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Food Safety Publications

The Food Safety Publications tracks research that is published across national and international peer-reviewed journals. Recent articles are available ahead of print and searchable by Journal, Article Title, and Category. The research publications are tracked across six categories: Bacterial Pathogens, Chemical Contaminants, Natural Toxins, Parasites, Produce Safety, and Viruses. Articles produced by USDA Grant Funding Agencies and FDA Grant Funding Agencies are also tracked.

Displaying 1 - 25 of 286

  1. Interplay of CodY and CcpA in Regulating Central Metabolism and Biofilm Formation in Staphylococcus aureus

    • Fri, 06/24/2022 - 04:00
    • Journal of Bacteriology
    • Journal of Bacteriology, Ahead of Print. Staphylococcus aureus is a medically important pathogen with high metabolic versatility allowing it to infect various niches within a host. S. aureus utilizes two major transcriptional regulators, namely, CodY and CcpA, to remodel metabolic and virulence gene expression in response to changing environmental conditions.

      • Bacterial pathogens
      • Staphylococcus aureus
  2. The AraC/XylS Protein MxiE and Its Coregulator IpgC Control a Negative Feedback Loop in the Transcriptional Cascade That Regulates Type III Secretion in Shigella flexneri

    • Thu, 06/16/2022 - 04:00
    • Journal of Bacteriology
    • Journal of Bacteriology, Ahead of Print. Members of the AraC family of transcriptional regulators (AFTRs) control the expression of many genes important to cellular processes, including virulence. In Shigella species, the type III secretion system (T3SS), a key determinant for host cell invasion, is regulated by the three-tiered VirF/VirB/MxiE transcriptional cascade. Both VirF and MxiE belong to the AFTRs and are characterized as positive transcriptional regulators.

      • Bacterial pathogens
      • Shigella
  3. Role of Staphylococcus aureus Tet38 in Transport of Tetracycline and Its Regulation in a Salt Stress Environment

    • Wed, 06/15/2022 - 04:00
    • Journal of Bacteriology
    • Journal of Bacteriology, Ahead of Print. Staphylococcus aureus Tet38 efflux pump has multiple functions, including conferring resistance to tetracycline and other compounds and enabling internalization and survival within epithelial cells. In this study, we evaluated the effects of sodium and potassium on tet38 expression. These monovalent cations are known to play a role in transport by the related S. aureus TetK and B.

      • Bacterial pathogens
      • Staphylococcus aureus
  4. Linking the Salmonella enterica 1,2-Propanediol Utilization Bacterial Microcompartment Shell to the Enzymatic Core via the Shell Protein PduB

    • Sat, 06/04/2022 - 04:00
    • Journal of Bacteriology
    • Journal of Bacteriology, Ahead of Print. Bacterial microcompartments (MCPs) are protein-based organelles that house the enzymatic machinery for metabolism of niche carbon sources, allowing enteric pathogens to outcompete native microbiota during host colonization. While much progress has been made toward understanding MCP biogenesis, questions still remain regarding the mechanism by which core MCP enzymes are enveloped within the MCP protein shell.

      • Bacterial pathogens
      • Salmonella
  5. A Genomic Island of Vibrio cholerae Encodes a Three-Component Cytotoxin with Monomer and Protomer Forms Structurally Similar to Alpha-Pore-Forming Toxins

    • Sat, 06/04/2022 - 04:00
    • Journal of Bacteriology
    • Journal of Bacteriology, Volume 204, Issue 5, May 2022. Alpha-pore-forming toxins (α-PFTs) are secreted by many species of bacteria, including Escherichia coli, Aeromonas hydrophila, and Bacillus thuringiensis, as part of their arsenal of virulence factors, and are often cytotoxic. In particular, for α-PFTs, the membrane-spanning channel they form is composed of hydrophobic α-helices.

      • Bacterial pathogens
      • Vibrio
  6. Regulatory Evolution of the phoH Ancestral Gene in Salmonella enterica Serovar Typhimurium

    • Sat, 06/04/2022 - 04:00
    • Journal of Bacteriology
    • Journal of Bacteriology, Volume 204, Issue 5, May 2022. One important event for the divergence of Salmonella from Escherichia coli was the acquisition by horizontal transfer of the Salmonella pathogenicity island 1 (SPI-1), containing genes required for the invasion of host cells by Salmonella. HilD is an AraC-like transcriptional regulator in SPI-1 that induces the expression of the SPI-1 and many other acquired virulence genes located in other genomic regions of Salmonella.

      • Bacterial pathogens
      • Salmonella
  7. Staphylococcus aureus Does Not Synthesize Arginine from Proline under Physiological Conditions

    • Sat, 06/04/2022 - 04:00
    • Journal of Bacteriology
    • Journal of Bacteriology, Ahead of Print. The Gram-positive pathogen Staphylococcus aureus is the only bacterium known to synthesize arginine from proline via the arginine-proline interconversion pathway despite having genes for the well-conserved glutamate pathway. Since the proline-arginine interconversion pathway is repressed by CcpA-mediated carbon catabolite repression (CCR), CCR has been attributed to the arginine auxotrophy of S. aureus.

      • Bacterial pathogens
      • Staphylococcus aureus
  8. Direct cobamide remodeling via additional function of cobamide biosynthesis protein CobS from Vibrio cholerae

    • Tue, 05/25/2021 - 10:01
    • Journal of Bacteriology
    • Vitamin B12 belongs to a family of structurally-diverse cofactors with over a dozen natural analogs, collectively referred to as cobamides. Most bacteria encode cobamide-dependent enzymes, many of which can only utilize a subset of cobamide analogs. Some bacteria employ a mechanism called cobamide remodeling, a process in which cobamides are converted into other analogs, to ensure that compatible cobamides are available in the cell.

      • Vibrio
      • Bacterial pathogens
  9. Transcription of Cystathionine {beta}-lyase (MetC) is Repressed by HeuR in Campylobacter jejuni and Methionine Biosynthesis Facilitates Colonocyte Invasion

    • Tue, 05/18/2021 - 10:01
    • Journal of Bacteriology
    • A previously identified transcriptional regulator in C. jejuni, termed HeuR, was found to positively regulate heme utilization. Additionally, transcriptomic work demonstrated the putative operons, CJJ81176_1390-1394 and CJJ81176_1214-1217, were upregulated in a HeuR mutant, suggesting HeuR negatively regulates expression of these genes. Because genes within these clusters include a cystathionine β-lyase (metC) and a methionine synthase (metE), it appeared HeuR negatively regulates C.

      • Campylobacter
      • Bacterial pathogens
  10. Low cytoplasmic magnesium increases the specificity of the Lon and ClpAP proteases

    • Tue, 05/04/2021 - 10:02
    • Journal of Bacteriology
    • Proteolysis is a fundamental property of all living cells. In the bacterium Salmonella enterica serovar Typhimurium (S. Typhimurium), the HspQ protein controls the specificities of the Lon and ClpAP proteases. Upon acetylation, HspQ stops being a Lon substrate and no longer enhances proteolysis of the Lon substrate Hha.

      • Salmonella
      • Bacterial pathogens
  11. Inhibition of Escherichia coli lipoprotein diacylglyceryl transferase is insensitive to resistance caused by deletion of Brauns lipoprotein

    • Tue, 04/20/2021 - 10:01
    • Journal of Bacteriology
    • Lipoprotein diacylglyceryl transferase (Lgt) catalyzes the first step in the biogenesis of Gram-negative bacterial lipoproteins which play crucial roles in bacterial growth and pathogenesis. We demonstrate that Lgt depletion in a clinical uropathogenic Escherichia coli strain leads to permeabilization of the outer membrane and increased sensitivity to serum killing and antibiotics.

      • Bacterial pathogens
  12. A Tail Fiber Protein and a Receptor-Binding Protein Mediate ICP2 Bacteriophage Interactions with Vibrio cholerae OmpU

    • Tue, 04/20/2021 - 10:01
    • Journal of Bacteriology
    • ICP2 is a virulent bacteriophage (phage) that preys on Vibrio cholerae. ICP2 was first isolated from cholera patient stool samples. Some of these stools also contained ICP2-resistant isogenic V. cholerae strains harboring missense mutations in the trimeric outer membrane porin protein OmpU, identifying it as the ICP2 receptor.

      • Vibrio
      • Bacterial pathogens
  13. A trigger phosphodiesterase modulates the global c-di-GMP pool, motility and biofilm formation in Vibrio parahaemolyticus.

    • Tue, 04/13/2021 - 10:01
    • Journal of Bacteriology
    • Vibrio parahaemolyticus cells transit from free swimming to surface adapted lifestyles, such as swarming colonies and three-dimensional biofilms. These transitions are regulated by sensory modules and regulatory networks that involve the second messenger cyclic dimeric guanosine monophosphate (c-di-GMP). In this work, we show that a previously uncharacterized c-di-GMP phosphodiesterase (VP1881) from V. parahaemolyticus plays an important role in modulating the c-di-GMP pool.

      • Bacterial pathogens
      • Vibrio
  14. An extracytoplasmic function (ECF) sigma/anti-sigma factor system regulates hypochlorous acid resistance and impacts expression of the type IV secretion system in Brucella melitensis

    • Tue, 04/06/2021 - 10:01
    • Journal of Bacteriology
    • The intracellular bacterial pathogen Brucella causes persistent infections in various mammalian species. To survive and replicate within macrophages, these bacteria must be able to withstand oxidative stresses and express the type IV secretion system (T4SS) to evade host immune responses. The extracytoplasmic function (ECF) sigma factor system is a major signal transduction mechanism in bacteria that senses environmental cues and responds by regulating gene expression.

      • Bacterial pathogens
  15. Large metabolic rewiring from small genomic changes between strains of Shigella flexneri

    • Tue, 03/23/2021 - 10:02
    • Journal of Bacteriology
    • The instability of Shigella genomes has been described, but how this instability causes phenotypic differences within the Shigella flexneri species is largely unknown and likely variable. We describe herein the genome of S. flexneri strain PE577, originally a clinical isolate, which exhibits several phenotypic differences compared to the model strain 2457T. Like many previously described strains of S. flexneri, PE577 lacks discernible, functional CRISPR and restriction-modification systems.

      • Shigella
      • Bacterial pathogens
  16. Sensor Domain of Histidine Kinase VxrA of Vibrio cholerae- A Hairpin-swapped Dimer and its Conformational Change

    • Tue, 03/23/2021 - 10:02
    • Journal of Bacteriology
    • VxrA and VxrB are cognate histidine kinase (HK) - response regulator (RR) pairs of a two-component signaling system (TCS) found in Vibrio cholerae, a bacterial pathogen that causes cholera. The VxrAB TCS positively regulates virulence, the Type VI Secretion System, biofilm formation, and cell wall homeostasis in V. cholerae, providing protection from environmental stresses and contributing to the transmission and virulence of the pathogen.

      • Vibrio
      • Bacterial pathogens
  17. VirB, a key transcriptional regulator of virulence plasmid genes in Shigella flexneri, forms DNA-binding site dependent foci in the bacterial cytoplasm

    • Tue, 03/16/2021 - 10:02
    • Journal of Bacteriology
    • VirB is a key regulator of genes located on the large virulence plasmid (pINV) in the bacterial pathogen Shigella flexneri. VirB is unusual; it is not related to other transcriptional regulators, instead, it belongs to a family of proteins that primarily function in plasmid and chromosome partitioning; exemplified by ParB. Despite this, VirB does not function to segregate DNA, but rather counters transcriptional silencing mediated by the nucleoid structuring protein, H-NS.

      • Shigella
      • Bacterial pathogens
  18. Behind the shield of Czc: ZntR controls expression of the gene for the zinc-exporting P-type ATPase ZntA in Cupriavidus metallidurans

    • Tue, 03/09/2021 - 10:04
    • Journal of Bacteriology
    • In the metallophilic beta-proteobacterium Cupriavidus metallidurans, the plasmid-encoded Czc metal homeostasis system adjusts the periplasmic zinc, cobalt and cadmium concentration, which influences subsequent uptake of these metals into the cytoplasm. Behind this shield, the PIB2-type APTase ZntA is responsible for removal of surplus cytoplasmic zinc ions, thereby providing a second level of defense against toxic zinc concentrations.

      • Chemical contaminants
      • Heavy Metals
  19. Cra and CRP Have Opposing Roles in the Regulation of fruB in Vibrio cholerae

    • Tue, 03/02/2021 - 10:02
    • Journal of Bacteriology
    • The Gram-negative bacterium Vibrio cholerae adapts to changes in environment by selectively producing the necessary machinery to uptake and metabolize available carbohydrates. The import of fructose by the fructose-specific phosphoenolpyruvate (PEP) phosphotransferase system (PTS) is of particular interest because of its putative connection to cholera pathogenesis and persistence.

      • Vibrio
      • Bacterial pathogens
  20. Genome sequencing of an historic Staphylococcus aureus collection reveals new enterotoxin genes and sheds light on the evolution and genomic organisation of this key virulence gene family

    • Tue, 03/02/2021 - 10:02
    • Journal of Bacteriology
    • We take advantage of an historic collection of 133 Staphylococcus aureus strains accessioned between 1924 and 2016, whose genomes have been long-read sequenced as part of a major National Collection of Type Cultures (NCTC) initiative, to conduct a gene family-wide computational analysis of enterotoxin genes. We identify two novel Staphylococcal enterotoxin (pseudo)genes (sel29p and sel30), the former of which has not been observed in any contemporary strain to date.

      • Staphylococcus aureus
      • Bacterial pathogens
  21. Elements in the LftR repressor operator interface contributing to regulation of aurantimycin resistance in Listeria monocytogenes

    • Tue, 03/02/2021 - 10:02
    • Journal of Bacteriology
    • The bacterium Listeria monocyctogenes ubiquitously occurs in the environment, but can cause severe invasive disease in susceptible individuals when ingested. We recently identified the L. monocytogenes genes lieAB and lftRS, encoding a multi drug resistance ABC transporter and a regulatory module, respectively. These genes jointly mediate resistance against aurantimycin, an antibiotic produced by the soil-dwelling species Streptomyces aurantiacus, and thus contribute to survival of L.

      • Listeria monocytogenes
      • Bacterial pathogens
  22. Specificity and selective advantage of an exclusion system in theintegrative and conjugative element ICEBs1 of Bacillus subtilis

    • Tue, 03/02/2021 - 10:02
    • Journal of Bacteriology
    • Integrative and conjugative elements (ICEs) are mobile genetic elements capable of transferring their own and other DNA. They contribute to the spread of antibiotic resistances and other important traits for bacterial evolution. Exclusion is a mechanism used by many conjugative plasmids and a few ICEs to prevent their host cell from acquiring a second copy of the cognate element.

  23. Inactivation of the Pta-AckA pathway impairs fitness of Bacillus anthracis during overflow metabolism.

    • Wed, 02/17/2021 - 10:02
    • Journal of Bacteriology
    • Under conditions of glucose excess, aerobically growing bacteria predominantly direct carbon flux towards acetate fermentation, a phenomenon known as overflow metabolism or the bacterial ‘Crabtree effect’. Numerous studies of the major acetate-generating pathway, the Pta-AckA, revealed its important role in bacterial fitness through the control of central metabolism to sustain balanced growth and cellular homeostasis.

      • Staphylococcus aureus
      • Bacterial pathogens
  24. The Coxiella burnetii QpH1 plasmid is a virulence factor for colonizing bone marrow-derived murine macrophages

    • Tue, 02/09/2021 - 10:02
    • Journal of Bacteriology
    • Coxiella burnetii strains carry one of four large, conserved, autonomously replicating plasmids (QpH1, QpRS, QpDV, and QpDG) or a QpRS-like chromosomally integrated sequence of unknown function. Here we report the characterization of the QpH1 plasmid of C. burnetii Nine Mile phase II by making QpH1-deficient strains. A shuttle vector pQGK containing the CBUA0036-0039a region (predicted as being required for the QpH1 maintenance) was constructed.

      • Bacterial pathogens
  25. Holin-dependent secretion of the large clostridial toxin TpeL by Clostridium perfringens

    • Tue, 02/02/2021 - 10:03
    • Journal of Bacteriology
    • Large clostridial toxins (LCTs) are secreted virulence factors found in several species, including Clostridioides difficile, Clostridium perfringens, Paeniclostridium sordellii, and Clostridium novyi. LCTs are large toxins that lack a secretion signal sequence and studies by others have shown the LCTs of C. difficile, TcdA and TcdB, require a holin-like protein, TcdE, for secretion. The TcdE gene is located on the PaLoc pathogenicity locus of C.

      • Bacterial pathogens
      • Clostridium perfringens