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Xie Y, Long X, Kim Y, Harris LJ, Nitin N. Survival of Salmonella enterica and Enterococcus faecium on Abiotic Surfaces During Storage at Low Relative Humidity. J Food Prot 2024; 87:100292. [PMID: 38718984 DOI: 10.1016/j.jfp.2024.100292] [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: 02/29/2024] [Revised: 04/26/2024] [Accepted: 04/30/2024] [Indexed: 05/23/2024]
Abstract
Currently, there is limited knowledge on the survival of bacteria on surfaces during postharvest handling of dry products such as onions. Extended survival of microorganisms, coupled with a lack of established and regular, validated cleaning or sanitation methods could enable cross-contamination of these products. The aim of the study was to evaluate the survival of a potential surrogate, Enterococcus faecium, and Salmonella enterica on typical onion handling surfaces, polyurethane (PU), and stainless steel (SS), under low relative humidity. The influence of onion extract on the survival of E. faecium and Salmonella on PU and SS was also investigated. Rifampin-resistant E. faecium NRRL B-2354 and a five-strain cocktail of Salmonella suspended in 0.1% peptone or onion extract were separately inoculated onto PU and SS coupons (2 × 2 cm), at high, moderate, or low (7, 5, or 3 log CFU/cm2) levels. The inoculated surfaces were stored at ∼34% relative humidity and 21°C for up to 84 days. Triplicate samples were enumerated at regular intervals in replicate trials. Samples were enriched when populations fell below the limit of detection by plating (0.48 log CFU/cm2). Scanning electron microscopy was used to observe the cell distribution on the coupons. Reductions of E. faecium of less than ∼2 log were observed on PU and SS over 12 weeks at all inoculum levels and with both inoculum carriers. In 0.1% peptone, Salmonella populations declined by 2 to 3 log over 12 weeks at the high and moderate inoculum levels; at the low inoculum level, Salmonella could not be recovered by enrichment at 84 days. Survival of E. faecium and Salmonella was significantly (P < 0.05) enhanced over 84 days of storage when suspended in onion extract, where cells were covered by a layer of onion extract. E. faecium might have utility as a conservative surrogate for Salmonella when evaluating microbial survival on dry food-contact surfaces.
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Affiliation(s)
- Yucen Xie
- Department of Food Science and Technology, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA.
| | - Xiaonuo Long
- Department of Food Science and Technology, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA.
| | - Yoonbin Kim
- Department of Food Science and Technology, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA.
| | - Linda J Harris
- Department of Food Science and Technology, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA; Western Center for Food Safety, University of California, Davis, CA 95616, USA.
| | - Nitin Nitin
- Department of Food Science and Technology, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA; Department of Agricultural and Biological Engineering, University of California, Davis, CA 95616, USA.
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2
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Gurtler JB, Garner CM, Grasso-Kelley EM, Fan X, Jin TZ. Inactivation of Desiccation-Resistant Salmonella on Apple Slices Following Treatment with ε-Polylysine, Sodium Bisulfate, or Peracetic Acid and Subsequent Dehydration. J Food Prot 2024; 87:100297. [PMID: 38734414 DOI: 10.1016/j.jfp.2024.100297] [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: 09/17/2023] [Revised: 05/02/2024] [Accepted: 05/04/2024] [Indexed: 05/13/2024]
Abstract
Salmonella is capable of surviving dehydration within various foods, such as dried fruit. Dried fruit, including apple slices, have been the subject of product recalls due to contamination with Salmonella. A study was conducted to determine the fate of Salmonella on apple slices, following immersion in three antimicrobial solutions (viz., ε-polylysine [epsilon-polylysine or EP], sodium bisulfate [SBS], or peracetic acid [PAA]), and subsequent hot air dehydration. Gala apples were aseptically cored and sliced into 0.4 cm thick rings, bisected, and inoculated with a five-strain composite of desiccation-resistant Salmonella, to a population of 8.28 log CFU/slice. Slices were then immersed for 2 min in various concentrations of antimicrobial solutions, including EP (0.005, 0.02, 0.05, and 0.1%), SBS (0.05, 0.1, 0.2, and 0.3%), PAA (18 or 42 ppm), or varying concentrations of PAA + EP, and then dehydrated at 60°C for 5 h. Salmonella populations in positive control samples (inoculated apple slices washed in sterile water) declined by 2.64 log after drying. In the present study, the inactivation of Salmonella, following EP and SBS treatments, increased with increasing concentrations, with maximum reductions of 3.87 and 6.20 log (with 0.1 and 0.3% of the two compounds, respectively). Based on preliminary studies, EP concentrations greater than 0.1% did not result in lower populations of Salmonella. Pretreatment washes with either 18 or 42 ppm of PAA inactivated Salmonella populations by 4.62 and 5.63 log, respectively, following desiccation. Combining PAA with up to 0.1% EP induced no greater population reductions of Salmonella than washing with PAA alone. The addition of EP to PAA solutions appeared to destabilize PAA concentrations, reducing its biocidal efficacy. These results may provide antimicrobial predrying treatment alternatives to promote the reduction of Salmonella during commercial or consumer hot air drying of apple slices.
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Affiliation(s)
- Joshua B Gurtler
- U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038-8551, USA.
| | - Christina M Garner
- U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038-8551, USA
| | | | - Xuetong Fan
- U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038-8551, USA
| | - Tony Z Jin
- U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038-8551, USA
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3
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Wang Y, Ling N, Jiao R, Zhang X, Ren Y, Zhao W, Chen H, Ye Y. A universal mechanism on desiccation tolerance of Cronobacter based on intracellular trehalose accumulation regulated by EnvZ/OmpR. Food Microbiol 2024; 119:104455. [PMID: 38225055 DOI: 10.1016/j.fm.2023.104455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 12/04/2023] [Accepted: 12/20/2023] [Indexed: 01/17/2024]
Abstract
Cronobacter (seven species) can survive in dry powdered infant formula for a long time, but the thorough molecular mechanism of resistance to desiccation remains elusive. Here we examine the regulation mechanism of Cronobacter's tolerance to desiccation by the typical two-component system (TCS) EnvZ/OmpR. When exposed to desiccation conditions, Cronobacter showed higher survival than other pathogens, as well as significantly up-regulated expression of ompR and otsAB genes with markedly decreased survival of their mutants, suggesting their relationship with desiccation tolerance. OmpR directly binds to the promoter of trehalose biosynthesis operon otsBA, significantly enhancing their expression, and boosting the trehalose levels. The ompR-deletion in other six species further confirmed its positive regulation in desiccation tolerance. Our data present a hypothesis that EnvZ/OmpR increases intracellular trehalose levels against damage to the cells, which prompts Cronobacter to survive in desiccation conditions. This study reveals a universal molecular mechanism for desiccation resistance in Cronobacter species.
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Affiliation(s)
- Yang Wang
- School of Food and Biological Engineering, Hefei University of Technology, Hefei, China
| | - Na Ling
- School of Food and Biological Engineering, Hefei University of Technology, Hefei, China
| | - Rui Jiao
- School of Food and Biological Engineering, Hefei University of Technology, Hefei, China
| | - Xiyan Zhang
- School of Food and Biological Engineering, Hefei University of Technology, Hefei, China
| | - Yuwei Ren
- School of Food and Biological Engineering, Hefei University of Technology, Hefei, China
| | - Wenhua Zhao
- School of Food and Biological Engineering, Hefei University of Technology, Hefei, China
| | - Hanfang Chen
- School of Food and Biological Engineering, Hefei University of Technology, Hefei, China
| | - Yingwang Ye
- School of Food and Biological Engineering, Hefei University of Technology, Hefei, China; State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Institute of Microbiology, Guangzhou, China.
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4
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Wang XY, Li P, Du XJ, Wang S. Effect of glutathione-transport-related gene gsiD on desiccation tolerance of Cronobacter sakazakii and its related regulatory mechanism. Appl Environ Microbiol 2024; 90:e0156223. [PMID: 38289135 PMCID: PMC10880603 DOI: 10.1128/aem.01562-23] [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: 09/13/2023] [Accepted: 11/16/2023] [Indexed: 02/22/2024] Open
Abstract
The outstanding desiccation tolerance of Cronobacter sakazakii (C. sakazakii) enables long-term persistence in food products with low-water activity to increase the infection risk, especially in low-birth-weight, immuno-compromised neonates, and infants less than 4 weeks of age. In our previous study, the disruption of glutathione transport-related gene gsiD by transposon was found to significantly increase its inactivation rate under drying stress challenges. However, the mechanism underlying the association between glutathione transport and desiccation tolerance of C. sakazakii remains to be clarified. In this study, the mechanism underlying their association was investigated in detail by constructing the gsiD gene deletion mutant. gsiD gene deletion was found to cause the dysfunction of the glutathione transport system GsiABCD and the limitation of glutathione import. The resulting decrease in intracellular glutathione caused the decreased potassium ions uptake and increased potassium ions efflux, inhibited the proline synthesis process, limited extracellular glutathione utilization, increased oxidant stress, reduced biofilm formation, and increased outer membrane permeability, which may be the main reasons for the significant reduction of the desiccation tolerance of C. sakazakii.IMPORTANCEContributing to its superior environmental adaptability, Cronobacter sakazakii can survive under many abiotic stress conditions. The outstanding desiccation tolerance makes this species persist in low-water activity foods, which increases harm to humans. For decades, many studies have focused on the desiccation tolerance of C. sakazakii, but the existing research is still insufficient. Our study found that gsiD gene deletion inhibited glutathione uptake and further decreased intracellular glutathione content, causing a decrease in desiccation tolerance and biofilm formation and an increase in outer membrane permeability. Moreover, the expression level of relative genes verified that gsiD gene deletion made the mutant not conducive to surviving in dry conditions due to restricting potassium ions uptake and efflux, inhibiting the conversion of glutamate to compatible solute proline, and increasing the oxidative stress of C. sakazakii. The above results enrich our knowledge of the desiccation tolerance mechanism of C. sakazakii.
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Affiliation(s)
- Xiao-yi Wang
- State Key Laboratory of Food Nutrition and Safety, College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin, China
| | - Ping Li
- State Key Laboratory of Food Nutrition and Safety, College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin, China
| | - Xin-jun Du
- State Key Laboratory of Food Nutrition and Safety, College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin, China
| | - Shuo Wang
- State Key Laboratory of Food Nutrition and Safety, College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin, China
- Tianjin Key Laboratory of Food Science and Health, College of Medicine, Nankai University, Tianjin, China
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Xue J, Lv J, Liu L, Duan F, Shi A, Ji X, Ding L. Maltodextrin-binding protein as a key factor in Cronobacter sakazakii survival under desiccation stress. Food Res Int 2024; 177:113871. [PMID: 38225116 DOI: 10.1016/j.foodres.2023.113871] [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: 09/01/2023] [Revised: 12/07/2023] [Accepted: 12/14/2023] [Indexed: 01/17/2024]
Abstract
Cronobacter sakazakii (C. sakazakii) is a notorious pathogen responsible for infections in infants and newborns, often transmitted through contaminated infant formula. Despite the use of traditional pasteurization methods, which can reduce microbial contamination, there remains a significant risk of pathogenic C. sakazakii surviving due to its exceptional stress tolerance. In our study, we employed a comparative proteomic approach by comparing wild-type strains with gene knockout strains to identify the essential genes crucial for the successful survival of C. sakazakii during desiccation. Our investigation revealed the significance of envZ-ompR, recA, and flhD gene cassettes in contributing to desiccation tolerance in C. sakazakii. Furthermore, through our comparative proteomic profiling, we identified the maltodextrin-binding protein encoded by ESA_03421 as a potential factor influencing dry tolerance. This protein is regulated by EnvZ-OmpR, RecA, and FlhD. Notably, the knockout of ESA_03421 resulted in a 150% greater reduction in Log CFU compared to the wild-type C. sakazakii. Overall, our findings offer valuable insights into the mechanisms underlying C. sakazakii desiccation tolerance and provide potential targets for the development of new antimicrobial strategies aimed at reducing the risk of infections in infants and newborns.
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Affiliation(s)
- Juan Xue
- Institute of Infection and Immunity, Department of Neurology, Department of Critical Care Medicine,Hubei Provincial Clinical Research Center for Umbilical Cord Blood Hematopoietic Stem Cells, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, China
| | - Jun Lv
- Institute of Infection and Immunity, Department of Neurology, Department of Critical Care Medicine,Hubei Provincial Clinical Research Center for Umbilical Cord Blood Hematopoietic Stem Cells, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, China
| | - Lanfang Liu
- Shiyan Center for Disease Control and Prevention, Shiyan, Hubei, China
| | - Fangfang Duan
- Institute of Infection and Immunity, Department of Neurology, Department of Critical Care Medicine,Hubei Provincial Clinical Research Center for Umbilical Cord Blood Hematopoietic Stem Cells, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, China
| | - Aiying Shi
- School of Medicine, Nankai University, Tianjin, China
| | - Xuemeng Ji
- School of Medicine, Nankai University, Tianjin, China.
| | - Li Ding
- Institute of Infection and Immunity, Department of Neurology, Department of Critical Care Medicine,Hubei Provincial Clinical Research Center for Umbilical Cord Blood Hematopoietic Stem Cells, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, China.
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Ohya K, Ikeuchi S, Hayashidani H, Hara-Kudo Y. [Detection of Salmonella and Enumeration of Hygienic Indicator Bacteria in Dried Wood Ear Mushrooms]. SHOKUHIN EISEIGAKU ZASSHI. JOURNAL OF THE FOOD HYGIENIC SOCIETY OF JAPAN 2024; 65:41-47. [PMID: 39034134 DOI: 10.3358/shokueishi.65.41] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/23/2024]
Abstract
An outbreak of Salmonella Stanley in the United States associated with dried wood ear mushrooms imported from China prompted us to conduct serotyping of Salmonella isolated from dried wood ear mushrooms in voluntary testing, and quantitative test for Salmonella along with enumeration of hygienic indicator bacteria in positive samples in order to evaluate the risk of Salmonella outbreak from dried wood ear mushrooms. The major serovars of Salmonella isolates obtained from 20 samples were as follows: O3,10 group-London (n=3) and Weltevreden (n=5) etc, totaling 9 strains; O4 serogroup-Saintpaul (n=2), Stanley (n=1), Typhimurium (including monophasic variant; n=3), totaling 6 strains. O7 serogroup (Potsdam) and O8 serogroup (Newport) were one strain each. Qualitative and quantitative tests for Salmonella were conducted on 10 samples with remaining amounts. As a result, one sample was 220 MPN/g, six samples were<0.6 MPN/g, and three samples were negative for Salmonella per 25 g. The mean aerobic bacterial counts and coliforms in these samples were 7.8 and 6.1 log10 CFU/g, respectively. Furthermore, qualitative test for Salmonella and enumeration of hygienic indicator bacteria were conducted on dried wood ear mushroom products (33 domestic and 30 imported products) retailed in Japan. No samples showed positive for Salmonella per 25 g, and the mean aerobic bacterial counts and coliforms were approximately 2 log10 CFU/g lower than those in the 10 samples where Salmonella was isolated during voluntary testing. While no Salmonella was detected in domestically retailed wood ear mushrooms products, the serovars associated with foodborne diseases were isolated from voluntary testing samples. It indicates that potential for consumption of Salmonella contaminated wood ear mushrooms, which is at risk of causing food poisoning.
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Affiliation(s)
- Kenji Ohya
- Division of Microbiology, National Institute of Health Sciences
| | - Shunsuke Ikeuchi
- Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology
| | - Hideki Hayashidani
- Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology
| | - Yukiko Hara-Kudo
- Division of Microbiology, National Institute of Health Sciences
- Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology
- School of Pharmacy and Pharmaceutical, Hoshi University
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Rapp D, Ross C, Cave V, Maclean P, Jauregui R, Brightwell G. Medium-term storage of calf beddings affects bacterial community and effectiveness to inactivate zoonotic bacteria. PLoS One 2023; 18:e0295843. [PMID: 38100478 PMCID: PMC10723701 DOI: 10.1371/journal.pone.0295843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 11/30/2023] [Indexed: 12/17/2023] Open
Abstract
Land-spreading of animal faecal wastes -such as animal beddings- can introduce zoonotic enteropathogens into the food system environment. The study evaluated the effectiveness of animal beddings naturally contaminated by calf manure to reduce E. coli O157:H7 or Salmonella enterica. The two pathogens were introduced separately as a four strains-cocktail and at high (>6.5 Log10 g-1) concentration into bedding materials, and their inactivation over a 10 weeks-period was monitored by using a Most Probable Number (MPN) enumeration method. Inactivation of E. coli O157:H7 was more effective in the bedding inoculated immediately after collection from calf pens than in the beddings inoculated after a 2 months-pre-storage period: E. coli O157:H7 levels were reduced by 6.6 Log10 g-1 in unstored bedding (0.5 Log10 g-1 recovered; 95%CI: 0.0-1.2), and by 4.9 Log10 g-1 in pre-stored bedding (2.2 Log10 g-1 recovered; 95%CI: 1.5-2.8) with a significant (p<0.05) difference between unstored and pre-stored. S. enterica was inactivated less effectively as counts were reduced by one order of magnitude, with no significant difference in inactivation between unstored and pre-stored beddings. Low levels of naturally occurring E. coli O157 and Salmonella spp. were detected in the non-inoculated beddings, as well as in the straw prior to use in the animal facility. To better understand the possible biological processes involved, the bacterial community present in the beddings was characterised by short-read 16S rRNA sequencing. Pre-storage of the bedding affected the composition but not the diversity of the bacterial community. Analyses of the key bacterial phyla suggested that the presence of a diverse and stable bacterial community might facilitate inactivation of the introduced pathogens, and a possible role of bacterial orders associated with lignocellulolytic resources. Overall, the study contributed to the understanding of the fate of zoonotic bacteria introduced in animal beddings during storage and identified bedding storage practices pre-and post-use in animal facilities that could be important to prevent the risk of zoonosis dissemination to the environment or to the dairy herds.
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Affiliation(s)
- Delphine Rapp
- Food System Integrity, AgResearch Ltd, Hopkirk Research Institute, Palmerston North, New Zealand
| | - Colleen Ross
- Food System Integrity, AgResearch Ltd, Hopkirk Research Institute, Palmerston North, New Zealand
| | - Vanessa Cave
- Data Science Team, AgResearch Ltd, Ruakura Research Centre, Hamilton, New Zealand
| | - Paul Maclean
- Data Science Team, AgResearch Ltd, Grasslands Research Centre, Palmerston North, New Zealand
| | - Ruy Jauregui
- Data Science Team, AgResearch Ltd, Grasslands Research Centre, Palmerston North, New Zealand
| | - Gale Brightwell
- Food System Integrity, AgResearch Ltd, Hopkirk Research Institute, Palmerston North, New Zealand
- New Zealand Food Safety Science & Research Centre, Hopkirk Research Institute, Palmerston North, New Zealand
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Chauhan R, Tall BD, Gopinath G, Azmi W, Goel G. Environmental risk factors associated with the survival, persistence, and thermal tolerance of Cronobacter sakazakii during the manufacture of powdered infant formula. Crit Rev Food Sci Nutr 2023; 63:12224-12239. [PMID: 35838158 DOI: 10.1080/10408398.2022.2099809] [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] [Indexed: 11/03/2022]
Abstract
Cronobacter sakazakii is an opportunistic foodborne pathogen of concern for foods having low water activity such as powdered infant formula (PIF). Its survival under desiccated stress can be attributed to its ability to adapt effectively to many different environmental stresses. Due to the high risk to neonates and its sporadic outbreaks in PIF, C. sakazakii received great attention among the scientific community, food industry and health care providers. There are many extrinsic and intrinsic factors that affect C. sakazakii survival in low-moisture foods. Moreover, short- or long-term pre-exposure to sub-lethal physiological stresses which are commonly encountered in food processing environments are reported to affect the thermal resistance of C. sakazakii. Additionally, acclimation to these stresses may render C. sakazakii resistance to antibiotics and other antimicrobial agents. This article reviews the factors and the strategies responsible for the survival and persistence of C. sakazakii in PIF. Particularly, studies focused on the influence of various factors on thermal resistance, antibiotic or antimicrobial resistance, virulence potential and stress-associated gene expression are reviewed.
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Affiliation(s)
- Rajni Chauhan
- Department of Biotechnology, Himachal Pradesh University, Shimla, India
| | | | - Gopal Gopinath
- Center for Food Safety and Applied Nutrition, U. S. Food and Drug Administration, Laurel, MD, USA
| | - Wamik Azmi
- Department of Biotechnology, Himachal Pradesh University, Shimla, India
| | - Gunjan Goel
- Department of Microbiology, School of Interdisciplinary and Applied Sciences, Central University of Haryana, Mahindra, India
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Fay ML, Salazar JK, Chavda NJ, Patil GR, Ingram DT. Survival kinetics of Listeria monocytogenes and Salmonella enterica on dehydrated enoki and wood ear mushrooms during long-term storage. Food Microbiol 2023; 114:104304. [PMID: 37290867 DOI: 10.1016/j.fm.2023.104304] [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: 04/20/2023] [Revised: 05/08/2023] [Accepted: 05/09/2023] [Indexed: 06/10/2023]
Abstract
Two specialty mushrooms have recently become novel vectors for foodborne outbreaks in the U.S.: fresh enoki and dried wood ear mushrooms were linked to a listeriosis and salmonellosis outbreak, respectively. The aim of this study was to evaluate the survival kinetics of Listeria monocytogenes and Salmonella enterica on dehydrated enoki and wood ear mushrooms during long-term storage. Following heat dehydration, mushrooms were inoculated with either L. monocytogenes or S. enterica, allowed to dry for 1 h, and then stored for up to 180 d at 25 °C and 33% relative humidity. Both pathogens were enumerated from the mushrooms at intervals during the storage period. Survival kinetics of both pathogens were modeled using both the Weibull and log-linear with tail models. After inoculation and 1 h drying, both pathogen populations decreased 2.26-2.49 log CFU/g on wood ear mushrooms; no decrease was observed on enoki. Both pathogens survived during storage on both mushroom types. On wood ear mushrooms, a 2-log decrease of both pathogens occurred during storage. On enoki mushrooms, 4-log decreases of both pathogens were modeled to occur after 127.50-156.60 d. The results of this study suggest that L. monocytogenes and S. enterica can persist on dehydrated specialty mushrooms during long-term storage.
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Affiliation(s)
- Megan L Fay
- Division of Food Processing Science and Technology, U. S. Food and Drug Administration, Bedford Park, IL, USA
| | - Joelle K Salazar
- Division of Food Processing Science and Technology, U. S. Food and Drug Administration, Bedford Park, IL, USA.
| | - Nirali J Chavda
- Illinois Institute of Technology, Department of Food Science and Nutrition, Bedford Park, IL, USA
| | - Gayatri R Patil
- Illinois Institute of Technology, Department of Food Science and Nutrition, Bedford Park, IL, USA
| | - David T Ingram
- Division of Produce Safety, U. S. Food and Drug Administration, College Park, MD, USA
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10
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Fay ML, Salazar JK, Ren Y, Wu Z, Mate M, Khouja BA, Lingareddygari P, Liggans G. Growth Kinetics of Listeria monocytogenes and Salmonella enterica on Dehydrated Vegetables during Rehydration and Subsequent Storage. Foods 2023; 12:2561. [PMID: 37444299 DOI: 10.3390/foods12132561] [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: 05/22/2023] [Revised: 06/20/2023] [Accepted: 06/25/2023] [Indexed: 07/15/2023] Open
Abstract
Dehydrated vegetables have low water activities and do not support the proliferation of pathogenic bacteria. Once rehydrated, vegetables can be incorporated into other foods or held for later use. The aim of this study was to examine the survival and proliferation of Listeria monocytogenes and Salmonella enterica on dehydrated vegetables during rehydration and subsequent storage. Carrots, corn, onion, bell peppers, and potatoes were heat dehydrated, inoculated at 4 log CFU/g, and rehydrated at either 5 or 25 °C for 24 h. Following rehydration, vegetables were stored at 5, 10, or 25 °C for 7 d. Both L. monocytogenes and S. enterica survived on all vegetables under all conditions examined. After 24 h of rehydration at 5 °C, pathogen populations on the vegetables were generally <1.70 log CFU/g, whereas rehydration at 25 °C resulted in populations of 2.28 to 6.25 log CFU/g. The highest growth rates during storage were observed by L. monocytogenes on potatoes and S. enterica on carrots (2.37 ± 0.61 and 1.63 ± 0.18 log CFU/g/d, respectively) at 25 °C when rehydration occurred at 5 °C. Results indicate that pathogen proliferation on the vegetables is both rehydration temperature and matrix dependent and highlight the importance of holding rehydrated vegetables at refrigeration temperatures to hinder pathogen proliferation. Results from this study inform time and temperature controls for the safety of these food products.
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Affiliation(s)
- Megan L Fay
- Division of Food Processing Science and Technology, U. S. Food and Drug Administration, Bedford Park, IL 60501, USA
| | - Joelle K Salazar
- Division of Food Processing Science and Technology, U. S. Food and Drug Administration, Bedford Park, IL 60501, USA
| | - Yuying Ren
- Department of Food Science and Nutrition, Illinois Institute of Technology, Bedford Park, IL 60501, USA
| | - Zihui Wu
- Department of Food Science and Nutrition, Illinois Institute of Technology, Bedford Park, IL 60501, USA
| | - Madhuri Mate
- Department of Food Science and Nutrition, Illinois Institute of Technology, Bedford Park, IL 60501, USA
| | - Bashayer A Khouja
- Division of Food Processing Science and Technology, U. S. Food and Drug Administration, Bedford Park, IL 60501, USA
| | - Pravalika Lingareddygari
- Division of Food Processing Science and Technology, U. S. Food and Drug Administration, Bedford Park, IL 60501, USA
| | - Girvin Liggans
- Office of Food Safety, U. S. Food and Drug Administration, College Park, MD 20740, USA
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Fay ML, Salazar JK, Zhang X, Zhou X, Stewart D. Long-Term Survival of Listeria monocytogenes in Nut, Seed, and Legume Butters. J Food Prot 2023; 86:100094. [PMID: 37086973 DOI: 10.1016/j.jfp.2023.100094] [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: 03/03/2023] [Revised: 04/12/2023] [Accepted: 04/17/2023] [Indexed: 04/24/2023]
Abstract
Nut, seed, and legume butters have become increasingly popular with consumers. Listeria monocytogenes contamination of a variety of butters has resulted in several recalls, although no known outbreaks have been identified. L. monocytogenes has been shown to survive on a variety of seeds for up to 6 months, legumes and nuts for over 12 months, and in peanut butter and peanut-chocolate spreads for 21 to 60 weeks depending on formulation; however, long-term survival in other butters has not yet been characterized. In this study, the survival of L. monocytogenes in various nut, seed, legume, and chocolate-containing butters (n=10) based on inoculation level, storage temperature, and the pH, aw, and nutrient contents of the butters, was examined. First, butters were inoculated with L. monocytogenes at 4 log CFU/g and stored at either 5 or 25°C with enumeration and/or enrichment at intervals over 12 months. L. monocytogenes survived in all butters examined with no significant change in population after storage at 5°C, whereas the population was reduced to <1.70 log CFU/g in as little as 3 months at 25°C; the only exception was for sunflower butter, where L. monocytogenes decreased approximately 1 log CFU/g. Subsequently, all butters were inoculated at 1 log CFU/g and stored at 25°C for 6 months with enrichment during storage. L. monocytogenes was detected in all butters, except pecan butter, after 6-month storage. Butters containing chocolate did not inhibit L. monocytogenes survival, regardless of the inoculation level. Results indicate there may be association between high fat and carbohydrate level and survivability of L. monocytogenes in various types of butters. This work highlights the need to mitigate the potential for cross-contamination of L. monocytogenes into nut, seed, and legume butters due to the potential for long-term survival. Running title: Listeria survival in butters.
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Affiliation(s)
- Megan L Fay
- Division of Food Processing Science and Technology, U. S. Food and Drug Administration, Bedford Park, IL, USA
| | - Joelle K Salazar
- Division of Food Processing Science and Technology, U. S. Food and Drug Administration, Bedford Park, IL, USA.
| | - Xinyuan Zhang
- Illinois Institute of Technology, Institute for Food Safety and Health, Bedford Park, IL, USA
| | - Xinyi Zhou
- Illinois Institute of Technology, Institute for Food Safety and Health, Bedford Park, IL, USA
| | - Diana Stewart
- Division of Food Processing Science and Technology, U. S. Food and Drug Administration, Bedford Park, IL, USA
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12
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Banerjee T, Panchal N, Sutton C, Elliott R, Patel T, Kajal K, Arogunyo E, Koti N, Santra S. Tunable Magneto-Plasmonic Nanosensor for Sensitive Detection of Foodborne Pathogens. BIOSENSORS 2023; 13:109. [PMID: 36671944 PMCID: PMC9856065 DOI: 10.3390/bios13010109] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 01/02/2023] [Accepted: 01/04/2023] [Indexed: 06/17/2023]
Abstract
Frequent outbreaks of food-borne pathogens, particularly E. coli O157:H7, continue to impact human health and the agricultural economy tremendously. The required cell count for this pathogenic strain of E. coli O157:H7 is relatively low and hence it is vital to detect at low colony forming unit (CFU) counts. Available detection methods, though sensitive, fall short in terms of timeliness and often require extensive sample processing. To overcome these limitations, we propose a novel magneto-plasmonic nanosensor (MPnS) by integrating surface plasmon resonance (SPR) properties with spin-spin magnetic relaxation (T2 MR) technology. We engineered MPnS by encapsulating several gold nanoparticles (GNPs) within the polymer-coating of iron oxide nanoparticles (IONPs). First, the polyacrylic acid (PAA)-coated IONPs were synthesized using a solvent precipitation method, then gold chloride solution was used to synthesize GNPs and encapsulate them within the PAA-coatings of IONPs in one step. A magnetic separation technique was used to purify the MPnS and the presence of GNPs within IONPs was characterized using transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDS), and other spectroscopic methods. The synthesized MPnS exhibits MR relaxation properties while possessing amplified optical properties than conventional GNPs. This allows for rapid and ultrasensitive detection of E. coli O157:H7 by SPR, T2 MR, and colorimetric readout. Experiments conducted in simple buffer and in milk as a complex media demonstrated that our MPnS-based assay could detect as low as 10 CFUs of this pathogenic strain of E. coli O157:H7 in minutes with no cross-reactivity. Overall, the formulated MPnS is robust and holds great potential for the ultrasensitive detection of E. coli O157:H7 in a simple and timely fashion. Moreover, this platform is highly customizable and can be used for the detection of other foodborne pathogens.
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Affiliation(s)
- Tuhina Banerjee
- Department of Chemistry and Biochemistry, College of Natural and Applied Sciences, Missouri State University, 901 S. National Avenue, Springfield, MO 65897, USA
| | - Nilamben Panchal
- Department of Chemistry, College and Arts and Sciences, Pittsburg State University, 1701 S. Broadway Street, Pittsburg, KS 66762, USA
| | - Carissa Sutton
- Department of Chemistry and Biochemistry, College of Natural and Applied Sciences, Missouri State University, 901 S. National Avenue, Springfield, MO 65897, USA
| | - Rebekah Elliott
- Department of Chemistry, College and Arts and Sciences, Pittsburg State University, 1701 S. Broadway Street, Pittsburg, KS 66762, USA
| | - Truptiben Patel
- Department of Chemistry, College and Arts and Sciences, Pittsburg State University, 1701 S. Broadway Street, Pittsburg, KS 66762, USA
| | - Kajal Kajal
- Department of Chemistry, College and Arts and Sciences, Pittsburg State University, 1701 S. Broadway Street, Pittsburg, KS 66762, USA
| | - Eniola Arogunyo
- Department of Chemistry, College and Arts and Sciences, Pittsburg State University, 1701 S. Broadway Street, Pittsburg, KS 66762, USA
| | - Neelima Koti
- Department of Chemistry, College and Arts and Sciences, Pittsburg State University, 1701 S. Broadway Street, Pittsburg, KS 66762, USA
| | - Santimukul Santra
- Department of Chemistry, College and Arts and Sciences, Pittsburg State University, 1701 S. Broadway Street, Pittsburg, KS 66762, USA
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13
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Practice and Progress: Updates on Outbreaks, Advances in Research, and Processing Technologies for Low-moisture Food Safety. J Food Prot 2023; 86:100018. [PMID: 36916598 DOI: 10.1016/j.jfp.2022.11.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 11/03/2022] [Accepted: 11/20/2022] [Indexed: 12/31/2022]
Abstract
Large, renowned outbreaks associated with low-moisture foods (LMFs) bring to light some of the potential, inherent risks that accompany foods with long shelf lives if pathogen contamination occurs. Subsequently, in 2013, Beuchat et al. (2013) noted the increased concern regarding these foods, specifically noting examples of persistence and resistance of pathogens in low-water activity foods (LWAFs), prevalence of pathogens in LWAF processing environments, and sources of and preventive measures for contamination of LWAFs. For the last decade, the body of knowledge related to LMF safety has exponentially expanded. This growing field and interest in LMF safety have led researchers to delve into survival and persistence studies, revealing that some foodborne pathogens can survive in LWAFs for months to years. Research has also uncovered many complications of working with foodborne pathogens in desiccated states, such as inoculation methods and molecular mechanisms that can impact pathogen survival and persistence. Moreover, outbreaks, recalls, and developments in LMF safety research have created a cascading feedback loop of pushing the field forward, which has also led to increased attention on how industry can improve LMF safety and raise safety standards. Scientists across academia, government agencies, and industry have partnered to develop and evaluate innovate thermal and nonthermal technologies to use on LMFs, which are described in the presented review. The objective of this review was to describe aspects of the extensive progress made by researchers and industry members in LMF safety, including lessons-learned about outbreaks and recalls, expansion of knowledge base about pathogens that contaminate LMFs, and mitigation strategies currently employed or in development to reduce food safety risks associated with LMFs.
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14
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da Silva MR, Alves de Almeida F, Coelho AÍM, da Silva FL, Vanetti MCD. Enhancing cell resistance for production of mixed microbiological reference materials with Salmonella and coliforms by freeze-drying. Braz J Microbiol 2022; 53:2107-2119. [PMID: 35962856 PMCID: PMC9679061 DOI: 10.1007/s42770-022-00808-z] [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: 02/08/2022] [Accepted: 07/29/2022] [Indexed: 01/13/2023] Open
Abstract
The reference material (RM) is a technical requirement for the quality assurance of analytical results and proficiency tests or interlaboratory comparisons. Microbiological RMs are most available in the dehydrated form, mainly by freeze-drying, and maintaining bacterial survival after preparation is a challenge. Thus, obtaining the most resistant cells is essential. Considering that bacteria present cross-response to dehydration after being submitted to an array of stress conditions, this study aimed to evaluate the influence of growth conditions on enterobacteria for the production of mixed microbiological RMs by freeze-drying in skim milk powder. Salmonella enterica serovar Enteritidis, Cronobacter sakazakii, Escherichia coli, and Citrobacter freundii were grown in a minimal medium with 0.5 M NaCl and 0 to 5.0 mM of manganese sulfate (MnSO4) until stationary phase. Salmonella Enteritidis presented an increased resistance to dehydration in the presence of Mn, while C. sakazakii was the most resistant to freeze-drying and further storage for 90 days. Mixed microbiological RMs were produced by freeze-drying and containing Salmonella Enteritidis and coliforms in skim milk powder with 100 mM of trehalose and the Salmonella survival rate was 91.2 to 93.6%. The mixed RM was stable after 30 days at -20 °C, and Salmonella and coliforms were detected by different methods being, the Rambach Agar the best for the bacterial differentiation. The results showed that the culture conditions applied in this study resulted in bacterial cells being more resistant to dehydration, freeze-drying, and stabilization for the production of mixed microbiological RMs more stable and homogeneous.
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Affiliation(s)
- Maria Roméria da Silva
- Department of Microbiology, Universidade Federal de Viçosa, Viçosa, MG, 36570-900, Brazil
- Department of Biochemistry and Molecular Biology, Universidade Federal de Viçosa, Viçosa, MG, 36570-900, Brazil
| | - Felipe Alves de Almeida
- Department of Nutrition, Universidade Federal de Juiz de Fora, Governador Valadares, MG, 35032-620, Brazil
| | | | - Fernanda Lopes da Silva
- Department of Food Technology, Universidade Federal de Viçosa, Viçosa, MG, 36570-900, Brazil
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15
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Balamurugan S, Zaidi M, Arvaj L, Pendyala B, Gabriel M, Farber JM, Sasges M, Patras A. Modeling the UV-C Inactivation Kinetics and Determination of Fluence Required for Incremental Inactivation of Cronobacter spp. J Food Prot 2022; 85:1625-1634. [PMID: 36075045 DOI: 10.4315/jfp-22-165] [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: 06/08/2022] [Accepted: 09/02/2022] [Indexed: 11/11/2022]
Abstract
ABSTRACT A study was undertaken to model the UV-C inactivation kinetics and determine the fluences required for the incremental inactivation of several strains of Cronobacter spp. suspended in clear phosphate-buffered saline (PBS). In total, 13 strains of Cronobacter spp. were individually suspended in PBS and treated with UV-C doses of 0, 2, 4, 6, 8, and 10 mJ cm-2 with a collimated beam device emitting UV-C at 253.7 nm. The log reduction from each treatment was identified using the plate count method and plotted against the UV-C dose and then curve fitted using several mathematical models. The UV-C dose required for incremental inactivation of each isolate was determined using both linear and nonlinear regression. For the 13 strains tested, a UV-C dose of 10 mJ cm-2 inactivated between 3.66 ± 0.101 and 5.04 ± 0.465 log CFU mL-1. The survival behavior of all strains was best fitted to the Weibull+tail model, with correlation coefficients between 97.17 and 99.71%, and was used to determine the fluences required for incremental inactivation. The UV-C fluences needed to inactivate 1 log (D10-value) of Cronobacter spp. in buffer were between 3.53 and 5.50 mJ cm-2, whereas a fluence greater than 6.57 mJ cm-2 was required to achieve a 4-log inactivation. A clear understanding of the UV-C dose-response of several strains of Cronobacter spp. lays the foundation to design effective UV-based disinfection systems. HIGHLIGHTS
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Affiliation(s)
- Sampathkumar Balamurugan
- Guelph Research and Development Centre, Agriculture and Agri-Food Canada, Guelph, Ontario, Canada N1G 5C9
| | - Mubashira Zaidi
- Guelph Research and Development Centre, Agriculture and Agri-Food Canada, Guelph, Ontario, Canada N1G 5C9.,Department of Food Science, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Laura Arvaj
- Guelph Research and Development Centre, Agriculture and Agri-Food Canada, Guelph, Ontario, Canada N1G 5C9
| | - Brahmaiah Pendyala
- Department of Agricultural and Environmental Sciences, Tennessee State University, Nashville, Tennessee 37209, USA
| | | | - Jeffrey M Farber
- Department of Food Science, University of Guelph, Guelph, Ontario, Canada N1G 2W1.,JM Farber Global Food Safety, Department of Food Science, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | | | - Ankit Patras
- Department of Agricultural and Environmental Sciences, Tennessee State University, Nashville, Tennessee 37209, USA
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16
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Li H, Zhao Y, Zhang J, Li W, You Q, Zeng X, Xu H. Silver nanoparticles reduce the tolerance of Cronobacter sakazakii to environmental stress by inhibiting expression of related genes. J Dairy Sci 2022; 105:6469-6482. [PMID: 35840406 DOI: 10.3168/jds.2022-21833] [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: 01/17/2022] [Accepted: 04/25/2022] [Indexed: 11/19/2022]
Abstract
Cronobacter sakazakii is a food-borne pathogen that is resistant to a variety of environmental stress conditions. It can survive in harsh environments. We studied the effects of silver nanoparticles (AgNP) on the environmental tolerance and biofilm formation of C. sakazakii. First, we determined the minimum inhibitory concentration (MIC) of AgNP to C. sakazakii and determined the growth curve of C. sakazakii treated with different concentrations of AgNP by using the plate counting method. After determining the sub-inhibition concentrations (SIC) of AgNP on C. sakazakii, we studied the effects of AgNP on the resistance of C. sakazakii to heat, desiccation, osmotic pressure, and acid. The antibiofilm activity of AgNP was also studied. Finally, real-time quantitative PCR was used to analyze the transcription levels of 16 genes related to the environmental tolerance of C. sakazakii. The SIC of AgNP significantly reduced the survival rate of C. sakazakii under various environmental stress conditions. The results showed that AgNP at 0.625 and 1.25 μg/mL significantly inhibited the formation of C. sakazakii biofilms. The expression levels of most genes were significantly downregulated in C. sakazakii cells treated with 0.625 and 1.25 μg/mL AgNP. Therefore, AgNP may reduce the environmental tolerance of C. sakazakii by inhibiting the expression of genes related to stress tolerance. Moreover, AgNP inhibited the production of ATP in C. sakazakii cells and the formation of C. sakazakii biofilms. Our research provides a theoretical basis for the application of AgNP in food packaging, bactericidal coatings, and other fields.
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Affiliation(s)
- Hui Li
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047, China
| | - Yi Zhao
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047, China
| | - Jingjing Zhang
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047, China
| | - Wen Li
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047, China
| | - Qixiu You
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047, China
| | - Xianxiang Zeng
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047, China
| | - Hengyi Xu
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047, China.
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17
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Aguilar-Vázquez JC, Godínez-Oviedo A, Lucero-Mejía JE, D'Souza DH, Palacios-Marmolejo A, Hernández-Iturriaga M. Microbiological Profile, Prevalence, and Characterization of Salmonella enterica in Peanuts, Pecans, Raisins, Sun-Dried Tomatoes, and Chocolate Sprinkles Sold in Bulk in Markets in Querétaro, Mexico. J Food Prot 2022; 85:1265-1272. [PMID: 35687746 DOI: 10.4315/jfp-21-432] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 06/06/2022] [Indexed: 11/11/2022]
Abstract
ABSTRACT In Mexico, the prevalence of Salmonella enterica in low-water-activity foods and its link to outbreaks are unknown. The aim of this study was to determine the microbiological profile and the prevalence of S. enterica in several low-water-activity foods, including peanuts, pecans, raisins, sun-dried tomatoes, and chocolate sprinkles, purchased in retail establishments in Querétaro, Mexico. Seventy samples of each food item sold in bulk were purchased. Aerobic plate count, molds, yeasts, total coliforms, Escherichia coli, and Staphylococcus aureus were quantified in 10-g samples. The prevalence of S. enterica in 25-g samples was determined. From positive samples, S. enterica isolates (60) were characterized based on their antimicrobial susceptibility to 14 antibiotics, the presence-absence of 13 virulence genes, and serotype. The concentration of aerobic plate count, molds, yeasts, total coliforms, and E. coli ranged from 3.1 to 5.2 log CFU g-1, from 2.0 to 2.4 log CFU g-1, from 2.0 to 3.0 log CFU g-1, from 0.6 to 1.1 log most probable number (MPN) g-1, and from 0.5 to 0.9 log MPN g-1, respectively. S. aureus was not detected in any sample (<10 CFU g-1). The prevalence of S. enterica in chocolate sprinkles, raisins, peanuts, pecans, and sun-dried tomatoes was 26, 29, 31, 40, and 52%, respectively. Most isolates (68.3%) were resistant to at least one antibiotic. Chromosome-associated virulence genes were found in all isolates, and only one strain had sopE, and 98.3% of the isolates were grouped in the same virulotype. Among the isolates, the most frequent serotype was Tennessee (51 of 60). According to the characteristics evaluated, we grouped the isolates into 24 clusters. The elevated prevalence of S. enterica highlights the role of low-water-activity food items sold in bulk at markets as potential vehicles for pathogen transmission. Regardless of the low variability among S. enterica isolates, their characterization could be helpful to elucidate which strains are circulating in these foods for improving epidemiological surveillance. HIGHLIGHTS
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Affiliation(s)
- J C Aguilar-Vázquez
- Departamento de Investigación y Posgrado en Alimentos, Facultad de Química, Universidad Autónoma de Querétaro, Cerro de las Campanas s/n, Col. Las Campanas, Querétaro, Querétaro, México, C.P. 76010
| | - A Godínez-Oviedo
- Departamento de Investigación y Posgrado en Alimentos, Facultad de Química, Universidad Autónoma de Querétaro, Cerro de las Campanas s/n, Col. Las Campanas, Querétaro, Querétaro, México, C.P. 76010.,Food Safety and Innovation Centre, Tasmanian Institute of Agriculture, University of Tasmania, Hobart, Australia 7005
| | - J E Lucero-Mejía
- Departamento de Investigación y Posgrado en Alimentos, Facultad de Química, Universidad Autónoma de Querétaro, Cerro de las Campanas s/n, Col. Las Campanas, Querétaro, Querétaro, México, C.P. 76010
| | - D H D'Souza
- Department of Food Science, University of Tennessee Institute of Agriculture, 2510 River Drive, Knoxville, Tennessee 37996, USA
| | - A Palacios-Marmolejo
- Laboratorio Estatal de Salud Pública de Aguascalientes, Av. Siglo XXI, Frac. Cd. Satélite Morelos, Aguascalientes, Aguascalientes, México, C.P. 20270
| | - M Hernández-Iturriaga
- Departamento de Investigación y Posgrado en Alimentos, Facultad de Química, Universidad Autónoma de Querétaro, Cerro de las Campanas s/n, Col. Las Campanas, Querétaro, Querétaro, México, C.P. 76010
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18
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Xie Y, Zhang S, Sun S, Zhu MJ, Sablani S, Tang J. Survivability of Salmonella and Enterococcus faecium in chili, cinnamon and black pepper powders during storage and isothermal treatments. Food Control 2022. [DOI: 10.1016/j.foodcont.2022.108935] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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19
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Recent development in low-moisture foods: Microbial safety and thermal process. Food Res Int 2022; 155:111072. [DOI: 10.1016/j.foodres.2022.111072] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 02/22/2022] [Accepted: 02/24/2022] [Indexed: 11/17/2022]
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20
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Salazar JK, Tesfaldet B, Zamperlini M, Streufert R, Fay M, Keller SE. Desiccation Survival of Salmonella enterica,Escherichia coli, and Enterococcus faecium Related to Initial Cell Level and Cellular Components. J Food Prot 2022; 85:398-405. [PMID: 34855937 DOI: 10.4315/jfp-21-320] [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: 08/19/2021] [Accepted: 12/01/2021] [Indexed: 11/11/2022]
Abstract
ABSTRACT Salmonella enterica is well known for its ability to survive and persist in low-moisture environments. Previous studies have indicated a link between the initial cell level and the population of Salmonella that survives after desiccation and subsequent storage; however, how the initial cell concentration affects survival is unknown. This study was conducted to examine this phenomenon and to determine whether it occurs in other microorganisms, specifically Shiga toxigenic Escherichia coli (STEC) and Enterococcus faecium. Salmonella, STEC, and E. faecium were grown as sessile cells on Trypticase soy agar with yeast extract (TSAYE) and harvested in buffered peptone water (BPW). To determine recovery at different initial cell levels, cultures were diluted to 9, 7, and 5 log CFU/mL and applied to filters. Filters were dried for 24 h and then stored for 28 days at 25°C and 33% relative humidity. During storage, cells were recovered from filters with BPW and cultivated on TSAYE. Recovery of both Salmonella and E. coli, but not E. faecium, was nonproportional. Lower initial populations were less viable after 24 h of desiccation; ≥10 log CFU/mL was recovered when 11 log CFU/mL was desiccated, but <3 log CFU/mL was recovered when 5 log CFU/mL was desiccated. Once dried, persistence did not appear affected by initial cell concentration. When inactivated (heat-treated) cells were added to the diluent, recovery of Salmonella was proportional with respect to the initial cell level. To further examine the response to desiccation, Salmonella was diluted in BPW containing 1 of 11 test cell components related to quorum sensing or known to affect desiccation resistance to assess recovery and persistence. Of the 11 additions, only cell debris fractions, cell-free extract, and peptidoglycan improved recovery of Salmonella. Desiccation survival appears related to cell wall components; however, the exact mechanism affecting survival remains unknown. HIGHLIGHTS
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Affiliation(s)
- Joelle K Salazar
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, 6502 South Archer Road, Bedford Park, Illinois 60501; and
| | - Bereket Tesfaldet
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, 5001 Campus Drive, College Park, Maryland 20740, USA
| | - Michelle Zamperlini
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, 5001 Campus Drive, College Park, Maryland 20740, USA
| | - Rachel Streufert
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, 6502 South Archer Road, Bedford Park, Illinois 60501; and
| | - Megan Fay
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, 6502 South Archer Road, Bedford Park, Illinois 60501; and
| | - Susanne E Keller
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, 6502 South Archer Road, Bedford Park, Illinois 60501; and
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21
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Why Does Cronobacter sakazakii Survive for a Long Time in Dry Environments? Contribution of the Glass Transition of Dried Bacterial Cells. Microbiol Spectr 2021; 9:e0138421. [PMID: 34908438 PMCID: PMC8672889 DOI: 10.1128/spectrum.01384-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To investigate the mechanism of adaptation of Cronobacter sakazakii to desiccation stress, the present study focused on the glass transition phenomenon of dried bacterial cells, using a thermomechanical technique. The mechanical glass transition temperature (Tg) of dried C. sakazakii cells per se, prepared by different drying methods (air drying and freeze-drying) and with different water activity (aw) levels (0.43, 0.57, 0.75, and 0.87), were determined. In addition, we investigated the survival of two strains of C. sakazakii (JCM 1233 and JCM 2127) prepared by different drying methods under different storage temperatures (4, 25, and 42°C) and aw conditions (0.43 and 0.87). While the Tg of the air-dried C. sakazakii cells increased as the aw decreased, the freeze-dried C. sakazakii cells showed an unclear aw dependency of the Tg. Air-dried C. sakazakii cells showed a higher Tg than freeze-dried C. sakazakii cells at an aw of <0.57. Freeze-dried C. sakazakii cells were more rapidly inactivated than air-dried cells regardless of the difference in aw and temperature. The difference between the Tg and storage temperature was used as an index that took into consideration the differences in the drying methods and aw levels. As the difference between the Tg and storage temperature increased to >20°C, the dried C. sakazakii cells survived stably regardless of the drying method. In contrast, when the difference between the Tg and storage temperature was reduced to <10°C, the viable cell numbers in dried C. sakazakii cells were quickly decreased. Thus, the Tg is a key factor affecting the desiccation tolerance of C. sakazakii. IMPORTANCE The mechanical glass transition temperature (Tg) of dried Cronobacter sakazakii cells varied depending on differences in drying methods and water activity (aw) levels. Because the Tg of the dried bacterial cells varied depending on the drying method and aw, the Tg will play an important role as an operational factor in the optimization of dry food processing for controlling microbial contamination in the future. Furthermore, the differences between the Tg and storage temperature were introduced as an integrated index for survival of bacterial cells under a desiccation environment that took into consideration the differences in the drying methods and aw levels. As the difference between the Tg and storage temperature decreased to <10°C, the dried C. sakazakii cells were inactivated quickly, regardless of the drying methods. The relationship between Tg and storage temperature will contribute to understanding the desiccation tolerance of bacterial cells.
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22
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Liu S, Wei X, Tang J, Qin W, Wu Q. Recent developments in low-moisture foods: microbial validation studies of thermal pasteurization processes. Crit Rev Food Sci Nutr 2021:1-16. [PMID: 34927484 DOI: 10.1080/10408398.2021.2016601] [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] [Indexed: 10/19/2022]
Abstract
Outbreaks associated with low-moisture foods (e.g., wheat flour, nuts, and cereals) have urged the development of novel technologies and re-validation of legacy pasteurization process. For various thermal pasteurization processes, they share same scientific facts (e.g., bacterial heat resistance increased at reduced water activity) and guidelines. However, they also face specific challenges because of their different heat transfer mechanisms, processing conditions, or associated low-moisture foods' formulations. In this article, we first introduced the general structural for validating a thermal process and the shared basic information that would support our understanding of the key elements of each thermal process. Then, we reviewed the current progress of validation studies of 7 individual heating technologies (drying roasting, radiofrequency-assisted pasteurization, superheated steam, etc.) and the combined treatments (e.g., infrared and hot air). Last, we discussed knowledge gaps that require more scientific data in the future studies. We aimed to provide a process-centric view point of thermal pasteurization studies of low-moisture foods. The information could provide detailed protocol for process developers, operators, and managers to enhance low-moisture foods safety.
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Affiliation(s)
- Shuxiang Liu
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China.,Institute of Food Processing and Safety, School of Food Science, Sichuan Agricultural University, Sichuan, China
| | - Xinyao Wei
- College of Biological Science and Engineering, Fuzhou University, Fuzhou, China
| | - Juming Tang
- Department of Biological Systems Engineering, Washington State University, Pullman, WA, USA
| | - Wen Qin
- Institute of Food Processing and Safety, School of Food Science, Sichuan Agricultural University, Sichuan, China
| | - Qingping Wu
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
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Inactivation of Salmonella spp., Escherichia coli O157:H7 and Listeria monocytogenes in Tahini by Microwave Heating. Foods 2021; 10:foods10122972. [PMID: 34945523 PMCID: PMC8700748 DOI: 10.3390/foods10122972] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 11/23/2021] [Accepted: 11/24/2021] [Indexed: 11/16/2022] Open
Abstract
Tahini (sesame paste) is a traditional food. Numerous foodborne outbreaks have been associated with it. This study aimed to (i) explore the efficiency of 2450 MHz microwave heating at 220, 330, 440, 550, and 660 W on the inactivation of Salmonella spp, Escherichia coli O157:H7, and Listeria monocytogenes in tahini; (ii) determine the impact of desiccation and starvation stresses on pathogen survival; (iii) assess the impact of microwave heating on the physicochemical characteristics of tahini. The inoculated microorganisms in tahini were reduced with higher microwave power levels (p < 0.05) and longer exposure times. The D-values of unstressed Salmonella spp., Escherichia coli O157:H7, and L. monocytogenes ranged from 6.18 to 0.50 min, 6.08 to 0.50 min, and 4.69 to 0.48 min, respectively, at power levels of 220 to 660 W, with z-values of 410, 440, and 460 W, respectively. Generally, desiccation and starvation stress levels prior to heating increased microbial resistance to heat treatment. Microwave heating did not affect acid, peroxide, p-anisidine, or color values of tahini up to 90 °C. These findings reveal microwave heating as a potential method for lowering the risk of Salmonella spp., E. coli O157:H7 and L. monocytogenes in tahini with no compromise on quality.
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Microbial contaminants in powdered infant formula: what is the impact of spray-drying on microbial inactivation? Curr Opin Food Sci 2021. [DOI: 10.1016/j.cofs.2021.06.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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Fate of Salmonella Typhimurium and Listeria monocytogenes on Whole Papaya during Storage and Antimicrobial Efficiency of Aqueous Chlorine Dioxide Generated with HCl, Malic Acid or Lactic Acid on Whole Papaya. Foods 2021; 10:foods10081871. [PMID: 34441647 PMCID: PMC8394176 DOI: 10.3390/foods10081871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 08/02/2021] [Accepted: 08/06/2021] [Indexed: 11/17/2022] Open
Abstract
Papaya-associated foodborne illness outbreaks have been frequently reported worldwide. The goal of this study was to evaluate the behavior of Salmonella Typhimurium and Listeria monocytogenes on whole papaya during storage and sanitizing process. Fresh green papayas were inoculated with approximately 7 log CFU of S. Typhimurium and L. monocytogenes and stored at 21 or 7 °C for 14 days. Bacteria counts were determined on day 0, 1, 7, 10 and 14. Fresh green papayas inoculated with approximately 8 log CFU of the bacteria were treated for 5 min with 2.5, 5 and 10 ppm aqueous chlorine dioxide (ClO2). The ClO2 solutions were generated by mixing sodium chlorite with an acid, which was HCl, lactic acid or malic acid. The detection limit of the enumeration method was 2.40 log CFU per papaya. At the end of storage period, S. Typhimurium and L. monocytogenes grew by 1.88 and 1.24 log CFU on papayas at 21 °C, respectively. Both bacteria maintained their initial population at inoculation on papayas stored at 7 °C. Higher concentrations of ClO2 reduced more bacteria on papaya. 10 ppm ClO2, regardless the acid used to generate the solutions, inactivated S. Typhimurium to undetectable level on papaya. 10 ppm ClO2 generated with HCl, lactic acid and malic acid reduced L. monocytogenes by 4.40, 6.54 and 8.04 log CFU on papaya, respectively. Overall, ClO2 generated with malic acid showed significantly higher bacterial reduction than ClO2 generated with HCl or lactic acid. These results indicate there is a risk of survival and growth for S. Typhimurium and L. monocytogenes on papaya at commercial storage conditions. Aqueous ClO2 generated with malic acid shows effectiveness in inactivating the pathogenic bacteria on papaya.
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Wang L, Forsythe SJ, Yang X, Fu S, Man C, Jiang Y. Invited review: Stress resistance of Cronobacter spp. affecting control of its growth during food production. J Dairy Sci 2021; 104:11348-11367. [PMID: 34364644 DOI: 10.3168/jds.2021-20591] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Accepted: 06/17/2021] [Indexed: 11/19/2022]
Abstract
Members of the Cronobacter genus include food-borne pathogens that can cause infections in infants, with a mortality rate as high as 40 to 80%. The high fatality rate of Cronobacter and its isolation from numerous types of food, especially from powdered infant formula, demonstrate the serious nature of this organism. The source tracking of Cronobacter spp. and the analysis of high-frequency species from different sources are helpful for a more targeted control. Furthermore, the persistence during food processing and storage may be attributed to strong resistance of Cronobacter spp. to environment stresses such as heat, pH, and desiccation. There are many factors that support the survival of Cronobacter spp. in harsh environments, such as some genes, regulatory systems, and biofilms. Advanced detection technology is helpful for the strict monitoring of Cronobacter spp. In addition to the traditional heat treatment, many new control techniques have been developed, and the ability to control Cronobacter spp. has been demonstrated. The control of this bacteria is required not only during manufacture, but also through the selection of packaging methods to reduce postprocessing contamination. At the same time, the effect of inactivation methods on product quality and safety must be considered. This review considers the advances in our understanding of environmental stress response in Cronobacter spp. with special emphasis on its implications in food processing.
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Affiliation(s)
- Lihan Wang
- Key Laboratory of Dairy Science, Ministry of Education, College of Food Science, Northeast Agricultural University, Harbin, China, 150030
| | - Stephen J Forsythe
- Foodmicrobe.com, Adams Hill, Keyworth, Nottingham, United Kingdom, NG12 5GY
| | - Xinyan Yang
- Key Laboratory of Dairy Science, Ministry of Education, College of Food Science, Northeast Agricultural University, Harbin, China, 150030
| | - Shiqian Fu
- Key Laboratory of Dairy Science, Ministry of Education, College of Food Science, Northeast Agricultural University, Harbin, China, 150030
| | - Chaoxin Man
- Key Laboratory of Dairy Science, Ministry of Education, College of Food Science, Northeast Agricultural University, Harbin, China, 150030.
| | - Yujun Jiang
- Key Laboratory of Dairy Science, Ministry of Education, College of Food Science, Northeast Agricultural University, Harbin, China, 150030.
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Desiccation and thermal resistance of Salmonella and Enterococcus faecium NRRL B-2354 in almond meal as impacted by water activity and storage temperature. Food Control 2021. [DOI: 10.1016/j.foodcont.2021.108037] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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29
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Harada AM, Nascimento MS. Efficacy of dry sanitizing methods on Listeria monocytogenes biofilms. Food Control 2021. [DOI: 10.1016/j.foodcont.2021.107897] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Ding Q, Ge C, Baker RC, Buchanan RL, Tikekar RV. Assessment of butylparaben (4-hydroxybenzoic acid butyl ester)-assisted heat treatment against Escherichia coli O157:H7 and Salmonella enterica serotype Typhimurium in meat and bone meal. J Food Sci 2021; 86:2569-2578. [PMID: 34009638 DOI: 10.1111/1750-3841.15742] [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: 10/14/2020] [Revised: 02/24/2021] [Accepted: 03/26/2021] [Indexed: 11/29/2022]
Abstract
Heat-resistant foodborne pathogens have been a concern in low-moisture foods and ingredients (LMFs). Due to low thermal conductivity of low moisture materials, thermal treatment is not efficient and may cause nutritional loss. This study investigated the enhancement of thermal treatment of meat and bone meal (MBM) at low water activity (aw ) by inclusion of butylparaben (BP) as a model antimicrobial compound. Stationary phase Escherichia coli O157:H7 (Shiga toxin-negative) or Salmonella enterica serotype Typhimurium was inoculated into MBM containing 0-2000 ppm BP and incubated at 55 or 60°C for up to 5 hr. A biphasic inactivation pattern was observed for both pathogens, indicating existence of potentially thermal resistant subpopulations. Addition of 1000 ppm BP to MBM (aw = 0.4) significantly lowered the D-value at 55°C for E. coli O157:H7 (2.6 ± 0.5 hr) compared to thermal treatment alone (5.1 ± 0.6 h) during the treatment after the first 1 hr (p < 0.05), indicating that addition of BP accelerated the inactivation of thermal-resistant subpopulation of E. coli O157:H7 in MBM. Interestingly, similar enhancement in thermal inactivation upon addition of BP was not observed in either the sensitive or resistant subpopulation of S. Typhimurium at aw of 0.4 or 0.7, which is likely caused by the higher thermal resistance developed by S. Typhimurium within a low aw environment (aw < 0.85). These results suggest that addition of certain antimicrobial compounds can improve the thermal processing efficiency in LMFs, while their efficiency against different pathogens may vary. PRACTICAL APPLICATION: Addition of appropriate food-grade compounds may help to improve thermal treatment efficiency in low moisture foods with varied efficiency against different pathogens. This approach has the potential to reduce the required heat treatment intensity while minimizing food safety risk.
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Affiliation(s)
- Qiao Ding
- Department of Nutrition and Food Science, University of Maryland, Baltimore, Maryland, USA
| | - Chongtao Ge
- Mars Global Food Safety Center, Beijing, China
| | | | - Robert L Buchanan
- Department of Nutrition and Food Science, University of Maryland, Baltimore, Maryland, USA.,Center for Food Safety and Security Systems, University of Maryland, Baltimore, Maryland, USA
| | - Rohan V Tikekar
- Department of Nutrition and Food Science, University of Maryland, Baltimore, Maryland, USA
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Zheng Z, Xie Y, Ma S, Tu J, Li J, Liang S, Xu Y, Shi C. Effect of 405-nm light-emitting diode on environmental tolerance of Cronobacter sakazakii in powdered infant formula. Food Res Int 2021; 144:110343. [PMID: 34053539 DOI: 10.1016/j.foodres.2021.110343] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 03/17/2021] [Accepted: 03/18/2021] [Indexed: 02/05/2023]
Abstract
Cronobacter sakazakii is an opportunistic pathogen that can survive extreme desiccation, heat, acid, and osmotic stress. This can increase the risk of infection, resulting in severe diseases, mainly in neonates. The inactivation effect of 405 ± 5-nm light-emitting diode (LED) illumination on C. sakazakii with different initial concentrations and C. sakazakii strains isolated from powdered infant formula (PIF) and baby rice cereal (BRC) were firstly evaluated. Then, the effect of 405 ± 5-nm LED on the tolerance of diverse environmental conditions of C. sakazakii in PIF was investigated. Conditions involving desiccation [PIF, Water activity (aw): 0.2-0.5], heat (45, 50, and 55 °C), acid (simulated gastric fluid: SGF, pH 4.75 ± 0.25), and bile salt (0.2%, bile salt solution) were used to study the effects of 405-nm LED on C. sakazakii resistance. The transcription levels of ten tolerance-associated genes and changes in bacterial cell membrane were examined to understand the response of C. sakazakii to LED illumination. The results showed that 405-nm LED effectively inactivated C. sakazakii ATCC 29544 with initial concentration from 8 to 1 log CFU/g in PIF and strains isolated from PIF and BRC. Moreover, 405-nm LED could decrease the tolerance of C. sakazakii in PIF to desiccation, heat treatment at 50 and 55 °C, SGF, and bile salt to different degrees, but the resistance to the heat treatment at 45 °C was not influenced by LED illumination. In addition, the transcription levels of the ten tolerance-associated genes measured in the LED-illuminated C. sakazakii cells were significantly downregulated compared with those in unilluminated controls. The damage on cell membrane was confirmed for LED-treated cells by LIVE/DEAD® assay. These results indicate that 405-nm LED illumination may be effective at reducing the environmental resistance of C. sakazakii in PIF. Furthermore, this study suggests the potential for applying 405-nm LED technology in the prevention and control of pathogens in food processing, production, and storage environments.
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Affiliation(s)
- Zhanwen Zheng
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Yawen Xie
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Sheng Ma
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Junhong Tu
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Jiahui Li
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Sen Liang
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology and Business University, Beijing 100048, China
| | - Yunfeng Xu
- College of Food and Bioengineering, Henan University of Science and Technology, Luoyang, Henan 471023, China
| | - Chao Shi
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China.
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Igo MJ, Schaffner DW. Models for factors influencing pathogen survival in low water activity foods from literature data are highly significant but show large unexplained variance. Food Microbiol 2021; 98:103783. [PMID: 33875211 DOI: 10.1016/j.fm.2021.103783] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Revised: 03/02/2021] [Accepted: 03/03/2021] [Indexed: 11/19/2022]
Abstract
Factors that control pathogen survival in low water activity foods are not well understood and vary greatly from food to food. A literature search was performed to locate data on the survival of foodborne pathogens in low-water activity (<0.70) foods held at temperatures <37 °C. Data were extracted from 67 publications and simple linear regression models were fit to each data set to estimate log linear rates of change. Multiple linear stepwise regression models for factors influencing survival rate were developed. Subset regression modeling gave relatively low adjusted R2 values of 0.33, 0.37, and 0.48 for Salmonella, E. coli and L. monocytogenes respectively, but all subset models were highly significant (p < 1.0e-9). Subset regression models showed that Salmonella survival was significantly (p < 0.05) influenced by temperature, serovar and strain type, water activity, inoculum preparation method, and inoculation method. E. coli survival was significantly influenced by temperature, water activity, and inoculum preparation. L. monocytogenes survival was significantly influenced by temperature, serovar and strain type, and inoculum preparation method. While many factors were highly significant (p < 0.001), the high degrees of variability show that there is still much to learn about the factors which govern pathogen survival in low water activity foods.
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Affiliation(s)
- Matthew J Igo
- Department of Food Science, Rutgers University, 65 Dudley Road, New Brunswick, NJ, 08901, USA
| | - Donald W Schaffner
- Department of Food Science, Rutgers University, 65 Dudley Road, New Brunswick, NJ, 08901, USA.
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Isothermal inactivation of Salmonella, Listeria monocytogenes, and Enterococcus faecium NRRL B-2354 in peanut butter, powder infant formula, and wheat flour. Food Control 2021. [DOI: 10.1016/j.foodcont.2020.107582] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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34
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Survivability of Salmonella Pathogens and Physicochemical Characteristics of Powder Goat Milk Stored under Different Storage Treatment Regimens. DAIRY 2020. [DOI: 10.3390/dairy1030018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Survivability of Salmonella pathogens in commercial powdered goat milk (PGM) under different storage treatments was investigated using three batches of PGM products stored at two temperatures (4 °C and 25 °C) and ten storage periods (0, 3, 7, 14, 21, 30, 60, 90, 120 and 180 days). A cocktail of three Salmonella serotypes (Salmonella agona, Salmonella enteritidis and Salmonella tennessee) was inoculated to the PGM samples and then survival of Salmonella counts was enumerated in the inoculated and non-inoculated control groups. Results showed that the initial Salmonella counts were 7.103 Log CFU (colony forming unit)/g at both temperatures. At the first 3 days, the viable Salmonella counts were reduced about 0.94 and 1.40 Log CFU/g at 4 °C and 25 °C, respectively, where the same levels were sustained for 14 days. Further reductions continued and at the end of 180 days storage, Salmonella survivability was 1.15 Log CFU/g higher at 4 °C than at 25 °C under the same water activity condition. As the storage period advanced, viable pathogen counts were gradually decreased. The pH of samples stored at 4 °C for 0 and 4 month were higher than those stored at 25 °C except for 2 months, while no differences were found in water activity (aw) between treatments of the PGM products. With regard to physicochemical characteristics, the samples stored at 25 °C showed higher POV (peroxide value) values than those stored at 4 °C for 2 and 4 month periods, indicating that the rate of lipid oxidation in the PGM was elevated by a higher storage temperature and a longer storage period. The basic nutrient compositions of the experimental PGM were similar to those reported in recent studies. Oleic acid (C18:1) was the highest, caprylic acid (C8:0) was the second highest, and behenic acid (C22:0) was the lowest concentration among all fatty acids identified in the PGM samples. Most of the fatty acid concentrations tended to decrease with advanced storage periods. This research indicates that the survivability of Salmonella pathogens in the PGM products stored at 4 °C for 180 days was higher than those stored at 25 °C under the same aw condition.
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Survivability of Salmonella and Escherichia coli O157:H7 Pathogens and Food Safety Concerns on Commercial Powder Milk Products. DAIRY 2020. [DOI: 10.3390/dairy1030014] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Milk and dairy products are susceptible to the incidence of foodborne illnesses by numerous pathogens, including Listeria monocytogenes, Salmonella spp., Escherichia coli, enteropathogenic Campylobacter jejuni, Yersinia enterocolitica, Cronobacter (Enterobacter sakazakii) and Staphylococcus aureus. Annually Salmonella infections cause approximately 93.8 million cases of gastroenteritis and 155,000 deaths worldwide. Including meat and poultry, dairy products are the most commonly contaminated foods by Salmonella. Studies show that Salmonella, Escherichia coli O157:H7 and Listeria monocytogenes are among the top 5 pathogens causing hospitalization and life-threatening foodborne illnesses. The U.S. Centers for Disease Control and Prevention (CDC) estimated that annually around 1.2 million foodborne illnesses with more than 23,000 hospitalizations, 450 deaths and 130 outbreaks were attributed to Salmonella infection in the U.S. The Salmonella enteric in skim milk powder survived at three months storage, with water activity as low as 0.33. With respect to Escherichia coli O157:H7, it is capable of causing disease at a low dosage, ranging from 5–50 cells. Viable cells of Escherichia coli O157:H7 reportedly survive in infant formula powder for one year at 5 °C. The survivability of Escherichia coli in powder milk was significantly reduced with the synergistic effects of storage time and temperature. The U.S. Dairy Export Council recommends that milk powder should be stored in a cool and dry place, at a temperature not to exceed 27 °C, and a relative humidity not to exceed 65%. Reports have recommended that milk powder products need to be stored in light, oxygen, and moisture-proof containers. In this article, the survival of the major foodborne pathogens including Salmonella and Escherichia coli O157:H7 in powdered milk products from common dairy species such as cow and goats are reviewed.
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Zhu M, Song X, Shen X, Tang J. Listeria monocytogenes in Almond Meal: Desiccation Stability and Isothermal Inactivation. Front Microbiol 2020; 11:1689. [PMID: 32849354 PMCID: PMC7427469 DOI: 10.3389/fmicb.2020.01689] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 06/29/2020] [Indexed: 01/11/2023] Open
Abstract
Almond are among the most consumed tree nuts and used in a variety of food products. Recent almond butter recalls due to potential contamination of Listeria monocytogenes highlight the need to control L. monocytogenes in almond products. The objectives of this study were to examine the stability of L. monocytogenes in almond meal during extended storage and analyze thermal resistance of L. monocytogenes in almond meal of controlled moisture contents or water activity (aw) using thermal death time (TDT) cells and thermal water activity (TWA) cells, respectively. L. monocytogenes maintained a stable population in almond meal for 44–48 weeks at 4°C regardless of aw; however, we observed about 1.69 and 2.14 log10 colony-forming units (CFU)/g reduction of L. monocytogenes in aw 0.25 and 0.45 almond meal over 44 to 48 weeks of storage at 22°C. Under all test conditions using either TDT or TWA cells, the inactivation kinetics of L. monocytogenes in almond meal fitted the log-linear model well; thermal resistance of L. monocytogenes in almond meal was inversely related to the aw of samples. D75-/D80-values of L. monocytogenes in aw 0.25 and 0.45 almond meal obtained using TDT cells were 47.6/22.0 versus 17.2/11.0 min, respectively. D80-, D85-, and D90-values of L. monocytogenes in aw 0.25 almond meal obtained using TWA cells were 59.5 ± 2.1, 27.7 ± 0.7, and 13.2 ± 1.1 min, respectively, in contrast to 22.0 ± 1.1, 10.6 ± 0.2, and 4.6 ± 0.4 min obtained using TDT cells. The z-value of L. monocytogenes in aw 0.25 almond meal was not affected by TWA and TDT cell type (15.4–15.5°C), whereas z-value of L. monocytogenes in aw 0.45 almond meal was 10°C higher than that in aw 0.25 almond meal. This study contributes to our understanding of L. monocytogenes in nuts and impacts of aw on the development of thermal resistance in low-moisture foods.
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Affiliation(s)
- Meijun Zhu
- School of Food Science, Washington State University, Pullman, WA, United States
| | - Xia Song
- School of Food Science, Washington State University, Pullman, WA, United States
| | - Xiaoye Shen
- School of Food Science, Washington State University, Pullman, WA, United States
| | - Juming Tang
- Department of Biological Systems Engineering, Washington State University, Pullman, WA, United States
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Abe H, Koyama K, Takeoka K, Doto S, Koseki S. Describing the Individual Spore Variability and the Parameter Uncertainty in Bacterial Survival Kinetics Model by Using Second-Order Monte Carlo Simulation. Front Microbiol 2020; 11:985. [PMID: 32508792 PMCID: PMC7248279 DOI: 10.3389/fmicb.2020.00985] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Accepted: 04/23/2020] [Indexed: 11/13/2022] Open
Abstract
The objective of this study was to separately describe the fitting uncertainty and the variability of individual cell in bacterial survival kinetics during isothermal and non-isothermal thermal processing. The model describing bacterial survival behavior and its uncertainties and variabilities during non-isothermal inactivation was developed from survival kinetic data for Bacillus simplex spores under fifteen isothermal conditions. The fitting uncertainties in the parameters used in the primary Weibull model was described by using the bootstrap method. The variability of individual cells in thermotolerance and the true randomness in the number of dead cells were described by using the Markov chain Monte Carlo (MCMC) method. A second-order Monte Carlo (2DMC) model was developed by combining both the uncertainties and variabilities. The 2DMC model was compared with reduction behavior under three non-isothermal profiles for model validation. The bacterial death estimations were validated using experimentally observed surviving bacterial count data. The fitting uncertainties in the primary Weibull model parameters, the individual thermotolerance heterogeneity, and the true randomness of inactivated spore counts were successfully described under all the iso-thermal conditions. Furthermore, the 2DMC model successfully described the variances in the surviving bacterial counts during thermal inactivation for all three non-isothermal profiles. As a template for risk-based process designs, the proposed 2DMC simulation approach, which considers both uncertainty and variability, can facilitate the selection of appropriate thermal processing conditions ensuring both food safety and quality.
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Affiliation(s)
- Hiroki Abe
- Graduate School of Agriculture Science, Hokkaido University, Sapporo, Japan
| | - Kento Koyama
- Graduate School of Agriculture Science, Hokkaido University, Sapporo, Japan
| | - Kohei Takeoka
- Graduate School of Agriculture Science, Hokkaido University, Sapporo, Japan
| | - Shinya Doto
- Graduate School of Agriculture Science, Hokkaido University, Sapporo, Japan
| | - Shigenobu Koseki
- Graduate School of Agriculture Science, Hokkaido University, Sapporo, Japan
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Lee K, Shoda M, Kawai K, Koseki S. Relationship between glass transition temperature, and desiccation and heat tolerance in Salmonella enterica. PLoS One 2020; 15:e0233638. [PMID: 32469949 PMCID: PMC7259547 DOI: 10.1371/journal.pone.0233638] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 05/08/2020] [Indexed: 11/19/2022] Open
Abstract
Pathogenic bacteria such as Salmonella enterica exhibit high desiccation tolerance, enabling long-term survival in low water activity (aw) environments. Although there are many reports on the effects of low aw on bacterial survival, the mechanism by which bacteria acquire desiccation tolerance and resistance to heat inactivation in low-aw foods remains unclear. We focused on the glass transition phenomenon, as bacteria may acquire environmental tolerance by state change due to glass transition. In this study, we determined the glass transition temperature (Tg) in S. enterica serovars under different aw conditions using thermal rheological analysis (TRA). The softening behaviour associated with the state change of bacterial cells was confirmed by TRA, and Tg was determined from the softening behaviour. Tg increased as the aw decreased in all S. enterica serovars. For example, while the Tg of five S. enterica serovars was determined as 35.16°C to 57.46°C at 0.87 aw, the Tg of all the five serovars increased by 77.10°C to 83.30°C at 0.43 aw. Furthermore, to verify the thermal tolerance of bacterial cells, a thermal inactivation assay was conducted at 60°C for 10 min under each aw condition. A higher survival ratio was observed as aw decreased; this represented an increase in Tg for Salmonella strains. These results suggest that the glass transition phenomenon of bacterial cells would associate with environmental tolerance.
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Affiliation(s)
- Kyeongmin Lee
- Graduate School of Agricultural Science, Hokkaido University, Sapporo, Japan
| | - Masaki Shoda
- Graduate School of Agricultural Science, Hokkaido University, Sapporo, Japan
| | - Kiyoshi Kawai
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan
| | - Shigenobu Koseki
- Graduate School of Agricultural Science, Hokkaido University, Sapporo, Japan
- * E-mail:
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39
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Stability of Listeria monocytogenes in non-fat dry milk powder during isothermal treatment and storage. Food Microbiol 2020; 87:103376. [DOI: 10.1016/j.fm.2019.103376] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 09/17/2019] [Accepted: 11/12/2019] [Indexed: 02/06/2023]
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40
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Effect of thymoquinone on the resistance of Cronobacter sakazakii to environmental stresses and antibiotics. Food Control 2020. [DOI: 10.1016/j.foodcont.2019.106944] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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41
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Salazar JK, Natarajan V, Stewart D, Suehr Q, Mhetras T, Gonsalves LJ, Tortorello ML. Survival kinetics of Listeria monocytogenes on chickpeas, sesame seeds, pine nuts, and black pepper as affected by relative humidity storage conditions. PLoS One 2019; 14:e0226362. [PMID: 31826019 PMCID: PMC6905538 DOI: 10.1371/journal.pone.0226362] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 11/24/2019] [Indexed: 11/18/2022] Open
Abstract
Nuts and seeds have been increasingly associated with recalls due to contamination with Listeria monocytogenes. Storage of these food commodities occurs at various relative humidity (RH) conditions for months or years. The objective of this study was to assess L. monocytogenes survival on four commodities representing dried legumes, seeds, and spices categories: chickpeas, sesame seeds, pine nuts, and black pepper kernels. Inoculated products at 10 log CFU/g were stored for 180 days (6 months) at 25°C and different relative humidity (RH) levels: 25% (low), 45% (ambient), and 75% (high). After 180 days at 25% RH, L. monocytogenes populations decreased to 2.67-6.59 log CFU/g; the highest survival of the pathogen was observed on pine nuts and sesame seeds with decay rates of -0.014± 0.001 log CFU/g per d. Significantly greater population reductions on all products were observed during storage at 45 and 75% RH. At 45% RH, L. monocytogenes levels decreased to 1.90-6.36 log CFU/g. On chickpeas and black pepper stored at 75% RH, the pathogen population decreased to below the limit of enumeration (1 log CFU/g) yet were still detected via enrichments. The lowest survival of L. monocytogenes occurred at 75% RH on black pepper with a decay rate of -0.058±0.003 log CFU/g per d. Overall, regardless of RH level, the ability of the products to support survival of the pathogen may be expressed in the following order: pine nuts > sesame seeds > chickpeas > black pepper. The results of this study can aid in understanding how L. monocytogenes survives on dried legumes, seeds, and spices, and the data can contribute to the risk assessment of this pathogen.
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Affiliation(s)
- Joelle K. Salazar
- Division of Food Processing Science and Technology, U. S. Food and Drug Administration, Bedford Park, Illinois, United States of America
- * E-mail:
| | - Vidya Natarajan
- Division of Food Processing Science and Technology, U. S. Food and Drug Administration, Bedford Park, Illinois, United States of America
| | - Diana Stewart
- Division of Food Processing Science and Technology, U. S. Food and Drug Administration, Bedford Park, Illinois, United States of America
| | - Quincy Suehr
- Division of Food Processing Science and Technology, U. S. Food and Drug Administration, Bedford Park, Illinois, United States of America
| | - Tanvi Mhetras
- Institute for Food Safety and Health, Illinois Institute of Technology, Bedford Park, Illinois, United States of America
| | - Lauren J. Gonsalves
- Division of Food Processing Science and Technology, U. S. Food and Drug Administration, Bedford Park, Illinois, United States of America
| | - Mary Lou Tortorello
- Division of Food Processing Science and Technology, U. S. Food and Drug Administration, Bedford Park, Illinois, United States of America
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42
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Portela JB, Coimbra PT, Cappato LP, Alvarenga VO, Oliveira RB, Pereira KS, Azeredo DR, Sant’Ana AS, Nascimento JS, Cruz AG. Predictive model for inactivation of salmonella in infant formula during microwave heating processing. Food Control 2019. [DOI: 10.1016/j.foodcont.2019.05.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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43
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Guo D, Wang S, Li J, Bai F, Yang Y, Xu Y, Liang S, Xia X, Wang X, Shi C. The antimicrobial activity of coenzyme Q 0 against planktonic and biofilm forms of Cronobacter sakazakii. Food Microbiol 2019; 86:103337. [PMID: 31703870 DOI: 10.1016/j.fm.2019.103337] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 07/31/2019] [Accepted: 09/17/2019] [Indexed: 10/26/2022]
Abstract
Coenzyme Q0 (CoQ0) has demonstrated antitumor, anti-inflammatory, and anti-angiogenic activities. Cronobacter sakazakii is an opportunistic foodborne pathogen associated with high mortality in neonates. In this study, the antimicrobial activity and possible antimicrobial mechanism of CoQ0 against C. sakazakii were investigated. Moreover, the inactivation effect of CoQ0 on C. sakazakii in biofilms was also evaluated. The minimum inhibitory concentration (MIC) of CoQ0 against C. sakazakii strains ranged from 0.1 to 0.2 mg/mL. Treatment caused cell membrane dysfunction, as evidenced by cell membrane hyperpolarization, decreased intracellular ATP concentration and cell membrane integrity, and changes in cellular morphology. CoQ0 combined with mild heat treatment (45, 50, or 55 °C) decreased the number of viable non-desiccated and desiccated C. sakazakii cells in a time- and dose-dependent manner in reconstituted infant milk. Furthermore, CoQ0 showed effective inactivation activity against C. sakazakii in biofilms on stainless steel, reducing the number of viable cells and damaging the structure of the biofilm. These findings suggest that CoQ0 has a strong inactivate effect on C. sakazakii and could be used in food production environments to effectively control C. sakazakii and reduce the number of illnesses associated with it.
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Affiliation(s)
- Du Guo
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Shuo Wang
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Jiahui Li
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Fangting Bai
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Yanpeng Yang
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Yunfeng Xu
- College of Food and Bioengineering, Henan University of Science and Technology, Luoyang, Henan, 471023, China
| | - Sen Liang
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology and Business University, Beijing, 100048, China
| | - Xiaodong Xia
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Xin Wang
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Chao Shi
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, 712100, China.
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44
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45
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Tsai HC, Ballom KF, Xia S, Tang J, Marks BP, Zhu MJ. Evaluation of Enterococcus faecium NRRL B-2354 as a surrogate for Salmonella during cocoa powder thermal processing. Food Microbiol 2019; 82:135-141. [DOI: 10.1016/j.fm.2019.01.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2018] [Revised: 01/07/2019] [Accepted: 01/11/2019] [Indexed: 10/27/2022]
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46
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Thermal resistance of Listeria monocytogenes in natural unsweetened cocoa powder under different water activity. Food Control 2019. [DOI: 10.1016/j.foodcont.2019.03.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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47
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Underestimated Risks of Infantile Infectious Disease from the Caregiver's Typical Handling Practices of Infant Formula. Sci Rep 2019; 9:9799. [PMID: 31278304 PMCID: PMC6611816 DOI: 10.1038/s41598-019-46181-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 06/25/2019] [Indexed: 11/11/2022] Open
Abstract
The impact on infant caregiver as a reservoir of pathogens has not been exploited with perspective to powdered infant formula (PIF). Here we reveal novel route of pathogen transfer through hand-spoon-PIF unexpectedly occurred by even typical practices of caregivers, handling of PIF and storage of feeding-spoon in PIF container. Hand-spoon-PIF contamination route was simulated to analyze the transfer and subsequent survival of pathogens. Major pathogens associated with infantile fatal diseases (Cronobacter sakazakii, Salmonella enterica, Staphylococcus aureus) were readily transmitted to PIF from skin (3−6 log CFU/hand) via spoons following long-term survival of transferred pathogens (3 weeks; use-by date of PIF) as the excessive level of infectious dose, highlighting direct onset of diseases. Low bacterial load on skin (ca. 1 log CFU/hand) could prevent cross-contamination of PIF, however, at least 72 h survival of transferred pathogen on spoons demonstrated the probability on re-contamination of PIF. To our knowledge, this is the first study to investigate the cross-contamination of utensils in contact with powdered-foods. Bacterial load on hands is the key determinant of pathogen transfer and the extent of risk are species-dependent. These evidential results redefine risk of caregivers’ practices and facilitate incorporation of cross-contamination into risk-assessment as underestimated route of infection.
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48
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Wiertzema JR, Borchardt C, Beckstrom AK, Dev K, Chen P, Chen C, Vickers Z, Feirtag J, Lee L, Ruan R, Baumler DJ. Evaluation of Methods for Inoculating Dry Powder Foods with Salmonella enterica, Enterococcus faecium, or Cronobacter sakazakii. J Food Prot 2019; 82:1082-1088. [PMID: 31135183 DOI: 10.4315/0362-028x.jfp-18-284] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 02/11/2019] [Indexed: 11/11/2022]
Abstract
Salmonella and Cronobacter are two bacteria of concern in powdered food ingredients with low water activity, due to their ability to remain viable for long periods of time. There is great interest in studying the survival of these bacteria in powdered foods, but discrepancies have been reported between broth-grown and lawn-grown bacterial cells and their thermal resistance and desiccation tolerance once inoculated onto powdered foods. The purpose of this study was to evaluate three different powdered food inoculation methods, two broth-grown and one lawn-grown. To evaluate these methods on three types of powdered food matrices, Salmonella enterica serovar Typhimurium LT2 (ATCC 700720), Salmonella surrogate Enterococcus faecium (NRRL B-2354), and Cronobacter sakazakii (ATCC 29544) were inoculated onto nonfat dry milk powder, organic soy flour, and all-purpose flour using one of the three previously developed inoculation methods. In the first broth-grown method, labeled broth-grown pelletized inoculation, a bacterial cell pellet was added to powdered foods directly and mixed with a sterile wooden stick. The second broth-grown method, labeled broth-grown spray inoculation, used a chromatography reagent sprayer to spray the bacterial cell suspension onto the powdered foods. The third inoculation method, lawn-grown liquid inoculation, made use of a spot inoculation and a stomacher to incorporate each bacterium into the powdered foods. Results indicated that the method of inoculation of each powder impacted repeatability and bacteria survivability postequilibration (4 to 6 days). Broth-grown spray inoculation, regardless of the powder and bacterium, resulted in the highest log reduction, with an average ∼1-log CFU/g reduction following equilibration. Broth-grown pelletized inoculation resulted in the second-highest log reduction (∼0.79 log CFU/g), and finally, lawn-grown liquid inoculation was the most stable inoculation method of the three, with ∼0.52-log CFU/g reduction. Overall, the results from this inoculation study demonstrate that inoculation methodologies impact the desiccation tolerance and homogeneity of C. sakazakii, E. faecium, and Salmonella Typhimurium LT2.
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Affiliation(s)
- Justin R Wiertzema
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, Minnesota 55108
| | - Christian Borchardt
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, Minnesota 55108
| | - Anna K Beckstrom
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, Minnesota 55108
| | - Kamal Dev
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, Minnesota 55108
| | - Paul Chen
- Center for Biorefining, and Department of Bioproducts and Biosystems Engineering, University of Minnesota, St. Paul, Minnesota 55108
| | - Chi Chen
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, Minnesota 55108
| | - Zata Vickers
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, Minnesota 55108
| | - Joellen Feirtag
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, Minnesota 55108
| | - Laurence Lee
- Biotechnology Institute, University of Minnesota, St. Paul, Minnesota 55108
| | - Roger Ruan
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, Minnesota 55108.,Center for Biorefining, and Department of Bioproducts and Biosystems Engineering, University of Minnesota, St. Paul, Minnesota 55108
| | - David J Baumler
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, Minnesota 55108.,Microbial and Plant Genomics Institute, University of Minnesota, St. Paul, Minnesota 55108.,LZL Engineering, Inc., 760 Crestview Lane, Owatonna, Minnesota 55060, USA
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49
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Ly V, Parreira VR, Farber JM. Current understanding and perspectives on Listeria monocytogenes in low-moisture foods. Curr Opin Food Sci 2019. [DOI: 10.1016/j.cofs.2019.02.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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50
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Du XJ, Wang XY, Dong X, Li P, Wang S. Characterization of the Desiccation Tolerance of Cronobacter sakazakii Strains. Front Microbiol 2018; 9:2867. [PMID: 30542333 PMCID: PMC6278591 DOI: 10.3389/fmicb.2018.02867] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 11/07/2018] [Indexed: 01/29/2023] Open
Abstract
Strong desiccation tolerance is an outstanding feature of Cronobacter sakazakii and can enable the bacterium to survive in a dry food matrix (such as milk powder) for a long time. Therefore, contamination of food possessing low water activity with C. sakazakii can increase the risk of infection in human beings, particularly in neonates and infants. However, the mechanism underlying the desiccation tolerance property of C. sakazakii is largely unknown. In this study, the desiccation tolerance characteristics of 42 C. sakazakii strains were analyzed. Simultaneously, the sequence types and biofilm formation abilities of the strains were investigated, and their correlations with desiccation tolerance were analyzed. The results showed no significant correlation between desiccation tolerance and sequence type. However, there was a positive correlation between biofilm formation ability and desiccation tolerance. Raman spectroscopy was employed to investigate the biofilm formed by strains with distinct desiccation tolerance levels, and the results showed that the levels of polysaccharide, proteins and carotenoid might play important roles in the resistance to dry environments. In addition, 10 genes involved in osmoprotectant synthesis or transport were selected, and their differential expression in strains with diverse desiccation tolerance levels was compared to investigate whether these genes were responsible for cytoprotection in the dry environment. The results revealed a great difference in gene expression among strains with different desiccation tolerance levels, suggesting that these genes play a regulatory role in the resistance of C. sakazakii to dry environments. Our study provides a useful reference for follow-up studies investigating the mechanism of desiccation tolerance in C. sakazakii.
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Affiliation(s)
- Xin-Jun Du
- State Key Laboratory of Food Nutrition and Safety, Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin University of Science and Technology, Tianjin, China
| | - Xiao-Yi Wang
- State Key Laboratory of Food Nutrition and Safety, Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin University of Science and Technology, Tianjin, China
| | - Xuan Dong
- State Key Laboratory of Food Nutrition and Safety, Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin University of Science and Technology, Tianjin, China
| | - Ping Li
- State Key Laboratory of Food Nutrition and Safety, Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin University of Science and Technology, Tianjin, China
| | - Shuo Wang
- State Key Laboratory of Food Nutrition and Safety, Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin University of Science and Technology, Tianjin, China.,Tianjin Key Laboratory of Food Science and Health, School of Medicine, Nankai University, Tianjin, China
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