scholarly journals Short-Term Inactivation Rates of Selected Gram-Positive and Gram-Negative Bacteria Attached to Metal Oxide Mineral Surfaces: Role of Solution and Surface Chemistry

2013 ◽  
Vol 47 (11) ◽  
pp. 5729-5737 ◽  
Author(s):  
Bahareh Asadishad ◽  
Subhasis Ghoshal ◽  
Nathalie Tufenkji
Keyword(s):  
Metal Oxide ◽  
Surface Chemistry ◽  
Gram Negative Bacteria ◽  
Mineral Surfaces ◽  
Short Term ◽  
Gram Positive ◽  
Gram Negative ◽  
Oxide Mineral

scholarly journals The Recombination Genes addAB Are Not Restricted to Gram-Positive Bacteria: Genetic Analysis of the Recombination Initiation Enzymes RecF and AddAB in Rhizobium etli

2004 ◽  
Vol 186 (23) ◽  
pp. 7905-7913 ◽  
Author(s):  
Jacobo Zuñiga-Castillo ◽  
David Romero ◽  
Jaime M. Martínez-Salazar
Keyword(s):  
Recombination Frequency ◽  
Double Strand Breaks ◽  
Additive Effect ◽  
Gram Negative Bacteria ◽  
Rhizobium Etli ◽  
Gram Positive ◽  
Gram Negative ◽  
Strand Breaks ◽  
Gram Positive Bacteria

ABSTRACT Single-strand gaps (SSGs) and double-strand breaks (DSBs) are the major initiation sites for recombination. In bacteria, the SSGs are repaired by RecFOR, while the DSBs are processed by RecBCD in gram-negative bacteria and AddAB in gram-positive bacteria. Unexpectedly, instead of recBCD genes, the addAB genes were found in members of the α-proteobacteria group (gram negative). Taking Rhizobium etli as a model, the role of recF and addAB genes in homologous recombination and repair of damaged DNA was evaluated. Inactivation of either recF or addA provoked strong sensitivity to UV radiation and mitomycin C, while an additive effect was observed in the recF-addA mutant. The DSBs generated by nalidixic acid caused low viability only in the addA mutant. The recombination frequency of large and small plasmids was reduced in the recF mutant (24- and 36-fold, respectively), whereas a slight decrease (threefold) in the addA mutant was observed. Moreover, an additive effect (47- and 90-fold, respectively) was observed in the double mutant, but it was not as dramatic as that in a recA mutant. Interestingly, the frequency of deletion and Campbell-type recombination was slightly affected in either single or double mutants. These results suggest that another pathway exists that allows plasmid and Campbell-type recombination in the absence of recF and addA genes.

scholarly journals Lipoproteins of Gram-Positive Bacteria: Key Players in the Immune Response and Virulence

2016 ◽  
Vol 80 (3) ◽  
pp. 891-903 ◽  
Author(s):  
Minh Thu Nguyen ◽  
Friedrich Götz
Keyword(s):  
Immune Response ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Content Type ◽  
Gram Positive Bacteria ◽  
Key Players ◽  
Toll Like Receptor 2 ◽  
Number Of Publications

SUMMARYSince the discovery in 1973 of the first of the bacterial lipoproteins (Lpp) inEscherichia coli, Braun's lipoprotein, the ever-increasing number of publications indicates the importance of these proteins. Bacterial Lpp belong to the class of lipid-anchored proteins that in Gram-negative bacteria are anchored in both the cytoplasmic and outer membranes and in Gram-positive bacteria are anchored only in the cytoplasmic membrane. In contrast to the case for Gram-negative bacteria, in Gram-positive bacteria lipoprotein maturation and processing are not vital. Physiologically, Lpp play an important role in nutrient and ion acquisition, allowing particularly pathogenic species to better survive in the host. Bacterial Lpp are recognized by Toll-like receptor 2 (TLR2) of the innate immune system. The important role of Lpp in Gram-positive bacteria, particularly in the phylumFirmicutes, as key players in the immune response and pathogenicity has emerged only in recent years. In this review, we address the role of Lpp in signaling and modulating the immune response, in inflammation, and in pathogenicity. We also address the potential of Lpp as promising vaccine candidates.

scholarly journals Stenotrophomonas maltophilia D457R Contains a Cluster of Genes from Gram-Positive Bacteria Involved in Antibiotic and Heavy Metal Resistance

2000 ◽  
Vol 44 (7) ◽  
pp. 1778-1782 ◽  
Author(s):  
Ana Alonso ◽  
Patricia Sanchez ◽  
José L. Martínez
Keyword(s):  
Heavy Metal ◽  
Stenotrophomonas Maltophilia ◽  
Heavy Metal Resistance ◽  
Metal Resistance ◽  
Gram Negative Bacteria ◽  
Negative Bacterium ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria

ABSTRACT A cluster of genes involved in antibiotic and heavy metal resistance has been characterized from a clinical isolate of the gram-negative bacterium Stenotrophomonas maltophilia. These genes include a macrolide phosphotransferase (mphBM) and a cadmium efflux determinant (cadA), together with the genecadC coding for its transcriptional regulator. ThecadC cadA region is flanked by a truncated IS257 sequence and a region coding for a bin3invertase. Despite their presence in a gram-negative bacterium, these genetic elements share a common gram-positive origin. The possible origin of these determinants as a remnant composite transposon as well as the role of gene transfer between gram-positive and gram-negative bacteria for the acquisition of antibiotic resistance determinants in chronic, mixed infections is discussed.

scholarly journals Toll-Like Receptor 4 Protects Against Clostridium perfringens Infection in Mice

2021 ◽  
Vol 11 ◽  
Author(s):  
Masaya Takehara ◽  
Keiko Kobayashi ◽  
Masahiro Nagahama
Keyword(s):  
Clostridium Perfringens ◽  
Gram Negative Bacteria ◽  
Toll Like Receptor ◽  
Toll Like Receptor 4 ◽  
Gram Positive ◽  
Gram Negative ◽  
Tlr4 Agonist ◽  
Innate Ability ◽  
Recognition Receptor

Toll-like receptor 4 (TLR4) has been reported to protect against Gram-negative bacteria by acting as a pathogen recognition receptor that senses mainly lipopolysaccharide (LPS) from Gram-negative bacteria. However, the role of TLR4 in Gram-positive bacterial infection is less well understood. Clostridium perfringens type A is a Gram-positive bacterium that causes gas gangrene characterized by severe myonecrosis. It was previously demonstrated that C. perfringens θ-toxin is a TLR4 agonist, but the role of TLR4 in C. perfringens infection is unclear. Here, TLR4-defective C3H/HeJ mice infected with C. perfringens showed a remarkable decrease in survival rate, an increase in viable bacterial counts, and accelerated destruction of myofibrils at the infection site compared with wild-type C3H/HeN mice. These results demonstrate that TLR4 plays an important role in the elimination of C. perfringens. Remarkable increases in levels of inflammatory cytokines, such as interleukin-1β (IL-1β), interleukin-6 (IL-6), and granulocyte colony-stimulating factor (G-CSF), were observed in C. perfringens-infected C3H/HeN mice, whereas the increases were limited in C3H/HeJ mice. Generally, increased G-CSF accelerates granulopoiesis in the bone marrow and the spleen to exacerbate neutrophil production, resulting in elimination of bacteria. The number of neutrophils in the spleen was increased in C. perfringens-infected C3H/HeN mice compared with non-infected mice, while the increase was lower in C. perfringens-infected C3H/HeJ mice. Furthermore, DNA microarray analysis revealed that the mutation in TLR4 partially affects host gene expression during C. perfringens infection. Together, our results illustrate that TLR4 is crucial for the innate ability to eliminate C. perfringens.

scholarly journals Myxococcus xanthus predation of Gram-positive or Gram-negative bacteria is mediated by different bacteriolytic mechanisms

2020 ◽  
Author(s):  
Kirstin I. Arend ◽  
Janka J. Schmidt ◽  
Tim Bentler ◽  
Carina Lüchtefeld ◽  
Daniel Eggerichs ◽  
...  
Keyword(s):  
Myxococcus Xanthus ◽  
Secreted Proteins ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Prey Cell ◽  
Gram Negative ◽  
Prey Killing ◽  
Cell Envelopes ◽  
Secreted Enzymes

Myxococcus xanthus kills other species to use their biomass as energy source. Its predation mechanisms allow feeding on a broad spectrum of bacteria, but the identity of predation effectors and their mode of action remains largely unknown. We initially focused on the role of hydrolytic enzymes for prey killing and compared the activity of secreted M. xanthus proteins against four prey strains. 72 secreted proteins were identified by mass spectrometry, and among them a family 19 glycoside hydrolase that displayed bacteriolytic activity in vivo and in vitro. This enzyme, which we name LlpM (lectin/lysozyme-like protein of M. xanthus), was not essential for predation, indicating that additional secreted components are required to disintegrate prey. Furthermore, secreted proteins lysed only Gram-positive, but not Gram-negative species. We thus compared the killing of different preys by cell-associated mechanisms: Individual M. xanthus cells killed all four test strains in a cell-contact dependent manner, but were only able to disintegrate Gram-negative, not Gram-positive cell envelopes. Thus, our data indicate that M. xanthus uses different, multifactorial mechanisms for killing and degrading different preys. Besides secreted enzymes, cell-associated mechanisms that have not been characterized so far, appear to play a major role for prey killing. IMPORTANCE Predation is an important survival strategy of the widespread myxobacteria, but it remains poorly understood on the mechanistic level. Without a basic understanding of how prey cell killing and consumption is achieved, it also remains difficult to investigate the role of predation for the complex myxobacterial lifestyle, reciprocal predator-prey relationships or the impact of predation on complex bacterial soil communities. We study predation in the established model organism Myxococcus xanthus, aiming to dissect the molecular mechanisms of prey cell lysis. In this study, we addressed the role of secreted bacteriolytic proteins, as well as potential mechanistic differences in the predation of Gram-positive and Gram-negative bacteria. Our observation shows that secreted enzymes are sufficient for killing and degrading Gram-positive species, but that cell-associated mechanisms may play a major role for killing Gram-negative and Gram-positive prey on fast timescales.

scholarly journals Effect of DNase and Antibiotics on Biofilm Characteristics

2008 ◽  
Vol 53 (3) ◽  
pp. 1204-1209 ◽  
Author(s):  
George V. Tetz ◽  
Natalia K. Artemenko ◽  
Victor V. Tetz
Keyword(s):  
Extracellular Dna ◽  
Gram Negative Bacteria ◽  
Bacterial Strains ◽  
Gram Positive ◽  
Gram Negative ◽  
Community Biomass ◽  
The Matrix ◽  
Average Size

ABSTRACT The role of extracellular DNA in the maintenance of biofilms formed by gram-positive and gram-negative bacteria was studied. This study evaluated all the bacterial strains that were tested for the presence of extracellular DNA with an average size of 30 kb in the matrix. Our results indicate changes in community biomass, architecture, morphology, and the numbers of CFU in the presence of DNase. This effect seems to be common to biofilms established by various unrelated gram-positive and gram-negative bacteria. The cleavage of extracellular DNA leads to the formation of an altered biofilm that permits the increased penetration of antibiotics. Thus, the addition of DNase enhances the effect of antibiotics, resulting in decreased biofilm biomass and numbers of CFU.

scholarly journals Differential effects of Gram-positive versus Gram-negative bacteria on NOSII and TNFα in macrophages: role of TLRs in synergy between the two

2006 ◽  
Vol 148 (8) ◽  
pp. 1067-1075 ◽  
Author(s):  
Mark J Paul-Clark ◽  
Shaun K Mc Master ◽  
Elizabeth Belcher ◽  
Rosalinda Sorrentino ◽  
Jasmine Anandarajah ◽  
...  
Keyword(s):  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Differential Effects
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