scholarly journals Persistence of Salmonella enterica and Enterococcus faecium NRRL B-2354 on Baby Spinach Subjected to Temperature Abuse after Exposure to Sub-Lethal Stresses

Foods ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 2141
Author(s):  
Zhao Chen ◽  
Jianghong Meng
Keyword(s):  
Foodborne Pathogens ◽  
Enterococcus Faecium ◽  
Salmonella Enterica ◽  
Critical Role ◽  
Safety Margin ◽  
Prior Exposure ◽  
Wild Type ◽  
Potential Health ◽  
Sample Unit ◽  
Leafy Greens

The exposure of foodborne pathogens such as Salmonella enterica to a sub-lethal stress may protect bacterial cells against distinct stresses during the production of leafy greens, which can constitute potential health hazards to consumers. In this study, we evaluated how the prior exposure of S. enterica to sub-lethal food processing-related stresses influenced its subsequent persistence on baby spinach under cold (4 °C for 7 days) and temperature abuse (37 °C for 2 h + 4 °C for 7 days) conditions. We also compared the survival characteristics of pre-stressed S. enterica and Enterococcus faecium NRRL B-2354 as its surrogate on baby spinach. A cocktail of three S. enterica serovars, as well as S. Typhimurium ATCC 14028 wild type and its ΔrpoS mutant, and E. faecium NRRL B-2354, was first exposed to sub-lethal desiccation, oxidation, heat shock, and acid stresses. Afterward, baby spinach was inoculated with unstressed or pre-stressed cells at 7.0 log CFU/sample unit, followed by 7-day storage under cold and temperature abuse conditions. The unstressed S. enterica (fresh cells in sterile 0.85% saline) decreased rapidly within the first day and thereafter persisted around 5.5 log CFU/sample unit under both conditions. The desiccation-stressed S. enterica showed the highest bacterial counts (p < 0.05) compared to other conditions. The unstressed S. enterica survived better (p < 0.05) than the oxidation- and acid-stressed S. enterica, while there were no significant differences (p > 0.05) between the unstressed and heat-shocked S. enterica. Unlike the wild type, temperature abuse did not lead to the enhanced survival of the ΔrpoS mutant after exposure to desiccation stress, indicating that the rpoS gene could play a critical role in the persistence of desiccation-stressed S. enterica subjected to temperature abuse. E. faecium NRRL B-2354 was more persistent (p < 0.05) than the pre-stressed S. enterica under both conditions, suggesting its use as a suitable surrogate for pre-stressed S. enterica by providing a sufficient safety margin. Our results demonstrate the merit of considering the prior exposure of foodborne pathogens to sub-lethal stresses when validating the storage conditions for leafy greens.

scholarly journals Recent Progress in the Study of Peroxiredoxin in the Harmful Algal Bloom Species Chattonella marina

Antioxidants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 162
Author(s):  
Yohei Shimasaki ◽  
Koki Mukai ◽  
Yuki Takai ◽  
Xuchun Qiu ◽  
Yuji Oshima
Keyword(s):  
Oxidative Stress ◽  
Growth Phase ◽  
Critical Role ◽  
High Irradiance ◽  
Growth Potential ◽  
Exponential Growth Phase ◽  
Wild Type ◽  
Chattonella Marina ◽  
Strong Light ◽  
Expression Strain

Peroxiredoxin (Prx) is a relatively recently discovered antioxidant enzyme family that scavenges peroxides and is known to be present in organisms from biological taxa ranging from bacteria to multicellular eukaryotes, including photosynthetic organisms. Although there have been many studies of the Prx family in higher plants, green algae, and cyanobacteria, few studies have concerned raphidophytes and dinoflagellates, which are among the eukaryotic algae that cause harmful algal blooms (HABs). In our proteomic study using 2-D electrophoresis, we found a highly expressed 2-Cys peroxiredoxin (2-CysPrx) in the raphidophyte Chattonella marina var. antiqua, a species that induces mass mortality of aquacultured fish. The abundance of the C. marina 2-CysPrx enzyme was highest in the exponential growth phase, during which photosynthetic activity was high, and it then decreased by about a factor of two during the late stationary growth phase. This pattern suggested that 2-CysPrx is a key enzyme involved in the maintenance of high photosynthesis activity. In addition, the fact that the depression of photosynthesis by excessively high irradiance was more severe in the 2-CysPrx low-expression strain (wild type) than in the normal-expression strain (wild type) of C. marina suggested that 2-CysPrx played a critical role in protecting the cell from oxidative stress caused by exposure to excessively high irradiance. In the field of HAB research, estimates of growth potential have been desired to predict the population dynamics of HABs for mitigating damage to fisheries. Therefore, omics approaches have recently begun to be applied to elucidate the physiology of the growth of HAB species. In this review, we describe the progress we have made using a molecular physiological approach to identify the roles of 2-CysPrx and other antioxidant enzymes in mitigating environmental stress associated with strong light and high temperatures and resultant oxidative stress. We also describe results of a survey of expressed Prx genes and their growth-phase-dependent behavior in C. marina using RNA-seq analysis. Finally, we speculate about the function of these genes and the ecological significance of 2-CysPrx, such as its involvement in circadian rhythms and the toxicity of C. marina to fish.

scholarly journals Influence of Bacterial Competitors on Salmonella enterica and Enterohemorrhagic Escherichia coli Growth in Microbiological Media and Attachment to Vegetable Seeds

Foods ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 285
Author(s):  
Da Liu ◽  
Ronald Walcott ◽  
Kevin Mis Solval ◽  
Jinru Chen
Keyword(s):  
Escherichia Coli ◽  
Foodborne Pathogens ◽  
Salmonella Enterica ◽  
Lactobacillus Rhamnosus ◽  
Probiotic Bacterium ◽  
Enterohemorrhagic Escherichia Coli ◽  
Biocontrol Agents ◽  
Human Pathogens ◽  
Bacterial Strains ◽  
Pathogen Populations

Interests in using biological agents for control of human pathogens on vegetable seeds are rising. This study evaluated whether probiotic bacterium Lactobacillus rhamnosus GG, bacterial strains previously used as biocontrol agents in plant science, as well as a selected plant pathogen could compete with foodborne human pathogens, such as Salmonella enterica and enterohemorrhagic Escherichia coli (EHEC), for growth in microbiological media and attachment to vegetable seeds; and to determine whether the metabolites in cell-free supernatants of competitive bacterial spent cultures could inhibit the growth of the two pathogens. The results suggest that the co-presence of competitive bacteria, especially L. rhamnosus GG, significantly (p < 0.05) inhibited the growth of Salmonella and EHEC. Cell-free supernatants of L. rhamnosus GG cultures significantly reduced the pathogen populations in microbiological media. Although not as effective as L. rhamnosus GG in inhibiting the growth of Salmonella and EHEC, the biocontrol agents were more effective in competing for attachment to vegetable seeds. The study observed the inhibition of human bacterial pathogens by competitive bacteria or their metabolites and the competitive attachment to sprout seeds among all bacteria involved. The results will help strategize interventions to produce vegetable seeds and seed sprouts free of foodborne pathogens.

scholarly journals The critical role of T cells in glucocorticoid-induced osteoporosis

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Lin Song ◽  
Lijuan Cao ◽  
Rui Liu ◽  
Hui Ma ◽  
Yanan Li ◽  
...  
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
Steady State ◽  
Side Effects ◽  
Critical Role ◽  
Wild Type ◽  
Receptor Activator ◽  
Steady State Levels ◽  
Induced Apoptosis

AbstractGlucocorticoids (GC) are widely used clinically, despite the presence of significant side effects, including glucocorticoid-induced osteoporosis (GIOP). While GC are believed to act directly on osteoblasts and osteoclasts to promote osteoporosis, the detailed underlying molecular mechanism of GC-induced osteoporosis is still not fully elucidated. Here, we show that lymphocytes play a pivotal role in regulating GC-induced osteoporosis. We show that GIOP could not be induced in SCID mice that lack T cells, but it could be re-established by adoptive transfer of splenic T cells from wild-type mice. As expected, T cells in the periphery are greatly reduced by GC; instead, they accumulate in the bone marrow where they are protected from GC-induced apoptosis. These bone marrow T cells in GC-treated mice express high steady-state levels of NF-κB receptor activator ligand (RANKL), which promotes the formation and maturation of osteoclasts and induces osteoporosis. Taken together, these findings reveal a critical role for T cells in GIOP.

scholarly journals A network of Rab GTPases controls phagosome maturation and is modulated by Salmonella enterica serovar Typhimurium

2007 ◽  
Vol 176 (3) ◽  
pp. 263-268 ◽  
Author(s):  
Adam C. Smith ◽  
Won Do Heo ◽  
Virginie Braun ◽  
Xiuju Jiang ◽  
Chloe Macrae ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Dominant Negative ◽  
Rab Gtpases ◽  
Wild Type ◽  
Intracellular Growth ◽  
Non Invasive ◽  
Serovar Typhimurium ◽  
Guanosine Triphosphatase ◽  
Kinetics Of

Members of the Rab guanosine triphosphatase (GTPase) family are key regulators of membrane traffic. Here we examined the association of 48 Rabs with model phagosomes containing a non-invasive mutant of Salmonella enterica serovar Typhimurium (S. Typhimurium). This mutant traffics to lysosomes and allowed us to determine which Rabs localize to a maturing phagosome. In total, 18 Rabs associated with maturing phagosomes, each with its own kinetics of association. Dominant-negative mutants of Rab23 and 35 inhibited phagosome–lysosome fusion. A large number of Rab GTPases localized to wild-type Salmonella-containing vacuoles (SCVs), which do not fuse with lysosomes. However, some Rabs (8B, 13, 23, 32, and 35) were excluded from wild-type SCVs whereas others (5A, 5B, 5C, 7A, 11A, and 11B) were enriched on this compartment. Our studies demonstrate that a complex network of Rab GTPases controls endocytic progression to lysosomes and that this is modulated by S. Typhimurium to allow its intracellular growth.

Transfer of Salmonella enterica Serovar Typhimurium from Beef to Tomato through Kitchen Equipment and the Efficacy of Intermediate Decontamination Procedures

2016 ◽  
Vol 79 (7) ◽  
pp. 1252-1258 ◽  
Author(s):  
E. GKANA ◽  
A. LIANOU ◽  
G.-J. E. NYCHAS
Keyword(s):  
Foodborne Pathogens ◽  
Salmonella Enterica ◽  
Fruits And Vegetables ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Tap Water ◽  
Pathogenic Microorganisms ◽  
Cross Contamination ◽  
Raw Meat ◽  
Serovar Typhimurium ◽  
Cutting Boards

ABSTRACT It is well established that a high percentage of foodborne illness is caused by failure of consumers to prepare food in a hygienic manner. Indeed, a common practice in households is to use the same kitchen equipment for both raw meat and fresh produce. Such a practice may lead to cross-contamination of fruits and vegetables, which are mainly consumed without further processing, with pathogenic microorganisms originating from raw meat. The present study was performed to examine the transfer of the pathogenic bacterium Salmonella enterica serovar Typhimurium from inoculated beef fillets to tomatoes via contact with high-density polyethylene (PE), stainless steel (SS), and wooden (WD) surfaces and through cutting with SS knives. Furthermore, the following decontamination procedures were applied: (i) rinsing with tap water, (ii) scrubbing with tap water and liquid dish detergent, and (iii) using a commercial antibacterial spray. When surfaces and knives that came into contact with contaminated beef fillets were not cleaned prior to handling tomatoes, the lowest level of pathogen transfer to tomatoes was observed through PE surfaces. All of the decontamination procedures applied were more effective on knives than on surfaces, while among the surface materials tested, WD surfaces were the most difficult to decontaminate, followed by PE and SS surfaces. Mechanical cleaning with tap water and detergent was more efficient in decontaminating WD surfaces than using commercial disinfectant spray, followed by rinsing only with water. Specifically, reductions of 2.07 and 1.09 log CFU/cm2 were achieved by washing the WD surfaces with water and detergent and spraying the surfaces with an antibacterial product, respectively. Although the pathogen's populations on SS and PE surfaces, as well as on tomatoes, after both aforementioned treatments were under the detection limit, the surfaces were all positive after enrichment, and thus, the potential risk of cross-contamination cannot be overlooked. As demonstrated by the results of this study, washing or disinfection of kitchen equipment may not be sufficient to avoid cross-contamination of ready-to-eat foods with foodborne pathogens, depending on the decontamination treatment applied and the material of the surfaces treated. Therefore, separate cutting boards and knives should be used for processing raw meat and preparing ready-to-eat foods in order to enhance food safety.

scholarly journals Contribution of Target Gene Mutations and Efflux to Decreased Susceptibility of Salmonella enterica Serovar Typhimurium to Fluoroquinolones and Other Antimicrobials

2006 ◽  
Vol 51 (2) ◽  
pp. 535-542 ◽  
Author(s):  
Sheng Chen ◽  
Shenghui Cui ◽  
Patrick F. McDermott ◽  
Shaohua Zhao ◽  
David G. White ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Efflux Pump ◽  
Critical Role ◽  
Gene Mutations ◽  
Efflux Pumps ◽  
Fluoroquinolone Resistance ◽  
Naturally Occurring ◽  
Serovar Typhimurium ◽  
Resistant Mutants ◽  
Increased Susceptibility

ABSTRACT The mechanisms involved in fluoroquinolone resistance in Salmonella enterica include target alterations and overexpression of efflux pumps. The present study evaluated the role of known and putative multidrug resistance efflux pumps and mutations in topoisomerase genes among laboratory-selected and naturally occurring fluoroquinolone-resistant Salmonella enterica serovar Typhimurium strains. Strains with ciprofloxacin MICs of 0.25, 4, 32, and 256 μg/ml were derived in vitro using serovar Typhimurium S21. These mutants also showed decreased susceptibility or resistance to many nonfluoroquinolone antimicrobials, including tetracycline, chloramphenicol, and several β-lactams. The expression of efflux pump genes acrA, acrB, acrE, acrF, emrB, emrD, and mdlB were substantially increased (≥2-fold) among the fluoroquinolone-resistant mutants. Increased expression was also observed, but to a lesser extent, with three other putative efflux pumps: mdtB (yegN), mdtC (yegO), and emrA among mutants with ciprofloxacin MICs of ≥32 μg/ml. Deletion of acrAB or tolC in S21 and its fluoroquinolone-resistant mutants resulted in increased susceptibility to fluoroquinolones and other tested antimicrobials. In naturally occurring fluoroquinolone-resistant serovar Typhimurium strains, deletion of acrAB or tolC increased fluoroquinolone susceptibility 4-fold, whereas replacement of gyrA double mutations (S83F D87N) with wild-type gyrA increased susceptibility >500-fold. These results indicate that a combination of topoisomerase gene mutations, as well as enhanced antimicrobial efflux, plays a critical role in the development of fluoroquinolone resistance in both laboratory-derived and naturally occurring quinolone-resistant serovar Typhimurium strains.

Characterization of Enterococcus faecium mutants resistant to mundticin KS, a class IIa bacteriocin

Microbiology ◽  
2003 ◽  
Vol 149 (10) ◽  
pp. 2901-2908 ◽  
Author(s):  
Youko Sakayori ◽  
Mizuho Muramatsu ◽  
Satoshi Hanada ◽  
Yoichi Kamagata ◽  
Shinichi Kawamoto ◽  
...  
Keyword(s):  
Enterococcus Faecium ◽  
Antimicrobial Agents ◽  
Wild Type Strain ◽  
Unsaturated Fatty Acids ◽  
Class I ◽  
Wild Type ◽  
Food Preservatives ◽  
In The Wild ◽  
Resistant Mutants

The emergence and spread of mutants resistant to bacteriocins would threaten the safety of using bacteriocins as food preservatives. To determine the physiological characteristics of resistant mutants, mutants of Enterococcus faecium resistant to mundticin KS, a class IIa bacteriocin, were isolated. Two types of mutant were found that had different sensitivities to other antimicrobial agents such as nisin (class I) and kanamycin. Both mutants were resistant to mundticin KS even in the absence of Mg2+ ions. The composition of unsaturated fatty acids in the resistant mutants was significantly increased in the presence of mundticin KS. The composition of the phospholipids in the two resistant mutants also differed from those in the wild-type strain. The putative zwitterionic amino-containing phospholipid in both mutants significantly increased, whereas amounts of phosphatidylglycerol and cardiolipin decreased. These changes in membrane structure may influence resistance of enterococci to class IIa and class I bacteriocins.

scholarly journals OmpR and LeuO Positively Regulate the Salmonella enterica Serovar Typhi ompS2 Porin Gene

2004 ◽  
Vol 186 (10) ◽  
pp. 2909-2920 ◽  
Author(s):  
Marcos Fernández-Mora ◽  
José Luis Puente ◽  
Edmundo Calva
Keyword(s):  
Salmonella Enterica ◽  
Type Strain ◽  
Wild Type Strain ◽  
Phosphorylation Site ◽  
Regulatory Region ◽  
Random Mutagenesis ◽  
Fold Increase ◽  
Upstream Regulatory Region ◽  
Wild Type ◽  
Transposon Insertion

ABSTRACT The Salmonella enterica serovar Typhi ompS2 gene codes for a 362-amino-acid outer membrane protein that contains motifs common to the porin superfamily. It is expressed at very low levels compared to the major OmpC and OmpF porins, as observed for S. enterica serovar Typhi OmpS1, Escherichia coli OmpN, and Klebsiella pneumoniae OmpK37 quiescent porins. A region of 316 bp, between nucleotides −413 and −97 upstream of the transcriptional start point, is involved in negative regulation, as its removal resulted in a 10-fold increase in ompS2 expression in an S. enterica serovar Typhi wild-type strain. This enhancement in expression was not observed in isogenic mutant strains, which had specific deletions of the regulatory ompB (ompR envZ) operon. Furthermore, ompS2 expression was substantially reduced in the presence of the OmpR D55A mutant, altered in the major phosphorylation site. Upon random mutagenesis, a mutant where the transposon had inserted into the upstream regulatory region of the gene coding for the LeuO regulator, showed an increased level of ompS2 expression. Augmented expression of ompS2 was also obtained upon addition of cloned leuO to the wild-type strain, but not in an ompR isogenic derivative, consistent with the notion that the transposon insertion had increased the cellular levels of LeuO and with the observed dependence on OmpR. Moreover, LeuO and OmpR bound in close proximity, but independently, to the 5′ upstream regulatory region. Thus, the OmpR and LeuO regulators positively regulate ompS2.

scholarly journals The Capsule Encoding the viaB Locus Reduces Interleukin-17 Expression and Mucosal Innate Responses in the Bovine Intestinal Mucosa during Infection with Salmonella enterica Serotype Typhi

2007 ◽  
Vol 75 (9) ◽  
pp. 4342-4350 ◽  
Author(s):  
Manuela Raffatellu ◽  
Renato L. Santos ◽  
Daniela Chessa ◽  
R. Paul Wilson ◽  
Sebastian E. Winter ◽  
...  
Keyword(s):  
Mouse Model ◽  
Salmonella Enterica ◽  
Intestinal Inflammation ◽  
Fluid Secretion ◽  
Interleukin 17 ◽  
Loop Model ◽  
Wild Type ◽  
Ileal Loop ◽  
Chemokine Production

ABSTRACT The viaB locus contains genes for the biosynthesis and export of the Vi capsular antigen of Salmonella enterica serotype Typhi. Wild-type serotype Typhi induces less CXC chemokine production in tissue culture models than does an isogenic viaB mutant. Here we investigated the in vivo relevance of these observations by determining whether the presence of the viaB region prevents inflammation in two animal models of gastroenteritis. Unlike S. enterica serotype Typhimurium, serotype Typhi or a serotype Typhi viaB mutant did not elicit marked inflammatory changes in the streptomycin-pretreated mouse model. In contrast, infection of bovine ligated ileal loops with a serotype Typhi viaB mutant resulted in more fluid accumulation and higher expression of the chemokine growth-related oncogene alpha (GROα) and interleukin-17 (IL-17) than did infection with the serotype Typhi wild type. There was a marked upregulation of IL-17 expression in both the bovine ligated ileal loop model and the streptomycin-pretreated mouse model, suggesting that this cytokine is an important component of the inflammatory response to infection with Salmonella serotypes. Introduction of the cloned viaB region into serotype Typhimurium resulted in a significant reduction of GROα and IL-17 expression and in reduced fluid secretion. Our data support the idea that the viaB region plays a role in reducing intestinal inflammation in vivo.

scholarly journals The integrin coactivator Kindlin-2 plays a critical role in angiogenesis in mice and zebrafish

Blood ◽  
2011 ◽  
Vol 117 (18) ◽  
pp. 4978-4987 ◽  
Author(s):  
Elzbieta Pluskota ◽  
James J. Dowling ◽  
Natalie Gordon ◽  
Jeffrey A. Golden ◽  
Dorota Szpak ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Critical Role ◽  
Integrin Αvβ3 ◽  
Tube Formation ◽  
Basement Membranes ◽  
Cytoskeletal Protein ◽  
Integrin Expression ◽  
Partial Reduction ◽  
Wild Type ◽  
Developmental Defects

Abstract Kindlin-2, a widely distributed cytoskeletal protein, has been implicated in integrin activation, and its absence is embryonically lethal in mice and causes severe developmental defects in zebrafish. Knockdown of kindlin-2 levels in endothelial cells resulted in defective adhesive and migratory responses, suggesting that angiogenesis might be aberrant even with partial reduction of kindlin-2. This hypothesis has now been tested in the kindlin-2+/− mice. RM1 prostate tumors grown in kindlin-2+/− mice had fewer blood vessels, which were thinner and shorter and supported less tumor growth compared with wild-type littermates. The vessels that did form in the kindlin-2+/− mice lacked smooth muscle cells and pericytes and had thinner basement membranes, indicative of immature vessels. VEGF-induced angiogenesis in matrigel implants was also abnormal in the kindlin-2+/− mice. Vessels in the kindlin-2+/− mice were leaky, and BM transplantation from kindlin-2+/− to WT mice did not correct this defect. Endothelial cells derived from kindlin-2+/− mice had integrin expression levels similar to WT mice but reduced αVβ3-dependent signaling, migration, adhesion, spreading, and tube formation. Developmental angiogenesis was markedly impaired by kindlin-2 morpholinos in zebrafish. Taken together, kindlin-2 plays an important role in pathologic and developmental angiogenesis, which arises from defective activation of integrin αVβ3.

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