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Zare F, Ghasemi N, Bansal N, Hosano H. Advances in pulsed electric stimuli as a physical method for treating liquid foods. Phys Life Rev 2023; 44:207-266. [PMID: 36791571 DOI: 10.1016/j.plrev.2023.01.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 01/28/2023] [Indexed: 02/05/2023]
Abstract
There is a need for alternative technologies that can deliver safe and nutritious foods at lower costs as compared to conventional processes. Pulsed electric field (PEF) technology has been utilised for a plethora of different applications in the life and physical sciences, such as gene/drug delivery in medicine and extraction of bioactive compounds in food science and technology. PEF technology for treating liquid foods involves engineering principles to develop the equipment, and quantitative biochemistry and microbiology techniques to validate the process. There are numerous challenges to address for its application in liquid foods such as the 5-log pathogen reduction target in food safety, maintaining the food quality, and scale up of this physical approach for industrial integration. Here, we present the engineering principles associated with pulsed electric fields, related inactivation models of microorganisms, electroporation and electropermeabilization theory, to increase the quality and safety of liquid foods; including water, milk, beer, wine, fruit juices, cider, and liquid eggs. Ultimately, we discuss the outlook of the field and emphasise research gaps.
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Affiliation(s)
- Farzan Zare
- School of Information Technology and Electrical Engineering, The University of Queensland, Brisbane, St Lucia QLD 4072, Australia; School of Agriculture and Food Sciences, The University of Queensland, St Lucia QLD 4072, Australia
| | - Negareh Ghasemi
- School of Information Technology and Electrical Engineering, The University of Queensland, Brisbane, St Lucia QLD 4072, Australia
| | - Nidhi Bansal
- School of Agriculture and Food Sciences, The University of Queensland, St Lucia QLD 4072, Australia
| | - Hamid Hosano
- Biomaterials and Bioelectrics Department, Institute of Industrial Nanomaterials, Kumamoto University, Kumamoto 860-8555, Japan.
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MAL62 overexpression enhances uridine diphosphoglucose-dependent trehalose synthesis and glycerol metabolism for cryoprotection of baker's yeast in lean dough. Microb Cell Fact 2020; 19:196. [PMID: 33076920 PMCID: PMC7574194 DOI: 10.1186/s12934-020-01454-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 10/09/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In Saccharomyces cerevisiae, alpha-glucosidase (maltase) is a key enzyme in maltose metabolism. In addition, the overexpression of the alpha-glucosidase-encoding gene MAL62 has been shown to increase the freezing tolerance of yeast in lean dough. However, its cryoprotection mechanism is still not clear. RESULTS RNA sequencing (RNA-seq) revealed that MAL62 overexpression increased uridine diphosphoglucose (UDPG)-dependent trehalose synthesis. The changes in transcript abundance were confirmed by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and enzyme activity assays. When the UDPG-dependent trehalose synthase activity was abolished, MAL62 overexpression failed to promote the synthesis of intracellular trehalose. Moreover, in strains lacking trehalose synthesis, the cell viability in the late phase of prefermentation freezing coupled with MAL62 overexpression was slightly reduced, which can be explained by the increase in the intracellular glycerol concentration. This result was consistent with the elevated transcription of glycerol synthesis pathway members. CONCLUSIONS The increased freezing tolerance by MAL62 overexpression is mainly achieved by the increased trehalose content via the UDPG-dependent pathway, and glycerol also plays an important role. These findings shed new light on the mechanism of yeast response to freezing in lean bread dough and can help to improve industrial yeast strains.
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Role and regulation of the stress activated sigma factor sigma B (σ B) in the saprophytic and host-associated life stages of Listeria monocytogenes. ADVANCES IN APPLIED MICROBIOLOGY 2019; 106:1-48. [PMID: 30798801 DOI: 10.1016/bs.aambs.2018.11.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The stress activated sigma factor sigma B (σB) plays a pivotal role in allowing the food-borne bacterial pathogen Listeria monocytogenes to modulate its transcriptional landscape in order to survive in a variety of harsh environments both outside and within the host. While we have a comparatively good understanding of the systems under the control of this sigma factor much less is known about how the activity of σB is controlled. In this review, we present a current model describing how this sigma factor is thought to be controlled including an overview of what is known about stress sensing and the early signal transduction events that trigger its activation. We discuss the known regulatory overlaps between σB and other protein and RNA regulators in the cell. Finally, we describe the role of σB in surviving both saprophytic and host-associated stresses. The complexity of the regulation of this sigma factor reflects the significant role that it plays in the persistence of this important pathogen in the natural environment, the food chain as well as within the host during the early stages of an infection. Understanding its regulation will be a critical step in helping to develop rational strategies to prevent its growth and survival in the food destined for human consumption and in the prevention of listeriosis.
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Koomen J, den Besten HM, Metselaar KI, Tempelaars MH, Wijnands LM, Zwietering MH, Abee T. Gene profiling-based phenotyping for identification of cellular parameters that contribute to fitness, stress-tolerance and virulence of Listeria monocytogenes variants. Int J Food Microbiol 2018; 283:14-21. [DOI: 10.1016/j.ijfoodmicro.2018.06.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 05/31/2018] [Accepted: 06/06/2018] [Indexed: 10/14/2022]
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Horn N, Bhunia AK. Food-Associated Stress Primes Foodborne Pathogens for the Gastrointestinal Phase of Infection. Front Microbiol 2018; 9:1962. [PMID: 30190712 PMCID: PMC6115488 DOI: 10.3389/fmicb.2018.01962] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 08/02/2018] [Indexed: 12/13/2022] Open
Abstract
The incidence of foodborne outbreaks and product recalls is on the rise. The ability of the pathogen to adapt and survive under stressful environments of food processing and the host gastrointestinal tract may contribute to increasing foodborne illnesses. In the host, multiple factors such as bacteriolytic enzymes, acidic pH, bile, resident microflora, antimicrobial peptides, and innate and adaptive immune responses are essential in eliminating pathogens. Likewise, food processing and preservation techniques are employed to eliminate or reduce human pathogens load in food. However, sub-lethal processing or preservation treatments may evoke bacterial coping mechanisms that alter gene expression, specifically and broadly, resulting in resistance to the bactericidal insults. Furthermore, environmentally cued changes in gene expression can lead to changes in bacterial adhesion, colonization, invasion, and toxin production that contribute to pathogen virulence. The shared microenvironment between the food preservation techniques and the host gastrointestinal tract drives microbes to adapt to the stressful environment, resulting in enhanced virulence and infectivity during a foodborne illness episode.
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Affiliation(s)
- Nathan Horn
- Department of Animal Sciences, Purdue University, West Lafayette, IN, United States
| | - Arun K. Bhunia
- Molecular Food Microbiology Laboratory, Department of Food Science, Purdue University, West Lafayette, IN, United States
- Department of Comparative Pathobiology, Purdue University, West Lafayette, IN, United States
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Keane SM, Culligan EP, Hoffmann RF, Gahan CGM, Hill C, Snelling WJ, Sleator RD. Shedding light on betL*: pPL2-lux mediated real-time analysis of betL* expression in Listeria monocytogenes. Bioengineered 2016; 7:116-9. [PMID: 27212260 DOI: 10.1080/21655979.2016.1171438] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
We propose a mechanism of action for the betL* mutation which is based on DNA topology. Removing a single thymine residue from the betL σ(A) promoter's -10 and -35 spacer results in a 'twist'-mediated activation of transcription which accounts for the osmotolerance phenotype observed for strains expressing betL*.
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Affiliation(s)
- Shauna M Keane
- a Department of Biological Sciences , Cork Institute of Technology , Rossa Avenue, Bishopstown, Cork , Ireland
| | - Eamonn P Culligan
- a Department of Biological Sciences , Cork Institute of Technology , Rossa Avenue, Bishopstown, Cork , Ireland
| | - Roland F Hoffmann
- b APC Microbiome Institute, University College Cork , College Road, Cork , Ireland
| | - Cormac G M Gahan
- b APC Microbiome Institute, University College Cork , College Road, Cork , Ireland.,c School of Microbiology, University College Cork , College Road, Cork , Ireland.,d School of Pharmacy, University College Cork , College Road, Cork , Ireland
| | - Colin Hill
- b APC Microbiome Institute, University College Cork , College Road, Cork , Ireland.,c School of Microbiology, University College Cork , College Road, Cork , Ireland
| | - William J Snelling
- e Biomedical Sciences Research Institute, Ulster University , Northern Ireland
| | - Roy D Sleator
- a Department of Biological Sciences , Cork Institute of Technology , Rossa Avenue, Bishopstown, Cork , Ireland.,b APC Microbiome Institute, University College Cork , College Road, Cork , Ireland
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Abstract
The review centers on the human gastrointestinal tract; focusing first on the bacterial stress responses needed to overcome the physiochemical defenses of the host, specifically how these stress survival strategies can be used as targets for alternative infection control strategies. The concluding section focuses on recent developments in molecular diagnostics; centring on the shifting paradigm from culture to molecular based diagnostics.
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Affiliation(s)
- Roy D Sleator
- a Department of Biological Sciences ; Cork Institute of Technology ; Bishopstown , Cork , Ireland
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Abstract
The use of antibiotics in animal husbandry has long been associated with the appearance of antibiotic resistance and virulence factor determinants. Nonetheless, the number of cases of human infection involving resistant or virulent microorganisms that originate in farms is increasing. While many antibiotics have been banned as dietary supplements in some countries, other additives thought to be innocuous in terms of the development and spread of antibiotic resistance are used as growth promoters. In fact, several clay materials are routinely added to animal feed with the aim of improving growth and animal product quality. However, recent findings suggest that sepiolite, a clay additive, mediates the direct transfer of plasmids between different bacterial species. We therefore hypothesize that clays present in animal feed facilitate the horizontal transfer of resistance determinants in the digestive tract of farm animals.
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Meadows JA, Wargo MJ. Carnitine in bacterial physiology and metabolism. MICROBIOLOGY (READING, ENGLAND) 2015; 161:1161-74. [PMID: 25787873 PMCID: PMC4635513 DOI: 10.1099/mic.0.000080] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 03/17/2015] [Indexed: 12/23/2022]
Abstract
Carnitine is a quaternary amine compound found at high concentration in animal tissues, particularly muscle, and is most well studied for its contribution to fatty acid transport into mitochondria. In bacteria, carnitine is an important osmoprotectant, and can also enhance thermotolerance, cryotolerance and barotolerance. Carnitine can be transported into the cell or acquired from metabolic precursors, where it can serve directly as a compatible solute for stress protection or be metabolized through one of a few distinct pathways as a nutrient source. In this review, we summarize what is known about carnitine physiology and metabolism in bacteria. In particular, recent advances in the aerobic and anaerobic metabolic pathways as well as the use of carnitine as an electron acceptor have addressed some long-standing questions in the field.
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Affiliation(s)
- Jamie A. Meadows
- Department of Microbiology and Molecular Genetics, University of Vermont College of Medicine, 95 Carrigan Drive, Burlington, VT, 05405, USA
| | - Matthew J. Wargo
- Department of Microbiology and Molecular Genetics, University of Vermont College of Medicine, 95 Carrigan Drive, Burlington, VT, 05405, USA
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Feeney A, Kropp KA, O’Connor R, Sleator RD. Cronobacter sakazakii: stress survival and virulence potential in an opportunistic foodborne pathogen. Gut Microbes 2015; 5:711-8. [PMID: 25562731 PMCID: PMC4615781 DOI: 10.4161/19490976.2014.983774] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
A characteristic feature of the opportunistic foodborne pathogen Cronobacter sakazakii is its ability to survive in extremely arid environments, such as powdered infant formula, making it a dangerous opportunistic pathogen of individuals of all age groups, especially infants and neonates. Herein, we provide a brief overview of the pathogen; clinical manifestations, environmental reservoirs and our current understanding of stress response mechanisms and virulence factors which allow it to cause disease.
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Affiliation(s)
- Audrey Feeney
- Department of Biological Sciences; Cork Institute of Technology; Bishopstown, Cork, Ireland
| | - Kai A Kropp
- Department of Biological Sciences; Cork Institute of Technology; Bishopstown, Cork, Ireland
| | - Roxana O’Connor
- Department of Biological Sciences; Cork Institute of Technology; Bishopstown, Cork, Ireland
| | - Roy D Sleator
- Department of Biological Sciences; Cork Institute of Technology; Bishopstown, Cork, Ireland,Correspondence to: Roy D Sleator;
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Hoffmann RF, McLernon S, Feeney A, Hill C, Sleator RD. A single point mutation in the listerial betL σ(A)-dependent promoter leads to improved osmo- and chill-tolerance and a morphological shift at elevated osmolarity. Bioengineered 2013; 4:401-7. [PMID: 23478432 PMCID: PMC3937201 DOI: 10.4161/bioe.24094] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Betaine uptake in Listeria monocytogenes is mediated by three independent transport systems, the simplest of which in genetic terms is the secondary transporter BetL. Using a random mutagenesis approach, based on the E. coli XL1 Red mutator strain, we identified a single point mutation in a putative promoter region upstream of the BetL coding region which leads to a significant increase in betL transcript levels under osmo- and chill-stress conditions and a concomitant increase in stress tolerance. Furthermore, the mutation appears to counter the heretofore unreported “twisted” cell morphology observed for L. monocytogenes grown at elevated osmolarities in tryptone soy broth.
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Affiliation(s)
- Roland F Hoffmann
- Alimentary Pharmabiotic Centre; University College Cork; Cork, Ireland; Department of Biological Sciences; Cork Institute of Technology; Cork, Ireland
| | - Susan McLernon
- Alimentary Pharmabiotic Centre; University College Cork; Cork, Ireland
| | - Audrey Feeney
- Department of Biological Sciences; Cork Institute of Technology; Cork, Ireland
| | - Colin Hill
- Alimentary Pharmabiotic Centre; University College Cork; Cork, Ireland
| | - Roy D Sleator
- Alimentary Pharmabiotic Centre; University College Cork; Cork, Ireland; Department of Biological Sciences; Cork Institute of Technology; Cork, Ireland
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Bowman JP, Hages E, Nilsson RE, Kocharunchitt C, Ross T. Investigation of the Listeria monocytogenes Scott A acid tolerance response and associated physiological and phenotypic features via whole proteome analysis. J Proteome Res 2012; 11:2409-26. [PMID: 22372944 DOI: 10.1021/pr201137c] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The global proteomic responses of the foodborne pathogen Listeria monocytogenes strain Scott A, during active growth and transition to the stationary growth phase under progressively more acidic conditions, created by addition of lactic acid and HCl, were investigated using label-free liquid chromatography/tandem mass spectrometry. Approximately 56% of the Scott A proteome was quantitatively assessable, and the data provides insight into its acquired acid tolerance response (ATR) as well as the relation of the ATR to the growth phase transition. Alterations in protein abundance due to acid stress were focused in proteins belonging to the L. monocytogenes common genome, with few strain-dependent proteins involved. However, one of the two complete prophage genomes appeared to enter lysogeny. During progressive acidification, the growth rate and yield were reduced 55% and 98%, respectively, in comparison to nonacidified control cultures. The maintenance of the growth rate was determined to be connected to activation of cytoplasmic pH homeostatic mechanisms while cellular reproductive-related and cell component turnover proteins were markedly more abundant in acid stressed cultures. Cell biomass accumulation was impeded predominantly due to repression of phosphodonor-linked enzymes involved with sugar phosphotransfer, glycolysis, and cell wall polymer biosynthesis. Acidification caused a shift from heterofermentation to an oxidatively stressed state in which ATP appears to be generated mainly through the pyruvate dehydrogenase/pyruvate oxidase/phosphotransacetylase/acetate kinase and branched chain acid dehydrogenase pathways. Analysis of regulons indicated energy conservation occurs due to repression by the GTP/isoleucine sensor CodY and also the RelA mediated stringent response. Whole proteome analysis proved to be an effective way to highlight proteins involved with the acquisition of the ATR.
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Affiliation(s)
- John P Bowman
- Food Safety Centre, Tasmanian Institute of Agriculture, University of Tasmania, Hobart, Tasmania, Australia.
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Abstract
An overwhelming array of structural variants has evolved from a comparatively small number of protein structural domains; which has in turn facilitated an expanse of functional derivatives. Herein, I review the primary mechanisms which have contributed to the vastness of our existing, and expanding, protein repertoires. Protein function prediction strategies, both sequence and structure based, are also discussed and their associated strengths and weaknesses assessed.
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Affiliation(s)
- Roy D Sleator
- Department of Biological Sciences, Cork Institute of Technology, Cork, Ireland.
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