), Puebla, México
| | | | - ANTONINO BAEZ
- Centro de Investigaciones en Ciencias Microbiológicas (CICM), Instituto de Ciencias (IC), Benemérita Universidad Autónoma de Puebla (BUAP), Puebla, México
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Licon CC, Moro A, Librán CM, Molina AM, Zalacain A, Berruga MI, Carmona M. Volatile Transference and Antimicrobial Activity of Cheeses Made with Ewes' Milk Fortified with Essential Oils. Foods 2020; 9:E35. [PMID: 31906406 PMCID: PMC7022313 DOI: 10.3390/foods9010035] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 12/21/2019] [Accepted: 12/26/2019] [Indexed: 12/24/2022] Open
Abstract
During the last decades, essential oils (EOs) have been proven to be a natural alternative to additives or pasteurization for the prevention of microbial spoilage in several food matrices. In this work, we tested the antimicrobial activity of EOs from Melissa officinalis, Ocimum basilicum, and Thymus vulgaris against three different microorganisms: Escherichia coli, Clostridium tyrobutyricum, and Penicillium verrucosum. Pressed ewes' cheese made from milk fortified with EOs (250 mg/kg) was used as a model. The carryover effect of each oil was studied by analyzing the volatile fraction of dairy samples along the cheese-making process using headspace stir bar sorptive extraction coupled to gas chromatography/mass spectrometry. Results showed that the EOs contained in T. vulgaris effectively reduced the counts of C. tyrobutyricum and inhibited completely the growth of P. verrucosum without affecting the natural flora present in the cheese. By contrast, the inhibitory effect of M. officinalis against lactic acid bacteria starter cultures rendered this oil unsuitable for this matrix.
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Affiliation(s)
- Carmen C. Licon
- Department of Food Science and Nutrition, California State University, Fresno, 5300 N Campus Drive M/S FF17, Fresno, CA 93740, USA;
| | - Armando Moro
- Facultad de Ingeniería Agronómica, Universidad Técnica de Manabí, Avda. José María Urbina y Che Guevara, 130105 Portoviejo, Manabí, Ecuador
| | - Celia M. Librán
- Food Product Quality Department, Consum S. Coop, Av. Alginet s/n, 46460 Silla, Valencia, Spain;
| | - Ana M. Molina
- Food Quality Research Group, Institute for Regional Development (IDR), Universidad de Castilla-La Mancha, Campus Universitario, 02071 Albacete, Spain; (A.M.M.); (M.I.B.)
| | - Amaya Zalacain
- Cátedra de Química Agrícola, E.T.S.I.A., Universidad de Castilla-La Mancha, Campus Universitario, 02071 Albacete, Spain;
| | - M. Isabel Berruga
- Food Quality Research Group, Institute for Regional Development (IDR), Universidad de Castilla-La Mancha, Campus Universitario, 02071 Albacete, Spain; (A.M.M.); (M.I.B.)
| | - Manuel Carmona
- School of Architecture, Engineering and Design, Food Technology Lab, Universidad Europea de Madrid, C/Tajo s/n, Villaviciosa de Odón, 28670 Madrid, Spain
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Laiño JE, Levit R, de Moreno de LeBlanc A, Savoy de Giori G, LeBlanc JG. Characterization of folate production and probiotic potential of Streptococcus gallolyticus subsp. macedonicus CRL415. Food Microbiol 2019; 79:20-26. [DOI: 10.1016/j.fm.2018.10.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 10/24/2018] [Accepted: 10/25/2018] [Indexed: 12/15/2022]
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7
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Khaldi TEM, Kebouchi M, Soligot C, Gomri MA, Kharroub K, Le Roux Y, Roux E. Streptococcus macedonicus strains isolated from traditional fermented milks: resistance to gastrointestinal environment and adhesion ability. Appl Microbiol Biotechnol 2019; 103:2759-2771. [PMID: 30701281 DOI: 10.1007/s00253-019-09651-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 12/27/2018] [Accepted: 01/15/2019] [Indexed: 12/12/2022]
Abstract
In this study, Streptococcus macedonicus (S. macedonicus) strains were identified from Algerian traditional fermented milks (Lben and Rayeb). Important prerequisites of probiotic interest such as acidity, bile salts tolerance, and adhesion ability to epithelial cells were investigated. A combination of phenotypic (ability to grow on Bile Esculin Azide medium, BEA; on high salt content medium NaCl 6.5%; on alkaline medium pH 9.6) and genotypic approaches (16S rRNA, ITS genes sequencing and MLST technique) allowed to identify four genetically distinct strains of S. macedonicus. These four strains and two references, Streptococcus thermophilus LMD-9 and Lactobacillus rhamnosus GG (LGG), were tested for their capacity to survive at low pH values, and at different concentrations of an equimolar bile salts mixture (BSM). Two different cell lines, Caco-2 TC7 and HT29-MTX, were used for the adhesion study. The results show that S. macedonicus strains selected constitute a distinct genetic entity from the Greek strain S. macedonicus ACA-DC-198. They were able to survive up to pH 3 and could tolerate high concentrations of bile salts (10 mM), unlike LMD-9 and LGG strains. Our strains also display in vitro adhesion similar to the LGG strain on Caco-2 TC7 and higher adhesion than the LMD-9 strain to Caco-2 TC7 and HT29-MTX cell models. This first characterization allows considering S. macedonicus as a potential candidate for possible probiotic effects that need to be investigated.
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Affiliation(s)
- Tedj El Moulouk Khaldi
- Laboratoire Alimentation, Nutrition et Santé (ALNUTS), Institut de la Nutrition, de l'Alimentation et des Technologies Agro Alimentaires (INATAA), Université Frères Mentouri Constantine 1 (UFMC1), Route de Ain El Bey, 25000, Constantine, Algeria
| | | | - Claire Soligot
- INRA, URAFPA, Université de Lorraine, F-54000, Nancy, France
| | - Mohamed Amine Gomri
- Laboratoire Biotechnologie et Qualité des Aliments (BIOQUAL), Equipe Métabolites des Extrêmophiles METEX, Institut de la Nutrition, de l'Alimentation et des Technologies Agro Alimentaires (INATAA), Université Frères Mentouri Constantine 1 (UFMC1), Route de Ain El Bey, 25000, Constantine, Algeria
| | - Karima Kharroub
- Laboratoire Biotechnologie et Qualité des Aliments (BIOQUAL), Equipe Métabolites des Extrêmophiles METEX, Institut de la Nutrition, de l'Alimentation et des Technologies Agro Alimentaires (INATAA), Université Frères Mentouri Constantine 1 (UFMC1), Route de Ain El Bey, 25000, Constantine, Algeria
| | - Yves Le Roux
- INRA, URAFPA, Université de Lorraine, F-54000, Nancy, France
| | - Emeline Roux
- CALBINOTOX, Université de Lorraine, F-54000, Nancy, France.
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Silvetti T, Morandi S, Brasca M. Growth factors affecting gas production and reduction potential of vegetative cell and spore inocula of dairy-related Clostridium species. Lebensm Wiss Technol 2018. [DOI: 10.1016/j.lwt.2018.02.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Silva CCG, Silva SPM, Ribeiro SC. Application of Bacteriocins and Protective Cultures in Dairy Food Preservation. Front Microbiol 2018; 9:594. [PMID: 29686652 PMCID: PMC5900009 DOI: 10.3389/fmicb.2018.00594] [Citation(s) in RCA: 264] [Impact Index Per Article: 44.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Accepted: 03/15/2018] [Indexed: 11/24/2022] Open
Abstract
In the last years, consumers are becoming increasingly aware of the human health risk posed by the use of chemical preservatives in foods. In contrast, the increasing demand by the dairy industry to extend shelf-life and prevent spoilage of dairy products has appeal for new preservatives and new methods of conservation. Bacteriocins are antimicrobial peptides, which can be considered as safe since they can be easily degraded by proteolytic enzymes of the mammalian gastrointestinal tract. Also, most bacteriocin producers belong to lactic acid bacteria (LAB), a group that occurs naturally in foods and have a long history of safe use in dairy industry. Since they pose no health risk concerns, bacteriocins, either purified or excreted by bacteriocin producing strains, are a great alternative to the use of chemical preservatives in dairy products. Bacteriocins can be applied to dairy foods on a purified/crude form or as a bacteriocin-producing LAB as a part of fermentation process or as adjuvant culture. A number of applications of bacteriocins and bacteriocin-producing LAB have been reported to successful control pathogens in milk, yogurt, and cheeses. One of the more recent trends consists in the incorporation of bacteriocins, directly as purified or semi-purified form or in incorporation of bacteriocin-producing LAB into bioactive films and coatings, applied directly onto the food surfaces and packaging. This review is focused on recent developments and applications of bacteriocins and bacteriocin-producing LAB for reducing the microbiological spoilage and improve safety of dairy products.
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Affiliation(s)
- Célia C. G. Silva
- Instituto de Investigação e Tecnologias Agrárias e do Ambiente, Universidade dos Açores, Angra do Heroísmo, Portugal
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Anastasiou R, Driessche GV, Boutou E, Kazou M, Alexandraki V, Vorgias CE, Devreese B, Tsakalidou E, Papadimitriou K. Engineered strains of Streptococcus macedonicus towards an osmotic stress resistant phenotype retain their ability to produce the bacteriocin macedocin under hyperosmotic conditions. J Biotechnol 2015; 212:125-33. [PMID: 26319319 DOI: 10.1016/j.jbiotec.2015.08.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2015] [Revised: 08/17/2015] [Accepted: 08/20/2015] [Indexed: 12/25/2022]
Abstract
Streptococcus macedonicus ACA-DC 198 produces the bacteriocin macedocin in milk only under low NaCl concentrations (<1.0%w/v). The thermosensitive plasmid pGh9:ISS1 was employed to generate osmotic stress resistant (osmr) mutants of S. macedonicus. Three osmr mutants showing integration of the vector in unique chromosomal sites were identified and the disrupted loci were characterized. Interestingly, the mutants were able to grow and to produce macedocin at considerably higher concentrations of NaCl compared to the wild-type (up to 4.0%w/v). The production of macedocin under hyperosmotic conditions solely by the osmr mutants was validated by the well diffusion assay and by mass spectrometry analysis. RT-PCR experiments demonstrated that the macedocin biosynthetic regulon was transcribed at high salt concentrations only in the mutants. Mutant osmr3, the most robust mutant, was converted in its markerless derivative (osmr3f). Co-culture of S. macedonicus with spores of Clostridium tyrobutyricum in milk demonstrated that only the osmr3f mutant and not the wild-type inhibited the growth of the spores under hyperosmotic conditions (i.e., 2.5%w/v NaCl) due to the production of macedocin. Our study shows how genetic manipulation of a strain towards a stress resistant phenotype could improve bacteriocin production under conditions of the same stress.
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Affiliation(s)
- Rania Anastasiou
- Laboratory of Dairy Research, Department of Food Science and Human Nutrition, Agricultural University of Athens, Iera Odos 75, 118 55 Athens, Greece
| | - Gonzalez Van Driessche
- Laboratory for Protein Biochemistry and Biomolecular Engineering, Ghent University, K.L. Ledeganckstraat 35, 9000 Ghent, Belgium
| | - Effrossyni Boutou
- Department of Biochemistry and Molecular Biology, Faculty of Biology, National and Kapodistrian University of Athens, Panepistimioupolis-Zographou, 157 84 Athens, Greece
| | - Maria Kazou
- Laboratory of Dairy Research, Department of Food Science and Human Nutrition, Agricultural University of Athens, Iera Odos 75, 118 55 Athens, Greece
| | - Voula Alexandraki
- Laboratory of Dairy Research, Department of Food Science and Human Nutrition, Agricultural University of Athens, Iera Odos 75, 118 55 Athens, Greece
| | - Constantinos E Vorgias
- Department of Biochemistry and Molecular Biology, Faculty of Biology, National and Kapodistrian University of Athens, Panepistimioupolis-Zographou, 157 84 Athens, Greece
| | - Bart Devreese
- Laboratory for Protein Biochemistry and Biomolecular Engineering, Ghent University, K.L. Ledeganckstraat 35, 9000 Ghent, Belgium
| | - Effie Tsakalidou
- Laboratory of Dairy Research, Department of Food Science and Human Nutrition, Agricultural University of Athens, Iera Odos 75, 118 55 Athens, Greece
| | - Konstantinos Papadimitriou
- Laboratory of Dairy Research, Department of Food Science and Human Nutrition, Agricultural University of Athens, Iera Odos 75, 118 55 Athens, Greece; Department of Biochemistry and Molecular Biology, Faculty of Biology, National and Kapodistrian University of Athens, Panepistimioupolis-Zographou, 157 84 Athens, Greece.
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Cosentino C, Paolino R, Valentini V, Musto M, Ricciardi A, Adduci F, D'Adamo C, Pecora G, Freschi P. Effect of jenny milk addition on the inhibition of late blowing in semihard cheese. J Dairy Sci 2015; 98:5133-42. [DOI: 10.3168/jds.2015-9458] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 04/03/2015] [Indexed: 11/19/2022]
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13
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Arias C, Oliete B, Seseña S, Jimenez L, Pérez-Guzmán M, Arias R. Importance of on-farm management practices on lactate-fermenting Clostridium spp. spore contamination of Manchega ewe milk: Determination of risk factors and characterization of Clostridium population. Small Rumin Res 2013. [DOI: 10.1016/j.smallrumres.2012.11.030] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Librán CM, Moro A, Zalacain A, Molina A, Carmona M, Berruga MI. Potential application of aromatic plant extracts to prevent cheese blowing. World J Microbiol Biotechnol 2013; 29:1179-88. [DOI: 10.1007/s11274-013-1280-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 02/05/2013] [Indexed: 11/30/2022]
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Garde S, Arias R, Gaya P, Nuñez M. Occurrence of Clostridium spp. in ovine milk and Manchego cheese with late blowing defect: Identification and characterization of isolates. Int Dairy J 2011. [DOI: 10.1016/j.idairyj.2010.11.003] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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16
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Maragkoudakis PA, Papadelli M, Georgalaki M, Panayotopoulou EG, Martinez-Gonzalez B, Mentis AF, Petraki K, Sgouras DN, Tsakalidou E. In vitro and in vivo safety evaluation of the bacteriocin producer Streptococcus macedonicus ACA-DC 198. Int J Food Microbiol 2009; 133:141-7. [PMID: 19515446 DOI: 10.1016/j.ijfoodmicro.2009.05.012] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Revised: 04/15/2009] [Accepted: 05/08/2009] [Indexed: 12/29/2022]
Abstract
Streptococcus macedonicus ACA-DC 198, a bacteriocin producer isolated from Greek Kasseri cheese, was used in a series of in vitro and in vivo experiments in order to evaluate its pathogenic potential. The strain was examined in vitro for haemolytic activity, antibiotic resistance and presence of pathogenicity genes encountered in Streptococcus pyogenes. Subsequently, the strain was orally administered to mice (8.9 log cfu daily), continuously over a period of 12 weeks, in order to ascertain the effects of its long term consumption on animal health and gastric inflammation. S. macedonicus ACA-DC 198 was found to be non-haemolytic and sensitive to ampicillin, chloramphenicol, ciprofloxacin, erythromycin, streptomycin, tetracycline, and vancomycin, with the only resistance observed against kanamycin. PCR amplification and DNA-DNA hybridization did not reveal the presence of any of the S.pyogenes pathogenicity genes examined, namely emm, scpA, hasA, speB, smez2, speJ, sagAB, hylA, ska, speF, speG, slo, hylP2 and mga. In the mouse study, no detrimental effects were observed in the behaviour, general well being, weight gain and water consumption of the animals receiving S. macedonicus ACA-DC 198. Histologic analysis showed no evidence of inflammation in the stomach of the animals receiving S. macedonicus ACA-DC 198, while faecal microbiological analysis revealed that the strain retained its viability passing through the mouse gastrointestinal tract. Finally, no evidence of translocation to the liver, spleen and mesenteric lymph nodes was observed. In conclusion, none of the examined virulence determinants were detected in S. macedonicus ACA-DC 198 and its long term, high dosage oral administration did not appear to induce any pathogenic effect in mice.
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