scholarly journals Microorganisms and cationic surfactants

2020 ◽  
Vol 74 ◽  
pp. 556-565
Author(s):  
Natalia Kula ◽  
Edyta Mazurkiewicz ◽  
Ewa Obłąk
Keyword(s):  
Cell Membrane ◽  
Cationic Surfactants ◽  
Heart Valves ◽  
Common Mechanism ◽  
Aqueous Environment ◽  
Gram Negative Bacteria ◽  
Amide Bonds ◽  
Planktonic Form ◽  
Hydrophobic Chain ◽  
Glass Metal

Quaternary ammonium salts (QAS) as cationic surfactants with an amphiphilic structure show biocidal activity against non-pathogenic and pathogenic microorganisms (Gram-positive, Gram-negative bacteria, fungi, as well as lipophilic viruses) occurring in planktonic form or forming biofilms. They can also coat the surface of various materials (glass, metal, silicone, polyester) from which medical devices are made, such as: catheters, implants, heart valves, endoprostheses, and this allows inhibiting the adhesion of microorganisms to these surfaces. In their chemical structure, these surfactants contain labile bonds, e.g. ester or amide bonds, which enable the biodegradation of the compounds. Thanks to this, they are classified as “green chemistry”. Their biological activity depends on the length of the hydrophobic chain and the structure of the hydrophilic head of the compound. QAS have an affinity for the cell membrane by interacting with its lipids and proteins, which can lead to its disintegration. They have the ability to inhibit the activity of H+-ATPase of the cell membrane, the enzyme responsible for its electrochemical gradient and the transport of nutrients to the cell, e.g. amino acids. These compounds can influence the lipid composition (quantitative and qualitative) of the cell membrane of microorganisms. They are also inhibitors of respiratory processes and can induce the formation of reactive oxygen species. These surfactants are capable of forming micelles and liposomes in an aqueous environment. They are widely used in medicine (as disinfectants, DNA carriers in gene therapy), in industry and environmental protection (as biocides, preservatives) and in agriculture (as fungicides). The widespread use of QAS in many fields causes the growing resistance of microorganisms to these compounds. A common mechanism that generates reduced susceptibility to QAS is the presence of efflux pumps.

scholarly journals Efficient Subgroup C Avian Sarcoma and Leukosis Virus Receptor Activity Requires the IgV Domain of the Tvc Receptor and Proper Display on the Cell Membrane

2008 ◽  
Vol 82 (22) ◽  
pp. 11419-11428 ◽  
Author(s):  
Audelia Munguia ◽  
Mark J. Federspiel
Keyword(s):  
Amino Acid ◽  
Cell Membrane ◽  
Conformational Changes ◽  
Aromatic Amino Acid ◽  
Receptor Activity ◽  
Site Directed Mutagenesis ◽  
Receptor Interaction ◽  
Common Mechanism ◽  
Amino Acid Residues ◽  
Avian Sarcoma

ABSTRACT We recently identified and cloned the receptor for subgroup C avian sarcoma and leukosis viruses [ASLV(C)], i.e., Tvc, a protein most closely related to mammalian butyrophilins, which are members of the immunoglobulin protein family. The extracellular domain of Tvc contains two immunoglobulin-like domains, IgV and IgC, which presumably each contain a disulfide bond important for native function of the protein. In this study, we have begun to identify the functional determinants of Tvc responsible for ASLV(C) receptor activity. We found that the IgV domain of the Tvc receptor is responsible for interacting with the glycoprotein of ASLV(C). Additional experiments demonstrated that a domain was necessary as a spacer between the IgV domain and the membrane-spanning domain for efficient Tvc receptor activity, most likely to orient the IgV domain a proper distance from the cell membrane. The effects on ASLV(C) glycoprotein binding and infection efficiency were also studied by site-directed mutagenesis of the cysteine residues of Tvc as well as conserved amino acid residues of the IgV Tvc domain compared to other IgV domains. In this initial analysis of Tvc determinants important for interacting with ASLV(C) glycoproteins, at least two aromatic amino acid residues in the IgV domain of Tvc, Trp-48 and Tyr-105, were identified as critical for efficient ASLV(C) infection. Interestingly, one or more aromatic amino acid residues have been identified as critical determinants in the other ASLV(A-E) receptors for a proper interaction with ASLV glycoproteins. This suggests that the ASLV glycoproteins may share a common mechanism of receptor interaction with an aromatic residue(s) on the receptor critical for triggering conformational changes in SU that initiate the fusion process required for efficient virus infection.

scholarly journals Research of antimicrobial efficacy of a composition with prolonged antiseptic effect against planktonic and film forms of clinical strains of non-fermentative Gram-negative bacteria

2020 ◽  
Vol 24 (1) ◽  
pp. 64-68
Author(s):  
O. A. Nazarchuk ◽  
V. I. Nahaichuk ◽  
O. V. Rymsha ◽  
V. H. Palii ◽  
I. M. Vovk ◽  
...  
Keyword(s):  
Comparative Study ◽  
Prolonged Exposure ◽  
Gram Negative Bacteria ◽  
Wound Surface ◽  
Gram Negative ◽  
Choice Of Treatment ◽  
Planktonic Form ◽  
Resistant Strains ◽  
Bacterial Film ◽  
Film Form

Annotation. The problem of treatment of burn wounds is closely related to the specificity of the spectrum of microorganisms that impair wound healing in this category of patients. A generally alarming trend in recent years is the significant increase in the etiological structure of wound infection, both in frequency and in severity and in the difficult choice of treatment tactics in the isolation of poly antimicrobial resistant strains of Pseudomonas aeruginosa, Acinetobacter baumannii. The aim of our study was to create a model of biofilm formed by bacteria on the wound surface and to investigate, in a comparative study, the sensitivity of planktonic and film forms of non-enzymatic gram-negative bacteria to a composition based on decamethoxin with prolonged antiseptic action. To determine the effect of the antiseptic composition on planktonic and film forms of bacteria there was used the method of two consecutive dilutions. The results of a comparative study of the activity of the antiseptic composition with decamethoxin planktonic and biofilm forms of strains of NFGB indicated that in the bacterial film bacteria were more resistant to drugs than in planktonic form. Film forms of A. baumannii and B. cepacia have a sensitivity to decamethoxin at a concentration of 13.6±1.95 µg/ml and 15.6±0 µg/ml, respectively. P. aeruginosa film forms have a higher degree of resistance to the test composition with decamethoxin (MBc 137.5±30.6 μg/ml). Disinfection of the planktonic form of NFGB is 10 times faster than the film form, the destruction of which is achieved with prolonged exposure of 120–150 minutes.

Structural changes in the model of the outer cell membrane of Gram-negative bacteria interacting with melittin: An in situ spectroelectrochemical study

2020 ◽  
Author(s):  
Izabella Brand ◽  
Bishoy Khairalla
Keyword(s):  
Cell Membrane ◽  
Structural Changes ◽  
Supramolecular Assembly ◽  
Outer Cell ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Langmuir Blodgett ◽  
A Cell ◽  
Experimental Challenge

A cell membrane of Gram-negative bacteria interacting with an antimicrobial peptide represents a complex supramolecular assembly. Fabrication of the models of bacterial cell membranes remains a large experimental challenge. Langmuir-Blodgett...

scholarly journals Novel Modifications of Nonribosomal Peptides from Brevibacillus laterosporus MG64 and Investigation of Their Mode of Action

2020 ◽  
Vol 86 (24) ◽  
Author(s):  
Zhibo Li ◽  
Reinder H. de Vries ◽  
Parichita Chakraborty ◽  
Chunxu Song ◽  
Xinghong Zhao ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Secondary Metabolites ◽  
Cell Membrane ◽  
Synergistic Effect ◽  
Mode Of Action ◽  
Nonribosomal Peptides ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Brevibacillus Laterosporus ◽  
Reductase Domain

ABSTRACT Nonribosomal peptides (NRPs) are a class of secondary metabolites usually produced by microorganisms. They are of paramount importance in different applications, including biocontrol and pharmacy. Brevibacillus spp. are a rich source of NRPs yet have received little attention. In this study, we characterize four novel bogorol variants (bogorols I to L, cationic linear lipopeptides) and four succilins (succilins I to L, containing a succinyl group that is attached to the Orn3/Lys3 in bogorols I to L) from the biocontrol strain Brevibacillus laterosporus MG64. Further investigation revealed that the bogorol family of peptides employs an adenylation pathway for lipoinitiation, different from the usual pattern, which is based on an external ligase and coenzyme A. Moreover, the formation of valinol was proven to be mediated by a terminal reductase domain and a reductase encoded by the bogI gene. Furthermore, succinylation, which is a novel type of modification in the family of bogorols, was discovered. Its occurrence requires a high concentration of the substrate (bogorols), but its responsible enzyme remains unknown. Bogorols display potent activity against both Gram-positive and Gram-negative bacteria. Investigation of their mode of action reveals that bogorols form pores in the cell membrane of both Gram-positive and Gram-negative bacteria. The combination of bogorols and relacidines, another class of NRPs produced by B. laterosporus MG64, displays a synergistic effect on different pathogens, suggesting the great potential of both peptides as well as their producer B. laterosporus MG64 for broad applications. Our study provides a further understanding of the bogorol family of peptides as well as their applications. IMPORTANCE NRPs form a class of secondary metabolites with biocontrol and pharmaceutical potential. This work describes the identification of novel bogorol variants and succinylated bogorols (namely, succilins) and further investigates their biosynthetic pathway and mode of action. Adenylation domain-mediated lipoinitiation of bogorols represents a novel pathway by which NRPs incorporate fatty acid tails. This pathway provides the possibility to engineer the lipid tail of NRPs without identifying a fatty acid coenzyme ligase, which is usually not present in the biosynthetic gene cluster. The terminal reductase domain (TD) and BogI-mediated valinol formation and their effect on the biological activity of bogorols are revealed. Succinylation, which is rarely reported in NRPs, was discovered in the bogorol family of peptides. We demonstrate that bogorols combat bacterial pathogens by forming pores in the cell membrane. We also report the synergistic effect of two natural products (relacidine B and bogorol K) produced by the same strain, which is relevant for competition for a niche.

scholarly journals A multifunctional platform with single-NIR-laser-triggered photothermal and NO release for synergistic therapy against multidrug-resistant Gram-negative bacteria and their biofilms

2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Baohua Zhao ◽  
He Wang ◽  
Wenjing Dong ◽  
Shaowen Cheng ◽  
Haisheng Li ◽  
...  
Keyword(s):  
Cell Membrane ◽  
Bacterial Cell ◽  
Multidrug Resistant ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
No Release ◽  
Bacterial Cell Membrane ◽  
Multifunctional Platform ◽  
Nir Laser

Abstract Background Infectious diseases caused by multidrug-resistant (MDR) bacteria, especially MDR Gram-negative strains, have become a global public health challenge. Multifunctional nanomaterials for controlling MDR bacterial infections via eradication of planktonic bacteria and their biofilms are of great interest. Results In this study, we developed a multifunctional platform (TG-NO-B) with single NIR laser-triggered PTT and NO release for synergistic therapy against MDR Gram-negative bacteria and their biofilms. When located at the infected sites, TG-NO-B was able to selectively bind to the surfaces of Gram-negative bacterial cells and their biofilm matrix through covalent coupling between the BA groups of TG-NO-B and the bacterial LPS units, which could greatly improve the antibacterial efficiency, and reduce side damages to ambient normal tissues. Upon single NIR laser irradiation, TG-NO-B could generate hyperthermia and simultaneously release NO, which would synergistically disrupt bacterial cell membrane, further cause leakage and damage of intracellular components, and finally induce bacteria death. On one hand, the combination of NO and PTT could largely improve the antibacterial efficiency. On the other hand, the bacterial cell membrane damage could improve the permeability and sensitivity to heat, decrease the photothermal temperature and avoid damages caused by high temperature. Moreover, TG-NO-B could be effectively utilized for synergistic therapy against the in vivo infections of MDR Gram-negative bacteria and their biofilms and accelerate wound healing as well as exhibit excellent biocompatibility both in vitro and in vivo. Conclusions Our study demonstrates that TG-NO-B can be considered as a promising alternative for treating infections caused by MDR Gram-negative bacteria and their biofilms.

The Effects of Amide Bonds and Aromatic Rings on the Surface Properties and Antimicrobial Activity of Cationic Surfactants

2018 ◽  
Vol 22 (2) ◽  
pp. 315-325 ◽  
Author(s):  
Xianyou He ◽  
Liyan Wang ◽  
Jianglei Wu ◽  
Jia Yang ◽  
Wenhui Ma ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Surface Properties ◽  
Cationic Surfactants ◽  
Aromatic Rings ◽  
Amide Bonds

scholarly journals Type III secretion: a bacterial device for close combat with cells of their eukaryotic host

2000 ◽  
Vol 355 (1397) ◽  
pp. 681-693 ◽  
Author(s):  
Guy R. Cornells
Keyword(s):  
Cell Membrane ◽  
Target Cell ◽  
Type Iii Secretion ◽  
Eukaryotic Cell ◽  
Gram Negative Bacteria ◽  
Bacterial Membranes ◽  
E Coli ◽  
Type Iii ◽  
Bacterial Proteins ◽  
New Type

Salmonella , Shigella , Yersinia , Pseudomonas aeruginosa , enteropathogenic Escherichia coli and several plantpathogenic Gram–negative bacteria use a new type of systems called ‘type III secretion’ to attack their host. These systems are activated by contact with a eukaryotic cell membrane and they allow bacteria to inject bacterial proteins across the two bacterial membranes and the eukaryotic cell membrane to reach a given compartment and destroy or subvert the target cell. These systems consist of a secretion apparatus made up of about 25 individual proteins and a set of proteins released by this apparatus. Some of these released proteins are ‘effectors’ that are delivered by extracellular bacteria into the cytosol of the target cell while the others are ‘translocators’ that help the ‘effectors’ to cross the membrane of the eukaryotic cell. Most of the ‘effectors’ act on the cytoskeleton or on intracellular signalling cascades. One of the proteins injected by the enteropathogenic E. coli serves as a membrane receptor for the docking of the bacterium itself at the surface of the cell.

scholarly journals T Cell Stimulation In Vivo by Lipopolysaccharide (LPS)

1997 ◽  
Vol 185 (12) ◽  
pp. 2089-2094 ◽  
Author(s):  
David F. Tough ◽  
Siquan Sun ◽  
Jonathan Sprent
Keyword(s):  
T Cells ◽  
B Cells ◽  
Common Mechanism ◽  
Type I ◽  
Gram Negative Bacteria ◽  
High Background ◽  
Gram Negative ◽  
Cd8 Cells ◽  
Stimulation Of

Lipopolysaccharide (LPS) from gram-negative bacteria causes polyclonal activation of B cells and stimulation of macrophages and other APC. We show here that, under in vivo conditions, LPS also induces strong stimulation of T cells. As manifested by CD69 upregulation, LPS injection stimulates both CD4 and CD8+ T cells, and, at high doses, stimulates naive (CD44lo) cells as well as memory (CD44hi) cells. However, in terms of cell division, the response of T cells after LPS injection is limited to the CD44hi subset of CD8+ cells. In contrast with B cells, proliferative responses of CD44hi CD8+ cells require only very low doses of LPS (10 ng). Based on studies with LPS-nonresponder and gene-knockout mice, LPS-induced proliferation of CD44hi CD8+ cells appears to operate via an indirect pathway involving LPS stimulation of APC and release of type I (α, β) interferon (IFN-I). Similar selective stimulation of CD44hi CD8+ cells occurs in viral infections and after injection of IFN-I, implying a common mechanism. Hence, intermittent exposure to pathogens (gram-negative bacteria and viruses) could contribute to the high background proliferation of memory–phenotype CD8+ cells found in normal animals.

Asymmetric cationic gemini surfactants: an improved synthetic procedure and the micellar and surface properties of a homologous series in the presence of simple salts

2018 ◽  
Vol 96 (7) ◽  
pp. 672-680
Author(s):  
David J. Greencorn ◽  
Victoria M. Sandre ◽  
Emily K. Piggott ◽  
Michael R. Hillier ◽  
A. James Mitchell ◽  
...  
Keyword(s):  
Cationic Surfactants ◽  
Gemini Surfactants ◽  
Aggregate Size ◽  
Morphological Properties ◽  
Micellar Properties ◽  
Micelle Structure ◽  
Surfactant Solutions ◽  
Synthetic Procedure ◽  
Cationic Gemini Surfactants ◽  
Hydrophobic Chain

The micellar and morphological properties of symmetric, cationic gemini surfactants have been well studied in the literature as a function of nature and type of the spacer group and the length and type of hydrophobic chain. In this paper, we have examined the effects of tail asymmetry on the properties of a series of cationic surfactants, the N-alkyl-1-N′-alkyl-2-N,N,N′,N′-tetramethyldiammonium dibromide. A novel synthetic method is used to prepare a series of these surfactants and the consequences of asymmetry on micellar properties are presented. This new method has been shown to be more efficient, with higher yields of the asymmetric surfactants than the yields of the accepted literature method. The critical micelle concentration values and the micelle sizes of the asymmetric gemini surfactants, 12-4-12, 12-4-10, 12-4-8, and 12-4-6 gemini surfactants, were obtained from conductivity and dynamic light scattering. With increasing chain asymmetry, the size of the micelle increased due to the formation of loose micelles. The addition of NaCl and Na2SO4 to the surfactant solutions increased the aggregate size, and this effect was more pronounced with increasing salt concentrations. These results are interpreted in terms of the effect these ions have on the “compactness” of the micelle structure.

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