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Silva BN, Teixeira JA, Cadavez V, Gonzales-Barron U. Mild Heat Treatment and Biopreservatives for Artisanal Raw Milk Cheeses: Reducing Microbial Spoilage and Extending Shelf-Life through Thermisation, Plant Extracts and Lactic Acid Bacteria. Foods 2023; 12:3206. [PMID: 37685139 PMCID: PMC10486694 DOI: 10.3390/foods12173206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 08/22/2023] [Accepted: 08/24/2023] [Indexed: 09/10/2023] Open
Abstract
The microbial quality of raw milk artisanal cheeses is not always guaranteed due to the possible presence of pathogens in raw milk that can survive during manufacture and maturation. In this work, an overview of the existing information concerning lactic acid bacteria and plant extracts as antimicrobial agents is provided, as well as thermisation as a strategy to avoid pasteurisation and its negative impact on the sensory characteristics of artisanal cheeses. The mechanisms of antimicrobial action, advantages, limitations and, when applicable, relevant commercial applications are discussed. Plant extracts and lactic acid bacteria appear to be effective approaches to reduce microbial contamination in artisanal raw milk cheeses as a result of their constituents (for example, phenolic compounds in plant extracts), production of antimicrobial substances (such as organic acids and bacteriocins, in the case of lactic acid bacteria), or other mechanisms and their combinations. Thermisation was also confirmed as an effective heat inactivation strategy, causing the impairment of cellular structures and functions. This review also provides insight into the potential constraints of each of the approaches, hence pointing towards the direction of future research.
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Affiliation(s)
- Beatriz Nunes Silva
- Centro de Investigação de Montanha (CIMO), Instituto Politécnico de Bragança, Campus de Santa Apolónia, 5300-253 Bragança, Portugal; (V.C.); (U.G.-B.)
- Laboratório Associado para a Sustentabilidade e Tecnologia em Regiões de Montanha (SusTEC), Instituto Politécnico de Bragança, Campus de Santa Apolónia, 5300-253 Bragança, Portugal
- CEB—Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal;
| | - José António Teixeira
- CEB—Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal;
- LABBELS—Associate Laboratory, 4710-057 Braga, Portugal
| | - Vasco Cadavez
- Centro de Investigação de Montanha (CIMO), Instituto Politécnico de Bragança, Campus de Santa Apolónia, 5300-253 Bragança, Portugal; (V.C.); (U.G.-B.)
- Laboratório Associado para a Sustentabilidade e Tecnologia em Regiões de Montanha (SusTEC), Instituto Politécnico de Bragança, Campus de Santa Apolónia, 5300-253 Bragança, Portugal
| | - Ursula Gonzales-Barron
- Centro de Investigação de Montanha (CIMO), Instituto Politécnico de Bragança, Campus de Santa Apolónia, 5300-253 Bragança, Portugal; (V.C.); (U.G.-B.)
- Laboratório Associado para a Sustentabilidade e Tecnologia em Regiões de Montanha (SusTEC), Instituto Politécnico de Bragança, Campus de Santa Apolónia, 5300-253 Bragança, Portugal
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Machado MAM, Castro VS, da Cunha-Neto A, Vallim DC, Pereira RDCL, Dos Reis JO, de Almeida PV, Galvan D, Conte-Junior CA, Figueiredo EEDS. Heat-resistant and biofilm-forming Escherichia coli in pasteurized milk from Brazil. Braz J Microbiol 2023; 54:1035-1046. [PMID: 36811769 PMCID: PMC10235242 DOI: 10.1007/s42770-023-00920-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 02/01/2023] [Indexed: 02/24/2023] Open
Abstract
Escherichia coli harboring a transmissible locus of stress tolerance (tLST) and the ability to form biofilms represent a serious risk in dairy production. Thus, we aimed to evaluate the microbiological quality of pasteurized milk from two dairy producers in Mato Grosso, Brazil, with a focus on determining the possible presence of E. coli with heat resistance (60 °C/6 min), biofilm-forming potential phenotypes and genotypes, and antimicrobial susceptibility. For this, fifty pasteurized milk samples from producers named A and B were obtained for 5 weeks to investigate the presence of Enterobacteriaceae members, coliforms, and E. coli. For heat resistance, E. coli isolates were exposed to a water bath at 60 °C for 0 and 6 min. In antibiogram analysis, eight antibiotics belonging to six antimicrobial classes were analyzed. The potential to form biofilms was quantified at 570 nm, and curli expression by Congo Red was analyzed. To determine the genotypic profile, we performed PCR for the tLST and rpoS genes, and pulsed-field gel electrophoresis (PFGE) was used to investigate the clonal profile of the isolates. Thus, producer A presented unsatisfactory microbiological conditions regarding Enterobacteriaceae and coliforms for weeks 4 and 5, while all samples analyzed for producer B were contaminated at above-the-limit levels established by national and international legislation. These unsatisfactory conditions enabled us to isolate 31 E. coli from both producers (7 isolates from producer A and 24 isolates from producer B). In this way, 6 E. coli isolates (5 from producer A and 1 from producer B) were highly heat resistant. However, although only 6 E. coli showed a highly heat-resistant profile, 97% (30/31) of all E. coli were tLST-positive. In contrast, all isolates were sensitive to all antimicrobials tested. In addition, moderate or weak biofilm potential was verified in 51.6% (16/31), and the expression of curli and presence of rpoS was not always related to this biofilm potential. Therefore, the results emphasize the spreading of heat-resistant E. coli with tLST in both producers and indicate the biofilm as a possible source of contamination during milk pasteurization. However, the possibility of E. coli producing biofilm and surviving pasteurization temperatures cannot be ruled out, and this should be investigated.
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Affiliation(s)
- Maxsueli Aparecida Moura Machado
- Graduate Program in Food Science, Chemistry Institute, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
- Center for Food Analysis (NAL), Technological Development Support Laboratory (LADETEC), Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | | | - Adelino da Cunha-Neto
- Department of Food and Nutrition, Federal University of Mato Grosso - Campus Cuiabá, Fernando Correa da Costa. Avenue, Boa Esperança, Mato Grosso, 78060-900, Brazil
| | | | | | | | | | - Diego Galvan
- Center for Food Analysis (NAL), Technological Development Support Laboratory (LADETEC), Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Carlos Adam Conte-Junior
- Graduate Program in Food Science, Chemistry Institute, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
- Center for Food Analysis (NAL), Technological Development Support Laboratory (LADETEC), Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Eduardo Eustáquio de Souza Figueiredo
- Department of Food and Nutrition, Federal University of Mato Grosso - Campus Cuiabá, Fernando Correa da Costa. Avenue, Boa Esperança, Mato Grosso, 78060-900, Brazil.
- Graduate Program in Animal Science, Federal University of Mato Grosso, Mato Grosso, Brazil.
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3
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Natrella G, Gambacorta G, Squeo G, Faccia M. Impact of Milk Thermization on the Quality Characteristics of P.D.O. "Canestrato Pugliese" Ovine Hard Cheese. Foods 2023; 12:foods12051080. [PMID: 36900597 PMCID: PMC10001226 DOI: 10.3390/foods12051080] [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: 01/27/2023] [Revised: 02/20/2023] [Accepted: 02/28/2023] [Indexed: 03/08/2023] Open
Abstract
The use of raw milk is compulsory in the manufacturing process of most of the European protected designation of origin (PDO) cheeses but, for ovine products, it is often responsible for faulty productions. Since pasteurization is hardly compatible with the PDO concept, a milder treatment (thermization) is allowed in some cases. An investigation was undertaken to assess the effect of thermization on the overall quality of Canestrato Pugliese, a PDO ovine hard cheese of Southern Italy that can be manufactured exclusively from raw milk. Three types of cheese were produced using raw, mild-thermized and high-thermized milk inoculated with a thermophilic commercial starter. The results demonstrated that the heat treatment did not cause remarkable differences in the gross composition, but the microbiological profiles had some differences despite the use of the selected starter. The raw milk cheese contained higher levels (0.5-1 log units) of mesophilic lactobacilli, total viables, total coliforms and enterococci with respect to the thermized counterparts, with the high-thermized cheese showing the lowest levels; these microbiological differences fitted well with the higher content and the different High Performance Liquid Chromatography (HPLC) pattern of soluble nitrogen. The sensory analysis revealed that the thermized cheeses lost some typical sensory characteristics, probably as a consequence of the reduced indigenous microbiota populations. It was concluded that milk thermization could be applied to Canestrato Pugliese manufacturing only together with the development and use of an autochthonous starter.
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Nagy D, Baranyai L, Nguyen LLP, Taczman Brückner A, Zsom T, Németh C, Felföldi J, Zsom-Muha V. Combined Effect of Ultrasound and Low-Heat Treatments on E. coli in Liquid Egg Products and Analysis of the Inducted Structural Alterations by NIR Spectroscopy. SENSORS (BASEL, SWITZERLAND) 2022; 22:9941. [PMID: 36560311 PMCID: PMC9785716 DOI: 10.3390/s22249941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Revised: 12/10/2022] [Accepted: 12/13/2022] [Indexed: 06/17/2023]
Abstract
In this study, sonication with mild heat treatment was used to reduce the E. coli count in inoculated liquid whole egg, egg yolk and albumen. Ultrasonic equipment (20/40 kHz, 180/300 W) has been used for 30/60 min with a 55 °C water bath. The combination of sonication and low-heat treatment was able to reduce the concentration of E. coli from 5-log CFU × mL-1 below 10 CFU × mL-1 at 300 W, 40 kHz and 60 min of sonication in liquid egg products. The 60 min treatment was able to reduce the E. coli concentration below 10 CFU × mL-1 in the case of egg yolk regardless of the applied frequency, absorbed power or applied energy dose. The 30 min treatment of sonication and heating was able to reduce significantly the number of E. coli in the egg products, as well. Our results showed that sonication with mild heat treatment can be a useful technique to decrease the number of microorganisms in liquid egg products to a very low level. Near-infrared spectroscopy was used to investigate structural changes in the samples, induced by the combined treatment. Principal component analysis showed that this method can alter the C-H, C-N, -OH and -NH bonds in these egg products.
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Affiliation(s)
- Dávid Nagy
- Department of Food Measurement and Process Control, Institute of Food Science and Technology, Hungarian University of Agriculture and Life Sciences, Somlói út 14–16, H-1118 Budapest, Hungary
| | - László Baranyai
- Department of Food Measurement and Process Control, Institute of Food Science and Technology, Hungarian University of Agriculture and Life Sciences, Somlói út 14–16, H-1118 Budapest, Hungary
| | - Lien Le Phuong Nguyen
- Department of Livestock Product and Food Preservation Technology, Institute of Food Science and Technology, Hungarian University of Agriculture and Life Sciences, Ménesi út 43–45, H-1118 Budapest, Hungary
- Institute of Biotechnology and Food Technology, Industrial University of Ho Chi Minh City, Ho Chi Minh City 700000, Vietnam
| | - Andrea Taczman Brückner
- Department of Food Microbiology, Hygiene and Safety, Institute of Food Science and Technology, Hungarian University of Agriculture and Life Sciences, Somlói út 14–16, H-1118 Budapest, Hungary
| | - Tamás Zsom
- Department of Postharvest, Supply Chain, Commerce and Sensory Science, Institute of Food Science and Technology, Hungarian University of Agriculture and Life Sciences, Ménesi út 43–45, H-1118 Budapest, Hungary
| | | | - József Felföldi
- Department of Food Measurement and Process Control, Institute of Food Science and Technology, Hungarian University of Agriculture and Life Sciences, Somlói út 14–16, H-1118 Budapest, Hungary
| | - Viktória Zsom-Muha
- Department of Food Measurement and Process Control, Institute of Food Science and Technology, Hungarian University of Agriculture and Life Sciences, Somlói út 14–16, H-1118 Budapest, Hungary
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5
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Wittwer M, Hammer P, Runge M, Valentin-Weigand P, Neubauer H, Henning K, Mertens-Scholz K. Inactivation Kinetics of Coxiella burnetii During High-Temperature Short-Time Pasteurization of Milk. Front Microbiol 2022; 12:753871. [PMID: 35069465 PMCID: PMC8770862 DOI: 10.3389/fmicb.2021.753871] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 11/29/2021] [Indexed: 11/30/2022] Open
Abstract
The Gram-negative, obligate intracellular bacterium Coxiella burnetii is the causative organism of the zoonosis Q fever and is known for its resistance toward various intra- and extracellular stressors. Infected ruminants such as cattle, sheep, and goats can shed the pathogen in their milk. Pasteurization of raw milk was introduced for the inactivation of C. burnetii and other milk-borne pathogens. Legal regulations for the pasteurization of milk are mostly based on recommendations of the Codex Alimentarius. As described there, C. burnetii is considered as the most heat-resistant non-spore-forming bacterial pathogen in milk and has to be reduced by at least 5 log10-steps during the pasteurization process. However, the corresponding inactivation data for C. burnetii originate from experiments performed more than 60 years ago. Recent scientific findings and the technological progress of modern pasteurization equipment indicate that C. burnetii is potentially more effectively inactivated during pasteurization than demanded in the Codex Alimentarius. In the present study, ultra-high heat-treated milk was inoculated with different C. burnetii field isolates and subsequently heat-treated in a pilot-plant pasteurizer. Kinetic inactivation data in terms of D- and z-values were determined and used for the calculation of heat-dependent log reduction. With regard to the mandatory 5 log10-step reduction of the pathogen, the efficacy of the established heat treatment regime was confirmed, and, in addition, a reduction of the pasteurization temperature seems feasible.
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Affiliation(s)
- Marcel Wittwer
- Institute of Bacterial Infections and Zoonoses, Friedrich-Loeffler-Institut, Jena, Germany
| | - Philipp Hammer
- Federal Research Institute of Nutrition and Food, Department of Microbiology and Biotechnology, Max Rubner-Institut, Kiel, Germany
| | - Martin Runge
- Food and Veterinary Institute, Braunschweig/Hannover, Lower Saxony State Office for Consumer Protection and Food Safety, Hanover, Germany
| | - Peter Valentin-Weigand
- Institute for Microbiology, University of Veterinary Medicine Hannover, Hanover, Germany
| | - Heinrich Neubauer
- Institute of Bacterial Infections and Zoonoses, Friedrich-Loeffler-Institut, Jena, Germany
| | - Klaus Henning
- Institute of Bacterial Infections and Zoonoses, Friedrich-Loeffler-Institut, Jena, Germany
| | - Katja Mertens-Scholz
- Institute of Bacterial Infections and Zoonoses, Friedrich-Loeffler-Institut, Jena, Germany
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6
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Xu ZS, Yang X, Gänzle MG. Resistance of biofilm- and pellicle-embedded strains of Escherichia coli encoding the transmissible locus of stress tolerance (tLST) to oxidative sanitation chemicals. Int J Food Microbiol 2021; 359:109425. [PMID: 34607035 DOI: 10.1016/j.ijfoodmicro.2021.109425] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 09/13/2021] [Accepted: 09/23/2021] [Indexed: 12/11/2022]
Abstract
Biofilm formation in food processing plants reduces the efficacy of sanitation. The presence of transmissible locus of stress tolerance (tLST) also enhances resistance of planktonic cells of Escherichia coli to sanitation chemicals but the role of tLST in resistance of biofilm-embedded cells remains unclear. This study investigated the link of tLST to biofilm formation and its contribution to resistance of biofilm-embedded E. coli to sanitation. Biofilms were formed as single-strain and as dual-strain biofilms in association with E. coli, Aeromonas australensis or Carnobacterium maltaromaticum. Biofilms on stainless steel were compared to floating biofilms formed at the air-liquid interface (pellicles). The resistance of biofilm-embedded tLST positive strains of E. coli to chlorine, hydrogen peroxide, and peroxyacetic acid was higher than the resistance of tLST negative strains. Higher biofilm density as measured by crystal violet staining was observed in tLST-positive strains of E. coli when compared to tLST negative strains. Biofilm density positively correlated to resistance to disinfectants. The use of confocal laser scanning microscopy detected more compact structure of pellicles compared to solid surface-attached biofilms, resulting in higher chlorine resistance despite the absence of tLST in strains of E. coli. Collectively, the findings of this study elucidated the impact of tLST in strains of E. coli on biofilm formation and sanitizer resistance. These findings may inform the development of improved sanitization protocols for food facilities.
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Affiliation(s)
- Zhaohui S Xu
- University of Alberta, Dept. of Agricultural, Food and Nutritional Science, Edmonton, AB, Canada
| | - Xianqin Yang
- Agriculture and Agri-Food Canada, Lacombe Research and Development Centre, 6000 C and E Trail, Lacombe T4L 1W1, AB, Canada
| | - Michael G Gänzle
- University of Alberta, Dept. of Agricultural, Food and Nutritional Science, Edmonton, AB, Canada.
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7
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Engstrom SK, Mays MF, Glass KA. Determination and validation of D-values for Listeria monocytogenes and Shiga toxin-producing Escherichia coli in cheese milk. J Dairy Sci 2021; 104:12332-12341. [PMID: 34600705 DOI: 10.3168/jds.2021-20350] [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: 02/22/2021] [Accepted: 08/18/2021] [Indexed: 11/19/2022]
Abstract
Certain cheeses can be legally produced in the United States using raw milk, but they must be aged for at least 60 d to reduce pathogen risks. However, some varieties, even when aged for 60 d, have been shown to support growth of Listeria monocytogenes or survival of Shiga toxin-producing Escherichia coli (STEC). Thermization, as a subpasteurization heat treatment, has been proposed as a control to reduce the risk of pathogens in raw cheese milk while retaining some quality attributes in the cheese. However, the temperature and time combinations needed to enhance safety have not been well characterized. The objective of this research was to determine and validate decimal reduction values (D-values) for L. monocytogenes and STEC at thermization temperatures 65.6, 62.8, and 60.0°C; a D-value at 57.2°C was also determined for L. monocytogenes only. Nonhomogenized, pasteurized whole-milk samples (1 mL) were inoculated with 8-log cfu/mL L. monocytogenes or STEC (5- or 7-strain mixtures, respectively), vacuum-sealed in moisture-impermeable pouches, and heated via water bath submersion. Duplicate samples were removed at appropriate intervals and immediately cooled in an ice bath. Surviving bacteria were enumerated on modified Oxford or sorbitol MacConkey overlaid with tryptic soy agar to aid in the recovery of heat-injured cells. Duplicate trials were conducted, and survival data were used to calculate thermal inactivation rates. D65.6°C-, D62.8°C-, and D60.0°C-values of 17.1 and 7.2, 33.8 and 16.9, and 146.6 and 60.0 s were found for L. monocytogenes and STEC, respectively, and a D57.2°C-value of 909.1 s was determined for L. monocytogenes. Triplicate validation trials were conducted for each test temperature using 100 mL of milk inoculated with 3 to 4 log cfu/mL of each pathogen cocktail, A 3-log reduction of each pathogen was achieved faster in larger volumes than what was predicted by D-values (D-values were fail-safe). Data were additionally compared with published results from 21 scientific studies investigating L. monocytogenes and STEC in whole milk heated to thermization temperatures (55.0-71.7°C). These data can be used to give producers of artisanal raw-milk cheese flexibility in designing thermal processes to reduce L. monocytogenes and STEC populations to levels that are not infectious to consumers.
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Affiliation(s)
- S K Engstrom
- Food Research Institute, University of Wisconsin-Madison, 1550 Linden Drive, Madison 53706
| | - M F Mays
- Department of Statistics, University of Wisconsin-Madison, 1276 Medical Sciences Center, Madison 53706
| | - K A Glass
- Food Research Institute, University of Wisconsin-Madison, 1550 Linden Drive, Madison 53706.
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9
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Katikaridis P, Bohl V, Mogk A. Resisting the Heat: Bacterial Disaggregases Rescue Cells From Devastating Protein Aggregation. Front Mol Biosci 2021; 8:681439. [PMID: 34017857 PMCID: PMC8129007 DOI: 10.3389/fmolb.2021.681439] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 04/12/2021] [Indexed: 11/23/2022] Open
Abstract
Bacteria as unicellular organisms are most directly exposed to changes in environmental growth conditions like temperature increase. Severe heat stress causes massive protein misfolding and aggregation resulting in loss of essential proteins. To ensure survival and rapid growth resume during recovery periods bacteria are equipped with cellular disaggregases, which solubilize and reactivate aggregated proteins. These disaggregases are members of the Hsp100/AAA+ protein family, utilizing the energy derived from ATP hydrolysis to extract misfolded proteins from aggregates via a threading activity. Here, we describe the two best characterized bacterial Hsp100/AAA+ disaggregases, ClpB and ClpG, and compare their mechanisms and regulatory modes. The widespread ClpB disaggregase requires cooperation with an Hsp70 partner chaperone, which targets ClpB to protein aggregates. Furthermore, Hsp70 activates ClpB by shifting positions of regulatory ClpB M-domains from a repressed to a derepressed state. ClpB activity remains tightly controlled during the disaggregation process and high ClpB activity states are likely restricted to initial substrate engagement. The recently identified ClpG (ClpK) disaggregase functions autonomously and its activity is primarily controlled by substrate interaction. ClpG provides enhanced heat resistance to selected bacteria including pathogens by acting as a more powerful disaggregase. This disaggregase expansion reflects an adaption of bacteria to extreme temperatures experienced during thermal based sterilization procedures applied in food industry and medicine. Genes encoding for ClpG are transmissible by horizontal transfer, allowing for rapid spreading of extreme bacterial heat resistance and posing a threat to modern food production.
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Affiliation(s)
- Panagiotis Katikaridis
- Center for Molecular Biology of the Heidelberg University and German Cancer Research Center, DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Valentin Bohl
- Center for Molecular Biology of the Heidelberg University and German Cancer Research Center, DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Axel Mogk
- Center for Molecular Biology of the Heidelberg University and German Cancer Research Center, DKFZ-ZMBH Alliance, Heidelberg, Germany
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Survival rate of Escherichia coli O157 in artificially contaminated raw and thermized ewe milk in different Pecorino cheese production processes. Int J Food Microbiol 2021; 347:109175. [PMID: 33812165 DOI: 10.1016/j.ijfoodmicro.2021.109175] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 02/04/2021] [Accepted: 03/20/2021] [Indexed: 11/24/2022]
Abstract
Pecorino is a typical Italian cheese, mostly produced in central and southern Italy regions using ewe raw milk and following traditional procedures. The use of raw milk constitutes a risk linked to the potential survival or multiplication of pathogenic microorganisms, as Shiga toxin-producing Escherichia coli (STEC). The aim of this study was to compare different Italian traditional Pecorino production methods to determine if there were any phases that could influence the Escherichia coli O157 survival rate, but also if they could negatively influence lactic acid bacteria survival rate, during the phases of production and ripening. Therefore batches of Pecorino cheese were prepared using different production methods, representing the real and typical cheese production in southern and central Italy regions: 1) heating the milk at 37 °C for about 40 min before curding, 2) heating the milk at 60 °C (thermization) for 13 min, so that the alkaline phosphatase reaction is still positive before curding, 3) cooking curd at 41 °C and 4) at 45 °C, both for 5 min. Our results demonstrated that traditional milk treatments different from pasteurization can help but do not eliminate serious microbiological treats, as E. coli O157, especially if the raw milk is heavily contaminated. The heat treatment at 60 °C applied to raw milk was able to decrease the concentration of E. coli O157 of 1.7 log10CFU/ml and, according to the inactivation slope, it would be further reduced prolonging the heating treatment. The results obtained also showed that, during the Pecorino cheese ripening, E. coli O157 was always enumerable for 60 days, remaining detectable after 90 days of ripening.
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Boyd E, Trmcic A, Taylor M, Shyng S, Hasselback P, Man S, Tchao C, Stone J, Janz L, Hoang L, Galanis E. Escherichia coli O121 outbreak associated with raw milk Gouda-like cheese in British Columbia, Canada, 2018. CANADA COMMUNICABLE DISEASE REPORT = RELEVE DES MALADIES TRANSMISSIBLES AU CANADA 2021; 47:11-16. [PMID: 33746616 PMCID: PMC7972179 DOI: 10.14745/ccdr.v47i01a03] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND In 2018, a Shiga toxin-producing Escherichia coli O121 outbreak that affected seven individuals was associated with raw milk Gouda-like cheese produced in British Columbia, Canada. OBJECTIVES To describe the E. coli O121 outbreak investigation and recommend greater control measures for raw milk Gouda-like cheese. METHODS Cases of E. coli O121 were identified through laboratory testing results and epidemiologic surveillance data. The cases were interviewed on exposures of interest, which were analyzed against Foodbook Report values for British Columbia. Environmental inspection of the dairy plant and the cheese products was conducted to ascertain a source of contamination. Whole genome multi-locus sequence typing (wgMLST) was performed on all positive E. coli O121 clinical and food isolates at the provincial laboratory. RESULTS Four out of the seven cases consumed the same raw milk Gouda-like cheese between August and October 2018. The implicated cheese was aged longer than the required minimum of 60 days, and no production deficiencies were noted. One sample of the implicated cheese tested positive for E. coli O121. The seven clinical isolates and one cheese isolate matched by wgMLST within 6.5 alleles. CONCLUSION Raw milk Gouda and Gouda-like cheese has been implicated in three previous Shiga toxin-producing E. coli outbreaks in North America. It was recommended product labelling to increase consumer awareness and thermization of milk to decrease the risk of illness associated with raw milk Gouda and Gouda-like cheese.
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Affiliation(s)
- Eva Boyd
- British Columbia Centre for Disease Control, Vancouver, BC
- Correspondence:
| | - Aljosa Trmcic
- British Columbia Centre for Disease Control, Vancouver, BC
| | - Marsha Taylor
- British Columbia Centre for Disease Control, Vancouver, BC
| | - Sion Shyng
- British Columbia Centre for Disease Control, Vancouver, BC
| | | | - Stephanie Man
- British Columbia Centre for Disease Control Public Health Laboratories, Vancouver, BC
| | - Christine Tchao
- British Columbia Centre for Disease Control Public Health Laboratories, Vancouver, BC
| | | | - Loretta Janz
- British Columbia Centre for Disease Control Public Health Laboratories, Vancouver, BC
| | - Linda Hoang
- British Columbia Centre for Disease Control, Vancouver, BC
- British Columbia Centre for Disease Control Public Health Laboratories, Vancouver, BC
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC
| | - Eleni Galanis
- British Columbia Centre for Disease Control, Vancouver, BC
- School of Population and Public Health, University of British Columbia, Vancouver, BC
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Wagner N, Matzen S, Walte HG, Neve H, Franz CM, Heller KJ, Hammer P. Extreme thermal stability of Lactococcus lactis bacteriophages: Evaluation of phage inactivation in a pilot-plant pasteurizer. Lebensm Wiss Technol 2018. [DOI: 10.1016/j.lwt.2018.02.056] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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13
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Biofilm Formation Potential of Heat-Resistant Escherichia coli Dairy Isolates and the Complete Genome of Multidrug-Resistant, Heat-Resistant Strain FAM21845. Appl Environ Microbiol 2017; 83:AEM.00628-17. [PMID: 28550056 PMCID: PMC5514686 DOI: 10.1128/aem.00628-17] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 05/18/2017] [Indexed: 02/07/2023] Open
Abstract
We tested the biofilm formation potential of 30 heat-resistant and 6 heat-sensitive Escherichia coli dairy isolates. Production of curli and cellulose, static biofilm formation on polystyrene (PS) and stainless steel surfaces, biofilm formation under dynamic conditions (Bioflux), and initial adhesion rates (IAR) were evaluated. Biofilm formation varied greatly between strains, media, and assays. Our results highlight the importance of the experimental setup in determining biofilm formation under conditions of interest, as correlation between different assays was often not a given. The heat-resistant, multidrug-resistant (MDR) strain FAM21845 showed the strongest biofilm formation on PS and the highest IAR and was the only strain that formed significant biofilms on stainless steel under conditions relevant to the dairy industry, and it was therefore fully sequenced. Its chromosome is 4.9 Mb long, and it harbors a total of five plasmids (147.2, 54.2, 5.8, 2.5, and 1.9 kb). The strain carries a broad range of genes relevant to antimicrobial resistance and biofilm formation, including some on its two large conjugative plasmids, as demonstrated in plate mating assays.IMPORTANCE In biofilms, cells are embedded in an extracellular matrix that protects them from stresses, such as UV radiation, osmotic shock, desiccation, antibiotics, and predation. Biofilm formation is a major bacterial persistence factor of great concern in the clinic and the food industry. Many tested strains formed strong biofilms, and especially strains such as the heat-resistant, MDR strain FAM21845 may pose a serious issue for food production. Strong biofilm formation combined with diverse resistances (some encoded on conjugative plasmids) may allow for increased persistence, coselection, and possible transfer of these resistance factors. Horizontal gene transfer may conceivably occur in the food production setting or the gastrointestinal tract after consumption.
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Boll EJ, Marti R, Hasman H, Overballe-Petersen S, Stegger M, Ng K, Knøchel S, Krogfelt KA, Hummerjohann J, Struve C. Turn Up the Heat-Food and Clinical Escherichia coli Isolates Feature Two Transferrable Loci of Heat Resistance. Front Microbiol 2017; 8:579. [PMID: 28439262 PMCID: PMC5383660 DOI: 10.3389/fmicb.2017.00579] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 03/21/2017] [Indexed: 11/24/2022] Open
Abstract
Heat treatment is a widely used process to reduce bacterial loads in the food industry or to decontaminate surfaces, e.g., in hospital settings. However, there are situations where lower temperatures must be employed, for instance in case of food production such as raw milk cheese or for decontamination of medical devices such as thermo-labile flexible endoscopes. A recently identified locus of heat resistance (LHR) has been shown to be present in and confer heat resistance to a variety of Enterobacteriaceae, including Escherichia coli isolates from food production settings and clinical ESBL-producing E. coli isolates. Here, we describe the presence of two distinct LHR variants within a particularly heat resistant E. coli raw milk cheese isolate. We demonstrate for the first time in this species the presence of one of these LHRs on a plasmid, designated pFAM21805, also encoding type 3 fimbriae and three bacteriocins and corresponding self-immunity proteins. The plasmid was highly transferable to other E. coli strains, including Shiga-toxin-producing strains, and conferred LHR-dependent heat resistance as well as type 3 fimbriae-dependent biofilm formation capabilities. Selection for and acquisition of this “survival” plasmid by pathogenic organisms, e.g., in food production environments, may pose great concern and emphasizes the need to screen for the presence of LHR genes in isolates.
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Affiliation(s)
- Erik J Boll
- Department of Microbiology and Infection Control, Statens Serum InstitutCopenhagen, Denmark
| | - Roger Marti
- Agroscope, Division of Food Microbial Systems, Microbiological Safety of Foods of Animal Origin GroupBern, Switzerland
| | - Henrik Hasman
- Department of Microbiology and Infection Control, Statens Serum InstitutCopenhagen, Denmark
| | | | - Marc Stegger
- Department of Microbiology and Infection Control, Statens Serum InstitutCopenhagen, Denmark
| | - Kim Ng
- Department of Microbiology and Infection Control, Statens Serum InstitutCopenhagen, Denmark
| | - Susanne Knøchel
- Department of Food Science, University of CopenhagenCopenhagen, Denmark
| | - Karen A Krogfelt
- Department of Microbiology and Infection Control, Statens Serum InstitutCopenhagen, Denmark
| | - Joerg Hummerjohann
- Agroscope, Division of Food Microbial Systems, Microbiological Safety of Foods of Animal Origin GroupBern, Switzerland
| | - Carsten Struve
- Department of Microbiology and Infection Control, Statens Serum InstitutCopenhagen, Denmark
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Marti R, Muniesa M, Schmid M, Ahrens CH, Naskova J, Hummerjohann J. Short communication: Heat-resistant Escherichia coli as potential persistent reservoir of extended-spectrum β-lactamases and Shiga toxin-encoding phages in dairy. J Dairy Sci 2016; 99:8622-8632. [PMID: 27568050 DOI: 10.3168/jds.2016-11076] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 07/13/2016] [Indexed: 12/11/2022]
Abstract
Here we report the isolation of heat-resistant Escherichia coli from raw milk cheeses. Detection of the heat-resistance markers clpK and orfI by PCR was followed by phenotypical confirmation of increased heat-resistance. These strains were Shiga toxin-negative and, although several were found to be multidrug resistant, no plasmids encoding extended-spectrum β-lactamases (ESBL) were found in any of the isolates. The aim of this study was to assess the potential of these strains to acquire ESBL plasmids and a modified Shiga toxin-encoding phage. Only 4 ESBL-encoding, heat-sensitive E. coli strains were isolated from 1,251 dairy samples (2/455 raw milk and 2/796 raw milk cheese samples). One incompatibility group FII plasmid (CTX-M-14, 79.0 kb) and 3 incompatibility group I1 plasmids (CTX-M-15, 95.2, 96.1, and 97.8 kb) were fully sequenced and de novo assembled. All 4 plasmids are readily transferred to heat-resistant E. coli isolates in plate matings (9.7×10-5 to 3.7×10-1 exconjugants per recipient) and, to a lesser extent, in milk (up to 7.4×10-5 exconjugants per recipient). Importantly, the plasmids are stably maintained during passaging in liquid media without antimicrobial pressure. The heat-resistant isolate FAM21805 was also shown to be capable of acting as donor of all 4 ESBL plasmids. In addition, 3 of 11 tested ESBL exconjugants of heat-resistant strains were lysogenized by the modified Shiga toxin-encoding phage 933W ∆stx::gfp::cat. The higher fraction of heat-resistant E. coli (93 of 256 isolates) compared with the estimated 2% previously predicted based on genomic prevalence of heat resistance genes seems to indicate a selection advantage in the raw milk cheese production environment. The combination of 2 factors may lead to said advantage: increased survival during thermization of raw milk (heating to subpasteurization temperatures) and increased survival rates during cheese ripening. Should these strains acquire ESBL-encoding plasmids, Shiga toxin-encoding phages, or both, these genetic elements would profit from the selection advantage of their host and become more abundant in this particular environment, which in turn could lead to an increased threat to consumers of raw milk products.
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Affiliation(s)
- Roger Marti
- Agroscope, Institute for Food Sciences IFS, Schwarzenburgstrasse 161, CH-3003 Bern, Switzerland
| | - Maite Muniesa
- Department of Microbiology, University of Barcelona, 08007 Barcelona, Spain
| | - Michael Schmid
- Agroscope, Institute for Plant Production Sciences IPS and Swiss Institute of Bioinformatics, Schloss 1, 8820 Wädenswil, Switzerland
| | - Christian H Ahrens
- Agroscope, Institute for Plant Production Sciences IPS and Swiss Institute of Bioinformatics, Schloss 1, 8820 Wädenswil, Switzerland
| | - Javorka Naskova
- Agroscope, Institute for Food Sciences IFS, Schwarzenburgstrasse 161, CH-3003 Bern, Switzerland
| | - Jörg Hummerjohann
- Agroscope, Institute for Food Sciences IFS, Schwarzenburgstrasse 161, CH-3003 Bern, Switzerland.
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Boll EJ, Frimodt-Møller J, Olesen B, Krogfelt KA, Struve C. Heat resistance in extended-spectrum beta-lactamase-producing Escherichia coli may favor environmental survival in a hospital setting. Res Microbiol 2016; 167:345-9. [PMID: 26946311 DOI: 10.1016/j.resmic.2016.02.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Revised: 12/30/2015] [Accepted: 02/03/2016] [Indexed: 11/16/2022]
Abstract
Nosocomial infections caused by extended-spectrum β-lactamase (ESBL)-producing Escherichia coli are a major concern worldwide. There is an urgent need to identify bacterial factors promoting survival and persistence of these organisms in the nosocomial environment. Here, we describe the presence of a gene cluster, containing the Clp ATPase ClpK, within a collection of Danish ESBL-producing E. coli isolates. The cluster conferred thermoprotection upon the isolates, and thus might facilitate survival on medical devices exposed to semi-high temperatures in a hospital setting.
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Affiliation(s)
- Erik J Boll
- Department of Microbiology & Infection Control, Statens Serum Institut, Denmark
| | | | - Bente Olesen
- Department of Clinical Microbiology, Herlev and Gentofte Hospital, University of Copenhagen, Denmark
| | - Karen A Krogfelt
- Department of Microbiology & Infection Control, Statens Serum Institut, Denmark
| | - Carsten Struve
- Department of Microbiology & Infection Control, Statens Serum Institut, Denmark.
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Hammer P, Richter E, Rüsch-Gerdes S, Walte HGC, Matzen S, Kiesner C. Inactivation of Mycobacterium bovis ssp. caprae in high-temperature, short-term pasteurized pilot-plant milk. J Dairy Sci 2015; 98:1634-9. [DOI: 10.3168/jds.2014-8939] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 11/25/2014] [Indexed: 11/19/2022]
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Peng S, Hummerjohann J, Stephan R, Hammer P. Erratum to “Short communication: Heat resistance of Escherichia coli strains in raw milk at different subpasteurization conditions” (J. Dairy Sci. 96:3543–3546). J Dairy Sci 2014. [DOI: 10.3168/jds.2014-97-10-6623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Hammer P, Kiesner C, Walte HGC. Short communication: Effect of homogenization on heat inactivation of Mycobacterium avium subspecies paratuberculosis in milk. J Dairy Sci 2014; 97:2045-8. [DOI: 10.3168/jds.2013-7361] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Accepted: 12/10/2013] [Indexed: 11/19/2022]
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