scholarly journals Bactericidal effect of nanostructures via lytic transglycosylases of Escherichia coli

RSC Advances ◽  
2022 ◽  
Vol 12 (3) ◽  
pp. 1645-1652
Author(s):  
Soma Mimura ◽  
Tomohiro Shimizu ◽  
Shoso Shingubara ◽  
Hiroaki Iwaki ◽  
Takeshi Ito
Keyword(s):  
Escherichia Coli ◽  
Growth Phase ◽  
Cell Damage ◽  
Bactericidal Effect ◽  
Active Cell ◽  
Lytic Transglycosylases ◽  
E Coli ◽  
Time Profiles

The time profiles of active cell ratios depended on the growth phase and the absence of some lytic transglycosylases of E. coli. Significant cell damage was not found on the autolysis inhibition condition.

scholarly journals Magnesium Hydroxide Nanoparticles Kill Exponentially Growing and Persister Escherichia coli Cells by Causing Physical Damage

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1584
Author(s):  
Yohei Nakamura ◽  
Kaede Okita ◽  
Daisuke Kudo ◽  
Dao Nguyen Duy Phuong ◽  
Yoshihito Iwamoto ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Magnesium Hydroxide ◽  
Cell Damage ◽  
Low Cost ◽  
Bactericidal Effect ◽  
Physical Damage ◽  
E Coli ◽  
In The Wild ◽  
Low Toxicity ◽  
Magnesium Hydroxide Nanoparticles

Magnesium hydroxide nanoparticles are widely used in medicinal and hygiene products because of their low toxicity, environment-friendliness, and low cost. Here, we studied the effects of three different sizes of magnesium hydroxide nanoparticles on antibacterial activity: NM80, NM300, and NM700. NM80 (D50 = 75.2 nm) showed a higher bactericidal effect against Escherichia coli than larger nanoparticles (D50 = 328 nm (NM300) or 726 nm (NM700)). Moreover, NM80 showed a high bactericidal effect against not only exponential cells but also persister cells, which are difficult to eliminate owing to their high tolerance to antibiotics. NM80 eliminated strains in which magnesium-transport genes were knocked out and exhibited a bactericidal effect similar to that observed in the wild-type strain. The bactericidal action involved physical cell damage, as confirmed using scanning electron microscopy, which showed that E. coli cells treated with NM80 were directly injured.

Potentiation by L-cysteine of the bactericidal effect of hydrogen peroxide in Escherichia coli

1982 ◽  
Vol 152 (1) ◽  
pp. 81-88
Author(s):  
E H Berglin ◽  
M B Edlund ◽  
G K Nyberg ◽  
J Carlsson
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Metal Ion ◽  
Chelating Agent ◽  
Fold Increase ◽  
Bactericidal Effect ◽  
Anaerobic Conditions ◽  
Dna Breakage ◽  
E Coli ◽  
K 12

Under anaerobic conditions an exponentially growing culture of Escherichia coli K-12 was exposed to hydrogen peroxide in the presence of various compounds. Hydrogen peroxide (0.1 mM) together with 0.1 mM L-cysteine or L-cystine killed the organisms more rapidly than 10 mM hydrogen peroxide alone. The exposure of E. coli to hydrogen peroxide in the presence of L-cysteine inhibited some of the catalase. This inhibition, however, could not fully explain the 100-fold increase in hydrogen peroxide sensitivity of the organism in the presence of L-cysteine. Of other compounds tested only some thiols potentiated the bactericidal effect of hydrogen peroxide. These thiols were effective, however, only at concentrations significantly higher than 0.1 mM. The effect of L-cysteine and L-cystine could be annihilated by the metal ion chelating agent 2,2'-bipyridyl. DNA breakage in E. coli K-12 was demonstrated under conditions where the organisms were killed by hydrogen peroxide.

Antimicrobial Effects of Novel H2O2-Ag+ Complex on Membrane Damage to Staphylococcus aureus,Escherichia coli and Salmonella typhimurium

2021 ◽  
Author(s):  
Bing Han ◽  
Xiaoyu Han ◽  
Mengmeng Ren ◽  
Yilin You ◽  
Jicheng Zhan ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Staphylococcus Aureus ◽  
Salmonella Typhimurium ◽  
Membrane Damage ◽  
Bactericidal Effect ◽  
E Coli ◽  
Bacterial Cell Membrane ◽  
Time Kill ◽  
Environmental Disinfection

Diseases caused by harmful microorganisms pose a serious threat to human health. Safe and environment-friendly disinfectants are, therefore, essential in preventing and controlling such pathogens. This study aimed to investigate the antimicrobial activity and mechanism of a novel hydrogen peroxide and silver (H 2 O 2 -Ag + ) complex (HSC) in combatting Staphylococcus aureus ATCC 29213, Escherichia coli O157:H7 NCTC 12900 and Salmonella typhimurium SL 1344. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values against S. aureus were found to be 0.014 % H 2 O 2 -3.125 mg/L Ag + , while 0.028 % H 2 O 2 -6.25 mg/L Ag + for both E. coli and S. typhimurium . Results of the growth curve assay and time-kill trial suggest that the HSC could inhibit the growth of the tested bacteria, as 99.9 % of viable cells were killed following treatment at the 1 MIC for 3 h. Compared with Oxytech D10 disinfectant (0.25 % H 2 O 2 -5 mg/L Ag + ), the HSC exhibited better antibacterial efficacy at a lower concentration (0.045 % H 2 O 2 -10 mg/L Ag + ). The mechanism of antibacterial action of HSC was found including the disruption of the bacterial cell membrane, followed by entry into the bacteria cell to reduce intracellular adenosine triphosphate (ATP) concentration, and inhibit the activity of antioxidases, superoxide dismutase (SOD) and catalase (CAT). The enhanced bactericidal effect of hydrogen peroxide combined with silver indicates a potential for its application in environmental disinfection, particularly in the food industry.

scholarly journals Functional Analysis of Genes Comprising the Locus of Heat Resistance in Escherichia coli

2017 ◽  
Vol 83 (20) ◽  
Author(s):  
Ryan Mercer ◽  
Oanh Nguyen ◽  
Qixing Ou ◽  
Lynn McMullen ◽  
Michael G. Gänzle
Keyword(s):  
Escherichia Coli ◽  
Heat Shock ◽  
Heat Shock Proteins ◽  
Heat Resistance ◽  
Growth Phase ◽  
Genomic Island ◽  
Enteric Bacteria ◽  
Content Type ◽  
E Coli ◽  
Shock Proteins

ABSTRACT The locus of heat resistance (LHR) is a 15- to 19-kb genomic island conferring exceptional heat resistance to organisms in the family Enterobacteriaceae, including pathogenic strains of Salmonella enterica and Escherichia coli. The complement of LHR-comprising genes that is necessary for heat resistance and the stress-induced or growth-phase-induced expression of LHR-comprising genes are unknown. This study determined the contribution of the seven LHR-comprising genes yfdX1 GI, yfdX2, hdeD GI, orf11, trx GI, kefB, and psiE GI by comparing the heat resistances of E. coli strains harboring plasmid-encoded derivatives of the different LHRs in these genes. (Genes carry a subscript “GI” [genomic island] if an ortholog of the same gene is present in genomes of E. coli.) LHR-encoded heat shock proteins sHSP20, ClpKGI, and sHSPGI are not sufficient for the heat resistance phenotype; YfdX1, YfdX2, and HdeD are necessary to complement the LHR heat shock proteins and to impart a high level of resistance. Deletion of trx GI, kefB, and psiE GI from plasmid-encoded copies of the LHR did not significantly affect heat resistance. The effect of the growth phase and the NaCl concentration on expression from the putative LHR promoter p2 was determined by quantitative reverse transcription-PCR and by a plasmid-encoded p2:GFP promoter fusion. The expression levels of exponential- and stationary-phase E. coli cells were not significantly different, but the addition of 1% NaCl significantly increased LHR expression. Remarkably, LHR expression in E. coli was dependent on a chromosomal copy of evgA. In conclusion, this study improved our understanding of the genes required for exceptional heat resistance in E. coli and factors that increase their expression in food. IMPORTANCE The locus of heat resistance (LHR) is a genomic island conferring exceptional heat resistance to several foodborne pathogens. The exceptional level of heat resistance provided by the LHR questions the control of pathogens by current food processing and preparation techniques. The function of LHR-comprising genes and their regulation, however, remain largely unknown. This study defines a core complement of LHR-encoded proteins that are necessary for heat resistance and demonstrates that regulation of the LHR in E. coli requires a chromosomal copy of the gene encoding EvgA. This study provides insight into the function of a transmissible genomic island that allows otherwise heat-sensitive enteric bacteria, including pathogens, to lead a thermoduric lifestyle and thus contributes to the detection and control of heat-resistant enteric bacteria in food.

scholarly journals Growth Phase-Dependent Regulation and Stringent Control of fis Are Conserved Processes in Enteric Bacteria and Involve a Single Promoter (fis P) in Escherichia coli

2004 ◽  
Vol 186 (1) ◽  
pp. 122-135 ◽  
Author(s):  
Prabhat Mallik ◽  
Timothy S. Pratt ◽  
Michael B. Beach ◽  
Meranda D. Bradley ◽  
Jayanthi Undamatla ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Growth Phase ◽  
Primer Extension ◽  
E Coli ◽  
Stringent Control ◽  
Regulatory Processes ◽  
Nutritional Environment ◽  
Nuclease Mapping ◽  
Single Promoter

ABSTRACT The intracellular concentration of the Escherichia coli factor for inversion stimulation (Fis), a global regulator of transcription and a facilitator of certain site-specific DNA recombination events, varies substantially in response to changes in the nutritional environment and growth phase. Under conditions of nutritional upshift, fis is transiently expressed at very high levels, whereas under induced starvation conditions, fis is repressed by stringent control. We show that both of these regulatory processes operate on the chromosomal fis genes of the enterobacteria Klebsiella pneumoniae, Serratia marcescens, Erwinia carotovora, and Proteus vulgaris, strongly suggesting that the physiological role of Fis is closely tied to its transcriptional regulation in response to the nutritional environment. These transcriptional regulatory processes were previously shown to involve a single promoter (fis P) preceding the fis operon in E. coli. Recent work challenged this notion by presenting evidence from primer extension assays which appeared to indicate that there are multiple promoters upstream of fis P that contribute significantly to the expression and regulation of fis in E. coli. Thus, a rigorous analysis of the fis promoter region was conducted to assess the contribution of such additional promoters. However, our data from primer extension analysis, S1 nuclease mapping, β-galactosidase assays, and in vitro transcription analysis all indicate that fis P is the sole E. coli fis promoter in vivo and in vitro. We further show how certain conditions used in the primer extension reactions can generate artifacts resulting from secondary annealing events that are the likely source of incorrect assignment of additional fis promoters.

scholarly journals Overproduction of Penicillin-Binding Protein 2 and Its Inactive Variants Causes Morphological Changes and Lysis in Escherichia coli

2007 ◽  
Vol 189 (14) ◽  
pp. 4975-4983 ◽  
Author(s):  
Blaine A. Legaree ◽  
Calvin B. Adams ◽  
Anthony J. Clarke
Keyword(s):  
Escherichia Coli ◽  
Signal Sequence ◽  
Morphological Changes ◽  
Binding Protein ◽  
Penicillin Binding Protein ◽  
Prolonged Incubation ◽  
Lytic Transglycosylases ◽  
E Coli ◽  
Derivatives Of

ABSTRACT Penicillin-binding protein 2 (PBP 2) has long been known to be essential for rod-shaped morphology in gram-negative bacteria, including Escherichia coli and Pseudomonas aeruginosa. In the course of earlier studies with P. aeruginosa PBP 2, we observed that E. coli was sensitive to the overexpression of its gene, pbpA. In this study, we examined E. coli overproducing both P. aeruginosa and E. coli PBP 2. Growth of cells entered a stationary phase soon after induction of gene expression, and cells began to lyse upon prolonged incubation. Concomitant with the growth retardation, cells were observed to have changed morphologically from typical rods into enlarged spheres. Inactive derivatives of the PBP 2s were engineered, involving site-specific replacement of their catalytic Ser residues with Ala in their transpeptidase module. Overproduction of these inactive PBPs resulted in identical effects. Likewise, overproduction of PBP 2 derivatives possessing only their N-terminal non-penicillin-binding module (i.e., lacking their C-terminal transpeptidase module) produced similar effects. However, E. coli overproducing engineered derivatives of PBP 2 lacking their noncleavable, N-terminal signal sequence and membrane anchor were found to grow and divide at the same rate as control cells. The morphological effects and lysis were also eliminated entirely when overproduction of PBP 2 and variants was conducted with E. coli MHD79, a strain lacking six lytic transglycosylases. A possible interaction between the N-terminal domain of PBP 2 and lytic transglycosylases in vivo through the formation of multienzyme complexes is discussed.

scholarly journals The Putrescine Importer PuuP of Escherichia coli K-12

2009 ◽  
Vol 191 (8) ◽  
pp. 2776-2782 ◽  
Author(s):  
Shin Kurihara ◽  
Yuichi Tsuboi ◽  
Shinpei Oda ◽  
Hyeon Guk Kim ◽  
Hidehiko Kumagai ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Gene Cluster ◽  
Growth Phase ◽  
Exponential Growth ◽  
Minimal Medium ◽  
Exponential Growth Phase ◽  
E Coli ◽  
Genes Encoding ◽  
K 12 ◽  
Utilization Pathway

ABSTRACT The Puu pathway is a putrescine utilization pathway involving gamma-glutamyl intermediates. The genes encoding the enzymes of the Puu pathway form a gene cluster, the puu gene cluster, and puuP is one of the genes in this cluster. In Escherichia coli, three putrescine importers, PotFGHI, PotABCD, and PotE, were discovered in the 1990s and have been studied; however, PuuP had not been discovered previously. This paper shows that PuuP is a novel putrescine importer whose kinetic parameters are equivalent to those of the polyamine importers discovered previously. A puuP + strain absorbed up to 5 mM putrescine from the medium, but a ΔpuuP strain did not. E. coli strain MA261 has been used in previous studies of polyamine transporters, but PuuP had not been identified previously. It was revealed that the puuP gene of MA261 was inactivated by a point mutation. When E. coli was grown on minimal medium supplemented with putrescine as the sole carbon or nitrogen source, only PuuP among the polyamine importers was required. puuP was expressed strongly when putrescine was added to the medium or when the puuR gene, which encodes a putative repressor, was deleted. When E. coli was grown in M9-tryptone medium, PuuP was expressed mainly in the exponential growth phase, and PotFGHI was expressed independently of the growth phase.

Inactivation of Escherichia coli O157:H7, Listeria monocytogenes, and Lactobacillus leichmannii by Combinations of Ozone and Pulsed Electric Field

2001 ◽  
Vol 64 (6) ◽  
pp. 777-782 ◽  
Author(s):  
RAGIP UNAL ◽  
JIN-GAB KIM ◽  
AHMED E. YOUSEF
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Electric Field ◽  
Pulsed Electric Field ◽  
Bactericidal Effect ◽  
Treatment Level ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Nonthermal Processing ◽  
Lactobacillus Leichmannii

Pulsed electric field (PEF) and ozone technologies are nonthermal processing methods with potential applications in the food industry. This research was performed to explore the potential synergy between ozone and PEF treatments against selected foodborne bacteria. Cells of Lactobacillus leichmannii ATCC 4797, Escherichia coli O157:H7 ATCC 35150, and Listeria monocytogenes Scott A were suspended in 0.1% NaCl and treated with ozone, PEF, and ozone plus PEF. Cells were treated with 0.25 to 1.00 μg of ozone per ml of cell suspension, PEF at 10 to 30 kV/cm, and selected combinations of ozone and PEF. Synergy between ozone and PEF varied with the treatment level and the bacterium treated. L. leichmannii treated with PEF (20 kV/cm) after exposure to 0.75 and 1.00 μg/ml of ozone was inactivated by 7.1 and 7.2 log10 CFU/ml, respectively; however, ozone at 0.75 and 1.00 μg/ml and PEF at 20 kV/cm inactivated 2.2, 3.6, and 1.3 log10 CFU/ml, respectively. Similarly, ozone at 0.5 and 0.75 μg/ml inactivated 0.5 and 1.8 log10 CFU/ml of E. coli, PEF at 15 kV/cm inactivated 1.8 log10 CFU/ml, and ozone at 0.5 and 0.75 μg/ml followed by PEF (15 kV/cm) inactivated 2.9 and 3.6 log10 CFU/ml, respectively. Populations of L. monocytogenes decreased 0.1, 0.5, 3.0, 3.9, and 0.8 log10 CFU/ml when treated with 0.25, 0.5, 0.75, and 1.0 μg/ml of ozone and PEF (15 kV/cm), respectively; however, when the bacterium was treated with 15 kV/cm, after exposure to 0.25, 0.5, and 0.75 μg/ml of ozone, 1.7, 2.0, and 3.9 log10 CFU/ml were killed, respectively. In conclusion, exposure of L. leichmannii, E. coli, and L. monocytogenes to ozone followed by the PEF treatment showed a synergistic bactericidal effect. This synergy was most apparent with mild doses of ozone against L. leichmannii.

scholarly journals Comparative assessment of the bactericidal effect of nanoparticles of copper oxide, silver, and chitosan-silver against Escherichia coli infection in broilers

2021 ◽  
Vol 41 (4) ◽  
Author(s):  
Eman I. Hassanen ◽  
Eman A. Morsy ◽  
Ahmed M. Hussien ◽  
Khaled Y. Farroh ◽  
Merhan E. Ali
Keyword(s):  
Escherichia Coli ◽  
Copper Oxide ◽  
Treated Group ◽  
Bactericidal Effect ◽  
Growth Promoter ◽  
Ag Nps ◽  
E Coli ◽  
Cuo Nps ◽  
Escherichia Coli Infection

Abstract Escherichia coli infection is considered one of the most economically important multi-systemic diseases in poultry farms. Several nanoparticles such as silver, chitosan, and copper oxide are known to be highly toxic to several microbes. However, there are no data concerning their success against in vivo experimental E. coli infection in broilers. Therefore, the present study was designed to investigate the bactericidal effect of low doses of CuO-NPs (5 mg/kg bwt), Ag-NPs (0.5 mg/kg bwt), and Ch-Ag NPs (0.5 mg/kg bwt) against E. coli experimental infection in broilers. One hundred chicks were divided into five groups as follows: (1) control; (2) E. coli (4 × 108 CFU/ml) challenged; (3) E. coli +CuO-NPs; (4) E. coli +Ag-NPs; (5) E. coli +Ch-Ag NPs. The challenged untreated group, not NPs treated groups, recorded the lowest weight gain as well as the highest bacterial count and lesion score in all examined organs. The highest liver content of silver was observed in Ag-NPs treated group compared with the Ch-Ag NPs treated group. Our results concluded that Ch-Ag NPs not only had the best antibacterial effects but also acted as a growth promoter in broilers without leaving any residues in edible organs. We recommend using Ch-Ag NPs in broiler farms instead of antibiotics or probiotics.

Antibacterial Activity of the Silver Nanoparticles against Escherichia coli and Enterobacter sp

2017 ◽  
Vol 1 (1) ◽  
Author(s):  
Kathirvel Maruthai ◽  
Kommoju Vallayyachari ◽  
Thirumurugan Ravibalan ◽  
Sheryl Ann Philip ◽  
Antony V. Samrot ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Chemical Method ◽  
Reduction Method ◽  
Clinical Importance ◽  
Bactericidal Effect ◽  
Bacterial Cells ◽  
E Coli ◽  
Protein Leakage ◽  
Glucose Reduction ◽  
Membrane Destabilization

In this study, spherical silver nanoparticle (AgNP) was produced by sustainable chemical method i.e. glucose reduction method and it was utilized to analyse the bactericidal effect against the pathogens of clinical importance - E. coli (ATCC 10536) and Enterobacter sp., KL46 by membrane destabilization and protein leakage analyses. Minimum inhibitory/bactericidal and antibiogram analyses reported that 20ng/ml was enough to inhibit/kill bacterial cells. Even 20ng/ml concentration of AgNPs was found to destabilize membrane and lead to protein leakage from bacterial cells. 

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