Electron Microscopy of
            <i>Staphylococcus aureus</i>
            Cell Wall Lysis

Virgilio, R; Gonzalez, Christian; Muñoz, Nubia; Mendoza, Sonia

doi:10.1128/jb.91.5.2018-2024.1966

Cited by 9 publications

(6 citation statements)

References 17 publications

(12 reference statements)

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“…These morphological changes in Staphylococcus aureus cells are speculated to be the result of lysozyme triggered autolysis of bacteria which is the generally accepted mechanism of lysozyme action on Staphylococcus aureus cells. 38,39 In conclusion, we have developed a unique multifunctional biomimetic material comprised of SWNT, DNA, and LSZ using LBL assembly. Precise control of both layer thickness and SWNT alignment within each layer was achieved, and the final coatings had robust mechanical properties.…”

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confidence: 96%

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Strong Antimicrobial Coatings: Single-Walled Carbon Nanotubes Armored with Biopolymers

et al. 2008

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Large scale biomimetic single-walled carbon nanotube (SWNT) coatings with significant antimicrobial activity, high Young's Modulus, and controlled morphology were fabricated using layer-by-layer assembly. Thickness was controlled within 1.6 nm and SWNT orientation was controlled using a directed air stream. This unique blend of multifunctionality and vertical and lateral control of a bottom-up assembly process is a significant advancement in developing macroscale assemblies with the combined attributes of SWNTs and natural materials.Concern about the spread of infections through contact with contaminated surfaces was once limited to specific groups of people including astronauts who are subject to confined living spaces and the virulence-enhancing effects of space flight 1 and people requiring surgery or implantable devices. 2 More recently, there has been growing concern about the role of contaminated surfaces in the spread of infections such as severe acute respiratory syndrome (SARS), 3,4 and Staphylococcus aureus, particularly methicillin-resistant Staphylococcus aureus (MSRA). 5 Antimicrobial surfaces are therefore desirable not only for the aerospace, defense, and medical industries but also for the consumer product and public transportation industries. We have used layer-by-layer assembly to produce coatings that combine the strength of single-walled carbon nanotubes (SWNTs) with the antimicrobial activity of lysozyme (LSZ).LSZ, a key member of ova-antimicrobials, is a powerful natural antibacterial protein. 6 It is in the class of enzymes which lyse the cell walls of Gram-positive bacteria by hydrolyzing the -1,4 linkage between N-acetylmuramic acid (NAM) and N-acetylglucosamine (NAG) of gigantic polymers in the peptidoglycan (murein). 7,8 Unlike many antimicrobials, LSZ has both enzymatic and nonenzymatic activity in both its native and denatured states and is useful even in processes which require heat treatment. The potential use of LSZ as an antimicrobial agent in pharmaceuticals, food preservatives, and packaging is an active area of research, 7,8 but the effective use of LSZ requires incorporating it with a more mechanically robust material. SWNTs are well-known for exceptional combination of mechanical, electrical, thermal, and optical properties. 9-11 However, the efficient transfer of SWNTs' inherent nanoscale properties to macroscopic structures and devices has been an ongoing research challenge comprised of three main issues: SWNT dispersion, controlled assembly, and efficient load transfer. There has been growing interest in using biological materials to stabilize dispersions of pristine SWNTs. DNA enables much higher concentrations of dispersions of individual and small bundles of SWNTs 11,12 than any other known material besides superacids; 13,14 DNA-SWNT dispersions have even been used to produce liquid crystalline dispersions for solution spinning. 15 Similarly, favorable intermolecular interactions enable dispersion of individual and small bundles of SWNTs in proteins such as LSZ...

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confidence: 96%

“…In contrast, on the uncoated silicon surface the cells remained intact and maintained their cocci structure. These morphological changes in Staphylococcus aureus cells are speculated to be the result of lysozyme triggered autolysis of bacteria which is the generally accepted mechanism of lysozyme action on Staphylococcus aureus cells. , …”

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confidence: 99%

Strong Antimicrobial Coatings: Single-Walled Carbon Nanotubes Armored with Biopolymers

et al. 2008

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“…There have been only a few reports of electron microscopic observations of the dissolution of cell walls of gram-positive bacteria by the action of lytic enzymes (2,5,14). Morphological observations of the autolytic dissolution of the cell walls of Streptococcus faecalis ATCC 9790 were of particular interest to us in view of recent reports (11,12) which indicated that the active form of the wall-bound autolysin preferentially acts on the most recently synthesized portion of the wall first.…”

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confidence: 99%

Autolytic Enzyme System of Streptococcus faecalis IV. Electron Microscopic Observations of Autolysin and Lysozyme Action

Shockman

Martin

1968

J Bacteriol

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Cell walls (LOG walls) were isolated from cultures of Streptococcus faecalis ATCC 9790 in the exponential phase of growth. These walls were either allowed to undergo autolytic dissolution (in the presence or absence of trypsin) or wall autolysis was inactivated with sodium dodecylsulfate (SDS walls). Inactivated walls were treated either with lysozyme or with isolated, partially purified S. faecalis autolysin. During wall lysis, samples were removed, negatively stained with phosphotungstate, and examined in the electron microscope. Both lysozyme and isolated autolysin appeared to act over the entire surface of SDS walls. After partial dissolution, a fibrous network over the surface was revealed. Lysozyme digestion revealed the presence of prominent, highly-contrasted equatorial and subequatorial bands around the walls. After trichloroacetic acid extraction, the bands were seen less frequently and less distinctly in the partially lysozyme digested walls, suggesting that the bands contained nonpeptidoglycan polymers. In the absence of trypsin (which activates a latent form of the autolysin), autolysis of LOG walls appeared to start at the equatorial bands and to proceed back towards the apex of the coccus. Ribbons of wall material coming off the wide edge of the nearly hemispherical wall fragments were observed. Activation of latent autolysis resulted in lytic action over the entire wall surface. The results are consistent with the previously postulated location of active autolysin at the areas of new wall synthesis and the random location of latent autolysin in LOG walls.

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“…However, nearly no bacteriostatic effect on S. aureus at any concentrations of LAML solution has been demonstrated (data not shown). Virgilio et al . (1966) reported that S. aureus proved resistant to treatment with several lytic agents, even a number of enzymes such as lysozyme, which completely dissolves certain gram‐positive bacteria, but had little or no action on S. aureus cells.…”

Section: Resultsmentioning

confidence: 99%

Physicochemical Characteristics and Bacteriostatic Ability of Modified Lysozyme From Lactic Acid-Induced Gelled Egg White Powder

ShiangLiang¹,

Weng²,

Huang³

et al. 2011

Journal of Food Processing and Preservation

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This study investigates the physicochemical characteristics and bacteriostatic ability of modified lysozyme from 6, 7, 8, 9 and 10% lactic acid-induced gelled egg white powder. The lactic acid modified lysozyme (LAML) powder was dissolved in solutions with pH values of 2-10 at incubation times of 30-720 min, showing enzymatic activity of 50% (2,000-6,000 U/mg). Following treatment in solutions of various concentrations of salt (0.1-3 M), the activity of LAML decreased with an increase in the concentration of salt. The enzymatic activity of LAML decreased with an increase in temperature (40-100C) and incubation time (10-120 min); the activity of LAML ceased when held at 100C for 120 min. The LAML showed quantities of a dimmer (28 kDa) structure appearing in native-polyacrylamide gel electrophoresis analysis. The bacteriostatic efficacy of LAML against Bacillus cereus BCRC 15324, Escherichia coli K12 and Salmonella typhimurium TA98 increased proportionally with the concentration of LAML solution. This study revealed that LAML has bacteriostatic ability against E. coli K12, S. typhimurium TA98 and B. cereus BCRC 15324 while maintaining enzymatic activity under a variety of conditions. PRACTICAL APPLICATIONSLysozyme from the egg whites from hens is an enzyme comprising approximately 3.4% of egg white protein. Lysozyme demonstrates strong antibacterial potential, mainly among gram-positive bacteria, and this phenomenon has found practical applications in the food and pharmaceutical industries. However, gram-negative bacteria are less susceptible to lysozyme activity.Various researchers have identified a synergistic relationship between lysozyme and other preservatives such as organic acids, resulting in significantly improved bacteriostatic activity against a wide range of bacteria. The present work shows that the enzymatic activity of the modified lysozyme with various concentrations of lactic acid solution remains stable while maintaining consistent bacteriostatic activity against Bacillus cereus BCRC 15324, Escherichia coli K12 and Salmonella typhimurium TA98. Lactic acid-induced gelled egg white powder represents a cost-effective alternative to the standard bacteriostatic additives used in the food industry.

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Electron Microscopy of Staphylococcus aureus Cell Wall Lysis

Cited by 9 publications

References 17 publications

Strong Antimicrobial Coatings: Single-Walled Carbon Nanotubes Armored with Biopolymers

Strong Antimicrobial Coatings: Single-Walled Carbon Nanotubes Armored with Biopolymers

Autolytic Enzyme System of Streptococcus faecalis IV. Electron Microscopic Observations of Autolysin and Lysozyme Action

Physicochemical Characteristics and Bacteriostatic Ability of Modified Lysozyme From Lactic Acid-Induced Gelled Egg White Powder

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