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Yuan L, Fan L, Liu S, Sant'Ana AS, Zhang Y, Zhou W, Zheng X, He G, Yang Z, Jiao X. Bacterial community analysis of infant foods obtained from Chinese markets by combining culture-dependent and high-throughput sequence methods. Food Res Int 2022; 162:112060. [DOI: 10.1016/j.foodres.2022.112060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 09/23/2022] [Accepted: 10/07/2022] [Indexed: 11/04/2022]
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2
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Zhang Y, Yuan L, Chen C, Mgomi FC, Yang Z, Jiao X. Specific detection of viable
Cronobacter sakazakii
in powdered infant formula by phage amplification combined with
qPCR
(
PAA‐qPCR
) assay. INT J DAIRY TECHNOL 2022. [DOI: 10.1111/1471-0307.12889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yuan‐Song Zhang
- School of Food Science and Technology Yangzhou University Yangzhou Jiangsu 225127 China
| | - Lei Yuan
- School of Food Science and Technology Yangzhou University Yangzhou Jiangsu 225127 China
| | - Cao‐Wei Chen
- School of Food Science and Technology Yangzhou University Yangzhou Jiangsu 225127 China
| | - Fedrick C Mgomi
- School of Food Science and Technology Yangzhou University Yangzhou Jiangsu 225127 China
| | - Zhen‐Quan Yang
- School of Food Science and Technology Yangzhou University Yangzhou Jiangsu 225127 China
- Jiangsu Key Laboratory of Zoonoses Yangzhou Jiangsu 225009 China
| | - Xin‐an Jiao
- Jiangsu Key Laboratory of Zoonoses Yangzhou Jiangsu 225009 China
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3
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Park S, Cho T, Rhee M. Characterization of the nitrite production of mesophilic spore-forming bacteria during the handling of reconstituted infant formula. Food Res Int 2022; 156:111332. [DOI: 10.1016/j.foodres.2022.111332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Revised: 04/28/2022] [Accepted: 04/30/2022] [Indexed: 11/30/2022]
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4
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Mezian L, Chincha AI, Vecchione A, Ghelardi E, Bonatto JMC, Marsaioli AJ, Campelo PH, Benamar I, Allah MA, Sant'Ana AS, Boumediene MB. Aerobic spore-forming bacteria in powdered infant formula: Enumeration, identification by MALDI-TOF mass spectrometry (MS), presence of toxin genes and rpoB gene typing. Int J Food Microbiol 2022; 368:109613. [DOI: 10.1016/j.ijfoodmicro.2022.109613] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 12/28/2021] [Accepted: 03/04/2022] [Indexed: 11/16/2022]
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5
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Dynamic tracing of bacterial community distribution and biofilm control of dominant species in milk powder processing. Lebensm Wiss Technol 2022. [DOI: 10.1016/j.lwt.2021.112855] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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6
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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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7
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Karaca B, Buzrul S, Cihan AC. Mathematical Models for the Biofilm Formation of Geobacillus and Anoxybacillus on Stainless Steel Surface in Whole Milk. Food Sci Anim Resour 2021; 41:288-299. [PMID: 33987549 PMCID: PMC8115000 DOI: 10.5851/kosfa.2020.e100] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 10/28/2020] [Accepted: 12/15/2020] [Indexed: 11/16/2022] Open
Abstract
Biofilm formation of Geobacillus thermodenitrificans,
Geobacillus thermoglucosidans and Anoxybacillus
flavithermus in milk on stainless steel were monitored at
55°C, 60°C, and 65°C for various incubation times. Although
species of Geobacillus showed a rapid response and produced
biofilm within 4 h on stainless steel, a delay (lag time) was observed for
Anoxybacillus. A hyperbolic equation and a hyperbolic
equation with lag could be used to describe the biofilm formation of
Geobacillus and Anoxybacillus,
respectively. The highest biofilm formation amount was obtained at 60°C
for both Geobacillus and Anoxybacillus.
However, the biofilm formation rates indicated that the lowest rates of
formation were obtained at 60°C for Geobacillus.
Moreover, biofilm formation rates of G. thermodenitrificans
(1.2–1.6 Log10CFU/mL·h) were higher than G.
thermoglucosidans (0.4–0.7 Log10CFU/mL·h).
Although A. flavithermus had the highest formation rate values
(2.7–3.6 Log10CFU/mL·h), this was attained after the
lag period (4 or 5 h). This study revealed that modeling could be used to
describe the biofilm formation of thermophilic bacilli in milk.
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Affiliation(s)
- Basar Karaca
- Department of Biology, Ankara University, Ankara, Turkey
| | - Sencer Buzrul
- Department of Food Engineering, Konya Food and Agriculture University, Konya, Turkey
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8
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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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9
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McHugh AJ, Yap M, Crispie F, Feehily C, Hill C, Cotter PD. Microbiome-based environmental monitoring of a dairy processing facility highlights the challenges associated with low microbial-load samples. NPJ Sci Food 2021; 5:4. [PMID: 33589631 PMCID: PMC7884712 DOI: 10.1038/s41538-021-00087-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 01/13/2021] [Indexed: 01/01/2023] Open
Abstract
Efficient and accurate identification of microorganisms throughout the food chain can potentially allow the identification of sources of contamination and the timely implementation of control measures. High throughput DNA sequencing represents a potential means through which microbial monitoring can be enhanced. While Illumina sequencing platforms are most typically used, newer portable platforms, such as the Oxford Nanopore Technologies (ONT) MinION, offer the potential for rapid analysis of food chain microbiomes. Initial assessment of the ability of rapid MinION-based sequencing to identify microbes within a simple mock metagenomic mixture is performed. Subsequently, we compare the performance of both ONT and Illumina sequencing for environmental monitoring of an active food processing facility. Overall, ONT MinION sequencing provides accurate classification to species level, comparable to Illumina-derived outputs. However, while the MinION-based approach provides a means of easy library preparations and portability, the high concentrations of DNA needed is a limiting factor.
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Affiliation(s)
- Aoife J McHugh
- Food Bioscience Department, Teagasc Food Research Centre, Cork, Ireland.,School of Microbiology, University College Cork, Cork, Ireland
| | - Min Yap
- Food Bioscience Department, Teagasc Food Research Centre, Cork, Ireland.,School of Microbiology, University College Cork, Cork, Ireland
| | - Fiona Crispie
- Food Bioscience Department, Teagasc Food Research Centre, Cork, Ireland.,APC Microbiome Ireland, Cork, Ireland
| | - Conor Feehily
- Food Bioscience Department, Teagasc Food Research Centre, Cork, Ireland.,APC Microbiome Ireland, Cork, Ireland
| | - Colin Hill
- School of Microbiology, University College Cork, Cork, Ireland.,APC Microbiome Ireland, Cork, Ireland
| | - Paul D Cotter
- Food Bioscience Department, Teagasc Food Research Centre, Cork, Ireland. .,APC Microbiome Ireland, Cork, Ireland.
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10
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Egan M, Dempsey E, Ryan CA, Ross RP, Stanton C. The Sporobiota of the Human Gut. Gut Microbes 2021; 13:1-17. [PMID: 33406976 PMCID: PMC7801112 DOI: 10.1080/19490976.2020.1863134] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 12/01/2020] [Accepted: 12/04/2020] [Indexed: 02/04/2023] Open
Abstract
The human gut microbiome is a diverse and complex ecosystem that plays a critical role in health and disease. The composition of the gut microbiome has been well studied across all stages of life. In recent years, studies have investigated the production of endospores by specific members of the gut microbiome. An endospore is a tough, dormant structure formed by members of the Firmicutes phylum, which allows for greater resistance to otherwise inhospitable conditions. This innate resistance has consequences for human health and disease, as well as in biotechnology. In particular, the formation of endospores is strongly linked to antibiotic resistance and the spread of antibiotic resistance genes, also known as the resistome. The term sporobiota has been used to define the spore-forming cohort of a microbial community. In this review, we present an overview of the current knowledge of the sporobiota in the human gut. We discuss the development of the sporobiota in the infant gut and the perinatal factors that may have an effect on vertical transmission from mother to infant. Finally, we examine the sporobiota of critically important food sources for the developing infant, breast milk and powdered infant formula.
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Affiliation(s)
- Muireann Egan
- Food Biosciences Department, Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork, Ireland
- APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Eugene Dempsey
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- Department of Neonatology, Cork University Maternity Hospital, Cork, Ireland
| | - C. Anthony Ryan
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- Department of Neonatology, Cork University Maternity Hospital, Cork, Ireland
| | - R. Paul Ross
- APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Catherine Stanton
- Food Biosciences Department, Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork, Ireland
- APC Microbiome Ireland, University College Cork, Cork, Ireland
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11
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Murphy SI, Kent D, Skeens J, Wiedmann M, Martin NH. A standard set of testing methods reliably enumerates spores across commercial milk powders. J Dairy Sci 2020; 104:2615-2631. [PMID: 33358815 DOI: 10.3168/jds.2020-19313] [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: 07/17/2020] [Accepted: 10/01/2020] [Indexed: 11/19/2022]
Abstract
Contamination of dairy powders with sporeforming bacteria is a concern for dairy processors who wish to penetrate markets with stringent spore count specifications (e.g., infant powders). Despite instituted specifications, no standard methodology is used for spore testing across the dairy industry. Instead, a variety of spore enumeration methods are in use, varying primarily by heat-shock treatments, plating method, recovery medium, and incubation temperature. Importantly, testing the same product using different methodologies leads to differences in spore count outcomes, which is a major issue for those required to meet specifications. As such, we set out to identify method(s) to recommend for standardized milk powder spore testing. To this end, 10 commercial milk powders were evaluated using methods varying by (1) heat treatment (e.g., 80°C/12 min), (2) plating method (e.g., spread plating), (3) medium type (e.g., plate count milk agar), and (4) incubation time and temperature combinations (e.g., 32°C for 48 h). The resulting data set included a total of 48 methods. With this data set, we used a stepwise process to identify optimal method(s) that would explain a high proportion of variance in spore count outcomes and would be practical to implement across the dairy industry. Ultimately, spore pasteurized mesophilic spore count (80°C/12 min, incubated at 32°C for 48 h), highly heat resistant thermophilic spore count (100°C/30 min, incubated at 55°C for 48 h), and specially thermoresistant spore enumeration (106°C/30 min, incubated at 55°C for 48 h) spread plating on plate count milk agar were identified as the optimal method set for reliable enumeration of spores in milk powders. Subsequently, we assessed different powder sampling strategies as a way to reduce variation in powder spore testing outcomes using our recommended method set. Results indicated that 33-g composite sampling may reduce variation in spore testing outcomes for highly heat resistant thermophilic spore count over 11-g and 33-g discrete sampling, whereas there was no significant difference across sampling strategies for specially thermoresistant spore enumeration or spore pasteurized mesophilic spore count. Finally, an interlaboratory study using our recommended method set and a modified method set (using tryptic soy agar with 1% starch) among both university and industry laboratories showed increased variation in spore count outcomes within milk powders, which not only was due to natural variation in powders but also was hypothesized to be due to technical errors, highlighting the need for specialized training for technicians who perform spore testing on milk powders. Overall, this study addresses challenges to milk powder spore testing and recommends a method set for standardized spore testing for implementation across the dairy industry.
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Affiliation(s)
- S I Murphy
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14853
| | - D Kent
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14853
| | - J Skeens
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14853
| | - M Wiedmann
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14853
| | - N H Martin
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14853.
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12
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Effect of ɣ-irradiation on the microbial inactivation, nutritional value, and antioxidant activities of infant formula. Lebensm Wiss Technol 2020. [DOI: 10.1016/j.lwt.2020.109211] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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13
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McHugh AJ, Feehily C, Fenelon MA, Gleeson D, Hill C, Cotter PD. Tracking the Dairy Microbiota from Farm Bulk Tank to Skimmed Milk Powder. mSystems 2020; 5:e00226-20. [PMID: 32265313 PMCID: PMC7141888 DOI: 10.1128/msystems.00226-20] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 03/17/2020] [Indexed: 11/20/2022] Open
Abstract
Microorganisms from the environment can enter the dairy supply chain at multiple stages, including production, milk collection, and processing, with potential implications for quality and safety. The ability to track these microorganisms can be greatly enhanced by the use of high-throughput DNA sequencing (HTS). Here HTS, both 16S rRNA gene amplicon and shotgun metagenomic sequencing were applied to investigate the microbiomes of fresh mid- and late-lactation milk collected from farm bulk tanks, collection tankers, milk silos, skimmed milk silos, a cream silo, and powder samples to investigate the microbial changes throughout a skim milk powder manufacturing process. 16S rRNA gene analysis established that the microbiota of raw milks from farm bulk tanks and in collection tankers were very diverse but that psychrotrophic genera associated with spoilage, Pseudomonas and Acinetobacter, were present in all samples. Upon storage within the whole-milk silo at the processing facility, the species Pseudomonas fluorescens and Acinetobacter baumannii became dominant. The skimmed milk powder generated during the mid-lactation period had a microbial composition that was very different from that of raw milk; specifically, two thermophilic genera, Thermus and Geobacillus, were enriched. In contrast, the microbiota of skimmed milk powder generated from late-lactation milk more closely resembled that of the raw milk and was dominated by spoilage-associated psychrotrophic bacteria. This study demonstrates that the dairy microbiota can differ significantly across different sampling days. More specifically, HTS can be used to trace microbial species from raw milks through processing to final powdered products.IMPORTANCE Microorganisms can enter and persist in dairy at several stages of the processing chain. Detection of microorganisms within dairy food processing is currently a time-consuming and often inaccurate process. This study provides evidence that high-throughput sequencing can be used as an effective tool to accurately identify microorganisms along the processing chain. In addition, it demonstrates that the populations of microbes change from raw milk to the end product. Routine implementation of high-throughput sequencing would elucidate the factors that influence population dynamics. This will enable a manufacturer to adopt control measures specific to each stage of processing and respond in an effective manner, which would ultimately lead to increased food safety and quality.
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Affiliation(s)
- Aoife J McHugh
- Food Bioscience Department, Teagasc Food Research Centre, Cork, Ireland
- School of Microbiology, University College Cork, Cork, Ireland
| | - Conor Feehily
- Food Bioscience Department, Teagasc Food Research Centre, Cork, Ireland
- APC Microbiome Ireland, Cork, Ireland
| | - Mark A Fenelon
- Food Chemistry and Technology Department, Teagasc Food Research Centre, Cork, Ireland
| | - David Gleeson
- Teagasc Animal and Grassland Research and Innovation Centre, Cork, Ireland
| | - Colin Hill
- School of Microbiology, University College Cork, Cork, Ireland
- APC Microbiome Ireland, Cork, Ireland
| | - Paul D Cotter
- Food Bioscience Department, Teagasc Food Research Centre, Cork, Ireland
- APC Microbiome Ireland, Cork, Ireland
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14
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Application of stochastic Bayesian modeling to assess safety status of baby formulas and quantify factors leading to unsafe products in China market. Food Control 2020. [DOI: 10.1016/j.foodcont.2019.106826] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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15
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Li F, Hunt K, Van Hoorde K, Butler F, Jordan K, Tobin JT. Occurrence and identification of spore-forming bacteria in skim-milk powders. Int Dairy J 2019. [DOI: 10.1016/j.idairyj.2019.05.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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16
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Influence of feed temperature to biofouling of ultrafiltration membrane during skim milk processing. Int Dairy J 2019. [DOI: 10.1016/j.idairyj.2019.02.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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17
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Whole-Genome Sequences of Five Geobacillus stearothermophilus Strains Isolated from Processing Lines of Powdered Infant Formula. Microbiol Resour Announc 2019; 8:MRA01452-18. [PMID: 30701238 PMCID: PMC6346187 DOI: 10.1128/mra.01452-18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 12/19/2018] [Indexed: 11/20/2022] Open
Abstract
Geobacillus stearothermophilus is the thermophile present in processing lines of powdered infant formula (PIF). We report the whole-genome sequences of G. stearothermophilus strains isolated from work-in-process products (sterilized and concentrated milk) of manufacturing plants. Understanding the genomic basis governing the metabolism of G. stearothermophilus can contribute to the safety management of PIF during its manufacture. Geobacillus stearothermophilus is the thermophile present in processing lines of powdered infant formula (PIF). We report the whole-genome sequences of G. stearothermophilus strains isolated from work-in-process products (sterilized and concentrated milk) of manufacturing plants. Understanding the genomic basis governing the metabolism of G. stearothermophilus can contribute to the safety management of PIF during its manufacture.
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18
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Cho TJ, Rhee MS. Underrecognized niche of spore-forming bacilli as a nitrite-producer isolated from the processing lines and end-products of powdered infant formula. Food Microbiol 2018; 80:50-61. [PMID: 30704596 DOI: 10.1016/j.fm.2018.12.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 11/20/2018] [Accepted: 12/21/2018] [Indexed: 01/14/2023]
Abstract
Although nitrite in powdered milk formula (PIF) is a recognized health risk for infants, the presence of nitrite in PIF has only been investigated as a chemical contaminant during the inspection of end-products. The risk posed by microbial sources of nitrite during the PIF manufacturing process has not been considered. This is the first study to report the taxonomy and physiological characteristics of nitrite-producing bacteria isolated from PIF processing environments. All isolates identified as nitrite-producers (133 out of 501 strains collected over four years) from work-in-process and end-products of PIF were spore-forming bacilli. Nitrite-producing metabolism under PIF processing conditions was found in not only thermophilic isolates (3 Bacillus, 60 Geobacillus from 63 strains; 100%) but also in mesophilic isolates (65 Bacillus, 1 Anoxybacillus from 70 strains; 65.7%). Geobacillus was the only highly heat-resistant sporeformer and vigorous nitrite-producer exhibiting dramatic increases in nitrite over short periods of incubation (a maximum value within 3 h). High conversions of nitrate to nitrite (up to 88.8%) was also observed, highlighting bacteria as a key source of nitrite in PIF processing lines. Further research into the diversity of metabolic activity observed in this study can facilitate specialized management of nitrite-producers in PIF processing lines.
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Affiliation(s)
- Tae Jin Cho
- Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, 02841, South Korea
| | - Min Suk Rhee
- Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, 02841, South Korea.
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