scholarly journals Give and Take: Salmonella Enterica Alters Macrosteles Quadrilineatus Feeding Behaviors Resulting in Altered S. Enterica Populations and Distribution on Leaves

2021 ◽  
Author(s):  
Victoria L. Harrod ◽  
Russell Groves ◽  
Ellie Guillemette ◽  
Jeri Barak
Keyword(s):  
Salmonella Enterica ◽  
Bacterial Colonization ◽  
Bacterial Pathogen ◽  
Feeding Preference ◽  
Cellular Damage ◽  
Feeding Behaviors ◽  
Bacterial Populations ◽  
Contaminated Irrigation Water ◽  
Pathogen Populations ◽  
Macrosteles Quadrilineatus

Abstract Hemipteran insects are ubiquitous inhabitants of the phyllosphere. Changes in microbial phyllosphere communities have recently been demonstrated following infestation by Macrosteles quadrilineatus (Aster Leafhopper). Although epiphytic Salmonella enterica populations naturally decline in the phyllosphere of plants, M. quadrilineatus infestation facilitated the growth of the bacterial pathogen populations. Here, we demonstrate that cellular damage by insect stylet penetration results in a localized beneficial niche on the leaf surface, leading to enhanced S. enterica populations. We measured S. enterica populations and colonization patterns on plants infested with Hemipterans with distinct feeding behaviors. M. quadrilineatus infestation resulted in higher solute leakage and significantly greater bacterial populations than plants absent of insects. Following immigration via contaminated irrigation water, the highest populations of S. enterica are naturally found on the tips of tomato leaflets. We discovered M. quadrilineatus feeding preference altered the natural distribution of S. enterica populations, and that the presence of S. enterica altered the distribution of probing attempts. These findings elucidate how cellular damage resulting from insect feeding drives changes in bacterial colonization of the phyllosphere.

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.

Bacterial colonization patterns of intactPinus sylvestrismycorrhizospheres in dry pine forest soil: an electron microscopy study

1997 ◽  
Vol 43 (11) ◽  
pp. 1017-1035 ◽  
Author(s):  
E. -L. Nurmiaho-Lassila ◽  
S. Timonen ◽  
K. Haahtela ◽  
R. Sen
Keyword(s):  
Electron Microscopy ◽  
Pinus Sylvestris ◽  
Forest Soil ◽  
Bacterial Colonization ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Paxillus Involutus ◽  
Intracellular Bacteria ◽  
Bacterial Populations ◽  
Suillus Bovinus

The bacterial populations associated with different plant and fungal habitats of intact Pinus sylvestris – Suillus bovinus or Pinus sylvestris – Paxillus involutus ectomycorrhizospheres grown in natural forest soil were examined by scanning and transmission electron microscopy. Surfaces of nonmycorrhizal Pinus sylvestris roots hosted large numbers of morphologically distinct bacteria. Bacteria were detected on the mantle surfaces and at inter- and intra-cellular locations in the mantle and Hartig net of Suillus bovinus mycorrhizas. The fungal strands were colonized by only a few bacteria unlike the outermost external fine hyphae on which extensive monolayers of bacteria were attached. The mycorrhizas of Paxillus involutus were mostly devoid of bacteria, but the intact external mycelium supported both bacterial colonies and solitary bacteria. Intracellular bacteria were not present in Paxillus involutus hyphae. In both mycorrhizal systems, bacterial aggregation and attachment to hyphae were mediated with electron-dense or -translucent material. Our study shows that the Pinus sylvestris mycorrhizospheres formed by two different ectomycorrhizal fungi are clearly dissimilar habitats for mycorrhizosphere-associated bacteria. Additionally, the spatially and physiologically defined mycorrhizosphere habitats were shown to host distinct populations of bacteria.Key words: ectomycorrhiza, intracellular bacteria, Paxillus involutus, soil bacteria, Suillus bovinus.

scholarly journals Crl Binds to Domain 2 of σS and Confers a Competitive Advantage on a Natural rpoS Mutant of Salmonella enterica Serovar Typhi

2010 ◽  
Vol 192 (24) ◽  
pp. 6401-6410 ◽  
Author(s):  
Véronique Monteil ◽  
Annie Kolb ◽  
Claudine Mayer ◽  
Sylviane Hoos ◽  
Patrick England ◽  
...  
Keyword(s):  
Competitive Advantage ◽  
Salmonella Enterica ◽  
Bacterial Population ◽  
Wild Type ◽  
Bacterial Populations ◽  
Salmonella Enterica Serovar Typhi ◽  
Bacterial Response ◽  
Modeled Structure ◽  
Rpos Mutant ◽  
Two Hybrid

ABSTRACTThe RpoS sigma factor (σS) is the master regulator of the bacterial response to a variety of stresses. Mutants inrpoSarise in bacterial populations in the absence of stress, probably as a consequence of a subtle balance between self-preservation and nutritional competence. We characterized here one naturalrpoSmutant ofSalmonella entericaserovar Typhi (Ty19). We show that therpoSallele of Ty19 (rpoSTy19) led to the synthesis of a σSTy19protein carrying a single glycine-to-valine substitution at position 282 in σSdomain 4, which was much more dependent than the wild-type σSprotein on activation by Crl, a chaperone-like protein that increases the affinity of σSfor the RNA polymerase core enzyme (E). We used the bacterial adenylate cyclase two-hybrid system to demonstrate that Crl bound to residues 72 to 167 of σSdomain 2 and that G282V substitution did not directly affect Crl binding. However, this substitution drastically reduced the ability of σSTy19to bind E in a surface plasmon resonance assay, a defect partially rescued by Crl. The modeled structure of the EσSholoenzyme suggested that substitution G282V could directly disrupt a favorable interaction between σSand E. TherpoSTy19allele conferred a competitive fitness when the bacterial population was wild type forcrlbut was outcompeted in Δcrlpopulations. Thus, these results indicate that the competitive advantage of therpoSTy19mutant is dependent on Crl and suggest thatcrlplays a role in the appearance ofrpoSmutants in bacterial populations.

scholarly journals A Salmonella enterica Serovar Typhimurium Translocated Leucine-Rich Repeat Effector Protein Inhibits NF-κB-Dependent Gene Expression

2003 ◽  
Vol 71 (7) ◽  
pp. 4052-4058 ◽  
Author(s):  
Andrea Haraga ◽  
Samuel I. Miller
Keyword(s):  
Gene Expression ◽  
Salmonella Enterica ◽  
Mammalian Cells ◽  
Inflammatory Responses ◽  
Bacterial Colonization ◽  
Shigella Flexneri ◽  
Nuclear Factor Κb ◽  
Effector Proteins ◽  
Activator Protein 1 ◽  
Serovar Typhimurium

ABSTRACT Nontyphoidal salmonellae are enteric pathogens that cause acute gastroenteritis and colonize the intestinal tract for prolonged periods. In the intestinal epithelia, these bacteria induce secretion of proinflammatory cytokines, such as interleukin-8 (IL-8), which leads to a profound inflammatory response through recruitment of polymorphonuclear leukocytes. Production of IL-8 induced by Salmonella spp. is due to the activation of the transcription factors nuclear factor κB (NF-κB) and activator protein-1 (AP-1). This work demonstrates that Salmonella enterica serovar Typhimurium can downmodulate IL-8 production after invasion of intestinal epithelial cells. The Salmonella translocated effector proteins SspH1 and SptP participate in this process. SspH1 is a member of the bacterial LPX repeat protein family that localizes to the mammalian nucleus and inhibits NF-κB-dependent gene expression. A Shigella flexneri translocated effector, IpaH9.8, which has a similar structure and subcellular localization in mammalian cells, also inhibits NF-κB-dependent gene expression. We propose that suppression of inflammatory responses by intracellular S. enterica serovar Typhimurium, and perhaps Shigella flexneri, contributes to bacterial colonization of host tissues and pathogenesis.

scholarly journals Transmission of Xylella fastidiosa to Grapevine by the Meadow Spittlebug

2016 ◽  
Vol 106 (11) ◽  
pp. 1285-1290 ◽  
Author(s):  
D. Cornara ◽  
A. Sicard ◽  
A. R. Zeilinger ◽  
F. Porcelli ◽  
A. H. Purcell ◽  
...  
Keyword(s):  
Xylella Fastidiosa ◽  
Transmission Efficiency ◽  
Access Time ◽  
Insect Vectors ◽  
Bacterial Populations ◽  
Plant Infection ◽  
Basic Parameters ◽  
Pathogen Populations ◽  
The Relationship ◽  
Meadow Spittlebug

There is little information available on Xylella fastidiosa transmission by spittlebugs (Hemiptera, Cercopoidea). This group of insect vectors may be of epidemiological relevance in certain diseases, so it is important to better understand the basic parameters of X. fastidiosa transmission by spittlebugs. We used grapevines as a host plant and the aphrophorid Philaenus spumarius as a vector to estimate the effect of plant access time on X. fastidiosa transmission to plants; in addition, bacterial population estimates in the heads of vectors were determined and correlated with plant infection status. Results show that transmission efficiency of X. fastidiosa by P. spumarius increased with plant access time, similarly to insect vectors in another family (Hemiptera, Cicadellidae). Furthermore, a positive correlation between pathogen populations in P. spumarius and transmission to plants was observed. Bacterial populations in insects were one to two orders of magnitude lower than those observed in leafhopper vectors, and population size peaked within 3 days of plant access period. These results suggest that P. spumarius has either a limited number of sites in the foregut that may be colonized, or that fluid dynamics in the mouthparts of these insects is different from that in leafhoppers. Altogether our results indicate that X. fastidiosa transmission by spittlebugs is similar to that by leafhoppers. In addition, the relationship between cell numbers in vectors and plant infection may have under-appreciated consequences to pathogen spread.

scholarly journals Disturbance opens recruitment sites for bacterial colonization in activated sludge

2015 ◽  
Author(s):  
David Vuono ◽  
Junko Munakata Marr ◽  
John Spear ◽  
Jörg Drewes
Keyword(s):  
Activated Sludge ◽  
Bacterial Colonization ◽  
Immigrant Community ◽  
Community Members ◽  
Bacterial Populations ◽  
Operational Conditions ◽  
Local Diversity ◽  
Disturbance Gradient ◽  
Solids Retention ◽  
Microbial Resource Management

Little is known about the role of immigration in shaping bacterial communities or the factors that may dictate success or failure of colonization by bacteria from regional species pools. To address these knowledge gaps, the influence of bacterial colonization into an ecosystem (activated sludge bioreactor) was measured through a disturbance gradient (successive decreases in the parameter solids retention time) relative to stable operational conditions. Through a DNA sequencing approach, we show that the most abundant bacteria within the immigrant community have a greater probability of colonizing the receiving ecosystem, but mostly as low abundance community members. Only during the disturbance do some of these bacterial populations significantly increase in abundance beyond background levels and in few cases become dominant community members post-disturbance. Two mechanisms facilitate the enhanced enrichment of immigrant populations during disturbance: 1) the availability of resources left unconsumed by established species and 2) the increased availability of niche space for colonizers to establish and displace resident populations. Thus, as a disturbance decreases local diversity, recruitment sites become available to promote colonization. This work advances our understanding of microbial resource management and diversity maintenance in complex ecosystems.

scholarly journals Lung Microbiome in Critically Ill Patients

Life ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 7
Author(s):  
Mélanie Fromentin ◽  
Jean-Damien Ricard ◽  
Damien Roux
Keyword(s):  
Acute Respiratory Distress Syndrome ◽  
Respiratory Distress Syndrome ◽  
Respiratory Distress ◽  
Distress Syndrome ◽  
Bacterial Pathogen ◽  
Normal Lung ◽  
Ventilator Associated Pneumonia ◽  
Bacterial Populations ◽  
Chronic Respiratory Diseases

The historical hypothesis of sterility of the lungs was invalidated over a decade ago when studies demonstrated the existence of sparse but very diverse bacterial populations in the normal lung and the association between pulmonary dysbiosis and chronic respiratory diseases. Under mechanical ventilation, dysbiosis occurs rapidly with a gradual decline in diversity over time and the progressive predominance of a bacterial pathogen (mainly Proteobacteria) when lung infection occurs. During acute respiratory distress syndrome, an enrichment in bacteria of intestinal origin, mainly Enterobacteriaceae, is observed. However, the role of this dysbiosis in the pathogenesis of ventilator-associated pneumonia and acute respiratory distress syndrome is not yet fully understood. The lack of exploration of other microbial populations, viruses (eukaryotes and prokaryotes) and fungi is a key issue. Further analysis of the interaction between these microbial kingdoms and a better understanding of the host-microbiome interaction are necessary to fully elucidate the role of the microbiome in the pathogenicity of acute diseases. The validation of a consensual and robust methodology in order to make the comparison of the different studies relevant is also required. Filling these different gaps should help develop preventive and therapeutic strategies for both acute respiratory distress syndrome and ventilator-associated pneumonia.

scholarly journals Machine learning identifies signatures of host adaptation in the bacterial pathogen Salmonella enterica

2017 ◽  
Author(s):  
Nicole E. Wheeler ◽  
Paul P. Gardner ◽  
Lars Barquist
Keyword(s):  
Random Forest ◽  
Host Range ◽  
Salmonella Enterica ◽  
Bacterial Pathogen ◽  
Host Adaptation ◽  
Random Forest Classifier ◽  
Sub Saharan Africa ◽  
Broad Host Range ◽  
Invasive Infection ◽  
Emerging Pathogens

AbstractEmerging pathogens are a major threat to public health, however understanding how pathogens adapt to new niches remains a challenge. New methods are urgently required to provide functional insights into pathogens from the massive genomic data sets now being generated from routine pathogen surveillance for epidemiological purposes. Here, we measure the burden of atypical mutations in protein coding genes across independently evolved Salmonella enterica lineages, and use these as input to train a random forest classifier to identify strains associated with extraintestinal disease. Members of the species fall along a continuum, from pathovars which cause gastrointestinal infection and low mortality, associated with a broad host-range, to those that cause invasive infection and high mortality, associated with a narrowed host range. Our random forest classifier learned to perfectly discriminate long-established gastrointestinal and invasive serovars of Salmonella. Additionally, it was able to discriminate recently emerged Salmonella Enteritidis and Typhimurium lineages associated with invasive disease in immunocompromised populations in sub-Saharan Africa, and within-host adaptation to invasive infection. We dissect the architecture of the model to identify the genes that were most informative of phenotype, revealing a common theme of degradation of metabolic pathways in extraintestinal lineages. This approach accurately identifies patterns of gene degradation and diversifying selection specific to invasive serovars that have been captured by more labour-intensive investigations, but can be readily scaled to larger analyses.

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