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Martins WF, Severo DDS, Longhi DA, de Aragão GMF. Comparison of SYBR® Green qPCR assay and plate count method to describe growth of Weissella viridescens and Leuconostoc mesenteroides in pure and mixed cultivation. Food Microbiol 2024; 119:104452. [PMID: 38225053 DOI: 10.1016/j.fm.2023.104452] [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: 06/15/2023] [Revised: 11/28/2023] [Accepted: 12/18/2023] [Indexed: 01/17/2024]
Abstract
The current study was conducted to statistically compare the SYBR® Green quantitative polymerase chain reaction (qPCR) assay and the conventional plate counting (PC) method to construct growth curves of a cocktail of Weissella viridescens in pure culture under different isothermal storage conditions (4, 8, 14, and 30 °C) and in mixed culture with Leuconostoc mesenteroides at 8 °C. The efficiency and specificity of the qPCR standard curves were confirmed, and both methods were adequate to quantify the growth kinetics of W. viridescens at all isothermal temperatures, demonstrating a good correlation and agreement. The efficiencies of the standard curves varied between 98% and 102%. The SYBR® Green qPCR assay was also able to differentiate the growth curves of W. viridescens and L. mesenteroides in the mixed culture at 8 °C. Additionally, the SYBR® Green qPCR method was considered a faster and more sensitive alternative to construct growth curves under different isothermal conditions and differentiate morphologically similar lactic acid bacteria. Overall, the results suggest that the SYBR® Green qPCR method is a reliable and efficient tool to study microbial growth kinetics in pure and mixed cultures.
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Affiliation(s)
- Wiaslan Figueiredo Martins
- Department of Food Technology, Goiano Federal Institute of Education, Science, and Technology, IF Goiano/Morrinhos Campus, Zip Code 75650-000, Morrinhos, GO, Brazil; Chemical and Food Engineering Department, Federal University of Santa Catarina, EQA/UFSC, Zip Code 88040-900, Florianopolis, SC, Brazil.
| | - Danielle de Sousa Severo
- Chemical and Food Engineering Department, Federal University of Santa Catarina, EQA/UFSC, Zip Code 88040-900, Florianopolis, SC, Brazil
| | - Daniel Angelo Longhi
- LaBeM - Laboratory of Bioactives and Microbiology, School of Food Engineering, Federal University of Paraná, UFPR/Jandaia do Sul Campus, Zip Code 86900-000, Jandaia do Sul, PR, Brazil
| | - Gláucia Maria Falcão de Aragão
- Chemical and Food Engineering Department, Federal University of Santa Catarina, EQA/UFSC, Zip Code 88040-900, Florianopolis, SC, Brazil
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2
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Jakobsen AN, Gabrielsen L, Johnsen EM, Rotabakk BT, Lerfall J. Application of soluble gas stabilization technology on ready-to-eat pre-rigor filleted Atlantic salmon (Salmo salar L.). J Food Sci 2022; 87:2377-2390. [PMID: 35546451 PMCID: PMC9322570 DOI: 10.1111/1750-3841.16164] [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: 07/07/2021] [Revised: 03/29/2022] [Accepted: 04/01/2022] [Indexed: 11/28/2022]
Abstract
Abstract The demand for high‐quality, convenient, and sustainable salmon products represents a potential for value‐added product development and novel packaging solutions. Soluble gas stabilization (SGS) technology, which applies dissolved CO2 in the product before packaging, represents a novel approach to retain product quality and prevent microbiological deterioration during cold storage of pre‐rigor filleted salmon loins. The present study aimed to examine the solubility of CO2 in salmon loins as affected by rigor status. In addition, the effect of predissolved CO2 on the overall quality of pre‐rigor vacuum‐packed Atlantic salmon (Salmo salar L.) was investigated during storage at 4°C. The CO2 pretreatment was conducted, exposing loins to 100% CO2 for 18 h at 4°C (the control group was kept in air at 4°C) before repackaging and storage for 15 days. Dissolved CO2 in the muscle (equilibrium achieved four days post packaging) was slightly higher in pre‐rigor than post‐rigor salmon loins (pequilibrium = 0.006). Moreover, the overall spoilage (Hvalue) and microbiological stability of salmon fillets stored in SGS‐vacuum were significantly improved compared to vacuum‐packed loins (p < 0.05). The results demonstrate that SGS technology can maintain the overall quality of pre‐rigor vacuum‐packed salmon loins without introducing the high gas‐to‐product volume ratio recognized by modified atmosphere packaging. Thus, the application of SGS technology on pre‐rigor loins can lead to higher economic gain and environmental benefits due to the reduced amount of required packaging material and reduced food waste. Practical Application CO2 can be dissolved in pre‐rigor salmon loins before vacuum packaging to increase product shelf life during cold storage.
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Affiliation(s)
- Anita Nordeng Jakobsen
- Department of Biotechnology and Food Science, NTNU- Norwegian University of Science and Technology, Trondheim, Norway
| | - Lisa Gabrielsen
- Department of Biotechnology and Food Science, NTNU- Norwegian University of Science and Technology, Trondheim, Norway
| | - Elena Marie Johnsen
- Department of Biotechnology and Food Science, NTNU- Norwegian University of Science and Technology, Trondheim, Norway
| | | | - Jørgen Lerfall
- Department of Biotechnology and Food Science, NTNU- Norwegian University of Science and Technology, Trondheim, Norway
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Jérôme M, Passerini D, Chevalier F, Marchand L, Leroi F, Macé S. Development of a rapid qPCR method to quantify lactic acid bacteria in cold-smoked salmon. Int J Food Microbiol 2021; 363:109504. [PMID: 34959088 DOI: 10.1016/j.ijfoodmicro.2021.109504] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 10/14/2021] [Accepted: 12/12/2021] [Indexed: 01/11/2023]
Abstract
Quantification of lactic acid bacteria (LAB) is essential to control quality of seafood products like cold-smoked salmon (CSS). In the present study, we report the design and optimization of a dual-labelled TaqMan ™ probe targeting the V7 region of 16S rRNA gene for the detection of LAB in CSS. This quantitative PCR (qPCR) assays is useful for the simultaneous detection of the ten LAB genera communally encountered in CSS as Aerococcus, Carnobacterium, Enterococcus, Lactobacillus, Lactococcus, Leuconostoc, Macrococcus, Streptococcus, Vagococcus and Weissella. The specificity of this method was demonstrated against 14 genera (44 isolates, 35 species) of Gram-positive bacteria and 19 genera of Gram-negative (40 isolates, 34 species). Calibration of the method was performed in CSS matrix using a mix of equimolar cultured solution of five LAB. Quantification with the qPCR method range from 3.5 to 8.5 Log CFU/g in CSS matrix, covering 5 orders of magnitude. On these artificially contaminated CSS slices, PCR method results correlated successfully (R2 = 0.9945) with the conventional enumeration on Elliker medium. In addition, the new method was successful on commercial CSS from five different origins with a quantification range from 3.7 Log CFU/g to 8.0 Log CFU/g. This one-step quantitative methodology is proposed as a rapid and complementary tool of the cultural methods to investigate the LAB microbiota and biodiversity of CSS.
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Affiliation(s)
- Marc Jérôme
- IFREMER, BRM, EM(3)B Laboratory, F-44000 Nantes 3, France
| | | | | | | | | | - Sabrina Macé
- IFREMER, BRM, EM(3)B Laboratory, F-44000 Nantes 3, France.
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Bahmani Z, Hosseini SV, Amanpour A. Effect of Nanocomposite Clay/low-density Polyethylene Film on the Quality of Rainbow Trout (Oncorhynchus mykiss) Fillets Stored with Four Different Packaging Conditions. JOURNAL OF AQUATIC FOOD PRODUCT TECHNOLOGY 2021. [DOI: 10.1080/10498850.2021.1988790] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Zabihalh Bahmani
- Persian Gulf & Oman Sea Ecological Research Center, Iranian Fisheries Science Research Institute (Ifsri), Agricultural Research Education and Extension Organization (Areeo), Bandar Abbas, Iran
| | - Seyed Vali Hosseini
- Department of Fisheries, Faculty of Natural Resources, University of Tehran, Karaj, Iran
| | - Asghar Amanpour
- Department of Nutrition and Dietetics, Faculty of Health Sciences, Biruni University, Istanbul, Turkey
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Wang D, Zhou F, Lai D, Zhang Y, Hu J, Lin S. Curcumin-mediated sono/photodynamic treatment preserved the quality of shrimp surimi and influenced its microbial community changes during refrigerated storage. ULTRASONICS SONOCHEMISTRY 2021; 78:105715. [PMID: 34391163 PMCID: PMC8374498 DOI: 10.1016/j.ultsonch.2021.105715] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Revised: 08/02/2021] [Accepted: 08/06/2021] [Indexed: 06/01/2023]
Abstract
Shrimp surimi is widely acknowledged as a value-added shrimp product due to its delicious taste, rich flavor, and nutrition. However, the refrigerated shrimp surimi is prone to deterioration due to rapid microbial growth during storage. The present study sought to assess the effects of curcumin-mediated sono/photodynamic treatment on bacterial spoilage and shrimp surimi quality stored at 4 °C. The total viable count (TVC), microbiota composition, and quality parameters, including the total volatile basic nitrogen (TVB-N), thiobarbituric acid reactive substance (TBARs), and pH were investigated. The results showed that the spoilage bacteria in shrimp surimi rapidly increased with a surge on day 2 during refrigeration storage. The Psychrobacter and Brochothrix were identified as the Specific Spoilage Organisms (SSOs), which were also positively correlated with TVB-N and TBARs. The results further elucidated that the sono/photodynamic treatment could significantly inhibit the growth of SSOs on the surface and interior of shrimp surimi and delay shrimp surimi quality deterioration. In conclusion, the sono/photodynamic treatment as a non-thermal sterilization method could be a reliable and potential method for inactivating spoilage microorganisms and preserving shrimp surimi quality.
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Affiliation(s)
- Dehua Wang
- Engineering Research Centre of Fujian-Taiwan Special Marine Food Processing and Nutrition, Ministry of Education, Fuzhou 350002, Fujian, China; College of Food Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Feng Zhou
- College of Food Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Danning Lai
- College of Food Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Yi Zhang
- Engineering Research Centre of Fujian-Taiwan Special Marine Food Processing and Nutrition, Ministry of Education, Fuzhou 350002, Fujian, China; College of Food Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Jiamiao Hu
- Engineering Research Centre of Fujian-Taiwan Special Marine Food Processing and Nutrition, Ministry of Education, Fuzhou 350002, Fujian, China; College of Food Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Shaoling Lin
- College of Food Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China; State Key Laboratory of Food Safety Technology for Meat Products, Xiamen 361100, Fujian, China.
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Bouju-Albert A, Saltaji S, Dousset X, Prévost H, Jaffrès E. Quantification of Viable Brochothrix thermosphacta in Cold-Smoked Salmon Using PMA/PMAxx-qPCR. Front Microbiol 2021; 12:654178. [PMID: 34335490 PMCID: PMC8316974 DOI: 10.3389/fmicb.2021.654178] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 06/17/2021] [Indexed: 11/17/2022] Open
Abstract
The aim of this study was to develop a rapid and accurate PMA-qPCR method to quantify viable Brochothrix thermosphacta in cold-smoked salmon. B. thermosphacta is one of the main food spoilage bacteria. Among seafood products, cold-smoked salmon is particularly impacted by B. thermosphacta spoilage. Specific and sensitive tools that detect and quantify this bacterium in food products are very useful. The culture method commonly used to quantify B. thermosphacta is time-consuming and can underestimate cells in a viable but not immediately culturable state. We designed a new PCR primer set from the single-copy rpoC gene. QPCR efficiency and specificity were compared with two other published primer sets targeting the rpoC and rpoB genes. The viability dyes PMA or PMAxx were combined with qPCR and compared with these primer sets on viable and dead B. thermosphacta cells in BHI broth and smoked salmon tissue homogenate (SSTH). The three primer sets displayed similar specificity and efficiency. The efficiency of new designed rpoC qPCR on viable B. thermosphacta cells in SSTH was 103.50%, with a linear determination coefficient (r2) of 0.998 and a limit of detection of 4.04 log CFU/g. Using the three primer sets on viable cells, no significant difference was observed between cells treated or untreated with PMA or PMAxx. When dead cells were used, both viability dyes suppressed DNA amplification. Nevertheless, our results did not highlight any difference between PMAxx and PMA in their efficiency to discriminate viable from unviable B. thermosphacta cells in cold-smoked salmon. Thus, this study presents a rapid, specific and efficient rpoC-PMA-qPCR method validated in cold-smoked salmon to quantify viable B. thermosphacta in foods.
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Andoni E, Ozuni E, Bijo B, Shehu F, Branciari R, Miraglia D, Ranucci D. Efficacy of Non-thermal Processing Methods to Prevent Fish Spoilage. JOURNAL OF AQUATIC FOOD PRODUCT TECHNOLOGY 2021. [DOI: 10.1080/10498850.2020.1866131] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Egon Andoni
- Veterinary Faculty of Tirana, Department of Public Health, Rr “Pajsi Vodica”, Koder-Kamez, Tirana, Albania
| | - Enkeleda Ozuni
- Veterinary Faculty of Tirana, Department of Public Health, Rr “Pajsi Vodica”, Koder-Kamez, Tirana, Albania
| | - Bizena Bijo
- Veterinary Faculty of Tirana, Department of Public Health, Rr “Pajsi Vodica”, Koder-Kamez, Tirana, Albania
| | - Fatmira Shehu
- Veterinary Faculty of Tirana, Department of Public Health, Rr “Pajsi Vodica”, Koder-Kamez, Tirana, Albania
| | | | - Dino Miraglia
- Department of Veterinary Medicine, University of Perugia, Perugia, Italy
| | - David Ranucci
- Department of Veterinary Medicine, University of Perugia, Perugia, Italy
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Biondi L, Randazzo CL, Russo N, Pino A, Natalello A, Van Hoorde K, Caggia C. Dietary Supplementation of Tannin-Extracts to Lambs: Effects on Meat Fatty Acids Composition and Stability and on Microbial Characteristics. Foods 2019; 8:E469. [PMID: 31658772 PMCID: PMC6836261 DOI: 10.3390/foods8100469] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 09/30/2019] [Accepted: 10/07/2019] [Indexed: 12/18/2022] Open
Abstract
Two extracts derived from plant material rich in hydrolysable (Tara, T; Caesalpinia spinosa) or condensed (Mimosa, M; Acacia mearnsii) tannins were added to lamb's diet and their effects on meat quality and on microbial population were evaluated; a diet without tannins represented the Control (C). Meat pH, vitamin E, intramuscular fat content and muscle fatty acid composition were determined. Oxidative stability and microbiological analyses were performed on meat samples after 0, 4 and 7 days of refrigerated storage. Psychrotrophic bacteria were identified through MALDI-TOF MS analysis. Regarding meat fatty acids, Tara treatment decreased the percentage of monounsaturated fatty acids. The counts of all microbial groups were similar among dietary treatments at day 0, while a significant reduction of microbial loads was observed in T-group at day 7. Pseudomonas fluorescens group count was significantly affected by T extract supplementation. The MALDI-TOF MS identification revealed the dominance of Pseudomonas fragi species in all samples while Pseudomonas lundensis, Brochothrix thermosphacta and Candida famata were revealed only in control ones. In conclusions, the tannin extract supplementation is a promising dietary strategy to preserve lamb meat quality.
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Affiliation(s)
- Luisa Biondi
- Department of Agriculture, Food and Environment, University of Catania, 95123 Catania, Italy.
| | - Cinzia L Randazzo
- Department of Agriculture, Food and Environment, University of Catania, 95123 Catania, Italy.
| | - Nunziatina Russo
- Department of Agriculture, Food and Environment, University of Catania, 95123 Catania, Italy.
| | - Alessandra Pino
- Department of Agriculture, Food and Environment, University of Catania, 95123 Catania, Italy.
| | - Antonio Natalello
- Department of Agriculture, Food and Environment, University of Catania, 95123 Catania, Italy.
| | - Koenraad Van Hoorde
- Service Foodborne Pathogens, Sciensano, B-1050 Brussels, Belgium.
- Faculty of Bioscience Engineering, Department of Biotechnology, Laboratory of Brewing Science and Technology, Ghent University, B-9000 Ghent, Belgium.
| | - Cinzia Caggia
- Department of Agriculture, Food and Environment, University of Catania, 95123 Catania, Italy.
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9
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Liu DY, Xiao X, Wang HH, Zhang QY, Zou YF. Characterization of the bacterial community of braised chicken, a specialty poultry product in China. Poult Sci 2019; 98:1055-1063. [PMID: 30137620 DOI: 10.3382/ps/pey375] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 07/22/2018] [Indexed: 11/20/2022] Open
Abstract
High-throughput sequencing of 16S rDNA and culture-dependent methods were applied to determine the bacterial communities of braised chicken during processing and storage. Environmental microorganisms were also evaluated using a sedimentation plate method. The results showed that airborne microbial counts in the braising room were higher than those in the control room (25°C, a space to lower the temperature of the chicken products) and storage rooms (4°C). The microbial identification technique 16S rDNA sequences has indicated that more than 229 operational bacterial species were associated with the microbiota present in braised chicken, largely involving Pseudomonas, Psychrobacter, Weissella, Kurthia, Brochothrix, and Lactobacillus in modified-atmosphere packing (MAP) products. The storage place and temperature during processing has great impact on the shelf life of the chicken. The microbes in MAP were significantly higher (P < 0.05) in 0 and 7th day, while the microbial activity in vacuum packaging (VP) was lower because the VP products were treated at higher temperature (100°C for 20 min). Within chicken products, Pseudomonas, Brochothrix, and Lactobacillus were most prevalent in MAP products. According to this research, in order to prolong the shelf life of meat products, proper storage places and packaging conditions are necessary to be improved to reduce the microbial load in the food products.
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Affiliation(s)
- Deng Yong Liu
- College of Food Science and Technology, Bohai University, Jinzhou 121013, China
| | - Xiong Xiao
- College of Food Science and Technology, Bohai University, Jinzhou 121013, China
| | - Hu Hu Wang
- Collaborative Innovation Center of Meat Production and Processing, Quality and Safety Control, Nanjing Agricultural University, Nanjing 210095, China
| | - Qing Yong Zhang
- Department of Quality Assurance, Shandong Dezhou Braised Chicken Co., Ltd., Dezhou 253003, China
| | - Yu Feng Zou
- Collaborative Innovation Center of Meat Production and Processing, Quality and Safety Control, Nanjing Agricultural University, Nanjing 210095, China
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Abel N, Rotabakk BT, Lerfall J. Effect of heat treatment and packaging technology on the microbial load of lightly processed seafood. Lebensm Wiss Technol 2019. [DOI: 10.1016/j.lwt.2018.11.025] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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11
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Seafood spoilage microbiota and associated volatile organic compounds at different storage temperatures and packaging conditions. Int J Food Microbiol 2018; 280:87-99. [PMID: 29478710 DOI: 10.1016/j.ijfoodmicro.2017.12.029] [Citation(s) in RCA: 94] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 12/21/2017] [Accepted: 12/30/2017] [Indexed: 01/12/2023]
Abstract
Seafood comprising of both vertebrate and invertebrate aquatic organisms are nutritious, rich in omega-3 fatty acids, essential vitamins, proteins, minerals and form part of healthy diet. However, despite the health and nutritional benefits, seafood is highly perishable. Spoilage of seafood could be as a result of microbial activity, autolysis or chemical oxidation. Microbial activity constitutes more spoilage than others. Spoilage bacteria are commonly Gram negative and produce off odours and flavours in seafood as a result of their metabolic activities. Storage temperature, handling and packaging conditions affect microbial growth and thus the shelf-life of seafood. Due to the complexity of the microbial communities in seafood, culture dependent methods of detection may not be useful, hence the need for culture independent methods are necessary to understand the diversity of microbiota and spoilage process. Similarly, the volatile organic compounds released by spoilage bacteria are not fully understood in some seafood. This review therefore highlights current knowledge and understanding of seafood spoilage microbiota, volatile organic compounds, effects of storage temperature and packaging conditions on quality of seafood.
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Hwanhlem N, Ivanova T, Haertlé T, Jaffrès E, Dousset X. Inhibition of food-spoilage and foodborne pathogenic bacteria by a nisin Z-producing Lactococcus lactis subsp. lactis KT2W2L. Lebensm Wiss Technol 2017. [DOI: 10.1016/j.lwt.2017.04.052] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Stanborough T, Fegan N, Powell SM, Tamplin M, Chandry PS. Insight into the Genome of Brochothrix thermosphacta, a Problematic Meat Spoilage Bacterium. Appl Environ Microbiol 2017; 83:e02786-16. [PMID: 27986732 PMCID: PMC5311415 DOI: 10.1128/aem.02786-16] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 12/14/2016] [Indexed: 01/16/2023] Open
Abstract
Brochothrix thermosphacta is a dominant but poorly studied meat spoilage organism. It is a close relative of the foodborne pathogen Listeria monocytogenes, and Brochothrix constitutes the second genus in the Listeriaceae family. Here, the genomes of 12 B. thermosphacta strains were sequenced, assembled into draft genomes, characterized, and compared with the genomes of Brochothrix campestris and L. monocytogenes Phenotypic properties including biogenic amine production and antibiotic and heavy metal susceptibilities were tested. Comparative genomic analyses revealed a high degree of similarity among the B. thermosphacta strains, with bacteriophage genes constituting a significant proportion of the accessory genome. Genes for the production of the malodorous compounds acetate, acetoin, butanediol, and fatty acids were found, as were stress response regulatory genes, which likely play important roles in the spoilage process. Amino acid decarboxylases were not identified in the genomes, and phenotypic testing confirmed their absence. Orthologs of Listeria virulence proteins involved in virulence regulation, intracellular survival, and surface protein anchoring were found; however, key virulence genes were absent. Analysis of antibiotic susceptibility showed that strains were sensitive to the four tested antibiotics, except for one tetracycline-resistant isolate with plasmid-mediated tetracycline resistance genes. Strains tolerated higher levels of copper and cobalt than of cadmium although not at concentrations high enough to categorize the strains as being resistant. This study provides insight into the Brochothrix genome, links previous phenotypic data and data provided here to the gene inventory, and identifies genes that may contribute to the persistence of this organism in the food chain.IMPORTANCE Despite increasing knowledge and advances in food preservation techniques, microbial spoilage of foods causes substantial losses, with negative social and economic consequences. To better control the contamination and microbial spoilage of foods, fundamental knowledge of the biology of key spoilage bacteria is crucial. As a common meat spoilage organism, B. thermosphacta contributes substantially to spoilage-associated losses. Nonetheless, this organism and particularly its genome remain largely unstudied. This study contributes to improving our knowledge of the Brochothrix genus. Spoilage-relevant pathways and genes that may play a role in the survival of this organism in a food processing environment were identified, linking previous phenotypic data and data provided here to the gene inventory of Brochothrix and establishing parallels to and differences from the closely related foodborne pathogen L. monocytogenes.
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Affiliation(s)
- Tamsyn Stanborough
- CSIRO Agriculture and Food, Werribee, Victoria, Australia
- Food Safety Centre, Tasmanian Institute of Agriculture, University of Tasmania, Hobart, Tasmania, Australia
| | - Narelle Fegan
- CSIRO Agriculture and Food, Werribee, Victoria, Australia
| | - Shane M Powell
- Food Safety Centre, Tasmanian Institute of Agriculture, University of Tasmania, Hobart, Tasmania, Australia
| | - Mark Tamplin
- Food Safety Centre, Tasmanian Institute of Agriculture, University of Tasmania, Hobart, Tasmania, Australia
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Silbande A, Adenet S, Smith-Ravin J, Joffraud JJ, Rochefort K, Leroi F. Quality assessment of ice-stored tropical yellowfin tuna (Thunnus albacares) and influence of vacuum and modified atmosphere packaging. Food Microbiol 2016; 60:62-72. [DOI: 10.1016/j.fm.2016.06.016] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 05/18/2016] [Accepted: 06/26/2016] [Indexed: 11/28/2022]
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Zeng D, Chen Z, Jiang Y, Xue F, Li B. Advances and Challenges in Viability Detection of Foodborne Pathogens. Front Microbiol 2016; 7:1833. [PMID: 27920757 PMCID: PMC5118415 DOI: 10.3389/fmicb.2016.01833] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Accepted: 11/01/2016] [Indexed: 11/13/2022] Open
Abstract
Foodborne outbreaks are a serious public health and food safety concern worldwide. There is a great demand for rapid, sensitive, specific, and accurate methods to detect microbial pathogens in foods. Conventional methods based on cultivation of pathogens have been the gold standard protocols; however, they take up to a week to complete. Molecular assays such as polymerase chain reaction (PCR), sequencing, microarray technologies have been widely used in detection of foodborne pathogens. Among molecular assays, PCR technology [conventional and real-time PCR (qPCR)] is most commonly used in the foodborne pathogen detection because of its high sensitivity and specificity. However, a major drawback of PCR is its inability to differentiate the DNA from dead and viable cells, and this is a critical factor for the food industry, regulatory agencies and the consumer. To remedy this shortcoming, researchers have used biological dyes such as ethidium monoazide and propidium monoazide (PMA) to pretreat samples before DNA extraction to intercalate the DNA of dead cells in food samples, and then proceed with regular DNA preparation and qPCR. By combining PMA treatment with qPCR (PMA-qPCR), scientists have applied this technology to detect viable cells of various bacterial pathogens in foods. The incorporation of PMA into PCR-based assays for viability detection of pathogens in foods has increased significantly in the last decade. On the other hand, some downsides with this approach have been noted, particularly to achieve complete suppression of signal of DNA from the dead cells present in some particular food matrix. Nowadays, there is a tendency of more and more researchers adapting this approach for viability detection; and a few commercial kits based on PMA are available in the market. As time goes on, more scientists apply this approach to a broader range of pathogen detections, this viability approach (PMA or other chemicals such as platinum compound) may eventually become a common methodology for the rapid, sensitive, and accurate detection of foodborne pathogens. In this review, we summarize the development in the field including progress and challenges and give our perspective in this area.
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Affiliation(s)
- Dexin Zeng
- College of Veterinary Medicine, Nanjing Agricultural University Nanjing, China
| | - Zi Chen
- College of Veterinary Medicine, Nanjing Agricultural UniversityNanjing, China; Animal Quarantine Laboratory, Jiangsu Entry-Exit Inspection and Quarantine BureauNanjing, China
| | - Yuan Jiang
- Animal Quarantine Laboratory, Jiangsu Entry-Exit Inspection and Quarantine BureauNanjing, China; Shanghai Entry-Exit Inspection and Quarantine BureauShanghai, China
| | - Feng Xue
- College of Veterinary Medicine, Nanjing Agricultural University Nanjing, China
| | - Baoguang Li
- Division of Molecular Biology, Center for Food Safety and Applied Nutrition, United States Food and Drug Administration, Laurel MD, USA
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Quantification of viable bacterial starter cultures of Virgibacillus sp. and Tetragenococcus halophilus in fish sauce fermentation by real-time quantitative PCR. Food Microbiol 2016; 57:54-62. [DOI: 10.1016/j.fm.2016.01.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Revised: 12/21/2015] [Accepted: 01/15/2016] [Indexed: 11/20/2022]
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17
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Assessment throughout a whole fishing year of the dominant microbiota of peeled brown shrimp (Crangon crangon) stored for 7 days under modified atmosphere packaging at 4 °C without preservatives. Food Microbiol 2016. [DOI: 10.1016/j.fm.2015.10.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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18
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Cattani F, Barth VC, Nasário JSR, Ferreira CAS, Oliveira SD. Detection and quantification of viable Bacillus cereus group species in milk by propidium monoazide quantitative real-time PCR. J Dairy Sci 2016; 99:2617-2624. [PMID: 26830746 DOI: 10.3168/jds.2015-10019] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 09/23/2015] [Indexed: 11/19/2022]
Abstract
The Bacillus cereus group includes important spore-forming bacteria that present spoilage capability and may cause foodborne diseases. These microorganisms are traditionally evaluated in food using culturing methods, which can be laborious and time-consuming, and may also fail to detect bacteria in a viable but nonculturable state. The purpose of this study was to develop a quantitative real-time PCR (qPCR) combined with a propidium monoazide (PMA) treatment to analyze the contamination of UHT milk by B. cereus group species viable cells. Thirty micrograms per milliliter of PMA was shown to be the most effective concentration for reducing the PCR amplification of extracellular DNA and DNA from dead cells. The quantification limit of the PMA-qPCR assay was 7.5 × 10(2) cfu/mL of milk. One hundred thirty-five UHT milk samples were analyzed to evaluate the association of PMA to qPCR to selectively detect viable cells. The PMA-qPCR was able to detect B. cereus group species in 44 samples (32.6%), whereas qPCR without PMA detected 78 positive samples (57.8%). Therefore, the PMA probably inhibited the amplification of DNA from cells that were killed during UHT processing, which avoided an overestimation of bacterial cells when using qPCR and, thus, did not overvalue potential health risks. A culture-based method was also used to detect and quantify B. cereus sensu stricto in the same samples and showed positive results in 15 (11.1%) samples. The culture method and PMA-qPCR allowed the detection of B. cereus sensu stricto in quantities compatible with the infective dose required to cause foodborne disease in 3 samples, indicating that, depending on the storage conditions, even after UHT treatment, infective doses may be reached in ready-to-consume products.
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Affiliation(s)
- Fernanda Cattani
- Laboratório de Imunologia e Microbiologia, Faculdade de Biociências, PUCRS, Porto Alegre, RS, Brazil
| | - Valdir C Barth
- Laboratório de Imunologia e Microbiologia, Faculdade de Biociências, PUCRS, Porto Alegre, RS, Brazil
| | - Jéssica S R Nasário
- Laboratório de Imunologia e Microbiologia, Faculdade de Biociências, PUCRS, Porto Alegre, RS, Brazil
| | - Carlos A S Ferreira
- Laboratório de Imunologia e Microbiologia, Faculdade de Biociências, PUCRS, Porto Alegre, RS, Brazil
| | - Sílvia D Oliveira
- Laboratório de Imunologia e Microbiologia, Faculdade de Biociências, PUCRS, Porto Alegre, RS, Brazil.
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19
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Podeur G, Dalgaard P, Leroi F, Prévost H, Emborg J, Martinussen J, Hansen LH, Pilet MF. Development of a real-time PCR method coupled with a selective pre-enrichment step for quantification of Morganella morganii and Morganella psychrotolerans in fish products. Int J Food Microbiol 2015; 203:55-62. [PMID: 25791250 DOI: 10.1016/j.ijfoodmicro.2015.03.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 02/25/2015] [Accepted: 03/01/2015] [Indexed: 10/23/2022]
Abstract
Histamine fish poisoning is common and due to toxic concentrations of histamine often produced by Gram-negative bacteria in fin-fish products with a high content of the free amino acid histidine. The genus Morganella includes two species previously reported to cause incidents of histamine fish poisoning. Morganella morganii and Morganella psychrotolerans are both strong producer of histamine. However, little is known about the occurrence and critical stages for fish contamination with these bacteria. To elucidate contamination routes of Morganella, specific real-time quantitative PCR (RTi qPCR) methods for quantification of M. morganii and M. psychrotolerans have been developed. Selective primers amplified a 110 bp region of the vasD gene for M. psychrotolerans and a 171 bp region of the galactokinase gene for M. morganii. These primer-sets showed high specificity as demonstrated by using purified DNA from 23 other histamine producing bacteria and 26 isolates with no or limited histamine production. The efficiency of the qPCR reactions on artificially contaminated fish samples were 100.8% and 96.3% respectively. The limit of quantification (LOQ) without enrichment was 4 log CFU/g. A quantitative enrichment step with a selective medium was included and improved the sensitivity of the methods to a LOQ of below 50 CFU/g in seafood. RTi qPCR methods with or without enrichment were evaluated for enumeration of Morganella species in naturally contaminated fresh fish and lightly preserved seafood from Denmark. These new methods will contribute to a better understanding of the occurrence and histamine production by Morganella species in fish products, information that is essential to reduce the unacceptably high frequency of histamine fish poisoning.
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Affiliation(s)
- Gaëtan Podeur
- Ifremer, Laboratory of Microbial Ecosystem and Marine Molecules for Biotechnology, Nantes, France; LUNAM Université, Oniris, UMR1014, Secalim, Nantes, France; INRA, Nantes, France
| | - Paw Dalgaard
- National Food Institute (DTU Food), Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Francoise Leroi
- Ifremer, Laboratory of Microbial Ecosystem and Marine Molecules for Biotechnology, Nantes, France
| | - Hervé Prévost
- LUNAM Université, Oniris, UMR1014, Secalim, Nantes, France; INRA, Nantes, France
| | - Jette Emborg
- National Food Institute (DTU Food), Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Jan Martinussen
- DTU System Biology, Technical University of Denmark, Kgs. Lyngby, Denmark
| | | | - Marie-France Pilet
- LUNAM Université, Oniris, UMR1014, Secalim, Nantes, France; INRA, Nantes, France.
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20
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Application of a nisin Z-producing Lactococcus lactis subsp. lactis KT2W2L isolated from brackish water for biopreservation in cooked, peeled and ionized tropical shrimps during storage at 8 °C under modified atmosphere packaging. Eur Food Res Technol 2015. [DOI: 10.1007/s00217-015-2428-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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21
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Barbau-Piednoir E, Mahillon J, Pillyser J, Coucke W, Roosens NH, Botteldoorn N. Evaluation of viability-qPCR detection system on viable and dead Salmonella serovar Enteritidis. J Microbiol Methods 2014; 103:131-7. [DOI: 10.1016/j.mimet.2014.06.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Revised: 06/02/2014] [Accepted: 06/02/2014] [Indexed: 11/25/2022]
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22
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Hwanhlem N, Chobert JM, H-Kittikun A. Bacteriocin-producing lactic acid bacteria isolated from mangrove forests in southern Thailand as potential bio-control agents in food: Isolation, screening and optimization. Food Control 2014. [DOI: 10.1016/j.foodcont.2014.01.021] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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23
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Vendrame M, Manzano M, Comi G, Bertrand J, Iacumin L. Use of propidium monoazide for the enumeration of viable Brettanomyces bruxellensis in wine and beer by quantitative PCR. Food Microbiol 2014; 42:196-204. [PMID: 24929737 DOI: 10.1016/j.fm.2014.03.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 01/29/2014] [Accepted: 03/13/2014] [Indexed: 11/25/2022]
Abstract
Brettanomyces bruxellensis is a current problem in winemaking all over the world, and the question if B. bruxellensis has a positive or negative impact on wine is one of the most controversial discussions in the world. The presence of live B. bruxellensis cells represents the risk of growth and an increase in cell numbers, which is related to the potential production of volatile phenols. In this work, the optimisation of a PMA-quantitative PCR (qPCR) method to enumerate only viable cells was carried out using the standard strain B. bruxellensis DSMZ 70726. The obtained detection limits were 0.83 log CFU/mL in red wine, 0.63 log CFU/mL in white wine and 0.23 log CFU/mL in beer. Moreover, the quantification was also performed by Reverse Transcription quantitative PCR (RT-qPCR), and the results showed a higher detection limit for all of the trials.
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Affiliation(s)
- Marco Vendrame
- Dipartimento di Scienze degli Alimenti, Università degli Studi di Udine, via Sondrio 2/A, 33100 Udine, Italy
| | - Marisa Manzano
- Dipartimento di Scienze degli Alimenti, Università degli Studi di Udine, via Sondrio 2/A, 33100 Udine, Italy
| | - Giuseppe Comi
- Dipartimento di Scienze degli Alimenti, Università degli Studi di Udine, via Sondrio 2/A, 33100 Udine, Italy
| | - Julien Bertrand
- Dipartimento di Scienze degli Alimenti, Università degli Studi di Udine, via Sondrio 2/A, 33100 Udine, Italy
| | - Lucilla Iacumin
- Dipartimento di Scienze degli Alimenti, Università degli Studi di Udine, via Sondrio 2/A, 33100 Udine, Italy.
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24
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Elizaquível P, Aznar R, Sánchez G. Recent developments in the use of viability dyes and quantitative PCR in the food microbiology field. J Appl Microbiol 2013; 116:1-13. [DOI: 10.1111/jam.12365] [Citation(s) in RCA: 117] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Revised: 10/08/2013] [Accepted: 10/08/2013] [Indexed: 01/09/2023]
Affiliation(s)
- P. Elizaquível
- Department of Microbiology and Ecology; University of Valencia; Valencia Spain
| | - R. Aznar
- Department of Microbiology and Ecology; University of Valencia; Valencia Spain
- Institute of Agrochemistry and Food Technology (IATA); Spanish Council for Scientific Research (CSIC); Valencia Spain
| | - G. Sánchez
- Institute of Agrochemistry and Food Technology (IATA); Spanish Council for Scientific Research (CSIC); Valencia Spain
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25
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Gribble A, Brightwell G. Spoilage characteristics of Brochothrix thermosphacta and campestris in chilled vacuum packaged lamb, and their detection and identification by real time PCR. Meat Sci 2013; 94:361-8. [DOI: 10.1016/j.meatsci.2013.03.016] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Revised: 02/28/2013] [Accepted: 03/01/2013] [Indexed: 10/27/2022]
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26
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Cattani F, Ferreira C, Oliveira S. The detection of viable vegetative cells of Bacillus sporothermodurans using propidium monoazide with semi-nested PCR. Food Microbiol 2013; 34:196-201. [DOI: 10.1016/j.fm.2012.12.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Revised: 11/12/2012] [Accepted: 12/26/2012] [Indexed: 11/26/2022]
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27
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Vendrame M, Iacumin L, Manzano M, Comi G. Use of propidium monoazide for the enumeration of viable Oenococcus oeni in must and wine by quantitative PCR. Food Microbiol 2013; 35:49-57. [PMID: 23628614 DOI: 10.1016/j.fm.2013.02.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Revised: 01/24/2013] [Accepted: 02/15/2013] [Indexed: 01/05/2023]
Abstract
Malolactic fermentation is an important step in winemaking, but it has to be avoided in some cases. It's carried out by lactic acid bacteria belonging mainly to the genus Oenococcus, which is known to be a slow growing bacterium. Classical microbiological methods to enumerate viable cells of Oenococcus oeni in must and wine take 7-9 days to give results. Moreover, RT-qPCR technique gives accurate quantitative results, but it requires time consuming steps of RNA extraction and reverse transcription. In the present work we developed a fast and reliable quantitative PCR (qPCR) method to enumerate cells of Oenococcus oeni, directly, in must and wine. For the first time we used a propidium monoazide treatment of samples to enumerate only Oenococcus oeni viable cells. The detection limit of the developed method is 0.33 log CFU/mL (2.14 CFU/mL) in must, and 0.69 log CFU/mL (4.90 CFU/mL) in wine, lower than that of the previously developed qPCR protocols.
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Affiliation(s)
- Marco Vendrame
- Dipartimento di Scienze degli Alimenti, Università degli Studi di Udine, via Sondrio 2/A, 33100 Udine, Italy
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28
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Development of a rapid real-time PCR method as a tool to quantify viable Photobacterium phosphoreum bacteria in salmon (Salmo salar) steaks. Appl Environ Microbiol 2013; 79:2612-9. [PMID: 23396343 DOI: 10.1128/aem.03677-12] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A specific real-time PCR quantification method combined with a propidium monoazide sample treatment step was developed to determine quantitatively the viable population of the Photobacterium phosphoreum species group in raw modified-atmosphere-packed salmon. Primers were designed to amplify a 350-bp fragment of the gyrase subunit B gene (gyrB) of P. phosphoreum. The specificity of the two primers was demonstrated by using purified DNA from 81 strains of 52 different bacterial species. When these primers were used for real-time PCR in pure culture, a good correlation (R(2) of 0.99) was obtained between this method and conventional enumeration on marine agar (MA). Quantification was linear over 5 log units as confirmed by using inoculated salmon samples. On naturally contaminated fresh salmon, the new real-time PCR method performed successfully with a quantification limit of 3 log CFU/g. A correlation coefficient (R(2)) of 0.963 was obtained between the PCR method and classic enumeration on MA, followed by identification of colonies (290 isolates identified by real-time PCR or by 16S rRNA gene sequencing). A good correlation with an R(2) of 0.940 was found between the new PCR method and an available specific conductance method for P. phosphoreum. This study presents a rapid tool for producing reliable quantitative data on viable P. phosphoreum bacteria in fresh salmon in 6 h. This new culture-independent method will be valuable for future fish inspection, the assessment of raw material quality in fish processing plants, and studies on the ecology of this important specific spoilage microorganism.
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29
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Fonseca S, Cachaldora A, Gómez M, Franco I, Carballo J. Monitoring the bacterial population dynamics during the ripening of Galician chorizo, a traditional dry fermented Spanish sausage. Food Microbiol 2013; 33:77-84. [DOI: 10.1016/j.fm.2012.08.015] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Revised: 08/07/2012] [Accepted: 08/31/2012] [Indexed: 10/27/2022]
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30
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Elizaquível P, Sánchez G, Aznar R. Application of propidium monoazide quantitative PCR for selective detection of live Escherichia coli O157:H7 in vegetables after inactivation by essential oils. Int J Food Microbiol 2012; 159:115-21. [PMID: 23072696 DOI: 10.1016/j.ijfoodmicro.2012.08.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Revised: 07/18/2012] [Accepted: 08/06/2012] [Indexed: 11/16/2022]
Abstract
The use of propidium monoazide (PMA) is enjoying increased popularity among researchers in different fields of microbiology. Its use in combination with real-time PCR (qPCR) represents one of the most successful approaches to detect viable cells. PMA-qPCR has successfully been used to evaluate the efficacy of various disinfection technologies in different microorganisms. Initially, in this study the effect of four essential oils (EOs), cumin, clove, oregano and cinnamon, was evaluated on suspensions of the enterohemorrhagic Escherichia coli O157:H7 by PMA-qPCR, LIVE/DEAD BacLight flow cytometry analysis (LIVE/DEAD-FCM), and plate count. E. coli O157:H7 cells treated with EOs at killing concentrations were permeable to PMA which was confirmed by LIVE/DEAD-FCM. However, the PMA-qPCR assay allows specific quantification among the autochthonous microbiota of food products. Therefore, the PMA-qPCR assay was used to evaluate its applicability in artificially contaminated iceberg lettuce and soya sprouts. Amplification signal was negative for the spiking tests performed with any of the EO-killed E. coli cells. It demonstrates that the PMA-qPCR assay is a suitable technique for monitoring E. coli O157:H7 inactivation by essential oils in fresh-cut vegetables.
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Affiliation(s)
- Patricia Elizaquível
- Departamento de Microbiología y Ecología, Universitat de València, Av. Dr. Moliner, 50, 46100 Burjassot, Valencia, Spain
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