scholarly journals A stress-induced block in dicarboxylate uptake and utilization in Salmonella

2019 ◽  
Author(s):  
Steven J. Hersch ◽  
Bojana Radan ◽  
Bushra Ilyas ◽  
Patrick Lavoie ◽  
William Wiley Navarre
Keyword(s):  
Pathogenic Bacteria ◽  
Constitutive Expression ◽  
Elongation Factor ◽  
Stringent Response ◽  
Close Relative ◽  
Translation Elongation ◽  
Growth And Survival ◽  
E Coli ◽  
Sense And Respond

AbstractBacteria have evolved to sense and respond to their environment by altering gene expression and metabolism to promote growth and survival. In this work we demonstrate that Salmonella displays an extensive (>30 hour) lag in growth when subcultured into media where dicarboxylates such as succinate are the sole carbon source. This growth lag is regulated in part by RpoS, the RssB anti-adaptor IraP, translation elongation factor P, and to a lesser degree the stringent response. We also show that small amounts of proline or citrate can trigger early growth in succinate media and that, at least for proline, this effect requires the multifunctional enzyme/regulator PutA. We demonstrate that activation of RpoS results in the repression of dctA, encoding the primary dicarboxylate importer, and that constitutive expression of dctA induced growth. This dicarboxylate growth lag phenotype is far more severe across multiple Salmonella isolates than in its close relative E. coli. Replacing 200 nt of the Salmonella dctA promoter region with that of E. coli was sufficient to eliminate the observed lag in growth. We hypothesize that this cis-regulatory divergence might be an adaptation to Salmonella’s virulent lifestyle where levels of phagocyte-produced succinate increase in response to bacterial LPS. We found that impairing dctA repression had no effect on Salmonella’s survival in acidified succinate or in macrophage but propose alternate hypotheses of fitness advantages acquired by repressing dicarboxylate uptake.ImportanceBacteria have evolved to sense and respond to their environment to maximize their chance of survival. By studying differences in the responses of pathogenic bacteria and closely related non-pathogens, we can gain insight into what environments they encounter inside of an infected host. Here we demonstrate that Salmonella diverges from its close relative E. coli in its response to dicarboxylates such as the metabolite succinate. We show that this is regulated by stress response proteins and ultimately can be attributed to Salmonella repressing its import of dicarboxylates. Understanding this phenomenon may reveal a novel aspect of the Salmonella virulence cycle, and our characterization of its regulation yields a number of mutant strains that can be used to further study it.

scholarly journals Stress-Induced Block in Dicarboxylate Uptake and Utilization in Salmonella enterica Serovar Typhimurium

2021 ◽  
Vol 203 (9) ◽  
Author(s):  
Steven J. Hersch ◽  
Bojana Radan ◽  
Bushra Ilyas ◽  
Patrick Lavoie ◽  
William Wiley Navarre
Keyword(s):  
Pathogenic Bacteria ◽  
Constitutive Expression ◽  
Elongation Factor ◽  
Stringent Response ◽  
Close Relative ◽  
Content Type ◽  
Growth And Survival ◽  
E Coli ◽  
Serovar Typhimurium ◽  
Sense And Respond

ABSTRACT Bacteria have evolved to sense and respond to their environment by altering gene expression and metabolism to promote growth and survival. In this work, we demonstrate that Salmonella displays an extensive (>30-h) lag in growth when subcultured into medium where dicarboxylates such as succinate are the sole carbon source. This growth lag is regulated in part by RpoS, the RssB antiadaptor IraP, translation elongation factor P, and to a lesser degree the stringent response. We also show that small amounts of proline or citrate can trigger early growth in succinate medium and that, at least for proline, this effect requires the multifunctional enzyme/regulator PutA. We demonstrate that activation of RpoS results in the repression of dctA, encoding the primary dicarboxylate importer, and that constitutive expression of dctA induces growth. This dicarboxylate growth lag phenotype is far more severe across multiple Salmonella isolates than it is in its close relative Escherichia coli. Replacing 200 nucleotides of the Salmonella dctA promoter region with that of E. coli was sufficient to eliminate the observed lag in growth. We hypothesized that this cis-regulatory divergence might be an adaptation to Salmonella’s virulent lifestyle, where levels of phagocyte-produced succinate increase in response to bacterial LPS; however, we found that impairing dctA repression had no effect on Salmonella’s survival in acidified succinate or in macrophages. IMPORTANCE Bacteria have evolved to sense and respond to their environment to maximize their chance of survival. By studying differences in the responses of pathogenic bacteria and closely related nonpathogens, we can gain insight into what environments they encounter inside of an infected host. Here, we demonstrate that Salmonella diverges from its close relative E. coli in its response to dicarboxylates such as the metabolite succinate. We show that this is regulated by stress response proteins and ultimately can be attributed to Salmonella repressing its import of dicarboxylates. Understanding this phenomenon may reveal a novel aspect of the Salmonella virulence cycle, and our characterization of its regulation yields a number of mutant strains that can be used to further study it.

scholarly journals Survey, Identification, and Characterization of Cylindrocarpon-Like Asexual Morphs in Spanish Forest Nurseries

Plant Disease ◽  
2018 ◽  
Vol 102 (11) ◽  
pp. 2083-2100 ◽  
Author(s):  
Beatriz Mora-Sala ◽  
Ana Cabral ◽  
Maela León ◽  
Carlos Agustí-Brisach ◽  
Josep Armengol ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Elongation Factor ◽  
Its Region ◽  
Phylogenetic Position ◽  
Translation Elongation ◽  
Forest Nurseries ◽  
Asexual Morphs ◽  
Identification And Characterization ◽  
Elongation Factor 1

Cylindrocarpon-like asexual morphs infect herbaceous and woody plants, mainly in agricultural scenarios, but also in forestry systems. The aim of the present study was to characterize a collection of Cylindrocarpon-like isolates recovered from the roots of a broad range of forest hosts from nurseries showing decline by morphological and molecular studies. Between 2009 and 2012, 17 forest nurseries in Spain were surveyed and a total of 103 Cylindrocarpon-like isolates were obtained. Isolates were identified based on DNA sequences of the partial gene regions histone H3 (his3). For the new species, the internal transcribed spacer and intervening 5.8S nrRNA gene (ITS) region, β-tubulin (tub2), and translation elongation factor 1-α (tef1) were also used to determine their phylogenetic position. Twelve species belonging to the genera Cylindrodendrum, Dactylonectria, and Ilyonectria were identified from damaged roots of 15 different host genera. The species C. alicantinum, D. macrodidyma, D. novozelandica, D. pauciseptata, D. pinicola, D. torresensis, I. capensis, I. cyclaminicola, I. liriodendri, I. pseudodestructans, I. robusta, and I. rufa were identified. In addition, two Dactylonectria species (D. hispanica sp. nov. and D. valentina sp. nov.), one Ilyonectria species (I. ilicicola sp. nov.), and one Neonectria species (N. quercicola sp. nov.) are newly described. The present study demonstrates the prevalence of this fungal group associated with seedlings of diverse hosts showing decline symptoms in forest nurseries in Spain.

Behavior of Escherichia coli O157:H7 on Damaged Leaves of Spinach, Lettuce, Cilantro, and Parsley Stored at Abusive Temperatures

2010 ◽  
Vol 73 (2) ◽  
pp. 212-220 ◽  
Author(s):  
ROWAIDA K. KHALIL ◽  
JOSEPH F. FRANK
Keyword(s):  
Escherichia Coli ◽  
Pathogenic Bacteria ◽  
Leaf Damage ◽  
Escherichia Coli O157 ◽  
Oxidation Reactions ◽  
Leaf Extracts ◽  
Romaine Lettuce ◽  
Growth And Survival ◽  
E Coli ◽  
Additional Information

Recent foodborne illness outbreaks associated with the consumption of leafy green produce indicates a need for additional information on the behavior of pathogenic bacteria on these products. Previous research indicates that pathogen growth and survival is enhanced by leaf damage. The objective of this study was to compare the behavior of Escherichia coli O157:H7 on damaged leaves of baby Romaine lettuce, spinach, cilantro, and parsley stored at three abusive temperatures (8, 12, and 15°C). The damaged portions of leaves were inoculated with approximately 105 CFU E. coli O157:H7 per leaf. The pathogen grew on damaged spinach leaves held for 3 days at 8 and 12°C (P < 0.05), with the population increasing by 1.18 and 2.08 log CFU per leaf, respectively. E. coli O157:H7 did not grow on damaged Romaine leaves at 8 or 12°C, but growth was observed after 8 h of storage at 15°C, with an increase of less than 1.0 log. Growth of E. coli O157:H7 on Romaine lettuce held at 8 or 12°C was enhanced when inocula were suspended in 0.05% ascorbic acid, indicating the possibility of inhibition by oxidation reactions associated with tissue damage. Damaged cilantro and Italian parsley leaves held at 8°C for 4 days did not support the growth of E. coli O157:H7. Behavior of the pathogen in leaf extracts differed from behavior on the damaged tissue. This study provides evidence that the damaged portion of a leafy green is a distinct growth niche that elicits different microbial responses in the various types of leafy greens.

scholarly journals Characterization of Two Toxin-Antitoxin Systems in Deep-Sea Streptomyces sp. SCSIO 02999

Marine Drugs ◽  
2019 ◽  
Vol 17 (4) ◽  
pp. 211 ◽  
Author(s):  
Waner Zhan ◽  
Jianyun Yao ◽  
Kaihao Tang ◽  
Yangmei Li ◽  
Yunxue Guo ◽  
...  
Keyword(s):  
Toxic Effect ◽  
Deep Sea ◽  
Pathogenic Bacteria ◽  
Direct Interaction ◽  
Streptomyces Sp ◽  
E Coli ◽  
Deep Sea Bacteria ◽  
Bona Fide ◽  
Ta Studies

Toxin-antitoxin (TA) systems are ubiquitous and abundant genetic elements in bacteria and archaea. Most previous TA studies have focused on commensal and pathogenic bacteria, but have rarely focused on marine bacteria, especially those isolated from the deep sea. Here, we identified and characterized three putative TA pairs in the deep-sea-derived Streptomyces sp. strain SCSIO 02999. Our results showed that Orf5461/Orf5462 and Orf2769/Orf2770 are bona fide TA pairs. We provide several lines of evidence to demonstrate that Orf5461 and Orf5462 constitute a type-II TA pair that are homologous to the YoeB/YefM TA pair from Escherichia coli. Although YoeB from SCSIO 02999 was toxic to an E. coli host, the homologous YefM antitoxin from SCSIO 02999 did not neutralize the toxic effect of YoeB from E. coli. For the Orf2769/Orf2770 TA pair, Orf2769 overexpression caused significant cell elongation and could lead to cell death in E. coli, and the neighboring Orf2770 could neutralize the toxic effect of Orf2769. However, no homologous toxin or antitoxin was found for this pair, and no direct interaction was found between Orf2769 and Orf2770. These results suggest that Orf2769 and Orf2770 may constitute a novel TA pair. Thus, deep-sea bacteria harbor typical and novel TA pairs. The biochemical and physiological functions of different TAs in deep-sea bacteria warrant further investigation.

scholarly journals Characterization of Botryosphaeriaceae Species as Causal Agents of Trunk Diseases on Grapevines

Plant Disease ◽  
2015 ◽  
Vol 99 (12) ◽  
pp. 1678-1688 ◽  
Author(s):  
Antonia Carlucci ◽  
Francesca Cibelli ◽  
Francesco Lops ◽  
Maria Luisa Raimondo
Keyword(s):  
Elongation Factor ◽  
Phylogenetic Study ◽  
Translation Elongation ◽  
Neofusicoccum Parvum ◽  
Grapevine Trunk Diseases ◽  
General Decline ◽  
Wide Range ◽  
Trunk Diseases ◽  
Pathogenicity Tests

Botryosphaeriaceae spp. have a cosmopolitan distribution and a wide range of plant hosts. Over the last 15 years, worldwide, 21 species of this family have been associated with grapevine trunk diseases that cause cankers and dieback on grapevines. Here, we surveyed vineyards of Vitis vinifera ‘Lambrusco’, ‘Sangiovese’, and ‘Montepulciano’ in three areas of the Foggia province (Cerignola, Foggia, and San Severo) in southern Italy. Wood samples from grapevines showing general decline, dieback, cankers, and wood and foliar discoloration yielded 344 fungal isolates identified as Botryosphaeriaceae spp. A phylogenetic study combining internal transcribed spacer and translation elongation factor 1-α sequences of 60 representative isolates identified nine botryosphaeriaceous species: Botryosphaeria dothidea, Diplodia corticola, D. mutila, D. seriata, Dothiorella iberica, Do. sarmentorum, Lasiodiplodia citricola, L. theobromae, and Neofusicoccum parvum. Pathogenicity tests confirmed that all nine species cause canker and dieback of grapevines. However, this is the first report of L. citricola as causal agent of wood cankers and dieback of grapevine. To date, including L. citricola, there are 25 botryosphaeriaceous species associated with V. vinifera worldwide, of which 12 have been reported for grapevines in Italy.

scholarly journals Molecular characterization and phylogenetic analyses of Lophodermella needle pathogens (Rhytismataceae) on Pinus species in the USA and Europe

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11435
Author(s):  
Jessa P. Ata ◽  
Kelly S. Burns ◽  
Suzanne Marchetti ◽  
Isabel A. Munck ◽  
Ludwig Beenken ◽  
...  
Keyword(s):  
Phylogenetic Analyses ◽  
Ribosomal Subunit ◽  
Elongation Factor ◽  
Translation Elongation ◽  
Phenotypic Characters ◽  
Elongation Factor 1 Alpha ◽  
The Usa ◽  
Phylogenetic Resolution ◽  
Elongation Factor 1

Increasing prevalence of conifer needle pathogens globally have prompted further studies on pathogen identification and a better understanding of phylogenetic relationships among needle pathogens. Several Lophodermella species can be aggressive pathogens causing needle cast in natural pine forests in the USA and Europe. However, their relationships with other Rhytismataceae species have historically been based on similarities of only limited phenotypic characters. Currently, no molecular studies have been completed to elucidate their relationships with other Lophodermella needle pathogens. This study collected and sequenced three gene loci, namely: internal transcribed spacer, large ribosomal subunit, and translation elongation factor 1-alpha, from five Lophodermella needle pathogens from North America (L. arcuata, L. concolor, L. montivaga) and Europe (L. conjuncta and L. sulcigena) to distinguish phylogeny within Rhytismatacaeae, including Lophophacidium dooksii. Phylogenetic analyses of the three loci revealed that all but L. conjuncta that were sampled in this study consistently clustered in a well-supported clade within Rhytismataceae. The multi-gene phylogeny also confirmed consistent nesting of L. dooksii, a needle pathogen of Pinus strobus, within the clade. Potential synapomorphic characters such as ascomata position and ascospore shape for the distinct clade were also explored. Further, a rhytismataceous species on P. flexilis that was morphologically identified as L. arcuata was found to be unique based on the sequences at the three loci. This study suggests a potential wider range of host species within the genus and the need for genetic characterization of other Lophodermella and Lophophacidium species to provide a higher phylogenetic resolution.

scholarly journals Survival of Selected Pathogenic Bacteria during PDO Pecorino Romano Cheese Ripening

Dairy ◽  
2020 ◽  
Vol 1 (3) ◽  
pp. 297-312
Author(s):  
Giacomo Lai ◽  
Rita Melillo ◽  
Massimo Pes ◽  
Margherita Addis ◽  
Antonio Fadda ◽  
...  
Keyword(s):  
Pathogenic Bacteria ◽  
Salt Content ◽  
Raw Milk ◽  
Salmonella Spp ◽  
Growth And Survival ◽  
E Coli ◽  
Cheese Ripening ◽  
Protected Designation Of Origin ◽  
Low Levels ◽  
First Time

This study was conducted to assess, for the first time, the survival of the pathogenic bacteria Listeria monocytogenes, Salmonella spp., Escherichia coli O157:H7, and Staphylococcus aureus during the ripening of protected designation of origin (PDO) Pecorino Romano cheese. A total of twenty-four cheese-making trials (twelve from raw milk and twelve from thermized milk) were performed under the protocol specified by PDO requirements. Sheep cheese milk was first inoculated before processing with approximately 106 colony-forming unit (CFU) mL−1 of each considered pathogen and the experiment was repeated six times for each selected pathogen. Cheese composition and pathogens count were then evaluated in inoculated raw milk, thermized milk, and cheese after 1, 90, and 150 days of ripening. pH, moisture, water activity, and salt content of cheese were within the range of the commercial PDO Pecorino Romano cheese. All the cheeses made from raw and thermized milk were microbiologically safe after 90 days and 1 day from their production, respectively. In conclusion, when Pecorino Romano cheese is produced under PDO specifications, from raw or thermized milk, a combination of factors including the speed and extent of curd acidification in the first phase of the production, together with an intense salting and a long ripening time, preclude the possibility of growth and survival of L. monocytogenes, Salmonella spp., and E. coli O157:H7. Only S. aureus can be still detectable at such low levels that it does not pose a risk to consumers.

Synthesis and Characterization of Tris(nicotinohydroxamato) Vanadium(III) Complex

2020 ◽  
Vol 12 (5) ◽  
pp. 695-701
Author(s):  
Sonika Sharma ◽  
Neeraj Sharma
Keyword(s):  
Pathogenic Bacteria ◽  
Free Ligand ◽  
Antimicrobial Activities ◽  
Nitrogen Atmosphere ◽  
Spectral Studies ◽  
Mass Spectral ◽  
E Coli ◽  
Concentration Method ◽  
Elemental Analyses

The tris(nicotinohydroxamato) vanadium(III) complex of composition [V(C5H4NCONHO)3] have been synthesized by the reaction of VCl3 with three equivalents of potassium salts of nicotinohydroxamate in methanol medium under nitrogen atmosphere. The characterization of complex has been accomplished by elemental analyses, molar conductivity, magnetic moment measurements, IR, electronic and mass spectral studies. An octahedral geometry around vanadium, inferred from physicochemical and spectral studies has been proposed for complex. The antimicrobial activities of the newly synthesized complex, ligand and precursor VCl3 have been evaluated against some pathogenic bacteria as E. coli, S. aureus, S. typhi, S. paratyphi, S. epidermidis and K. pneumoniae and fungi such as A. niger, B. fulva and M. circinelloid by minimum inhibitory concentration method. The complex exhibited promising antimicrobial activity relative to free ligand and metal precursor.

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