scholarly journals Study of exogenous oxidative stress response in Escherichia coli, Pseudomonas spp., Bacillus spp., and Salmonella spp.

2014 ◽  
Vol 38 ◽  
pp. 502-509 ◽  
Author(s):  
Ifratun NUR ◽  
Mohammad Sakil MUNNA ◽  
Rashed NOOR
Keyword(s):  
Oxidative Stress ◽  
Escherichia Coli ◽  
Stress Response ◽  
Oxidative Stress Response ◽  
Salmonella Spp ◽  
Pseudomonas Spp ◽  
Bacillus Spp

scholarly journals Antibiogram of Bacteria Isolated from Tympanotonus fuscatus Var. Radula (Prosobranchia:Potamididae) Sold in Markets in Nasarawa State, Nigeria

2020 ◽  
pp. 1-9
Author(s):  
U. K. Asemota ◽  
M. D. Makut ◽  
S. O. Obiekezie ◽  
J. E. Owuna ◽  
M. O. Adamu
Keyword(s):  
Escherichia Coli ◽  
Bacterial Load ◽  
Bacterial Count ◽  
Total Bacterial Count ◽  
Bacterial Isolates ◽  
Salmonella Spp ◽  
Pseudomonas Spp ◽  
Gram Positive Bacteria ◽  
Bacillus Spp ◽  
Gram Negative Organisms

The aim of this study was to determine the antibiogram of bacterial isolates from Tympanotonus fuscatus var. radula sold in markets in Nasarawa State. Nigeria. Samples of Tympanotonus fuscatus var. radula (periwinkles) were bought from soup ingredient sellers at different sale locations in Keffi, Masaka and Orange markets and were analyzed using standard bacteriological methods. The bacterial isolates were identified using morphological, cultural and biochemical techniques. The total bacteria count varied from 1.18–3.20 x 108 CFU/g for the raw samples while the total bacterial count for the boiled samples varied from 0–1.57 x 108 CFU/g. Periwinkle samples with shells from Masaka market had the highest bacterial load with a mean total bacterial count of 2.94 x 10⁸ CFU/g and mean total coliform count of 2.80 x 10⁶ CFU/g. Raw periwinkle samples with shells had a higher bacterial load than samples without shells. There was also a drastic reduction in the bacterial load in the periwinkle samples after boiling under laboratory conditions. The bacteria isolated were Bacillus spp. and Staphylococcus aureus were the Gram-positive bacteria isolated. Enterobacter spp., Escherichia coli, Salmonella spp., Pseudomonas spp., Serratia spp. and Proteus spp. The most frequently occurring gram positive bacteria was Escherichia coli with an isolation frequency of 6(24%), the least frequently occurring was Bacillus spp., 8(32)%. Antibiotic susceptibility test showed that all the gram negative organisms exhibited sensitivity to ciprofloxacin: Escherichia coli (32 mm), Enterobacter spp. (41.5 mm), Proteus spp. (40.0 mm), Salmonella spp. (37.0 mm), Serratia spp. (26.0 mm), Pseudomonas spp. (23.0 mm). All the gram negative organisms showed marked resistance to vancomycin: Escherichia coli (12.0 mm), Enterobacter spp. (10.0 mm), Proteus spp. (11.0 mm), Salmonella spp. (5.0 mm), Serratia spp. (10.0 mm) and Pseudomonas spp. (4.5 mm).

scholarly journals Escherichia coli K-12 YfgF is an anaerobic cyclic di-GMP phosphodiesterase with roles in cell surface remodelling and the oxidative stress response

Microbiology ◽  
2010 ◽  
Vol 156 (9) ◽  
pp. 2873-2886 ◽  
Author(s):  
Melissa M. Lacey ◽  
Jonathan D. Partridge ◽  
Jeffrey Green
Keyword(s):  
Oxidative Stress ◽  
Escherichia Coli ◽  
Stress Response ◽  
Cell Surface ◽  
Regulatory Networks ◽  
Oxidative Stress Response ◽  
Cyclase Activity ◽  
Diguanylate Cyclase ◽  
Phosphodiesterase Activity ◽  
K 12

The Escherichia coli K-12 yfgF gene encodes a protein with domains associated with cyclic di-GMP signalling: GGDEF (associated with diguanylate cyclase activity) and EAL (associated with cyclic di-GMP phosphodiesterase activity). Here, it is shown that yfgF is expressed under anaerobic conditions from a class II FNR (regulator of fumarate and nitrate reduction)-dependent promoter. Anaerobic expression of yfgF is greatest in stationary phase, and in cultures grown at 28 °C, suggesting that low growth rates promote yfgF expression. Mutation of yfgF resulted in altered cell surface properties and enhanced sensitivity when anaerobic cultures were exposed to peroxides. The purified YfgF GGDEF-EAL (YfgFGE) and EAL (YfgFE) domains possessed cyclic di-GMP-specific phosphodiesterase activity, but lacked diguanylate cyclase activity. However, the catalytically inactive GGDEF domain was required for YfgFGE dimerization and enhanced cyclic di-GMP phosphodiesterase activity in the presence of physiological concentrations of Mg2+. The cyclic di-GMP phosphodiesterase activity of YfgFGE and YfgFE was inhibited by the product of the reaction, 5′-phosphoguanylyl-(3′–5′)-guanosine (pGpG). Thus, it is shown that the yfgF gene encodes an anaerobic cyclic di-GMP phosphodiesterase that is involved in remodelling the cell surface of E. coli K-12 and in the response to peroxide shock, with implications for integrating three global regulatory networks, i.e. oxygen regulation, cyclic di-GMP signalling and the oxidative stress response.

scholarly journals Increasing the Oxidative Stress Response Allows Escherichia coli To Overcome Inhibitory Effects of Condensed Tannins

2003 ◽  
Vol 69 (6) ◽  
pp. 3406-3411 ◽  
Author(s):  
Alexandra H. Smith ◽  
James A. Imlay ◽  
Roderick I. Mackie
Keyword(s):  
Oxidative Stress ◽  
Escherichia Coli ◽  
Stress Response ◽  
Condensed Tannins ◽  
Resistant Mutant ◽  
Inhibitory Effect ◽  
Oxidative Stress Response ◽  
Inhibitory Effects ◽  
Acacia Mearnsii ◽  
E Coli

ABSTRACT Tannins are plant-derived polyphenols with antimicrobial effects. The mechanism of tannin toxicity towards Escherichia coli was determined by using an extract from Acacia mearnsii (Black wattle) as a source of condensed tannins (proanthocyanidins). E. coli growth was inhibited by tannins only when tannins were exposed to oxygen. Tannins auto-oxidize, and substantial hydrogen peroxide was generated when they were added to aerobic media. The addition of exogenous catalase permitted growth in tannin medium. E. coli mutants that lacked HPI, the major catalase, were especially sensitive to tannins, while oxyR mutants that constitutively overexpress antioxidant enzymes were resistant. A tannin-resistant mutant was isolated in which a promoter-region point mutation increased the level of HPI by 10-fold. Our results indicate that wattle condensed tannins are toxic to E. coli in aerobic medium primarily because they generate H2O2. The oxidative stress response helps E. coli strains to overcome their inhibitory effect.

scholarly journals 3-phenylpropionate catabolism and the Escherichia coli oxidative stress response

2005 ◽  
Vol 156 (3) ◽  
pp. 312-321 ◽  
Author(s):  
Evelyne Turlin ◽  
Odile Sismeiro ◽  
Jean Pierre Le Caer ◽  
Valérie Labas ◽  
Antoine Danchin ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Escherichia Coli ◽  
Stress Response ◽  
Oxidative Stress Response
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