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 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.

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.

scholarly journals GC-MS Profiling of Anti-bacterial Metabolic Compounds from the Extract of Azadirachta indica

2020 ◽  
pp. 17-23
Keyword(s):  
Plant Extract ◽  
Plant Extracts ◽  
Azadirachta Indica ◽  
Pathogenic Bacteria ◽  
Antibacterial Activities ◽  
Dioctyl Phthalate ◽  
Gas Chromatography Mass Spectrometry ◽  
Antimicrobial Compounds ◽  
E Coli

Azadirachta indica is a very common plant used very frequently due to its medicinal significance. The antibacterial activities of 0.001, 0.01, 0.1, 1.0 and 10 mg/mL of the plant extract were determined against different pathogenic bacteria. Concentration of 0.01 mg/mL killed the E. coli, E. aerogenes, P. stuartii and 10, 1.0 and 0.1 mg/mL were very effective against the E. cloacae, K. pneumoniae and P. mirabilis and killed them 100% in culture plates. The plant extracts were analyzed for the characterization of the different antimicrobial compounds through gas chromatography-mass spectrometry (GC-MS). An array of antibacterial compounds such as azulene, tetrasiloxane, phthalic acid, cyclopentasiloxane, hexadecanoic acid, spiropentane, dioctyl phthalate were detected in the plant extract through GC-MS. The antibacterial activities of the plant extracts were might be because of their compound which had been reported previously as well as antimicrobial compounds.

scholarly journals Characterization of novel bacteriophage phiC119 capable of lysing multidrug-resistant Shiga toxin-producingEscherichia coliO157:H7

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2423 ◽  
Author(s):  
Luis Amarillas ◽  
Cristóbal Chaidez ◽  
Arturo González-Robles ◽  
Yadira Lugo-Melchor ◽  
Josefina León-Félix
Keyword(s):  
Host Range ◽  
Shiga Toxin ◽  
Pathogenic Bacteria ◽  
Genetic Material ◽  
Multidrug Resistant ◽  
Broad Host Range ◽  
Antibiotic Resistant ◽  
E Coli ◽  
Tract Infections

BackgroundShiga toxin-producingEscherichia coli(STEC) is one of the most common and widely distributed foodborne pathogens that has been frequently implicated in gastrointestinal and urinary tract infections. Moreover, high rates of multiple antibiotic-resistantE. colistrains have been reported worldwide. Due to the emergence of antibiotic-resistant strains, bacteriophages are considered an attractive alternative to biocontrol pathogenic bacteria. Characterization is a preliminary step towards designing a phage for biocontrol.MethodsIn this study, we describe the characterization of a bacteriophage designated phiC119, which can infect and lyse several multidrug-resistant STEC strains and someSalmonellastrains. The phage genome was screened to detect thestx-genes using PCR, morphological analysis, host range was determined, and genome sequencing were carried out, as well as an analysis of the cohesive ends and identification of the type of genetic material through enzymatic digestion of the genome.ResultsAnalysis of the bacteriophage particles by transmission electron microscopy showed that it had an icosahedral head and a long tail, characteristic of the familySiphoviridae. The phage exhibits broad host range against multidrug-resistant and highly virulentE. coliisolates. One-step growth experiments revealed that the phiC119 phage presented a large burst size (210 PFU/cell) and a latent period of 20 min. Based on genomic analysis, the phage contains a linear double-stranded DNA genome with a size of 47,319 bp. The phage encodes 75 putative proteins, but lysogeny and virulence genes were not found in the phiC119 genome.ConclusionThese results suggest that phage phiC119 may be a good biological control agent. However, further studies are required to ensure its control of STEC and to confirm the safety of phage use.

Cloning and characterization of dihydrofolate reductases from deep-sea bacteria

2009 ◽  
Vol 147 (4) ◽  
pp. 591-599 ◽  
Author(s):  
C. Murakami ◽  
E. Ohmae ◽  
S. i. Tate ◽  
K. Gekko ◽  
K. Nakasone ◽  
...  
Keyword(s):  
Deep Sea ◽  
Deep Sea Bacteria ◽  
Dihydrofolate Reductases

scholarly journals Characterization of a Hemoglobin Protease Secreted by the Pathogenic Escherichia coli Strain EB1

1998 ◽  
Vol 188 (6) ◽  
pp. 1091-1103 ◽  
Author(s):  
Ben R. Otto ◽  
Silvy J.M. van Dooren ◽  
Jan H. Nuijens ◽  
Joen Luirink ◽  
Bauke Oudega
Keyword(s):  
Escherichia Coli ◽  
Pathogenic Bacteria ◽  
Affinity Purification ◽  
Coli Strain ◽  
E Coli ◽  
Heme Acquisition ◽  
Pathogenic Escherichia Coli ◽  
Iga1 Protease ◽  
Animal Pathogens

Many pathogenic bacteria can use heme compounds as a source of iron. Pathogenic Escherichia coli strains are capable of using hemoglobin as an iron source. However, the mechanism of heme acquisition from hemoglobin is not understood for this microorganism. We present the first molecular characterization of a hemoglobin protease (Hbp) from a human pathogenic E. coli strain. The enzyme also appeared to be a heme-binding protein. Affinity purification of this bifunctional protein enabled us to identify the extracellular gene product, and to clone and analyze its gene. A purification procedure developed for Hbp allowed us to perform functional studies. The protein interacted with hemoglobin, degraded it and subsequently bound the released heme. These results suggest that the protein is involved in heme acquisition by this human pathogen. Hbp belongs to the so-called IgA1 protease-like proteins, as indicated by the kinetics of its membrane transfer and DNA sequence similarity. The gene of this protein appears to be located on the large pColV-K30 episome, that only has been isolated from human and animal pathogens. All these characteristics indicate that Hbp may be an important virulence factor that may play a significant role in the pathogenesis of E. coli infections.

scholarly journals Characterization of Two Unique Cold-Active Lipases Derived from a Novel Deep-Sea Cold Seep Bacterium

2021 ◽  
Vol 9 (4) ◽  
pp. 802
Author(s):  
Chenchen Guo ◽  
Rikuan Zheng ◽  
Ruining Cai ◽  
Chaomin Sun ◽  
Shimei Wu
Keyword(s):  
Deep Sea ◽  
Bacterial Species ◽  
Deep Ocean ◽  
Cold Seep ◽  
Bacterial Strains ◽  
E Coli ◽  
Cold Active ◽  
Genes Encoding ◽  
Potential Inhibitors

The deep ocean microbiota has unexplored potential to provide enzymes with unique characteristics. In order to obtain cold-active lipases, bacterial strains isolated from the sediment of the deep-sea cold seep were screened, and a novel strain gcc21 exhibited a high lipase catalytic activity, even at the low temperature of 4 °C. The strain gcc21 was identified and proposed to represent a new species of Pseudomonas according to its physiological, biochemical, and genomic characteristics; it was named Pseudomonas marinensis. Two novel encoding genes for cold-active lipases (Lipase 1 and Lipase 2) were identified in the genome of strain gcc21. Genes encoding Lipase 1 and Lipase 2 were respectively cloned and overexpressed in E. coli cells, and corresponding lipases were further purified and characterized. Both Lipase 1 and Lipase 2 showed an optimal catalytic temperature at 4 °C, which is much lower than those of most reported cold-active lipases, but the activity and stability of Lipase 2 were much higher than those of Lipase 1 under different tested pHs and temperatures. In addition, Lipase 2 was more stable than Lipase 1 when treated with different metal ions, detergents, potential inhibitors, and organic solvents. In a combination of mutation and activity assays, catalytic triads of Ser, Asp, and His in Lipase 1 and Lipase 2 were demonstrated to be essential for maintaining enzyme activity. Phylogenetic analysis showed that both Lipase 1 and Lipase 2 belonged to lipase family III. Overall, our results indicate that deep-sea cold seep is a rich source for novel bacterial species that produce potentially unique cold-active enzymes.

scholarly journals Characterization of mcr-1-Harboring Plasmids from Pan Drug-Resistant Escherichia coli Strains Isolated from Retail Raw Chicken in South Korea

2019 ◽  
Vol 7 (9) ◽  
pp. 344 ◽  
Author(s):  
Jinshil Kim ◽  
Bo Kyoung Hwang ◽  
HyeLim Choi ◽  
Yang Wang ◽  
Sang Ho Choi ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
South Korea ◽  
Whole Genome Sequencing ◽  
Genome Sequencing ◽  
Pathogenic Bacteria ◽  
Fluoroquinolone Resistance ◽  
Whole Genome ◽  
Drug Resistant ◽  
E Coli

A number of studies from different countries have characterized mcr-1-harboring plasmids isolated from food; however, nothing has been reported about it in South Korea. In this study, we report the characterization of mcr-1 plasmids from pan drug-resistant (PDR) Escherichia coli strains isolated from retail food in the country. Colistin-resistant E. coli strains were isolated from retail raw chicken, and PCR was carried out to detect the mcr-1 gene. Whole genome sequencing of the mcr-1-positive strains was performed for further characterization. The results of whole genome sequencing revealed that all mcr-1 plasmids belonged to the IncI2 type. In addition to the mcr-1 plasmids, all of the isolates also carried additional plasmids possessing multiple antibiotic resistance genes, and the PDR was mediated by resistant plasmids except for fluoroquinolone resistance resulting from mutations in gyrA and parC. Interestingly, the mcr-1 plasmids were transferred by conjugation to other pathogenic strains including enterohemorrhagic E. coli (EHEC), enterotoxigenic E. coli (ETEC), enteroaggregative E. coli (EAEC), Salmonella, and Klebsiella at the frequencies of 10−3−10−6, 10−2−10−5, 10−4−10−5, 10−4−10−6, and 10−5−10−6, respectively. The results showed that mcr-1 plasmids can be easily transmitted to pathogenic bacteria by conjugation.

scholarly journals Study of antibacterial activity of Streptomyces sp. SS473 isolated from plants against ESBL-producing Escherichia coli

2021 ◽  
Vol 63 (9) ◽  
pp. 26-32
Author(s):  
Trung Hieu Nguyen ◽  
◽  
Phuoc Dat Nguyen ◽  
Thi Ngoc Quyen Nguyen ◽  
Le Truc Ha Tran ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Broad Spectrum ◽  
Bacterial Infections ◽  
Pathogenic Bacteria ◽  
Antibacterial Properties ◽  
Morphological Identification ◽  
Rrna Gene ◽  
Streptomyces Sp ◽  
E Coli ◽  
New Antibiotics

The broad spectrum β-lactamase-producing E. coli(ESBL) is a dangerous bacterial pathogen in humans due to its resistance to many antibiotics. This is especially serious in the context of a limited number of new antibiotics for treating bacterial infections. This leads to a global public health threat and places an urgent need for new antibiotics. In this study, the authors investigated the antibacterial properties of an actinomyces strain isolated from the plant Clinacanthus nutans against the ESBL-producing E. coli strains. These actinomyces strains were designated as SS473. Moreover, SS473 showed a broad spectrum of antibacterial activity on several clinically isolated pathogenic bacteria. Culture media have different effects on the antibacterial activity of SS473. In stability tests, the antibacterial activity of strain SS473 remained at a temperature up to 80oC but was lost at pH 3 and 13. By contrast, the antibacterial activity was not affected by UV and protease treatments. Based on the results of morphological identification with specific media for Streptomyces and molecular identification on 16S rRNA gene, strain SS473 was suggested to belong to the Streptomyces genus and was named Streptomycessp. SS473. The results in this study will pave the way for the following research on the identification of secondary metabolites having antibacterial activity and their biosynthetic pathways in Streptomyces sp. SS473 in the future

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