Disinfection performance of nanosilver and impacts of environmental conditions on viral inactivation by nanosilver

2013 ◽  
Vol 14 (1) ◽  
pp. 150-157 ◽  
Author(s):  
Yang Xu ◽  
Xiaona Chu ◽  
Jiangyong Hu ◽  
Say Leong Ong
Keyword(s):  
Escherichia Coli ◽  
Silver Nanoparticles ◽  
Humic Acid ◽  
Ionic Strength ◽  
Environmental Conditions ◽  
Contact Time ◽  
Chloride Ion ◽  
Viral Inactivation ◽  
E Coli ◽  
High Concentrations

Three types of nanosilver materials, which were commercial, chemically-synthesized and biologically-synthesized, respectively, were compared in terms of the disinfection efficiencies against Escherichia coli and MS2 coliphage in order to pinpoint promising material with the best performance. Disinfection results showed biologically-synthesized silver nanoparticles (referred to hereafter as ‘bio-AgNPs’) had the best disinfection performance, 10 mg/L of which was able to inactivate all the E. coli in 1 min (>6 log removals) and achieved 4 log removals of MS2 coliphage. Bio-AgNPs were therefore selected for further study in terms of effects of the concentration and contact time as well as the impacts of environmental conditions on the viral inactivation. Given the viral inactivation profile of bio-AgNPs shown in this study, it could be concluded that viral inactivation by bio-AgNPs could be inhibited by total organic carbon (TOC) (10 mg/L as humic acid) and chloride ion (5 mg/L) to a large extent while Ca2+/Mg2+/ionic strength only had minor effects on the viral inactivation at high concentrations (188 mg/L as CaCO3 of hardness or 5.6 mM of ionic strength, respectively). This part of the study may help enlighten further mechanism studies on viral inactivation by nanosilver.

Antimicrobial Activity of Silver Nanoparticles Prepared Under an Ultrasonic Field

2011 ◽  
Vol 4 (3) ◽  
pp. 1491-1496
Author(s):  
Umadevi M ◽  
Rani T ◽  
Balakrishnan T ◽  
Ramanibai R
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Activity ◽  
Silver Nanoparticles ◽  
Reduction Method ◽  
Therapeutic Potential ◽  
Chemical Reduction ◽  
Ultrasonic Field ◽  
Great Promise ◽  
Chemical Reduction Method ◽  
E Coli

Nanotechnology has great promise for improving the therapeutic potential of medicinal molecules and related agents. In this study, silver nanoparticles of different sizes were synthesized in an ultrasonic field using the chemical reduction method with sodium borohydride as a reducing agent. The size effect of silver nanoparticles on antimicrobial activity were tested against the microorganisms Staphylococcus aureus (MTCC No. 96), Bacillus subtilis (MTCC No. 441), Streptococcus mutans (MTCC No. 497), Escherichia coli (MTCC No. 739) and Pseudomonas aeruginosa (MTCC No. 1934). The results shows that B. subtilis, and E. coli were more sensitive to silver nanoparticles and its size, indicating the superior antimicrobial efficacy of silver nanoparticles. 

scholarly journals Transcriptome analysis of Escherichia coli K1 after therapy with hesperidin conjugated with silver nanoparticles

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Abdulkader Masri ◽  
Naveed Ahmed Khan ◽  
Muhammad Zarul Hanifah Md Zoqratt ◽  
Qasim Ayub ◽  
Ayaz Anwar ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Silver Nanoparticles ◽  
Minimum Inhibitory Concentration ◽  
Inhibitory Concentration ◽  
Neonatal Meningitis ◽  
E Coli ◽  
Drug Candidates ◽  
Metabolic Genes ◽  
Genetic Mechanisms ◽  
Cell Stress Response

Abstract Backgrounds Escherichia coli K1 causes neonatal meningitis. Transcriptome studies are indispensable to comprehend the pathology and biology of these bacteria. Recently, we showed that nanoparticles loaded with Hesperidin are potential novel antibacterial agents against E. coli K1. Here, bacteria were treated with and without Hesperidin conjugated with silver nanoparticles, and silver alone, and 50% minimum inhibitory concentration was determined. Differential gene expression analysis using RNA-seq, was performed using Degust software and a set of genes involved in cell stress response and metabolism were selected for the study. Results 50% minimum inhibitory concentration with silver-conjugated Hesperidin was achieved with 0.5 μg/ml of Hesperidin conjugated with silver nanoparticles at 1 h. Differential genetic analysis revealed the expression of 122 genes (≥ 2-log FC, P< 0.01) in both E. coli K1 treated with Hesperidin conjugated silver nanoparticles and E. coli K1 treated with silver alone, compared to untreated E. coli K1. Of note, the expression levels of cation efflux genes (cusA and copA) and translocation of ions, across the membrane genes (rsxB) were found to increase 2.6, 3.1, and 3.3- log FC, respectively. Significant regulation was observed for metabolic genes and several genes involved in the coordination of flagella. Conclusions The antibacterial mechanism of nanoparticles maybe due to disruption of the cell membrane, oxidative stress, and metabolism in E. coli K1. Further studies will lead to a better understanding of the genetic mechanisms underlying treatment with nanoparticles and identification of much needed novel antimicrobial drug candidates.

Emerging investigator series: interacting effects of environmental factors on Daphnia magna removal of Escherichia coli from wastewater

2021 ◽  
Vol 7 (4) ◽  
pp. 726-738
Author(s):  
Seyyed M. H. Abtahi ◽  
Ojaswi Aryal ◽  
Niveen S. Ismail
Keyword(s):  
Escherichia Coli ◽  
Environmental Factors ◽  
Daphnia Magna ◽  
Environmental Conditions ◽  
E Coli

Zooplankton can significantly impact E. coli inactivation in wastewater, but inactivation rates are dependent on environmental conditions.

scholarly journals Strain improvement of Escherichia coli K-12 for recombinant production of deuterated proteins

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Vinardas Kelpšas ◽  
Claes von Wachenfeldt
Keyword(s):  
Escherichia Coli ◽  
Structural Biology ◽  
Strain Improvement ◽  
Growth Media ◽  
Genomic Changes ◽  
E Coli ◽  
Recombinant Production ◽  
High Concentrations ◽  
Neutron Protein Crystallography ◽  
K 12

AbstractDeuterium isotope labelling is important for structural biology methods such as neutron protein crystallography, nuclear magnetic resonance and small angle neutron scattering studies of proteins. Deuterium is a natural low abundance stable hydrogen isotope that in high concentrations negatively affect growth of cells. The generation time for Escherichia coli K-12 in deuterated medium is substantially increased compared to cells grown in hydrogenated (protiated) medium. By using a mutagenesis plasmid based approach we have isolated an E. coli strain derived from E. coli K-12 substrain MG1655 that show increased fitness in deuterium based growth media, without general adaptation to media components. By whole-genome sequencing we identified the genomic changes in the obtained strain and show that it can be used for recombinant production of perdeuterated proteins in amounts typically needed for structural biology studies.

scholarly journals Poikilothermic Animals as a Previously Unrecognized Source of Fecal Indicator Bacteria in a Backwater Ecosystem of a Large River

2018 ◽  
Vol 84 (16) ◽  
Author(s):  
Christina Frick ◽  
Julia Vierheilig ◽  
Rita Linke ◽  
Domenico Savio ◽  
Horst Zornig ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Clostridium Perfringens ◽  
Fecal Indicator Bacteria ◽  
Indicator Bacteria ◽  
Primary Sources ◽  
Fecal Indicator ◽  
Content Type ◽  
E Coli ◽  
High Concentrations ◽  
Intestinal Enterococci

ABSTRACTQuantitative information regarding the presence ofEscherichia coli, intestinal enterococci, andClostridium perfringensin poikilotherms is notably scarce. Therefore, this study was designed to allow a systematic comparison of the occurrence of these standard fecal indicator bacteria (SFIB) in the excreta of wild homeothermic (ruminants, boars, carnivores, and birds) and poikilothermic (earthworms, gastropods, frogs, and fish) animals inhabiting an alluvial backwater area in eastern Austria. With the exception of earthworms, the average concentrations ofE. coliand enterococci in the excreta of poikilotherms were equal to or only slightly lower than those observed in homeothermic excreta and were 1 to 4 orders of magnitude higher than the levels observed in the ambient soils and sediments. Enterococci reached extraordinarily high concentrations in gastropods. Additional estimates of the daily excreted SFIB (E. coliand enterococcus) loads (DESL) further supported the importance of poikilotherms as potential pollution sources. The newly established DESL metric also allowed comparison to the standing stock of SFIB in the sediment and soil of the investigated area. In agreement with its biological characteristics, the highest concentrations ofC. perfringenswere observed in carnivores. In conclusion, the long-standing hypothesis that only humans and homeothermic animals are primary sources of SFIB is challenged by the results of this study. It may be necessary to extend the fecal indicator concept by additionally considering poikilotherms as potential important primary habitats of SFIB. Further studies in other geographical areas are needed to evaluate the general significance of our results. We hypothesize that the importance of poikilotherms as sources of SFIB is strongly correlated with the ambient temperature and would therefore be of increased significance in subtropical and tropical habitats and water resources.IMPORTANCEThe current fecal indicator concept is based on the assumption that the standard fecal indicator bacteria (SFIB)Escherichia coli, intestinal enterococci, andClostridium perfringensmultiply significantly only in the guts of humans and other homeothermic animals and can therefore indicate fecal pollution and the potential presence of pathogens from those groups. The findings of the present study showed that SFIB can also occur in high concentrations in poikilothermic animals (i.e., animals with body temperatures that vary with the ambient environmental temperature, such as fish, frogs, and snails) in an alluvial backwater area in a temperate region, indicating that a reconsideration of this long-standing indicator paradigm is needed. This study suggests that poikilotherms must be considered to be potential primary sources of SFIB in future studies.

Screening of OXA-244 producers, a difficult-to-detect and emerging OXA-48 variant?

2020 ◽  
Author(s):  
Cecile Emeraud ◽  
Laura Biez ◽  
Delphine Girlich ◽  
Agnès B Jousset ◽  
Thierry Naas ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Hydrolytic Activity ◽  
Single Amino Acid ◽  
Broth Microdilution ◽  
Mlst Analysis ◽  
E Coli ◽  
Amino Acid Variant ◽  
High Prevalence ◽  
High Concentrations

Abstract Background OXA-244, a single amino acid variant of OXA-48, demonstrates weaker hydrolytic activity towards carbapenems and temocillin compared with OXA-48. Of note, these antimicrobials are present in high concentrations in several carbapenemase-producing Enterobacterales (CPE) screening media. As a result, some screening media fail to grow OXA-244-producing isolates, while the prevalence of OXA-244 producers is constantly increasing in France. Methods Here, we evaluate the performance of three commercially available CPE screening media [ChromID® CARBA SMART (bioMérieux), Brilliance™ CRE (Thermo Fisher) and mSuperCARBA™ (MAST Diagnostic)] for their ability to detect OXA-244 producers (n = 101). As OXA-244 producers may also express an ESBL, two additional ESBL screening media were tested (Brilliance™ ESBL and ChromID® BLSE). MICs of temocillin and imipenem were determined by broth microdilution. The clonality of OXA-244-producing Escherichia coli isolates (n = 97) was assessed by MLST. Results Overall, the sensitivity of the ChromID® CARBA SMART, Brilliance™ CRE and mSuperCARBA™ media were 14% (95% CI = 8.1%–22.5%), 54% (95% CI = 43.3%–63.4%) and 99% (95% CI = 93.8%–100%), respectively, for the detection of OXA-244 producers. Among the 101 OXA-244-producing isolates, 96% were E. coli and 77%–78% grew on ESBL screening media. MLST analysis identified five main STs among OXA-244-producing E. coli isolates: ST38 (n = 37), ST361 (n = 17), ST69 (n = 12), ST167 (n = 11) and ST10 (n = 8). Conclusions Our results demonstrated that the mSuperCARBA™ medium is very efficient in the detection of OXA-244 producers, unlike the ChromID® CARBA SMART medium. The high prevalence of ESBLs among OXA-244 producers allowed detection of 77%–78% of them using ESBL-specific screening media.

Adsorption behavior of Th(IV) onto illite: Effect of contact time, pH value, ionic strength, humic acid and temperature

2016 ◽  
Vol 127-128 ◽  
pp. 35-43 ◽  
Author(s):  
Zhang Hongxia ◽  
Wang Xiaoyun ◽  
Liang Honghong ◽  
Tan Tianshe ◽  
Wu Wangsuo
Keyword(s):  
Humic Acid ◽  
Ionic Strength ◽  
Contact Time ◽  
Ph Value ◽  
Adsorption Behavior

Interaction of Humic Acid with Graphene Oxide: Relation to Antibacterial Activities Against Escherichia coli

2021 ◽  
Vol 21 (3) ◽  
pp. 1430-1438
Author(s):  
Hongyang Yu ◽  
Runxuan Chu ◽  
Xue Li ◽  
Bing Wang ◽  
Wei Chen ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Antibacterial Activity ◽  
Graphene Oxide ◽  
Humic Acid ◽  
Environmental Remediation ◽  
Saline Solution ◽  
Antibacterial Activities ◽  
Titration Calorimetry ◽  
E Coli ◽  
Dose Dependent

Graphene oxide (GO) sheets attracted great attention as effectively antibacterial agents in water treatment and environmental remediation applications. In the study, the interaction of humic acid (HA) as the model of natural organic matter (NOM) with GO and their antibacterial activities against Escherichia coli (E. coli) was investigated. The interaction between GO and HA molecules was analyzed by isothermal titration calorimetry (ITC) and fluorescence spectroscopy analysis. The study demonstrated that GO reaction with HA was a spontaneously exothermic process, which enabled formation of stable and well dispersed GO-HA complex in aqueous solution. Both GO and GO-HA could significantly inhibit the growth of E. coli and present dose-dependent bactericidal property. GO and GO-HA showed more obvious antibacterial activity in saline solution than in LB broth. We suggest the surface wrinkles of GO and GO-HA could contribute to the firm wrapping of E. coli, which is the principle factor for the antibacterial activity of GO and GO-HA. Especially, GO-HA exhibit less surface wrinkles in comparison with GO, corresponding to its reduced antibacterial activity in saline solution.

SOME OBSERVATIONS OF THE EFFECT OF FILTRATES OF SEVERAL REPRESENTATIVE CONCOMITANT BACTERIA ON CLOSTRIDIUM BOTULINUM TYPE A

1961 ◽  
Vol 7 (4) ◽  
pp. 633-639 ◽  
Author(s):  
F. D. Crisley ◽  
G. E. Helz
Keyword(s):  
Escherichia Coli ◽  
Phosphate Buffer ◽  
Clostridium Botulinum ◽  
Type A ◽  
Complete Medium ◽  
Clostridium Sporogenes ◽  
Streptococcus Faecalis ◽  
E Coli ◽  
Botulinum Type ◽  
High Concentrations

Filtrates of growing cultures of Bacillus sphacricus, Clostridium sporogenes, Escherichia coli, and Streptococcus faecalis inhibited germination of spores of Clostridium botulinum type A. Of the four filtrates only that of E. coli was inactive at low (1:8) concentrations, and all were inhibitory at high (1:2) levels. Only filtrates of B. sphaericus and C. sporogenes affected lysis (increased) of washed cells of C. botulinum, and only S. faecalis filtrate altered botulinal toxigenicity in a complete medium. S. faecalis filtrate enhanced the final toxicity when present in high concentrations in the presence of phosphate buffer.

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