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Guillén S, Nadal L, Halaihel N, Mañas P, Cebrián G. Isolation and characterization of Salmonella Typhimurium SL1344 variants with increased resistance to different stressing agents and food processing technologies. Food Microbiol 2025; 128:104714. [PMID: 39952745 DOI: 10.1016/j.fm.2024.104714] [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: 08/09/2024] [Revised: 12/04/2024] [Accepted: 12/12/2024] [Indexed: 02/17/2025]
Abstract
In this study, resistant variants of Salmonella enterica serovar Typhimurium SL1344 to different stressors were selected. In addition, a genetic and phenotypic study was performed to explore the mechanisms underlying the acquisition of resistance. We isolated 4 variants with increased stable resistance to acid, osmotic stress, high hydrostatic pressure (HHP) and Ultraviolet-C light (UV-C) after repeated rounds of exposure to these agents and outgrowth of survivors. A PEF-resistant variant (SL1344-RS), previously isolated by Sagarzazu et al. (2013), was also included in the analysis. The results indicated that the isolated variants showed resistance to at least one other agent. This increased resistance, in general terms, had a fitness cost in growth, and exerted a variable impact on virulence (mainly in cell adhesion capacity), increased antibiotic resistance but did not influence in biofilm formation capacity. Whole Genome Sequencing (WGS) analysis allowed us to identify the genetic changes responsible for these phenotypic differences, and revealed that in 3 out of the 5 variants (including SL1344-RS) a mutation was found in hnr gene, an anti-sigma factor that promotes RpoS proteolysis. Hence the expression of several rpoS-regulated genes was quantified and found higher in these variants. This increase in RpoS activity would explain the lower growth rates observed in these 3 variants, as it would lead to increased transcription of genes involved in growth arrest and resistance to various types of stress. However, further analysis of a set of 22 additional Salmonella strains obtained from different culture collections indicated that a direct relationship between RpoS activity and stress resistance might not exist within Salmonella.
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Affiliation(s)
- S Guillén
- Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Instituto Agroalimentario de Aragón- IA2, Universidad de Zaragoza-CITA, 50013, Zaragoza, Spain
| | - L Nadal
- Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Instituto Agroalimentario de Aragón- IA2, Universidad de Zaragoza-CITA, 50013, Zaragoza, Spain
| | - N Halaihel
- Departamento I+D+i, Alquizvetek S.L, Zaragoza, 50013, Zaragoza, Spain
| | - P Mañas
- Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Instituto Agroalimentario de Aragón- IA2, Universidad de Zaragoza-CITA, 50013, Zaragoza, Spain
| | - G Cebrián
- Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Instituto Agroalimentario de Aragón- IA2, Universidad de Zaragoza-CITA, 50013, Zaragoza, Spain.
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Bucka-Kolendo J, Kiousi DE, Wojtczak A, Doulgeraki AI, Galanis A, Sokołowska B. Depiction of the In Vitro and Genomic Basis of Resistance to Hop and High Hydrostatic Pressure of Lactiplantibacillus plantarum Isolated from Spoiled Beer. Genes (Basel) 2023; 14:1710. [PMID: 37761850 PMCID: PMC10530735 DOI: 10.3390/genes14091710] [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: 08/04/2023] [Revised: 08/22/2023] [Accepted: 08/24/2023] [Indexed: 09/29/2023] Open
Abstract
Among the beer-spoiling microorganisms, the dominant ones belong to the genera Lactobacillus, Leuconostoc, Oenococcus, and Pediococcus. It is assumed that resistance to hop bitters correlates with resistance to other factors and can significantly impact the brewing industry. Beer preservation with high hydrostatic pressure eliminates the spoiling microorganisms while preserving all desired properties of the beer. Here, we present comprehensive in vitro and genomic analysis of the beer-spoiling Lactiplantibacillus plantarum KKP 3573 capacity to resist hop and high hydrostatic pressure. Lp. plantarum KKP 3573 is a strain isolated from spoiled beer. Our finding suggests that the growth rate of the strain depends on the medium variant, where a small concentration of beer (5 IBU) stimulates the growth, suggesting that the limited concentration has a positive effect on cell growth. At the same time, increased concentrations of 20 IBU, 30 IBU, and pure beer 43.6 IBU decreased the growth rate of the KKP 3573 strain. We observed that higher extract content in the pressurized beer increased microbial survivability. The wort and Vienna Lager beer can stimulate the baroprotective effect. The taxonomy of the novel strain was confirmed after whole genome sequencing (WGS) and comparative genomic analysis. More specifically, it contains a chromosome of 3.3 Mb with a GC content of 44.4%, indicative of the Lp. plantarum species. Accordingly, it possesses high genomic similarity (>98%) with other species members. Annotation algorithms revealed that the strain carries several genes involved in resistance to stress, including extreme temperature, hop bitters and high pressure, and adaptation to the brewing environment. Lastly, the strain does not code for toxins and virulence proteins and cannot produce biogenic amines.
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Affiliation(s)
- Joanna Bucka-Kolendo
- Department of Microbiology, Prof. Waclaw Dabrowski Institute of Agricultural and Food Biotechnology, State Research Institute, Rakowiecka 36 Street, 02-532 Warsaw, Poland; (A.W.); (B.S.)
| | - Despoina Eugenia Kiousi
- Department of Molecular Biology and Genetics, Faculty of Health Sciences, Democritus University of Thrace, 68100 Alexandroupolis, Greece; (D.E.K.); (A.G.)
| | - Adrian Wojtczak
- Department of Microbiology, Prof. Waclaw Dabrowski Institute of Agricultural and Food Biotechnology, State Research Institute, Rakowiecka 36 Street, 02-532 Warsaw, Poland; (A.W.); (B.S.)
| | - Agapi I. Doulgeraki
- Laboratory of Food Microbiology and Hygiene, Department of Food Science & Technology, Faculty of Agriculture, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece;
| | - Alex Galanis
- Department of Molecular Biology and Genetics, Faculty of Health Sciences, Democritus University of Thrace, 68100 Alexandroupolis, Greece; (D.E.K.); (A.G.)
| | - Barbara Sokołowska
- Department of Microbiology, Prof. Waclaw Dabrowski Institute of Agricultural and Food Biotechnology, State Research Institute, Rakowiecka 36 Street, 02-532 Warsaw, Poland; (A.W.); (B.S.)
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Guillén S, Nadal L, Halaihel N, Mañas P, Cebrián G. Genotypic and phenotypic characterization of a Salmonella Typhimurium strain resistant to pulsed electric fields. Food Microbiol 2023; 113:104285. [PMID: 37098417 DOI: 10.1016/j.fm.2023.104285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 03/29/2023] [Accepted: 04/11/2023] [Indexed: 04/27/2023]
Abstract
Pulsed Electric Fields (PEF) technology is regarded as one of the most interesting alternatives to current food preservation methods, due to its capability to inactivate vegetative microorganisms while leaving the product's organoleptic and nutritional properties mostly unchanged. However, many aspects regarding the mechanisms of bacterial inactivation by PEF are still not fully understood. The aim of this study was to obtain further insight into the mechanisms responsible for the increased resistance to PEF of a Salmonella Typhimurium SL1344 variant (SL1344-RS, Sagarzazu et al., 2013), and to quantify the impact that the acquisition of PEF resistance has on other aspects of S. enterica physiology, such as growth fitness, biofilm formation ability, virulence and antibiotic resistance. WGS, RNAseq and qRT-PCR assays indicated that the increased PEF resistance of the SL1344-RS variant is due to a higher RpoS activity caused by a mutation in the hnr gene. This increased RpoS activity also results in higher resistance to multiple stresses (acidic, osmotic, oxidative, ethanol and UV-C, but not to heat and HHP), decreased growth rate in M9-Gluconate (but not in TSB-YE or LB-DPY), increased ability to adhere to Caco-2 cells (but no significant change in invasiveness) and enhanced antibiotic resistance (to six out of eight agents). This study significantly contributes to the understanding of the mechanisms of the development of stress resistance in Salmonellae and underscores the crucial role played by RpoS in this process. Further studies are needed to determine whether this PEF-resistant variant would represent a higher, equal or lower associated hazard than the parental strain.
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Affiliation(s)
- S Guillén
- Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Instituto Agroalimentario de Aragón- IA2, Universidad de Zaragoza-CITA, 50013, Zaragoza, Spain
| | - L Nadal
- Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Instituto Agroalimentario de Aragón- IA2, Universidad de Zaragoza-CITA, 50013, Zaragoza, Spain
| | - N Halaihel
- Departamento I+D+i, Alquizvetek S.L, Zaragoza, 50013, Zaragoza, Spain
| | - P Mañas
- Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Instituto Agroalimentario de Aragón- IA2, Universidad de Zaragoza-CITA, 50013, Zaragoza, Spain
| | - G Cebrián
- Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Instituto Agroalimentario de Aragón- IA2, Universidad de Zaragoza-CITA, 50013, Zaragoza, Spain.
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Milani G, Belloso Daza MV, Cortimiglia C, Bassi D, Cocconcelli PS. Genome engineering of Stx1-and Stx2-converting bacteriophages unveils the virulence of the dairy isolate Escherichia coli O174:H2 strain UC4224. Front Microbiol 2023; 14:1156375. [PMID: 37426006 PMCID: PMC10326431 DOI: 10.3389/fmicb.2023.1156375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 06/06/2023] [Indexed: 07/11/2023] Open
Abstract
The past decade witnessed the emergence in Shiga toxin-producing Escherichia coli (STEC) infections linked to the consumption of unpasteurized milk and raw milk cheese. The virulence of STEC is primarily attributed to the presence of Shiga toxin genes (stx1 and stx2) carried by Stx-converting bacteriophages, along with the intimin gene eae. Most of the available information pertains to the "Top 7" serotypes associated with STEC infections. The objectives of this study were to characterize and investigate the pathogenicity potential of E. coli UC4224, a STEC O174:H2 strain isolated from semi-hard raw milk cheese and to develop surrogate strains with reduced virulence for use in food-related studies. Complete genome sequence analysis of E. coli UC4224 unveiled the presence of a Stx1a bacteriophage, a Stx2a bacteriophage, the Locus of Adhesion and Autoaggregation (LAA) pathogenicity island, plasmid-encoded virulence genes, and other colonization facilitators. In the Galleria mellonella animal model, E. coli UC4224 demonstrated high pathogenicity potential with an LD50 of 6 CFU/10 μL. Upon engineering E. coli UC4224 to generate single and double mutant derivatives by inactivating stx1a and/or stx2a genes, the LD50 increased by approximately 1 Log-dose in the single mutants and 2 Log-doses in the double mutants. However, infectivity was not completely abolished, suggesting the involvement of other virulence factors contributing to the pathogenicity of STEC O174:H2. Considering the possibility of raw milk cheese serving as a reservoir for STEC, cheesemaking model was developed to evaluate the survival of UC4224 and the adequacy of the respective mutants as reduced-virulence surrogates. All tested strains exhibited the ability to survive the curd cooking step at 48°C and multiplied (3.4 Log CFU) in cheese within the subsequent 24 h. These findings indicate that genomic engineering did not exert any unintended effect on the double stx1-stx2 mutant behaviour, making it as a suitable less-virulent surrogate for conducting studies during food processing.
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Shao L, Sun Y, Zou B, Zhao Y, Li X, Dai R. Sublethally injured microorganisms in food processing and preservation: Quantification, formation, detection, resuscitation and adaption. Food Res Int 2023; 165:112536. [PMID: 36869540 DOI: 10.1016/j.foodres.2023.112536] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Revised: 01/14/2023] [Accepted: 01/21/2023] [Indexed: 01/29/2023]
Abstract
Sublethally injured state has been recognized as a survival strategy for microorganisms suffering from stressful environments. Injured cells fail to grow on selective media but can normally grow on nonselective media. Numerous microorganism species can form sublethal injury in various food matrices during processing and preservation with different techniques. Injury rate was commonly used to evaluate sublethal injury, but mathematical models for the quantification and interpretation of sublethally injured microbial cells still require further study. Injured cells can repair themselves and regain viability on selective media under favorable conditions when stress is removed. Conventional culture methods might underestimate microbial counts or present a false negative result due to the presence of injured cells. Although the structural and functional components may be affected, the injured cells pose a great threat to food safety. This work comprehensively reviewed the quantification, formation, detection, resuscitation and adaption of sublethally injured microbial cells. Food processing techniques, microbial species, strains and food matrix all significantly affect the formation of sublethally injured cells. Culture-based methods, molecular biological methods, fluorescent staining and infrared spectroscopy have been developed to detect the injured cells. Cell membrane is often repaired first during resuscitation of injured cells, meanwhile, temperature, pH, media and additives remarkably influence the resuscitation. The adaption of injured cells negatively affects the microbial inactivation during food processing.
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Affiliation(s)
- Lele Shao
- Beijing Higher Institution Engineering Research Center of Animal Product, College of Food Science and Nutritional Engineering, China Agricultural University, No. 17 Qinghua East Road, Haidian District, Beijing 100083, PR China
| | - Yingying Sun
- Beijing Higher Institution Engineering Research Center of Animal Product, College of Food Science and Nutritional Engineering, China Agricultural University, No. 17 Qinghua East Road, Haidian District, Beijing 100083, PR China
| | - Bo Zou
- Beijing Higher Institution Engineering Research Center of Animal Product, College of Food Science and Nutritional Engineering, China Agricultural University, No. 17 Qinghua East Road, Haidian District, Beijing 100083, PR China
| | - Yijie Zhao
- Beijing Higher Institution Engineering Research Center of Animal Product, College of Food Science and Nutritional Engineering, China Agricultural University, No. 17 Qinghua East Road, Haidian District, Beijing 100083, PR China
| | - Xingmin Li
- Beijing Higher Institution Engineering Research Center of Animal Product, College of Food Science and Nutritional Engineering, China Agricultural University, No. 17 Qinghua East Road, Haidian District, Beijing 100083, PR China
| | - Ruitong Dai
- Beijing Higher Institution Engineering Research Center of Animal Product, College of Food Science and Nutritional Engineering, China Agricultural University, No. 17 Qinghua East Road, Haidian District, Beijing 100083, PR China.
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Gayán E, Wang Z, Salvador M, Gänzle MG, Aertsen A. Dynamics of high hydrostatic pressure resistance development in RpoS-deficient Escherichia coli. Food Res Int 2023; 164:112280. [PMID: 36737893 DOI: 10.1016/j.foodres.2022.112280] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 10/17/2022] [Accepted: 11/28/2022] [Indexed: 12/12/2022]
Abstract
High hydrostatic pressure (HHP) treatment is one of the most widely accepted non-thermal food processing methods, but HHP-resistance development in pathogenic or spoilage bacteria might compromise the safety and stability of HHP-treated foods. Charting the possible routes and mechanisms of HHP resistance development in foodborne bacteria is therefore essential to anticipate or prevent the appearance of resistant variants. While upregulation of the RpoS-governed general stress response is a well-established route for increased HHP resistance in Escherichia coli, previous work revealed that mutations causing attenuated cAMP/CRP activity or aggregation-prone TnaA variants can evolve to overcome the HHP-hypersensitivity of an E. coli ΔrpoS mutant. In this study, further directed evolution and genetic analysis approaches allowed us to demonstrate that both kinds of mutants tend to co-emerge and compete with each other in E. coli ΔrpoS populations evolving towards HHP resistance, because of the higher HHP resistance of cAMP/CRP mutants and the faster growth rate of the TnaA mutants. Moreover, closer scrutiny of evolving populations revealed RpoS, cAMP/CRP and TnaA independent routes of HHP resistance development, based on downregulation of YegW or RppH activity.
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Affiliation(s)
- Elisa Gayán
- Department of Microbial and Molecular Systems, KU Leuven, Faculty of Bioscience Engineering, Kasteelpark Arenberg 20, 3001 Leuven, Belgium
| | - Zhiying Wang
- Department of Agricultural, Food and Nutritional Science, 4-10 Ag/For Centre, University of Alberta, Edmonton, AB T6G 2P5, Canada
| | - Maika Salvador
- Department of Animal Production and Food Science, AgriFood Institute of Aragon (IA2), University of Zaragoza-CITA, Faculty of Veterinary, Miguel Servet 177, 50013 Zaragoza, Spain
| | - Michael G Gänzle
- Department of Agricultural, Food and Nutritional Science, 4-10 Ag/For Centre, University of Alberta, Edmonton, AB T6G 2P5, Canada
| | - Abram Aertsen
- Department of Microbial and Molecular Systems, KU Leuven, Faculty of Bioscience Engineering, Kasteelpark Arenberg 20, 3001 Leuven, Belgium.
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Fernández-Gómez P, Trigal E, Alegría Á, Santos JA, López M, Prieto M, Alvarez-Ordóñez A. Biofilm formation ability and tolerance to food-associated stresses among ESBL-producing Escherichia coli strains from foods of animal origin and human patients. Lebensm Wiss Technol 2022. [DOI: 10.1016/j.lwt.2022.113961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Hao J, Lei Y, Gan Z, Zhao W, Shi J, Jia C, Sun A. Synergetic Inactivation Mechanism of Protocatechuic Acid and High Hydrostatic Pressure against Escherichia coli O157:H7. Foods 2021; 10:foods10123053. [PMID: 34945604 PMCID: PMC8701084 DOI: 10.3390/foods10123053] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 11/12/2021] [Accepted: 12/03/2021] [Indexed: 11/16/2022] Open
Abstract
With the wide application of high hydrostatic pressure (HHP) technology in the food industry, safety issues regarding food products, resulting in potential food safety hazards, have arisen. To address such problems, this study explored the synergetic bactericidal effects and mechanisms of protocatechuic acid (PCA) and HHP against Escherichia coli O157:H7. At greater than 200 MPa, PCA (1.25 mg/mL for 60 min) plus HHP treatments had significant synergetic bactericidal effects that positively correlated with pressure. After a combined treatment at 500 MPa for 5 min, an approximate 9.0 log CFU/mL colony decline occurred, whereas the individual HHP and PCA treatments caused 4.48 and 1.06 log CFU/mL colony decreases, respectively. Mechanistically, membrane integrity and morphology were damaged, and the permeability increased when E. coli O157: H7 was exposed to the synergetic stress of PCA plus HHP. Inside cells, the synergetic treatment additionally targeted the activities of enzymes such as superoxide dismutase, catalase and ATPase, which were inhibited significantly (p ≤ 0.05) when exposed to high pressure. Moreover, an analysis of circular dichroism spectra indicated that the synergetic treatment caused a change in DNA structure, which was expressed as the redshift of the characteristic absorption peak. Thus, the synergetic treatment of PCA plus HHP may be used as a decontamination method owing to the good bactericidal effects on multiple targets.
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Affiliation(s)
- Jingyi Hao
- College of Biological Sciences and Biotechnology, Beijing Forestry University, No. 35 Qinghua East Road, Haidian District, Beijing 100083, China; (J.H.); (Y.L.); (Z.G.); (W.Z.); (J.S.); (C.J.)
- Beijing Key Laboratory of Food Processing and Safety in Forestry, No. 35 Qinghua East Road, Haidian District, Beijing 100083, China
| | - Yuqing Lei
- College of Biological Sciences and Biotechnology, Beijing Forestry University, No. 35 Qinghua East Road, Haidian District, Beijing 100083, China; (J.H.); (Y.L.); (Z.G.); (W.Z.); (J.S.); (C.J.)
- Beijing Key Laboratory of Food Processing and Safety in Forestry, No. 35 Qinghua East Road, Haidian District, Beijing 100083, China
| | - Zhilin Gan
- College of Biological Sciences and Biotechnology, Beijing Forestry University, No. 35 Qinghua East Road, Haidian District, Beijing 100083, China; (J.H.); (Y.L.); (Z.G.); (W.Z.); (J.S.); (C.J.)
- Beijing Key Laboratory of Food Processing and Safety in Forestry, No. 35 Qinghua East Road, Haidian District, Beijing 100083, China
| | - Wanbin Zhao
- College of Biological Sciences and Biotechnology, Beijing Forestry University, No. 35 Qinghua East Road, Haidian District, Beijing 100083, China; (J.H.); (Y.L.); (Z.G.); (W.Z.); (J.S.); (C.J.)
- Beijing Key Laboratory of Food Processing and Safety in Forestry, No. 35 Qinghua East Road, Haidian District, Beijing 100083, China
| | - Junyan Shi
- College of Biological Sciences and Biotechnology, Beijing Forestry University, No. 35 Qinghua East Road, Haidian District, Beijing 100083, China; (J.H.); (Y.L.); (Z.G.); (W.Z.); (J.S.); (C.J.)
- Beijing Key Laboratory of Food Processing and Safety in Forestry, No. 35 Qinghua East Road, Haidian District, Beijing 100083, China
| | - Chengli Jia
- College of Biological Sciences and Biotechnology, Beijing Forestry University, No. 35 Qinghua East Road, Haidian District, Beijing 100083, China; (J.H.); (Y.L.); (Z.G.); (W.Z.); (J.S.); (C.J.)
- Beijing Key Laboratory of Food Processing and Safety in Forestry, No. 35 Qinghua East Road, Haidian District, Beijing 100083, China
| | - Aidong Sun
- College of Biological Sciences and Biotechnology, Beijing Forestry University, No. 35 Qinghua East Road, Haidian District, Beijing 100083, China; (J.H.); (Y.L.); (Z.G.); (W.Z.); (J.S.); (C.J.)
- Beijing Key Laboratory of Food Processing and Safety in Forestry, No. 35 Qinghua East Road, Haidian District, Beijing 100083, China
- Correspondence: ; Tel.: +86-010-62336700
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Genetic Determinants of Stress Resistance in Desiccated Salmonella enterica. Appl Environ Microbiol 2021; 87:e0168321. [PMID: 34586905 DOI: 10.1128/aem.01683-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Enteric pathogens, including Salmonella, are capable of long-term survival after desiccation and resist heat treatments that are lethal to hydrated cells. The mechanisms of dry-heat resistance differ from those of wet-heat resistance. To elucidate the mechanisms of dry-heat resistance in Salmonella, screening of the dry-heat resistance of 108 Salmonella strains, representing 39 serotypes, identified the 22 most resistant and the 8 most sensitive strains for comparative genome analysis. A total of 289 genes of the accessory genome were differently distributed between resistant and sensitive strains. Among these genes, 28 proteins with a putative relationship to stress resistance were selected for to quantify relative gene expression before and after desiccation and expression by solid-state cultures on agar plates relative to cultures growing in liquid culture media. Of these 28 genes, 15 genes were upregulated (P < 0.05) after desiccation or by solid-state cultures on agar plates. These 15 genes were cloned into the low-copy-number vector pRK767 under the control of the lacZ promoter. The expression of 6 of these 15 genes increased (P < 0.05) resistance to dry heat and to treatment with pressure of 500 MPa. Our finding extends the knowledge of mechanisms of stress resistance in desiccated Salmonella to improve control of this bacterium in dry food. IMPORTANCE This study directly targeted an increasing threat to food safety and developed knowledge and targeted strategies that can be used by the food industry to help reduce the risk of foodborne illness in their dry products and thereby reduce the overall burden of foodborne illness. Genomic and physiological analyses have elucidated mechanisms of bacterial resistance to many food preservation technologies, including heat, pressure, disinfection chemicals, and UV light; however, information on bacterial mechanisms of resistance to dry heat is scarce. Mechanisms of tolerance to desiccation likely also contribute to resistance to dry heat, but this assumption has not been verified experimentally. It remains unclear how mechanisms of resistance to wet heat relate to dry-heat resistance. Thus, this study will fill a knowledge gap to improve the safety of dry foods.
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Pressure-resistant acclimation of lactic acid bacteria from a natural fermentation product using high pressure. INNOV FOOD SCI EMERG 2021. [DOI: 10.1016/j.ifset.2021.102660] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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González-Angulo M, Serment-Moreno V, Clemente-García L, Tonello C, Jaime I, Rovira J. Assessing the pressure resistance of Escherichia coli O157:H7, Listeria monocytogenes and Salmonella enterica to high pressure processing (HPP) in citric acid model solutions for process validation. Food Res Int 2021; 140:110091. [PMID: 33648306 DOI: 10.1016/j.foodres.2020.110091] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 12/22/2020] [Accepted: 12/26/2020] [Indexed: 10/22/2022]
Abstract
Despite the commercial success of high pressure processing (HPP) in the juice industry, some regulatory agencies still require process validation. However, there is a lack of consensus on various aspects regarding validation protocols, including the selection of representative strains to be used in challenge tests. This study characterized the variable response of Escherichia coli O157:H7 (34 strains), Listeria monocytogenes (44 strains) and Salmonella enterica (45 strains) to HPP, and identified potential candidates to use in process validation. Stationary phase cells were submitted to 500 MPa for 1 min at 10 °C in model solutions consisting of tryptic soy broth + 0.6% yeast extract (TSBYE) adjusted to pH 4.5 and 6.0 with citric acid. At pH 6.0, pressure resistance widely varied between species and within strains of the same species. E. coli O157:H7 and L. monocytogenes were the most pressure resistant and showed high variability at strain level, as the total count range given by minimum and maximum counts spread between 2.0 and 6.5 log10 CFU/ml. S. enterica was the least resistant pathogen with more than 82% of the isolates displaying non-detectable counts after HPP. Recovery through storage at 12 °C was also variable for all pathogens, but eventually most strains recovered with median counts on day 14 between 8.3 and 8.9 log10 CFU/ml. For pH 4.5 solutions, 26 E. coli O157:H7 strains displayed survivors after HPP but did not adapt, registering non-detectable counts in the next sampling dates. None of the L. monocytogenes and S. enterica strains survived HPP or incubation at pH 4.5 (<2.0 log10 CFU/ml), suggesting that citric acid at 4.16 g/l is a safe barrier for pathogen control under moderate HPP conditions. Principal component and cluster analyses served to propose strain cocktails for each species based on their pressure resistant and adaptation phenotypes. Additionally, S. enterica was identified as less pressure resistant and less prone to recover following HPP than E. coli O157:H7 and L. monocytogenes, so its relevance in process validation for juices should be questioned. Future work will validate the proposed strain cocktails on real food systems.
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Affiliation(s)
- Mario González-Angulo
- Hiperbaric, S.A., Department of Applications and Food Processing, C/ Condado de Treviño, 6, 09001 Burgos, Spain; University of Burgos, Department of Biotechnology and Food Science, Faculty of Sciences, Pza. Misael Bañuelos s/n, 09001 Burgos, Spain.
| | - Vinicio Serment-Moreno
- Hiperbaric USA Corporation, Department of Applications and Food Processing, 2250 NW 84(th) Avenue, 101, Miami, FL 33122, United States
| | - Laura Clemente-García
- Hiperbaric, S.A., Department of Applications and Food Processing, C/ Condado de Treviño, 6, 09001 Burgos, Spain
| | - Carole Tonello
- Hiperbaric, S.A., Department of Applications and Food Processing, C/ Condado de Treviño, 6, 09001 Burgos, Spain
| | - Isabel Jaime
- University of Burgos, Department of Biotechnology and Food Science, Faculty of Sciences, Pza. Misael Bañuelos s/n, 09001 Burgos, Spain
| | - Jordi Rovira
- University of Burgos, Department of Biotechnology and Food Science, Faculty of Sciences, Pza. Misael Bañuelos s/n, 09001 Burgos, Spain
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Sehrawat R, Kaur BP, Nema PK, Tewari S, Kumar L. Microbial inactivation by high pressure processing: principle, mechanism and factors responsible. Food Sci Biotechnol 2021; 30:19-35. [PMID: 33552614 DOI: 10.1007/s10068-020-00831-6] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 09/20/2020] [Accepted: 09/23/2020] [Indexed: 12/12/2022] Open
Abstract
High-pressure processing (HPP) is a novel technology for the production of minimally processed food products with better retention of the natural aroma, fresh-like taste, additive-free, stable, convenient to use. In this regard safety of products by microbial inactivation is likely to become an important focus for food technologists from the research and industrial field. High pressure induces conformational changes in the cell membranes, cell morphology. It perturbs biochemical reactions, as well as the genetic mechanism of the microorganisms, thus ensures the reduction in the microbial count. Keeping in view the commercial demand of HPP products, the scientific literature available on the mechanism of inactivation by high pressure and intrinsic and extrinsic factors affecting the efficiency of HPP are systematically and critically analyzed in this review to develop a clear understanding of these issues. Modeling applied to study the microbial inactivation kinetics by HPP is also discussed for the benefit of interested readers.
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Affiliation(s)
- Rachna Sehrawat
- Department of Food Engineering, National Institute of Food Technology Entrepreneurship and Management, Kundli, Sonepat, Haryana 131028 India.,Department of Food Process Engineering, National Institute of Technology Rourkela, Rourkela, Odisha 769008 India
| | - Barjinder Pal Kaur
- Department of Food Engineering, National Institute of Food Technology Entrepreneurship and Management, Kundli, Sonepat, Haryana 131028 India
| | - Prabhat K Nema
- Department of Food Engineering, National Institute of Food Technology Entrepreneurship and Management, Kundli, Sonepat, Haryana 131028 India
| | - Somya Tewari
- Department of Food Engineering, National Institute of Food Technology Entrepreneurship and Management, Kundli, Sonepat, Haryana 131028 India
| | - Lokesh Kumar
- Department of Wine, Food and Molecular Biosciences, Lincoln University, Lincoln, Canterbury 7647 New Zealand
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13
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Gayán E, Van den Bergh B, Michiels J, Michiels CW, Aertsen A. Synthetic reconstruction of extreme high hydrostatic pressure resistance in Escherichia coli. Metab Eng 2020; 62:287-297. [PMID: 32979485 DOI: 10.1016/j.ymben.2020.09.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 09/18/2020] [Accepted: 09/21/2020] [Indexed: 12/17/2022]
Abstract
Although high hydrostatic pressure (HHP) is an interesting parameter to be applied in bioprocessing, its potential is currently limited by the lack of bacterial chassis capable of surviving and maintaining homeostasis under pressure. While several efforts have been made to genetically engineer microorganisms able to grow at sublethal pressures, there is little information for designing backgrounds that survive more extreme pressures. In this investigation, we analyzed the genome of an extreme HHP-resistant mutant of E. coli MG1655 (designated as DVL1), from which we identified four mutations (in the cra, cyaA, aceA and rpoD loci) causally linked to increased HHP resistance. Analysing the functional effect of these mutations we found that the coupled effect of downregulation of cAMP/CRP, Cra and the glyoxylate shunt activity, together with the upregulation of RpoH and RpoS activity, could mechanistically explain the increased HHP resistance of the mutant. Using combinations of three mutations, we could synthetically engineer E. coli strains able to comfortably survive pressures of 600-800 MPa, which could serve as genetic backgrounds for HHP-based biotechnological applications.
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Affiliation(s)
- Elisa Gayán
- Department of Microbial and Molecular Systems, KU Leuven. Faculty of Bioscience Engineering, Kasteelpark Arenberg 20, 3001, Leuven, Belgium.
| | - Bram Van den Bergh
- Department of Microbial and Molecular Systems, KU Leuven. Faculty of Bioscience Engineering, Kasteelpark Arenberg 20, 3001, Leuven, Belgium; VIB Center for Microbiology, Flanders Institute for Biotechnology, Kasteelpark Arenberg 20, 3001, Leuven, Belgium
| | - Jan Michiels
- Department of Microbial and Molecular Systems, KU Leuven. Faculty of Bioscience Engineering, Kasteelpark Arenberg 20, 3001, Leuven, Belgium; VIB Center for Microbiology, Flanders Institute for Biotechnology, Kasteelpark Arenberg 20, 3001, Leuven, Belgium
| | - Chris W Michiels
- Department of Microbial and Molecular Systems, KU Leuven. Faculty of Bioscience Engineering, Kasteelpark Arenberg 20, 3001, Leuven, Belgium
| | - Abram Aertsen
- Department of Microbial and Molecular Systems, KU Leuven. Faculty of Bioscience Engineering, Kasteelpark Arenberg 20, 3001, Leuven, Belgium.
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14
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Podolak R, Whitman D, Black DG. Factors Affecting Microbial Inactivation during High Pressure Processing in Juices and Beverages: A Review. J Food Prot 2020; 83:1561-1575. [PMID: 32866244 DOI: 10.4315/jfp-20-096] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 04/30/2020] [Indexed: 11/11/2022]
Abstract
ABSTRACT The purpose of this article is to review and discuss the factors affecting high pressure processing (HPP) in juices and beverages. The inactivation of microorganisms by HPP depends on numerous factors, including the magnitude of the pressure and the holding time, process temperature, compression and decompression rates, the microbiota, and the intrinsic properties of juices and beverages. Although extensive HPP research has been performed to characterize many of these factors, a number of issues, such as the rates of compression and decompression, still remain unresolved and need further investigation. In addition, some published results are conflicting and do not provide enough evidence to develop juice HPP "safe-harbor" parameters to achieve a minimum 5-log reduction of the pertinent microorganism and produce safe fruit juices and beverages. HIGHLIGHTS
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Affiliation(s)
- Richard Podolak
- U.S. Food and Drug Administration, 5001 Campus Drive, College Park, Maryland 20740
| | - David Whitman
- U.S. Food and Drug Administration, 5001 Campus Drive, College Park, Maryland 20740
| | - Darryl Glenn Black
- U.S. Food and Drug Administration, 6502 South Archer Road, Bedford Park, Illinois 60501, USA
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15
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Dos Santos Rosario AIL, da Silva Mutz Y, Castro VS, da Silva MCA, Conte-Junior CA, da Costa MP. Everybody loves cheese: crosslink between persistence and virulence of Shiga-toxin Escherichia coli. Crit Rev Food Sci Nutr 2020; 61:1877-1899. [PMID: 32519880 DOI: 10.1080/10408398.2020.1767033] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
General cheese manufacturing involves high temperatures, fermentation and ripening steps that function as hurdles to microbial growth. On the other hand, the application of several different formulations and manufacturing techniques may create a bacterial protective environment. In cheese, the persistent behavior of Shiga toxin-producing Escherichia coli (STEC) relies on complex mechanisms that enable bacteria to respond to stressful conditions found in cheese matrix. In this review, we discuss how STEC manages to survive to high and low temperatures, hyperosmotic conditions, exposure to weak organic acids, and pH decreasing related to cheese manufacturing, the cheese matrix itself and storage. Moreover, we discuss how these stress responses interact with each other by enhancing adaptation and consequently, the persistence of STEC in cheese. Further, we show how virulence genes eae and tir are affected by stress response mechanisms, increasing either cell adherence or virulence factors production, which leads to a selection of more resistant and virulent pathogens in the cheese industry, leading to a public health issue.
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Affiliation(s)
- Anisio Iuri Lima Dos Santos Rosario
- Postgraduate Program in Food Science, Faculty of Pharmacy, Universidade Federal da Bahia, Salvador, Brazil.,Department of Preventive Veterinary Medicine and Animal Production, School of Veterinary Medicine and Zootechnics of Veterinary, Universidade Federal da Bahia, Salvador, Brazil
| | - Yhan da Silva Mutz
- Postgraduate Program in Food Science, Chemistry Institute, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.,Department of Food Technology, Faculty of Veterinary, Universidade Federal Fluminense, Niterói, Brazil
| | - Vinícius Silva Castro
- Postgraduate Program in Food Science, Chemistry Institute, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Maurício Costa Alves da Silva
- Department of Preventive Veterinary Medicine and Animal Production, School of Veterinary Medicine and Zootechnics of Veterinary, Universidade Federal da Bahia, Salvador, Brazil
| | - Carlos Adam Conte-Junior
- Postgraduate Program in Food Science, Chemistry Institute, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.,Department of Food Technology, Faculty of Veterinary, Universidade Federal Fluminense, Niterói, Brazil.,National Institute for Health Quality Control, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil
| | - Marion Pereira da Costa
- Postgraduate Program in Food Science, Faculty of Pharmacy, Universidade Federal da Bahia, Salvador, Brazil.,Department of Preventive Veterinary Medicine and Animal Production, School of Veterinary Medicine and Zootechnics of Veterinary, Universidade Federal da Bahia, Salvador, Brazil
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16
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Lakshmikandan M, Murugesan A, Wang S, Abomohra AEF, Jovita PA, Kiruthiga S. Sustainable biomass production under CO2 conditions and effective wet microalgae lipid extraction for biodiesel production. JOURNAL OF CLEANER PRODUCTION 2020; 247:119398. [DOI: 10.1016/j.jclepro.2019.119398] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
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17
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Wu D, Forghani F, Daliri EBM, Li J, Liao X, Liu D, Ye X, Chen S, Ding T. Microbial response to some nonthermal physical technologies. Trends Food Sci Technol 2020. [DOI: 10.1016/j.tifs.2019.11.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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18
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19
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Identification of novel genes involved in high hydrostatic pressure resistance of Escherichia coli. Food Microbiol 2019; 78:171-178. [DOI: 10.1016/j.fm.2018.10.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 09/19/2018] [Accepted: 10/21/2018] [Indexed: 12/16/2022]
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20
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Population-Wide Survey of Salmonella enterica Response to High-Pressure Processing Reveals a Diversity of Responses and Tolerance Mechanisms. Appl Environ Microbiol 2018; 84:AEM.01673-17. [PMID: 29101197 DOI: 10.1128/aem.01673-17] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 10/27/2017] [Indexed: 01/24/2023] Open
Abstract
High-pressure processing is a nonthermal method of food preservation that uses pressure to inactivate microorganisms. To ensure the effective validation of process parameters, it is important that the design of challenge protocols consider the potential for resistance in a particular species. Herein, the responses of 99 diverse Salmonella enterica strains to high pressure are reported. Members of this population belonged to 24 serovars and were isolated from various Canadian sources over a period of 26 years. When cells were exposed to 600 MPa for 3 min, the average reduction in cell numbers for this population was 5.6 log10 CFU/ml, with a range of 0.9 log10 CFU/ml to 6 log10 CFU/ml. Eleven strains, from 5 serovars, with variable levels of pressure resistance were selected for further study. The membrane characteristics (propidium iodide uptake during and after pressure treatment, sensitivity to membrane-active agents, and membrane fatty acid composition) and responses to stressors (heat, nutrient deprivation, desiccation, and acid) for this panel suggested potential roles for the cell membrane and the RpoS regulon in mediating pressure resistance in S. enterica The data indicate heterogeneous and multifactorial responses to high pressure that cannot be predicted for individual S. enterica strains.IMPORTANCE The responses of foodborne pathogens to increasingly popular minimal food decontamination methods are not understood and therefore are difficult to predict. This report shows that the responses of Salmonella enterica strains to high-pressure processing are diverse. The magnitude of inactivation does not depend on how closely related the strains are or where they were isolated. Moreover, strains that are resistant to high pressure do not behave similarly to other stresses, suggesting that more than one mechanism might be responsible for resistance to high pressure and the mechanisms used may vary from one strain to another.
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21
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Gayán E, Cambré A, Michiels CW, Aertsen A. RpoS-independent evolution reveals the importance of attenuated cAMP/CRP regulation in high hydrostatic pressure resistance acquisition in E. coli. Sci Rep 2017; 7:8600. [PMID: 28819154 PMCID: PMC5561100 DOI: 10.1038/s41598-017-08958-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 07/20/2017] [Indexed: 11/09/2022] Open
Abstract
High hydrostatic pressure (HHP) processing is an attractive non-thermal alternative to food pasteurization. Nevertheless, the large inter- and intra-species variations in HHP resistance among foodborne pathogens and the ease by which they can acquire extreme resistance are an issue of increasing concern. Since RpoS activity has been considered as a central determinant in the HHP resistance of E. coli and its pathovars, this study probed for the potential of an E. coli MG1655 ΔrpoS mutant to acquire HHP resistance by directed evolution. Despite the higher initial HHP sensitivity of the ΔrpoS mutant compared to the wild-type strain, evolved lineages of the former readily managed to restore or even succeed wild-type levels of resistance. A number of these ΔrpoS derivatives were affected in cAMP/CRP regulation, and this could be causally related to their HHP resistance. Subsequent inspection revealed that some of previously isolated HHP-resistant mutants derived from the wild-type strain also incurred a causal decrease in cAMP/CRP regulation. cAMP/CRP attenuated HHP-resistant mutants also exhibited higher resistance to fosfomycin, a preferred treatment for STEC infections. As such, this study reveals attenuation of cAMP/CRP regulation as a relevant and RpoS-independent evolutionary route towards HHP resistance in E. coli that coincides with fosfomycin resistance.
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Affiliation(s)
- Elisa Gayán
- KU Leuven, Laboratory of Food Microbiology, Department of Microbial and Molecular Systems (M2S), Faculty of Bioscience Engineering, Leuven, Belgium
| | - Alexander Cambré
- KU Leuven, Laboratory of Food Microbiology, Department of Microbial and Molecular Systems (M2S), Faculty of Bioscience Engineering, Leuven, Belgium
| | - Chris W Michiels
- KU Leuven, Laboratory of Food Microbiology, Department of Microbial and Molecular Systems (M2S), Faculty of Bioscience Engineering, Leuven, Belgium
| | - Abram Aertsen
- KU Leuven, Laboratory of Food Microbiology, Department of Microbial and Molecular Systems (M2S), Faculty of Bioscience Engineering, Leuven, Belgium.
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22
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Impact of high hydrostatic pressure on bacterial proteostasis. Biophys Chem 2017; 231:3-9. [PMID: 28365058 DOI: 10.1016/j.bpc.2017.03.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2017] [Accepted: 03/20/2017] [Indexed: 02/01/2023]
Abstract
High hydrostatic pressure (HHP) is an important factor that limits microbial growth in deep-sea ecosystems to specifically adapted piezophiles. Furthermore, HHP treatment is used as a novel food preservation technique because of its ability to inactivate pathogenic and spoilage bacteria while minimizing the loss of food quality. Disruption of protein homeostasis (i.e. proteostasis) as a result of HHP-induced conformational changes in ribosomes and proteins has been considered as one of the limiting factors for both microbial growth and survival under HHP conditions. This work therefore reviews the effects of sublethal (≤100MPa) and lethal (>100MPa) pressures on protein synthesis, structure, and functionality in bacteria. Furthermore, current understanding on the mechanisms adopted by piezophiles to maintain proteostasis in HHP environments and responses developed by atmospheric-adapted bacteria to protect or restore proteostasis after HHP exposure are discussed.
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23
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Effect of cell membrane fatty acid composition of Escherichia coli on the resistance to pulsed electric field (PEF) treatment. Lebensm Wiss Technol 2017. [DOI: 10.1016/j.lwt.2016.10.019] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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24
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Li H, Gänzle M. Some Like It Hot: Heat Resistance of Escherichia coli in Food. Front Microbiol 2016; 7:1763. [PMID: 27857712 PMCID: PMC5093140 DOI: 10.3389/fmicb.2016.01763] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 10/20/2016] [Indexed: 11/13/2022] Open
Abstract
Heat treatment and cooking are common interventions for reducing the numbers of vegetative cells and eliminating pathogenic microorganisms in food. Current cooking method requires the internal temperature of beef patties to reach 71°C. However, some pathogenic Escherichia coli such as the beef isolate E. coli AW 1.7 are extremely heat resistant, questioning its inactivation by current heat interventions in beef processing. To optimize the conditions of heat treatment for effective decontaminations of pathogenic E. coli strains, sufficient estimations, and explanations are necessary on mechanisms of heat resistance of target strains. The heat resistance of E. coli depends on the variability of strains and properties of food formulations including salt and water activity. Heat induces alterations of E. coli cells including membrane, cytoplasm, ribosome and DNA, particularly on proteins including protein misfolding and aggregations. Resistant systems of E. coli act against these alterations, mainly through gene regulations of heat response including EvgA, heat shock proteins, σE and σS, to re-fold of misfolded proteins, and achieve antagonism to heat stress. Heat resistance can also be increased by expression of key proteins of membrane and stabilization of membrane fluidity. In addition to the contributions of the outer membrane porin NmpC and overcome of osmotic stress from compatible solutes, the new identified genomic island locus of heat resistant performs a critical role to these highly heat resistant strains. This review aims to provide an overview of current knowledge on heat resistance of E. coli, to better understand its related mechanisms and explore more effective applications of heat interventions in food industry.
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Affiliation(s)
- Hui Li
- Department of Agricultural, Food and Nutritional Science, University of Alberta, EdmontonAB, Canada
| | - Michael Gänzle
- Department of Agricultural, Food and Nutritional Science, University of Alberta, EdmontonAB, Canada
- College of Bioengineering and Food Science, Hubei University of TechnologyHubei, China
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25
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Praveenkumar R, Kim B, Lee J, Vijayan D, Lee K, Nam B, Jeon SG, Kim DM, Oh YK. Mild pressure induces rapid accumulation of neutral lipid (triacylglycerol) in Chlorella spp. BIORESOURCE TECHNOLOGY 2016; 220:661-665. [PMID: 27634024 DOI: 10.1016/j.biortech.2016.09.025] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2016] [Revised: 09/04/2016] [Accepted: 09/06/2016] [Indexed: 06/06/2023]
Abstract
Effective enhancement of neutral lipid (especially triacylglycerol, TAG) content in microalgae is an important issue for commercialization of microalgal biorefineries. Pressure is a key physical factor affecting the morphological, physiological, and biochemical behaviors of organisms. In this paper, we report a new stress-based method for induction of TAG accumulation in microalgae (specifically, Chlorella sp. KR-1 and Ch. sp. AG20150) by very-short-duration application of mild pressure. Pressure treatments of 10-15bar for 2h resulted in a considerable, ∼55% improvement of the 10-100g/Lcells' TAG contents compared with the untreated control. The post-pressure-treatment increase of cytoplasmic TAG granules was further confirmed by transmission electron microscopy (TEM). Notwithstanding the increased TAG content, the total lipid content was not changed by pressurization, implying that pressure stress possibly induces rapid remodeling/transformation of algal lipids rather than de novo biosynthesis of TAG.
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Affiliation(s)
- Ramasamy Praveenkumar
- Biomass and Waste Energy Laboratory, Korea Institute of Energy Research, Daejeon 34129, Republic of Korea; Department of Chemistry and Bioengineering, Tampere University of Technology, Tampere 33720, Finland
| | - Bohwa Kim
- Biomass and Waste Energy Laboratory, Korea Institute of Energy Research, Daejeon 34129, Republic of Korea; Department of Fine Chemical Engineering and Applied Chemistry, Chungnam National University, Daejeon 34134, Republic of Korea
| | - Jiye Lee
- Biomass and Waste Energy Laboratory, Korea Institute of Energy Research, Daejeon 34129, Republic of Korea
| | - Durairaj Vijayan
- Biomass and Waste Energy Laboratory, Korea Institute of Energy Research, Daejeon 34129, Republic of Korea
| | - Kyubock Lee
- Biomass and Waste Energy Laboratory, Korea Institute of Energy Research, Daejeon 34129, Republic of Korea; Graduate School of Energy Science and Technology, Chungnam National University, Daejeon 34134, Republic of Korea
| | - Bora Nam
- Biomass and Waste Energy Laboratory, Korea Institute of Energy Research, Daejeon 34129, Republic of Korea
| | - Sang Goo Jeon
- Biomass and Waste Energy Laboratory, Korea Institute of Energy Research, Daejeon 34129, Republic of Korea
| | - Dong-Myung Kim
- Department of Fine Chemical Engineering and Applied Chemistry, Chungnam National University, Daejeon 34134, Republic of Korea
| | - You-Kwan Oh
- Biomass and Waste Energy Laboratory, Korea Institute of Energy Research, Daejeon 34129, Republic of Korea.
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Stress-Induced Evolution of Heat Resistance and Resuscitation Speed in Escherichia coli O157:H7 ATCC 43888. Appl Environ Microbiol 2016; 82:6656-6663. [PMID: 27590820 DOI: 10.1128/aem.02027-16] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 08/27/2016] [Indexed: 11/20/2022] Open
Abstract
The development of resistance in foodborne pathogens to food preservation techniques is an issue of increasing concern, especially in minimally processed foods where safety relies on hurdle technology. In this context, mild heat can be used in combination with so-called nonthermal processes, such as high hydrostatic pressure (HHP), at lower individual intensities to better retain the quality of the food. However, mild stresses may increase the risk of (cross-)resistance development in the surviving population, which in turn might compromise food safety. In this investigation, we examined the evolution of Escherichia coli O157:H7 strain ATCC 43888 after recurrent exposure to progressively intensifying mild heat shocks (from 54.0°C to 60.0°C in 0.5°C increments) with intermittent resuscitation and growth of survivors. As such, mutant strains were obtained after 10 cycles of selection with ca. 106-fold higher heat resistance than that for the parental strain at 58.0°C, although this resistance did not extend to temperatures exceeding 60.0°C. Moreover, these mutant strains typically displayed cross-resistance against HHP shock and displayed signs of enhanced RpoS and RpoH activity. Interestingly, additional cycles of selection maintaining the intensity of the heat shock constant (58.5°C) selected for mutant strains in which resuscitation speed, rather than resistance, appeared to be increased. Therefore, it seems that resistance and resuscitation speed are rapidly evolvable traits in E. coli ATCC 43888 that can compromise food safety. IMPORTANCE In this investigation, we demonstrated that Escherichia coli O157:H7 ATCC 43888 rapidly acquires resistance to mild heat exposure, with this resistance yielding cross-protection to high hydrostatic pressure treatment. In addition, mutants of E. coli ATCC 43888 in which resuscitation speed, rather than resistance, appeared to be improved were selected. As such, both resistance and resuscitation speed seem to be rapidly evolvable traits that can compromise the control of foodborne pathogens in minimal processing strategies, which rely on the efficacy of combined mild preservation stresses for food safety.
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Prieto-Calvo M, López M, Prieto M, Alvarez-Ordóñez A. Variability in resistance to Cold Atmospheric Plasma (CAP) and Ultraviolet light (UV) and multiple stress resistance analysis of pathogenic verocytotoxigenic Escherichia coli (VTEC). Food Res Int 2016. [DOI: 10.1016/j.foodres.2015.12.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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28
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Toledo Del Árbol J, Pérez Pulido R, Grande MJ, Gálvez A, Lucas R. Survival and High-Hydrostatic Pressure Inactivation of Foodborne Pathogens in Salmorejo, a Traditional Ready-to-Eat Food. J Food Sci 2015; 80:M2517-21. [PMID: 26448479 DOI: 10.1111/1750-3841.13067] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2015] [Accepted: 08/07/2015] [Indexed: 11/28/2022]
Abstract
UNLABELLED Salmorejo is a traditional tomato-based creamy product. Because salmorejo is not heat-processed, there is a risk of contamination with foodborne pathogens from raw materials. Even though bacterial growth in salmorejo is strongly inhibited because of its acidic pH (close to 3.9), the growth and survival of 3 foodborne pathogens in this food has not been studied before. In this study, 3 cocktails consisting of Escherichia coli O157, Salmonella enterica serovar Enteritidis, and Listeria monocytogenes strains were inoculated in freshly prepared salmorejo. The food was treated by high hydrostatic pressure (HHP) at 400, 500, or 600 MPa for 8 min, or left untreated, and stored at 4 °C for 30 d. Viable cell counts were determined on selective media and also by the triple-layer agar method in order to detect sublethally injured cells. In control samples, L. monocytogenes viable cells decreased by 2.4 log cycles at day 7 and were undetectable by day 15. S. enterica cells decreased by 0.5 or 2.4 log cycles at days 7 and 15 respectively, but still were detectable at day 30. E. coli O157 cells survived much better in salmorejo, decreasing only by 1.5 log cycles at day 30. Treatments at pressures of 400 MPa or higher reduced viable counts of L. monocytogenes and S. enterica to undetectable levels. HHP treatments significantly (P < 0.05) reduced E. coli counts by approximately 5.2 to 5.4 log cycles, but also yielded surviving cells that apparently were sublethally injured. Only samples treated at 600 MPA for 8 min were devoid of detectable E. coli cells during storage. PRACTICAL APPLICATION Salmorejo is a traditional, vitamin-rich food, usually produced on a small scale. HHP treatment at 600 MPa for 8 min can be an efficient nonthermal method for industrial-scale preparation of preservative-free salmorejo with improved safety against transmission of foodborne pathogens L. monocytogenes serotyes 4a and 4b, S. enterica serovar Enteritidis, and E. coli O157.
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Affiliation(s)
- Julia Toledo Del Árbol
- Área de Microbiología. Depto. de Ciencias de la Salud, Facultad de Ciencias Experimentales, Univ. de Jaén, P.O. Box 23071, Jaén, Spain
| | - Rubén Pérez Pulido
- Área de Microbiología. Depto. de Ciencias de la Salud, Facultad de Ciencias Experimentales, Univ. de Jaén, P.O. Box 23071, Jaén, Spain
| | - Ma José Grande
- Área de Microbiología. Depto. de Ciencias de la Salud, Facultad de Ciencias Experimentales, Univ. de Jaén, P.O. Box 23071, Jaén, Spain
| | - Antonio Gálvez
- Área de Microbiología. Depto. de Ciencias de la Salud, Facultad de Ciencias Experimentales, Univ. de Jaén, P.O. Box 23071, Jaén, Spain
| | - Rosario Lucas
- Área de Microbiología. Depto. de Ciencias de la Salud, Facultad de Ciencias Experimentales, Univ. de Jaén, P.O. Box 23071, Jaén, Spain
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29
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Gänzle M, Liu Y. Mechanisms of pressure-mediated cell death and injury in Escherichia coli: from fundamentals to food applications. Front Microbiol 2015; 6:599. [PMID: 26157424 PMCID: PMC4478891 DOI: 10.3389/fmicb.2015.00599] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 06/01/2015] [Indexed: 12/12/2022] Open
Abstract
High hydrostatic pressure is commercially applied to extend the shelf life of foods, and to improve food safety. Current applications operate at ambient temperature and 600 MPa or less. However, bacteria that may resist this pressure level include the pathogens Staphylococcus aureus and strains of Escherichia coli, including shiga-toxin producing E. coli. The resistance of E. coli to pressure is variable between strains and highly dependent on the food matrix. The targeted design of processes for the safe elimination of E. coli thus necessitates deeper insights into mechanisms of interaction and matrix-strain interactions. Cellular targets of high pressure treatment in E. coli include the barrier properties of the outer membrane, the integrity of the cytoplasmic membrane as well as the activity of membrane-bound enzymes, and the integrity of ribosomes. The pressure-induced denaturation of membrane bound enzymes results in generation of reactive oxygen species and subsequent cell death caused by oxidative stress. Remarkably, pressure resistance at the single cell level relates to the disposition of misfolded proteins in inclusion bodies. While the pressure resistance E. coli can be manipulated by over-expression or deletion of (stress) proteins, the mechanisms of pressure resistance in wild type strains is multi-factorial and not fully understood. This review aims to provide an overview on mechanisms of pressure-mediated cell death in E. coli, and the use of this information for optimization of high pressure processing of foods.
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Affiliation(s)
- Michael Gänzle
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada
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Baccus-Taylor GSH, Falloon OC, Henry N. Pressure resistance of cold-shocked Escherichia coli O157:H7 in ground beef, beef gravy and peptone water. J Appl Microbiol 2015; 118:1521-9. [PMID: 25766637 DOI: 10.1111/jam.12794] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Revised: 02/27/2015] [Accepted: 03/10/2015] [Indexed: 01/06/2023]
Abstract
AIMS (i) To study the effects of cold shock on Escherichia coli O157:H7 cells. (ii) To determine if cold-shocked E. coli O157:H7 cells at stationary and exponential phases are more pressure-resistant than their non-cold-shocked counterparts. (iii) To investigate the baro-protective role of growth media (0·1% peptone water, beef gravy and ground beef). METHODS AND RESULTS Quantitative estimates of lethality and sublethal injury were made using the differential plating method. There were no significant differences (P > 0·05) in the number of cells killed; cold-shocked or non-cold-shocked. Cells grown in ground beef (stationary and exponential phases) experienced lowest death compared with peptone water and beef gravy. Cold-shock treatment increased the sublethal injury to cells cultured in peptone water (stationary and exponential phases) and ground beef (exponential phase), but decreased the sublethal injury to cells in beef gravy (stationary phase). CONCLUSIONS Cold shock did not confer greater resistance to stationary or exponential phase cells pressurized in peptone water, beef gravy or ground beef. Ground beef had the greatest baro-protective effect. SIGNIFICANCE AND IMPACT OF THE STUDY Real food systems should be used in establishing food safety parameters for high-pressure treatments; micro-organisms are less resistant in model food systems, the use of which may underestimate the organisms' resistance.
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Affiliation(s)
- G S H Baccus-Taylor
- Food Science and Technology Unit, Department of Chemical Engineering, The University of the West Indies, St Augustine, Trinidad and Tobago, West Indies
| | - O C Falloon
- Food Science and Technology Unit, Department of Chemical Engineering, The University of the West Indies, St Augustine, Trinidad and Tobago, West Indies
| | - N Henry
- Food Science and Technology Unit, Department of Chemical Engineering, The University of the West Indies, St Augustine, Trinidad and Tobago, West Indies
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Reineke K, Sevenich R, Hertwig C, Janßen T, Fröhling A, Knorr D, Wieler LH, Schlüter O. Comparative study on the high pressure inactivation behavior of the Shiga toxin-producing Escherichia coli O104:H4 and O157:H7 outbreak strains and a non-pathogenic surrogate. Food Microbiol 2015; 46:184-194. [DOI: 10.1016/j.fm.2014.07.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Revised: 07/01/2014] [Accepted: 07/26/2014] [Indexed: 12/13/2022]
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Garcia-Hernandez R, McMullen L, Gänzle MG. Development and validation of a surrogate strain cocktail to evaluate bactericidal effects of pressure on verotoxigenic Escherichia coli. Int J Food Microbiol 2015; 205:16-22. [PMID: 25866907 DOI: 10.1016/j.ijfoodmicro.2015.03.028] [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: 01/12/2015] [Revised: 03/19/2015] [Accepted: 03/24/2015] [Indexed: 12/21/2022]
Abstract
Many strains of verotoxigenic Escherichia coli (VTEC) are highly resistant to pressure. To facilitate future studies to improve the elimination of VTEC by pressure processing of food, this study developed and validated a cocktail of non-pathogenic strains of E. coli with equal or higher resistance to pressure when compared to pressure resistant strains of VTEC. Strains of E. coli obtained from a beef processing plant were screened for their resistance to heat and pressure. Treatments were carried out in LB broth. Cell counts of 3 out of 16 strains were reduced by 5-6 log (cfu/mL) after 30 min at 60 °C, and cell counts of 10 out of 16 strains were reduced by 5-6 log (cfu/mL) after 30 min at 40 °C and 400 MPa. All highly heat resistant strains were also pressure resistant but not all pressure resistant strains were also heat resistant. Pressure resistant and -sensitive strains of E. coli were treated in presence of 0 or 2% NaCl and at 3, 20, or 40 °C. The effect of these parameters on the lethality of pressure treatments was comparable for all strains. The addition of 2% NaCl did not increase pressure resistance. The bactericidal effect of treatments at 3 and 20 °C and 600 MPa was comparable but inactivation of E. coli was faster at 40 °C and 600 MPa. The resistance to treatment with 600 MPa at 20 °C of a cocktail of 5 non-pathogenic strains of E. coli was compared to a 5 strain cocktail of pressure resistant VTEC. Treatments were performed in ground beef containing 15% fat. Survival and sublethal injury of the two cocktails was comparable; cell counts of beef inoculated with either cocktail were reduced by about 4 log (cfu/mL) after 30 min of treatment. In conclusion, this study validated a cocktail of non-pathogenic strains of E. coli for use as surrogate organisms in studies on the elimination of E. coli by pressure.
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Affiliation(s)
| | - Lynn McMullen
- University of Alberta, Department of Agricultural, Food and Nutritional Science, Edmonton, Canada
| | - Michael G Gänzle
- University of Alberta, Department of Agricultural, Food and Nutritional Science, Edmonton, Canada.
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Syed QA, Buffa M, Guamis B, Saldo J. Factors Affecting Bacterial Inactivation during High Hydrostatic Pressure Processing of Foods: A Review. Crit Rev Food Sci Nutr 2015; 56:474-83. [DOI: 10.1080/10408398.2013.779570] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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34
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Polymorphisms in stress response genes in Lactobacillus plantarum: implications for classification and heat stress response. ANN MICROBIOL 2015. [DOI: 10.1007/s13213-014-0862-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Feyaerts J, Rogiers G, Corthouts J, Michiels CW. Thiol-reactive natural antimicrobials and high pressure treatment synergistically enhance bacterial inactivation. INNOV FOOD SCI EMERG 2015. [DOI: 10.1016/j.ifset.2014.12.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Liu Y, Gill A, McMullen L, Gänzle MG. Variation in heat and pressure resistance of verotoxigenic and nontoxigenic Escherichia coli. J Food Prot 2015; 78:111-20. [PMID: 25581185 DOI: 10.4315/0362-028x.jfp-14-267] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This study evaluated the heat and pressure resistance of 112 strains of Escherichia coli, including 102 strains of verotoxigenic E. coli (VTEC) representing 23 serotypes and four phylogenetic groups. In an initial screening, the heat and pressure resistance of 100 strains, including 94 VTEC strains, were tested in phosphate-buffered saline (PBS). Treatment at 60°C for 5 min reduced cell counts by 2.0 to 5.5 log CFU/ml; treatment at 600 MPa for 3 min at 25°C reduced the cell counts by 1.1 to 5.5 log CFU/ml. Heat or pressure resistance did not correlate to the phylogenetic group or the serotype. A smaller group of E. coli strains was evaluated for heat and pressure resistance in Luria-Bertani (LB) broth. Generally, the levels of heat resistance of E. coli strains in LB and PBS were similar; however, the levels of pressure resistance observed for treatments in LB broth or PBS were variable. The cell counts of pressure-resistant strains of VTEC were reduced by less than 1.5 log CFU/ml after treatment at 600 MPa for 3 min. E. coli strains were also treated with 600 MPa for 3 min in ground beef or inoculated into beef patties and grilled to 63 or 71°C. The cell counts of the VTEC E. coli O26:H11 strain 05-6544 were reduced by 2 log CFU/g by pressure treatment in ground beef. The cell counts of the heat-resistant E. coli strain AW1.7 were reduced by 1.4 and 3.4 log CFU/g in beef patties grilled to internal temperatures of 63 and 71°C, respectively. The cell counts of E. coli 05-6544 were reduced by less than 3 and 6 log CFU/g in beef patties grilled to internal temperatures of 63 and 71°C, respectively. To study whether the composition of the beef patties influenced heat resistance, E. coli strains AW1.7, AW1.7 Δ pHR1, MG1655, and LMM1030 were mixed into beef patties containing 15 or 35% fat and 0 or 2% NaCl, and the patties were grilled to an internal temperature of 63°C. The highest heat resistance of E. coli was observed in patties containing 15% fat and 2% NaCl.
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Affiliation(s)
- Yang Liu
- University of Alberta, Department of Agricultural, Food and Nutritional Science, Edmonton, Canada
| | - Alex Gill
- Health Canada/Sante Canada, Microbiology Research Division, Bureau of Microbial Hazards, Ottawa, Canada
| | - Lynn McMullen
- University of Alberta, Department of Agricultural, Food and Nutritional Science, Edmonton, Canada
| | - Michael G Gänzle
- University of Alberta, Department of Agricultural, Food and Nutritional Science, Edmonton, Canada; School of Food and Pharmaceutical Engineering, Hubei University of Technology, Wuhan, People's Republic of China.
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Prieto-Calvo M, Prieto M, López M, Alvarez-Ordóñez A. Effects of high hydrostatic pressure on Escherichia coli ultrastructure, membrane integrity and molecular composition as assessed by FTIR spectroscopy and microscopic imaging techniques. Molecules 2014; 19:21310-23. [PMID: 25529018 PMCID: PMC6271356 DOI: 10.3390/molecules191221310] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Revised: 11/27/2014] [Accepted: 12/09/2014] [Indexed: 11/24/2022] Open
Abstract
High hydrostatic pressure (HHP) is a novel food processing technology that is considered as an attractive alternative to conventional heat treatments for the preservation of foods, due to its lethal effects on pathogenic and spoilage microorganisms, while causing minor effects on food quality and sensorial attributes. This study is aimed at investigating how HHP treatments at varying intensities in the range 50-900 MPa affect the viability, membrane integrity, ultrastructure and molecular composition of Escherichia coli. Results of membrane integrity tests (measurement of cellular leakage and monitoring of propidium iodide uptake through fluorescence microscopy) and ultrastructural observations by transmission electron microscopy demonstrated that HHP gave rise to cellular enlargement, membrane damage or detachment, DNA and protein denaturation and loss of intracellular contents. Fourier-transform infrared (FTIR) spectroscopy analyses evidenced minor changes in molecular composition in response to high pressures, which were mostly observed on the spectral region w4 (1200-900 cm-1), mainly informative of carbohydrates and polysaccharides of the cell wall. These findings suggest that exposure of E. coli cells to HHP causes alterations in their physical integrity while producing minor modifications in biochemical cellular composition. The current study increases the knowledge on the mechanisms of E. coli inactivation by HHP and provides valuable information for the design of more effective food preservation regimes based on the integration of mild HHP in combination with other food preservation strategies into a multi-target hurdle technology approach.
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Affiliation(s)
- María Prieto-Calvo
- Institute of Food Science and Technology, University of León, León 24071, Spain.
| | - Miguel Prieto
- Institute of Food Science and Technology, University of León, León 24071, Spain.
| | - Mercedes López
- Department of Food Hygiene and Technology, University of León, León 24071, Spain.
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Hazael R, Foglia F, Kardzhaliyska L, Daniel I, Meersman F, McMillan P. Laboratory investigation of high pressure survival in Shewanella oneidensis MR-1 into the gigapascal pressure range. Front Microbiol 2014; 5:612. [PMID: 25452750 PMCID: PMC4233909 DOI: 10.3389/fmicb.2014.00612] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 10/28/2014] [Indexed: 11/13/2022] Open
Abstract
The survival of Shewanella oneidensis MR-1 at up to 1500 MPa was investigated by laboratory studies involving exposure to high pressure followed by evaluation of survivors as the number (N) of colony forming units (CFU) that could be cultured following recovery to ambient conditions. Exposing the wild type (WT) bacteria to 250 MPa resulted in only a minor (0.7 log N units) drop in survival compared with the initial concentration of 108 cells/ml. Raising the pressure to above 500 MPa caused a large reduction in the number of viable cells observed following recovery to ambient pressure. Additional pressure increase caused a further decrease in survivability, with approximately 102 CFU/ml recorded following exposure to 1000 MPa (1 GPa) and 1.5 GPa. Pressurizing samples from colonies resuscitated from survivors that had been previously exposed to high pressure resulted in substantially greater survivor counts. Experiments were carried out to examine potential interactions between pressure and temperature variables in determining bacterial survival. One generation of survivors previously exposed to 1 GPa was compared with WT samples to investigate survival between 37 and 8°C. The results did not reveal any coupling between acquired high pressure resistance and temperature effects on growth.
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Affiliation(s)
- Rachael Hazael
- Christopher Ingold Laboratories, Department of Chemistry, University College London London, UK
| | - Fabrizia Foglia
- Christopher Ingold Laboratories, Department of Chemistry, University College London London, UK
| | - Liya Kardzhaliyska
- Christopher Ingold Laboratories, Department of Chemistry, University College London London, UK
| | - Isabelle Daniel
- Laboratoire de Géologie de Lyon, UMR 5276 CNRS, ENS de Lyon and Université Claude Bernard Lyon 1 - Université de Lyon Lyon, France
| | - Filip Meersman
- Christopher Ingold Laboratories, Department of Chemistry, University College London London, UK ; Biomolecular and Analytical Mass Spectrometry group, Department of Chemistry, University of Antwerp Antwerpen, Belgium
| | - Paul McMillan
- Christopher Ingold Laboratories, Department of Chemistry, University College London London, UK
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Carter MQ, Louie JW, Huynh S, Parker CT. Natural rpoS mutations contribute to population heterogeneity in Escherichia coli O157:H7 strains linked to the 2006 US spinach-associated outbreak. Food Microbiol 2014; 44:108-18. [PMID: 25084652 DOI: 10.1016/j.fm.2014.05.021] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 05/12/2014] [Accepted: 05/26/2014] [Indexed: 01/14/2023]
Abstract
We previously reported significantly different acid resistance between curli variants derived from the same Escherichia coli O157:H7 strain, although the curli fimbriae were not associated with this phenotypic divergence. Here we investigated the underlying molecular mechanism by examining the genes encoding the common transcriptional regulators of curli biogenesis and acid resistance. rpoS null mutations were detected in all curli-expressing variants of the 2006 spinach-associated outbreak strains, whereas a wild-type rpoS was present in all curli-deficient variants. Consequently curli-expressing variants were much more sensitive to various stress challenges than curli-deficient variants. This loss of general stress fitness appeared solely to be the result of rpoS mutation since the stress resistances could be restored in curli-expressing variants by a functional rpoS. Comparative transcriptomic analyses between the curli variants revealed a large number of differentially expressed genes, characterized by the enhanced expression of metabolic genes in curli-expressing variants, but a marked decrease in transcription of genes related to stress resistances. Unlike the curli-expressing variants of the 1993 US hamburger-associated outbreak strains (Applied Environmental Microbiology 78: 7706-7719), all curli-expressing variants of the 2006 spinach-associated outbreak strains carry a functional rcsB gene, suggesting an alternative mechanism governing intra-strain phenotypic divergence in E. coli O157:H7.
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Affiliation(s)
- Michelle Qiu Carter
- Produce Safety and Microbiology Research Unit, Western Regional Research Center, Agricultural Research Service, US Department of Agriculture, Albany, CA, USA.
| | - Jacqueline W Louie
- Produce Safety and Microbiology Research Unit, Western Regional Research Center, Agricultural Research Service, US Department of Agriculture, Albany, CA, USA
| | - Steven Huynh
- Produce Safety and Microbiology Research Unit, Western Regional Research Center, Agricultural Research Service, US Department of Agriculture, Albany, CA, USA
| | - Craig T Parker
- Produce Safety and Microbiology Research Unit, Western Regional Research Center, Agricultural Research Service, US Department of Agriculture, Albany, CA, USA
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40
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Huang HW, Lung HM, Yang BB, Wang CY. Responses of microorganisms to high hydrostatic pressure processing. Food Control 2014. [DOI: 10.1016/j.foodcont.2013.12.007] [Citation(s) in RCA: 140] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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41
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The effect of the rpoSam allele on gene expression and stress resistance in Escherichia coli. Arch Microbiol 2014; 196:589-600. [PMID: 24862098 DOI: 10.1007/s00203-014-0994-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 02/17/2014] [Accepted: 05/13/2014] [Indexed: 10/25/2022]
Abstract
The RNA polymerase associated with RpoS transcribes many genes related to stationary phase and stress survival in Escherichia coli. The DNA sequence of rpoS exhibits a high degree of polymorphism. A C to T transition at position 99 of the rpoS ORF, which results in a premature amber stop codon often found in E. coli strains. The rpoSam mutant expresses a truncated and partially functional RpoS protein. Here, we present new evidence regarding rpoS polymorphism in common laboratory E. coli strains. One out of the six tested strains carries the rpoSam allele, but expressed a full-length RpoS protein owing to the presence of an amber supressor mutation. The rpoSam allele was transferred to a non-suppressor background and tested for RpoS level, stress resistance and for the expression of RpoS and sigma70-dependent genes. Overall, the rpoSam strain displayed an intermediate phenotype regarding stress resistance and the expression of σ(S)-dependent genes when compared to the wild-type rpoS(+) strain and to the rpoS null mutant. Surprisingly, overexpression of rpoSam had a differential effect on the expression of the σ(70)-dependent genes phoA and lacZ that, respectively, encode the enzymes alkaline phosphatase and β-galactosidase. The former was enhanced while the latter was inhibited by high levels of RpoSam.
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42
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The stress response factor RpoS is required for the natural transformation of Escherichia coli. CHINESE SCIENCE BULLETIN-CHINESE 2014. [DOI: 10.1007/s11434-013-0014-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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43
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Loss of cAMP/CRP regulation confers extreme high hydrostatic pressure resistance in Escherichia coli O157:H7. Int J Food Microbiol 2013; 166:65-71. [PMID: 23831733 DOI: 10.1016/j.ijfoodmicro.2013.06.020] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 06/13/2013] [Accepted: 06/15/2013] [Indexed: 11/22/2022]
Abstract
Application of high hydrostatic pressure (HHP) constitutes a valuable non-thermal pasteurization process in modern food conservation. Triggered by our interest in the rapid adaptive evolution towards HHP resistance in the food-borne pathogen E. coli O157:H7 (strain ATCC 43888) that was demonstrated earlier, we used genetic screening to identify specific loci in which a loss-of-function mutation would be sufficient to markedly increase HHP survival. As such, individual loss of RssB (anti RpoS-factor), CRP (catabolite response protein) and CyaA (adenylate cyclase) were each found to confer significant HHP resistance in the 300MPa range (i.e. >1,000-fold), and this phenotype invariably coincided with increased resistance against heat as well. In contrast to loss of RssB, however, loss of CRP or CyaA also conferred significantly increased resistance to 600MPa (i.e. >10,000-fold), suggesting cAMP/CRP homeostasis to affect extreme HHP resistance independently of increased RpoS activity. Surprisingly, none of the rapidly emerging HHP-resistant mutants of ATCC 43888 that were isolated previously did incur any mutations in rssB, crp or cyaA, indicating that a number of other loci can guide the rapid emergence of HHP resistance in E. coli O157:H7 as well. The inability of spontaneous rssB, crp or cyaA mutants to emerge during selective enrichment under HHP selection likely stems from their decreased competitive fitness during growth. Overall, this study is the first to shed light on the possible genetic strategies supporting the acquisition of HHP resistance in E. coli O157:H7.
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Uhlich GA, Chen CY, Cottrell BJ, Hofmann CS, Dudley EG, Strobaugh TP, Nguyen LH. Phage insertion in mlrA and variations in rpoS limit curli expression and biofilm formation in Escherichia coli serotype O157: H7. MICROBIOLOGY-SGM 2013; 159:1586-1596. [PMID: 23744902 DOI: 10.1099/mic.0.066118-0] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Biofilm formation in Escherichia coli is a tightly controlled process requiring the expression of adhesive curli fibres and certain polysaccharides such as cellulose. The transcriptional regulator CsgD is central to biofilm formation, controlling the expression of the curli structural and export proteins and the diguanylate cyclase adrA, which indirectly activates cellulose production. CsgD itself is highly regulated by two sigma factors (RpoS and RpoD), multiple DNA-binding proteins, small regulatory RNAs and several GGDEF/EAL proteins acting through c-di-GMP. One such transcription factor MlrA binds the csgD promoter to enhance the RpoS-dependent transcription of csgD. Bacteriophage, often carrying the stx1 gene, utilize an insertion site in the proximal mlrA coding region of E. coli serotype O157 : H7 strains, and the loss of mlrA function would be expected to be the major factor contributing to poor curli and biofilm expression in that serotype. Using a bank of 55 strains of serotype O157 : H7, we investigated the consequences of bacteriophage insertion. Although curli/biofilm expression was restored in many of the prophage-bearing strains by a wild-type copy of mlrA on a multi-copy plasmid, more than half of the strains showed only partial or no complementation. Moreover, the two strains carrying an intact mlrA were found to be deficient in biofilm formation. However, RpoS mutations that attenuated or inactivated RpoS-dependent functions such as biofilm formation were found in >70 % of the strains, including the two strains with an intact mlrA. We conclude that bacteriophage interruption of mlrA and RpoS mutations provide major obstacles limiting curli expression and biofilm formation in most serotype O157 : H7 strains.
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Affiliation(s)
- Gaylen A Uhlich
- Molecular Characterization of Foodborne Pathogens Research Unit, Eastern Regional Research Center, Agricultural Research Service, US Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA, USA
| | - Chin-Yi Chen
- Molecular Characterization of Foodborne Pathogens Research Unit, Eastern Regional Research Center, Agricultural Research Service, US Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA, USA
| | - Bryan J Cottrell
- Molecular Characterization of Foodborne Pathogens Research Unit, Eastern Regional Research Center, Agricultural Research Service, US Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA, USA
| | - Christopher S Hofmann
- Molecular Characterization of Foodborne Pathogens Research Unit, Eastern Regional Research Center, Agricultural Research Service, US Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA, USA
| | - Edward G Dudley
- Department of Food Science, Penn State University, University Park, PA, USA
| | - Terence P Strobaugh
- Molecular Characterization of Foodborne Pathogens Research Unit, Eastern Regional Research Center, Agricultural Research Service, US Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA, USA
| | - Ly-Huong Nguyen
- Molecular Characterization of Foodborne Pathogens Research Unit, Eastern Regional Research Center, Agricultural Research Service, US Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA, USA
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Vanlint D, Rutten N, Govers SK, Michiels CW, Aertsen A. Exposure to high hydrostatic pressure rapidly selects for increased RpoS activity and general stress-resistance in Escherichia coli O157:H7. Int J Food Microbiol 2013; 163:28-33. [PMID: 23500612 DOI: 10.1016/j.ijfoodmicro.2013.02.001] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2012] [Revised: 02/03/2013] [Accepted: 02/06/2013] [Indexed: 11/19/2022]
Abstract
Exposure to high hydrostatic pressure (HHP) is increasingly being used in food preservation as a non-thermal pasteurization process, and its further implementation necessitates a more thorough understanding of bacterial resistance development and intraspecies variability with regard to inactivation by HHP. In this report, we discovered that exposure to high hydrostatic pressure stress can rapidly select for strongly increased RpoS activity in a hypersensitive Escherichia coli O157:H7 strain (ATCC 43888), leading to a simultaneous increase in HHP and heat resistance. Moreover, the level of RpoS activity correlated well with the original hypersensitivity and the extent of acquired HHP resistance, and extremely HHP-resistant mutants of ATCC 43888 clearly incurred a number of additional RpoS-dependent phenotypes. These findings suggest that implementation of novel processing techniques in the food production chain can readily affect the physiology of food-borne pathogens.
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Affiliation(s)
- Dietrich Vanlint
- Laboratory of Food Microbiology and Leuven Food Science and Nutrition Research Centre (LFoRCe), Department of Microbial and Molecular Systems (M(2)S), Faculty of Bioscience Engineering, KU Leuven, Kasteelpark Arenberg 22, B-3001 Leuven, Belgium
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Alvarez-Ordóñez A, Alvseike O, Omer MK, Heir E, Axelsson L, Holck A, Prieto M. Heterogeneity in resistance to food-related stresses and biofilm formation ability among verocytotoxigenic Escherichia coli strains. Int J Food Microbiol 2012; 161:220-30. [PMID: 23337122 DOI: 10.1016/j.ijfoodmicro.2012.12.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Revised: 09/26/2012] [Accepted: 12/02/2012] [Indexed: 01/14/2023]
Abstract
This study assessed the resistance of ten verocytotoxigenic Escherichia coli (VTEC) isolates of commonly encountered serogroups/-types and two non-pathogenic E. coli strains to various food-related stresses (acid, alkaline, heat and high hydrostatic pressure treatments) and their biofilm formation ability. In addition, the global changes in the cellular composition in response to the exposure to these adverse environments were monitored by Fourier Transform Infrared (FT-IR) spectroscopy for two of the strains. Large inter-strain variations in stress resistance were observed. The most tolerant strains belonged to serogroup O157 which included both the O157:H7 type strain EDL933 and a representative isolate of the sorbitol fermenting O157:H- VTEC clone (strain MF3582). Strain C-600, a non-pathogenic laboratory strain, was sensitive to multiple stresses. Although wide variation in biofilm-forming ability was observed among VTEC isolates, no consistent relationships between biofilm-forming ability and capacity to withstand stress exposures were found. Analysis of the allelic status of the rpoS gene, involved in the general stress response of stationary-phase cells, allowed detection of loss-of-function mutations for two strains, E218/02 and MF2411, both of them showing as common features a high sensitivity to alkaline and heat treatments and a poor ability to form mature biofilms. Evidences found in this study confirm rpoS as a highly mutable gene in nature, and suggest its relevance not only for the mount of an active stress response but also for the establishment of mature biofilm communities. Our findings contribute to increase the knowledge on the resistance of VTEC to environmental stresses commonly encountered in the food chain, which can lead to improved strategies for preventing VTEC infections.
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Affiliation(s)
- A Alvarez-Ordóñez
- Department of Food Hygiene and Technology, University of León, Campus de Vegazana, E-24071 León, Spain.
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Yang B, Shi Y, Xia X, Xi M, Wang X, Ji B, Meng J. Inactivation of foodborne pathogens in raw milk using high hydrostatic pressure. Food Control 2012. [DOI: 10.1016/j.foodcont.2012.04.030] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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van Hoek AH, Aarts HJ, Bouw E, van Overbeek WM, Franz E. The role ofrpoSinEscherichia coliO157 manure-amended soil survival and distribution of allelic variations among bovine, food and clinical isolates. FEMS Microbiol Lett 2012; 338:18-23. [DOI: 10.1111/1574-6968.12024] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 10/03/2012] [Accepted: 10/04/2012] [Indexed: 12/27/2022] Open
Affiliation(s)
- Angela H.A.M. van Hoek
- National Institute for Public Health and the Environment; Centre for Infectious Disease Control; Laboratory for Zoonoses and Environmental Microbiology; Bilthoven; The Netherlands
| | - Henk J.M. Aarts
- National Institute for Public Health and the Environment; Centre for Infectious Disease Control; Laboratory for Zoonoses and Environmental Microbiology; Bilthoven; The Netherlands
| | - El Bouw
- National Institute for Public Health and the Environment; Centre for Infectious Disease Control; Laboratory for Zoonoses and Environmental Microbiology; Bilthoven; The Netherlands
| | - Wendy M. van Overbeek
- National Institute for Public Health and the Environment; Centre for Infectious Disease Control; Laboratory for Zoonoses and Environmental Microbiology; Bilthoven; The Netherlands
| | - Eelco Franz
- National Institute for Public Health and the Environment; Centre for Infectious Disease Control; Laboratory for Zoonoses and Environmental Microbiology; Bilthoven; The Netherlands
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Peroxide resistance in Escherichia coli serotype O157 : H7 biofilms is regulated by both RpoS-dependent and -independent mechanisms. Microbiology (Reading) 2012; 158:2225-2234. [DOI: 10.1099/mic.0.059535-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Ricciardi A, Parente E, Guidone A, Ianniello RG, Zotta T, Abu Sayem SM, Varcamonti M. Genotypic diversity of stress response in Lactobacillus plantarum, Lactobacillus paraplantarum and Lactobacillus pentosus. Int J Food Microbiol 2012; 157:278-85. [PMID: 22704047 DOI: 10.1016/j.ijfoodmicro.2012.05.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Revised: 05/16/2012] [Accepted: 05/19/2012] [Indexed: 10/28/2022]
Abstract
Lactobacillus plantarum, Lactobacillus pentosus and Lactobacillus paraplantarum are three closely related species which are widespread in food and non-food environments, and are important as starter bacteria or probiotics. In order to evaluate the phenotypic diversity of stress tolerance in the L. plantarum group and the ability to mount an adaptive heat shock response, the survival of exponential and stationary phase and of heat adapted exponential phase cells of six L. plantarum subsp. plantarum, one L. plantarum subsp. argentoratensis, one L. pentosus and two L. paraplantarum strains selected in a previous work upon exposure to oxidative, heat, detergent, starvation and acid stresses was compared to that of the L. plantarum WCFS1 strain. Furthermore, to evaluate the genotypic diversity in stress response genes, ten genes (encoding for chaperones DnaK, GroES and GroEL, regulators CtsR, HrcA and CcpA, ATPases/proteases ClpL, ClpP, ClpX and protease FtsH) were amplified using primers derived from the WCFS1 genome sequence and submitted to restriction with one or two endonucleases. The results were compared by univariate and multivariate statistical methods. In addition, the amplicons for hrcA and ctsR were sequenced and compared by multiple sequence alignment and polymorphism analysis. Although there was evidence of a generalized stress response in the stationary phase, with increase of oxidative, heat, and, to a lesser extent, starvation stress tolerance, and for adaptive heat stress response, with increased tolerance to heat, acid and detergent, different growth phases and adaptation patterns were found. Principal component analysis showed that while heat, acid and detergent stresses respond similarly to growth phase and adaptation, tolerance to oxidative and starvation stresses implies completely unrelated mechanisms. A dendrogram obtained using the data from multilocus restriction typing (MLRT) of stress response genes clearly separated two groups of L. plantarum strains from the other species but there was no correlation between genotypic grouping and grouping obtained on the basis of the stress response pattern, nor with the phylograms obtained from hrcA and ctsR sequences. Differences in sequence in L. plantarum strains were mostly due to single nucleotide polymorphisms with a high frequency of synonymous nucleotide changes and, while hrcA was characterized by an excess of low frequency polymorphism, very low diversity was found in ctsR sequences. Sequence alignment of hrcA allowed a correct discrimination of the strains at the species level, thus confirming the relevance of stress response genes for taxonomy.
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Affiliation(s)
- Annamaria Ricciardi
- Dipartimento di Biologia, Difesa e Biotecnologie Agro-Forestali, Università degli Studi della Basilicata, Potenza, Italy.
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