scholarly journals Identification and Characterization of Cronobacter Iron Acquisition Systems

2012 ◽  
Vol 78 (17) ◽  
pp. 6035-6050 ◽  
Author(s):  
C. J. Grim ◽  
M. H. Kothary ◽  
G. Gopinath ◽  
K. G. Jarvis ◽  
J. Jean-Gilles Beaubrun ◽  
...  
Keyword(s):  
Plant Pathogens ◽  
Iron Acquisition ◽  
Natural Habitat ◽  
Clinical Samples ◽  
Powdered Infant Formula ◽  
Bacterial Strains ◽  
Emerging Pathogens ◽  
Content Type ◽  
Virulence Potential ◽  
Genes Encoding

ABSTRACTCronobacterspp. are emerging pathogens that cause severe infantile meningitis, septicemia, or necrotizing enterocolitis. Contaminated powdered infant formula has been implicated as the source ofCronobacterspp. in most cases, but questions still remain regarding the natural habitat and virulence potential for each strain. The iron acquisition systems in 231Cronobacterstrains isolated from different sources were identified and characterized. AllCronobacterspp. have both the Feo and Efe systems for acquisition of ferrous iron, and all plasmid-harboring strains (98%) have the aerobactin-like siderophore, cronobactin, for transport of ferric iron. AllCronobacterspp. have the genes encoding an enterobactin-like siderophore, although it was not functional under the conditions tested. Furthermore, allCronobacterspp. have genes encoding five receptors for heterologous siderophores. A ferric dicitrate transport system (fecsystem) is encoded specifically by a subset ofCronobacter sakazakiiandC. malonaticusstrains, of which a high percentage were isolated from clinical samples. Phylogenetic analysis confirmed that thefecsystem is most closely related to orthologous genes present in human-pathogenic bacterial strains. Moreover, all strains ofC. dublinensisandC. muytjensiiencode two receptors, FcuA and Fct, for heterologous siderophores produced by plant pathogens. Identification of putative Fur boxes and expression of the genes under iron-depleted conditions revealed which genes and operons are components of the Fur regulon. Taken together, these results support the proposition thatC. sakazakiiandC. malonaticusmay be more associated with the human host andC. dublinensisandC. muytjensiiwith plants.

scholarly journals Genomic investigation of clinically significant coagulase-negative staphylococci

2021 ◽  
Author(s):  
Kevin Cole ◽  
Bridget Atkins ◽  
Martin Llewelyn ◽  
John Paul
Keyword(s):  
High Resolution ◽  
Genomic Analysis ◽  
Staphylococcal Infection ◽  
Clinical Samples ◽  
Future Research ◽  
Emerging Pathogens ◽  
Coagulase Negative Staphylococci ◽  
Content Type ◽  
History Of ◽  
Clinically Significant

Introduction. Coagulase-negative staphylococci have been recognized both as emerging pathogens and contaminants of clinical samples. High-resolution genomic investigation may provide insights into their clinical significance. Aims. To review the literature regarding coagulase-negative staphylococcal infection and the utility of genomic methods to aid diagnosis and management, and to identify promising areas for future research. Methodology. We searched Google Scholar with the terms ( Staphylococcus ) AND (sequencing OR (infection)). We prioritized papers that addressed coagulase-negative staphylococci, genomic analysis, or infection. Results. A number of studies have investigated specimen-related, phenotypic and genetic factors associated with colonization, infection and virulence, but diagnosis remains problematic. Conclusion. Genomic investigation provides insights into the genetic diversity and natural history of colonization and infection. Such information allows the development of new methodologies to identify and compare relatedness and predict antimicrobial resistance. Future clinical studies that employ suitable sampling frames coupled with the application of high-resolution whole-genome sequencing may aid the development of more discriminatory diagnostic approaches to coagulase-staphylococcal infection.

scholarly journals Proteolytic Processing, Maturation, and Unique Synteny of the Streptomyces Hemagglutinin SHA

2021 ◽  
Author(s):  
Yoko Fujita-Yamaguchi ◽  
Hideyuki Muramatsu ◽  
Alonso Tapia ◽  
Karine Bagramyan ◽  
Moksha Desai ◽  
...  
Keyword(s):  
Proteolytic Processing ◽  
Bacterial Strains ◽  
Content Type ◽  
Streptomyces Lavendulae ◽  
Homologous Genes ◽  
Genes Encoding

Lectins are extremely useful molecules for the study of glycans and carbohydrates. Here, we show that homologous genes encoding the l -rhamnose- and d -galactose-binding lectins, SHAs, are present in multiple bacterial strains, genetically related to Streptomyces lavendulae .

scholarly journals Comparative genomics of Salmonella enterica subsp. diarizonae serovar 61:k:1,5,(7) reveals lineage-specific host adaptation of ST432

2021 ◽  
Vol 7 (8) ◽  
Author(s):  
Laura Uelze ◽  
Maria Borowiak ◽  
Carlus Deneke ◽  
Jennie Fischer ◽  
Antje Flieger ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Iron Acquisition ◽  
Sampling Period ◽  
Clinical Samples ◽  
Source Information ◽  
Content Type ◽  
Link Type ◽  
Type Iv ◽  
Genetic Features ◽  
Sequence Types

Unlike most Salmonella enterica subsp. diarizonae , which are predominantly associated with cold-blooded animals such as reptiles, the serovar IIIb 61:k:1,5,(7) (termed SASd) is regarded as host-adapted to sheep. The bacterium is rarely associated with disease in humans but, nevertheless, SASd isolates are sporadically obtained from human clinical samples. It is unclear whether these transmissions are directly linked to sheep or whether transmissions may, for example, occur through other domestic animals also carrying SASd. For this reason, we utilized whole-genome sequencing to investigate a set of 119 diverse SASd isolates, including sheep-associated and human-associated isolates, as well as isolates obtained from other matrices. We discovered that serovar IIIb 61:k:1,5,(7) is composed of two distinct lineages defined by their sequence types ST432 and ST439. These two lineages are distinguished by a number of genetic features, as well as their prevalence and reservoir. ST432 appears to be the more prevalent sequence type, with the majority of isolates investigated in this study belonging to ST432. In contrast, only a small number of isolates were attributed to ST439. While ST432 isolates were of sheep, human or other origin, all ST439 isolates with source information available, were obtained from human clinical samples. Regarding their genetic features, lineage ST432 shows increased pseudogenization, harbours a virB/D4 plasmid that encodes a type IV secretion system (T4SS) and does not possess the iro gene cluster, which encodes a salmochelin siderophore for iron acquisition. These characteristics likely contribute to the ability of ST432 to persistently colonize the intestines of sheep. Furthermore, we found isolates of the lineage ST432 to be highly clonal, with little variation over the sampling period of almost 20 years. We conclude from the genomic comparisons that SASd underlies a microevolutionary process and that it is specifically lineage ST432 that should be considered as host-adapted to sheep.

scholarly journals Borrelia Host Adaptation Protein (BadP) Is Required for the Colonization of a Mammalian Host by the Agent of Lyme Disease

2018 ◽  
Vol 86 (7) ◽  
Author(s):  
Trever C. Smith ◽  
Sarah M. Helm ◽  
Yue Chen ◽  
Ying-Han Lin ◽  
S. L. Rajasekhar Karna ◽  
...  
Keyword(s):  
Gene Expression ◽  
Lyme Disease ◽  
Immunoblot Analysis ◽  
Growth Defect ◽  
Mammalian Host ◽  
Content Type ◽  
Magnesium Chelatase ◽  
Virulence Potential ◽  
Genes Encoding

ABSTRACT Borrelia burgdorferi , the agent of Lyme disease (LD), uses host-derived signals to modulate gene expression during the vector and mammalian phases of infection. Microarray analysis of mutants lacking the B orrelia host ad aptation r egulator (BadR) revealed the downregulation of genes encoding enzymes whose role in the pathophysiology of B. burgdorferi is unknown. Immunoblot analysis of the badR mutants confirmed reduced levels of these enzymes, and one of these enzymes, encoded by bb0086 , shares homology to prokaryotic magnesium chelatase and Lon-type proteases. The BB0086 levels in B. burgdorferi were higher under conditions mimicking those in fed ticks. Mutants lacking bb0086 had no apparent in vitro growth defect but were incapable of colonizing immunocompetent C3H/HeN or immunodeficient SCID mice. Immunoblot analysis revealed reduced levels of proteins critical for the adaptation of B. burgdorferi to the mammalian host, such as OspC, DbpA, and BBK32. Both RpoS and BosR, key regulators of gene expression in B. burgdorferi , were downregulated in the bb0086 mutants. Therefore, we designated BB0086 the B orrelia host ad aptation p rotein (BadP). Unlike badP mutants, the control strains established infection in C3H/HeN mice at 4 days postinfection, indicating an early colonization defect in mutants due to reduced levels of the lipoproteins/regulators critical for initial stages of infection. However, badP mutants survived within dialysis membrane chambers (DMCs) implanted within the rat peritoneal cavity but, unlike the control strains, did not display complete switching of OspA to OspC, suggesting incomplete adaptation to the mammalian phase of infection. These findings have opened a novel regulatory mechanism which impacts the virulence potential of B . burgdorferi .

scholarly journals Growth of Aerobic Ripening Bacteria at the Cheese Surface Is Limited by the Availability of Iron

2012 ◽  
Vol 78 (9) ◽  
pp. 3185-3192 ◽  
Author(s):  
Christophe Monnet ◽  
Alexandre Back ◽  
Françoise Irlinger
Keyword(s):  
Iron Acquisition ◽  
Microbial Interactions ◽  
Limiting Factor ◽  
Iron Availability ◽  
Content Type ◽  
Desferrioxamine B ◽  
Reverse Transcription Pcr ◽  
Abc Transport ◽  
Expression Of Genes ◽  
Genes Encoding

ABSTRACTThe microflora on the surface of smear-ripened cheeses is composed of various species of bacteria and yeasts that contribute to the production of the desired organoleptic properties. The objective of the present study was to show that iron availability is a limiting factor in the growth of typical aerobic ripening bacteria in cheese. For that purpose, we investigated the effect of iron or siderophore addition in model cheeses that were coinoculated with a yeast and a ripening bacterium. Both iron and the siderophore desferrioxamine B stimulated the growth of ripening bacteria belonging to the generaArthrobacter,Corynebacterium, andBrevibacterium. The extent of stimulation was strain dependent, and generally, the effect of desferrioxamine B was greater than that of iron. Measurements of the expression of genes related to the metabolism of iron byArthrobacter arilaitensisRe117 by real-time reverse transcription-PCR showed that these genes were transcribed during growth in cheese. The addition of desferrioxamine B increased the expression of two genes encoding iron-siderophore ABC transport binding proteins. The addition of iron decreased the expression of siderophore biosynthesis genes and of part of the genes encoding iron-siderophore ABC transport components. It was concluded that iron availability is a limiting factor in the growth of typical cheese surface bacteria. The selection of strains with efficient iron acquisition systems may be useful for the development of defined-strain surface cultures. Furthermore, the importance of iron metabolism in the microbial ecology of cheeses should be investigated since it may result in positive or negative microbial interactions.

scholarly journals Biochemical Characteristics, Adhesion, and Cytotoxicity of Environmental and Clinical Isolates of Herbaspirillum spp.

2014 ◽  
Vol 53 (1) ◽  
pp. 302-308 ◽  
Author(s):  
Ana C. Q. Marques ◽  
Katia S. Paludo ◽  
Cibelle B. Dallagassa ◽  
Monica Surek ◽  
Fábio O. Pedrosa ◽  
...  
Keyword(s):  
Plant Growth Promoting Rhizobacteria ◽  
Eukaryotic Cells ◽  
Clinical Samples ◽  
Environmental Isolates ◽  
Biochemical Tests ◽  
Cytotoxic Effects ◽  
Content Type ◽  
Virulence Potential ◽  
Plant Growth Promoting ◽  
Growth Promoting

Herbaspirillumbacteria are best known as plant growth-promoting rhizobacteria but have also been recovered from clinical samples. Here, biochemical tests, matrix-assisted laser deionization–time of flight (MALDI-TOF) mass spectrometry, adherence, and cytotoxicity to eukaryotic cells were used to compare clinical and environmental isolates ofHerbaspirillumspp. Discrete biochemical differences were observed between human and environmental strains. All strains adhered to HeLa cells at low densities, and cytotoxic effects were discrete, supporting the view thatHerbaspirillumbacteria are opportunists with low virulence potential.

scholarly journals Acidovorax pan-genome reveals specific functional traits for plant beneficial and pathogenic plant-associations

2021 ◽  
Vol 7 (12) ◽  
Author(s):  
Roberto Siani ◽  
Georg Stabl ◽  
Caroline Gutjahr ◽  
Michael Schloter ◽  
Viviane Radl
Keyword(s):  
Plant Growth ◽  
Plant Pathogens ◽  
Growth Promotion ◽  
Lotus Japonicus ◽  
Bacterial Strains ◽  
Secretion Systems ◽  
Free Living ◽  
Single Strain ◽  
Content Type ◽  
Link Type

Beta-proteobacteria belonging to the genus Acidovorax have been described from various environments. Many strains can interact with a range of hosts, including humans and plants, forming neutral, beneficial or detrimental associations. In the frame of this study, we investigated the genomic properties of 52 bacterial strains of the genus Acidovorax , isolated from healthy roots of Lotus japonicus, with the intent of identifying traits important for effective plant-growth promotion. Based on single-strain inoculation bioassays with L. japonicus, performed in a gnotobiotic system, we distinguished seven robust plant-growth promoting strains from strains with no significant effects on plant-growth. We showed that the genomes of the two groups differed prominently in protein families linked to sensing and transport of organic acids, production of phytohormones, as well as resistance and production of compounds with antimicrobial properties. In a second step, we compared the genomes of the tested isolates with those of plant pathogens and free-living strains of the genus Acidovorax sourced from public repositories. Our pan-genomics comparison revealed features correlated with commensal and pathogenic lifestyle. We showed that commensals and pathogens differ mostly in their ability to use plant-derived lipids and in the type of secretion-systems being present. Most free-living Acidovorax strains did not harbour any secretion-systems. Overall, our data indicate that Acidovorax strains undergo extensive adaptations to their particular lifestyle by horizontal uptake of novel genetic information and loss of unnecessary genes.

scholarly journals Intramuscular Immunization of Mice with a Live-Attenuated Triple Mutant of Yersinia pestis CO92 Induces Robust Humoral and Cell-Mediated Immunity To Completely Protect Animals against Pneumonic Plague

2015 ◽  
Vol 22 (12) ◽  
pp. 1255-1268 ◽  
Author(s):  
Bethany L. Tiner ◽  
Jian Sha ◽  
Duraisamy Ponnusamy ◽  
Wallace B. Baze ◽  
Eric C. Fitts ◽  
...  
Keyword(s):  
Yersinia Pestis ◽  
Cell Mediated Immunity ◽  
Interleukin 17 ◽  
Triple Mutant ◽  
Pneumonic Plague ◽  
Content Type ◽  
Virulence Potential ◽  
Genes Encoding ◽  
Subsequent Exposure ◽  
Vaccine Potential

ABSTRACTEarlier, we showed that the ΔlppΔmsbBΔailtriple mutant ofYersinia pestisCO92 with deleted genes encoding Braun lipoprotein (Lpp), an acyltransferase (MsbB), and the attachment invasion locus (Ail), respectively, was avirulent in a mouse model of pneumonic plague. In this study, we further evaluated the immunogenic potential of the ΔlppΔmsbBΔailtriple mutant and its derivative by different routes of vaccination. Mice were immunized via the subcutaneous (s.c.) or the intramuscular (i.m.) route with two doses (2 × 106CFU/dose) of the above-mentioned triple mutant with 100% survivability of the animals. Upon subsequent pneumonic challenge with 70 to 92 50% lethal doses (LD50) of wild-type (WT) strain CO92, all of the mice survived when immunization occurred by the i.m. route. Since Ail has virulence and immunogenic potential, a mutated version of Ail devoid of its virulence properties was created, and the genetically modifiedailreplaced the nativeailgene on the chromosome of the ΔlppΔmsbBdouble mutant, creating a ΔlppΔmsbB::ailL2vaccine strain. This newly generated mutant was attenuated similarly to the ΔlppΔmsbBΔailtriple mutant when administered by the i.m. route and provided 100% protection to animals against subsequent pneumonic challenge. Not only were the two above-mentioned mutants cleared rapidly from the initial i.m. site of injection in animals with no histopathological lesions, the immunized mice did not exhibit any disease symptoms during immunization or after subsequent exposure to WT CO92. These two mutants triggered balanced Th1- and Th2-based antibody responses and cell-mediated immunity. A substantial increase in interleukin-17 (IL-17) from the T cells of vaccinated mice, a cytokine of the Th17 cells, further augmented their vaccine potential. Thus, the ΔlppΔmsbBΔailand ΔlppΔmsbB::ailL2mutants represent excellent vaccine candidates for plague, with the latter mutant still retaining Ail immunogenicity but with a much diminished virulence potential.

Three novel species of the Bacillus cereus group isolated from clinical samples in Japan

2021 ◽  
Vol 71 (9) ◽  
Author(s):  
Mari Tohya ◽  
Tomomi Hishinuma ◽  
Shin Watanabe ◽  
Masahito Shimojima ◽  
Miho Ogawa ◽  
...  
Keyword(s):  
Bacillus Cereus ◽  
Type Strain ◽  
Type Species ◽  
Novel Species ◽  
Clinical Samples ◽  
Rrna Gene ◽  
Bacterial Strains ◽  
Phenotypic Data ◽  
Content Type ◽  
Link Type

Three Gram-positive bacterial strains, BML-BC004, BML-BC017 and BML-BC059, isolated from blood samples from three inpatients in Japan, were identified as members of Bacillus cereus using matrix-assisted laser desorption ionization time-of-flight MS. The 16S rRNA gene sequences of these three strains were more than 97.1 % similar to 18 type strains belonging to the B. cereus group. Whole-genome comparisons, using average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH), confirmed that the three strains represented three individual distinct species belonging to the B. cereus group. A phylogenetic tree showed that BML-BC004, BML-BC017 and BML-BC059 were located close to B. luti , B. mobilis and B. paramycoides , respectively. Based on these phylogenetic and phenotypic data, including values below the threshold for ANI and dDDH, the three strains should be classified as representing three different novel species of the B. cereus group: Bacillus sanguinis sp. nov., with type strain BML-BC004T (=DSM 111102T=JCM 34122T), Bacillus paramobilis sp. nov., with type strain BML-BC017T (=DSM 111100T=JCM 34124T) and Bacillus hominis sp. nov., with type strain BML-BC059T (=DSM 111101T=JCM 34125T).

Non-O157 Shiga Toxin–Producing Escherichia coli in Foods

2010 ◽  
Vol 73 (9) ◽  
pp. 1721-1736 ◽  
Author(s):  
EMILY C. MATHUSA ◽  
YUHUAN CHEN ◽  
ELENA ENACHE ◽  
LLOYD HONTZ
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Practical Method ◽  
The United States ◽  
Control Measures ◽  
Clinical Samples ◽  
Emerging Pathogens ◽  
Virulence Potential ◽  
Detection And Identification ◽  
Substantial Progress

Non-O157 Shiga toxin–producing Escherichia coli (STEC) strains have been linked to outbreaks and sporadic cases of illness worldwide. Illnesses linked to STEC serotypes other than O157:H7 appear to be on the rise in the United States and worldwide, indicating that some of these organisms may be emerging pathogens. As more laboratories are testing for these organisms in clinical samples, more cases are uncovered. Some cases of non-O157 STEC illness appear to be as severe as cases associated with O157, although in general cases attributed to non-O157 are less severe. There is much variation in virulence potential within STEC serotypes, and many may not be pathogenic. Of more than 400 serotypes isolated, fewer than 10 serotypes cause the majority of STEC-related human illnesses. Various virulence factors are involved in non-O157 STEC pathogenicity; the combined presence of both eae and stx genes has been associated with enhanced virulence. A scientific definition of a pathogenic STEC has not yet been accepted. Several laboratories have attempted to develop detection and identification methods, and although substantial progress has been made, a practical method of STEC detection has yet to be validated. Worldwide, foods associated with non-O157 STEC illness include sausage, ice cream, milk, and lettuce, among others. Results from several studies suggest that control measures for O157 may be effective for non-O157 STEC. More research is needed to uncover unique characteristics and resistances of non-O157 STEC strains if they exist. The public health significance of non-O157 STEC and the implications for industry practices and regulatory actions are discussed.

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