scholarly journals Characterization of the biological properties of bacteriophages Staphylococcus aureus variant bovis

2019 ◽  
Vol 21 (96) ◽  
pp. 47-52
Author(s):  
Yu. V. Horiuk
Keyword(s):  
Staphylococcus Aureus ◽  
Biological Properties ◽  
Lytic Activity ◽  
Effect Of Temperature ◽  
Economic Losses ◽  
Temperature Dependent ◽  
Phage Strain ◽  
Effects Of Temperature

Cattle mastitis is the main cause of economic losses in milk production worldwide, and Staphylococcus aureus is the pathogen that causes it most. Bacteriophages may be an alternative treatment for this disease. In this study, we studied the effect of temperature and pH on the lytic activity of bacteriophages isolated from cows with signs of mastitis. The isolation and production of pure phage lines were performed on an indicator culture of Staphylococcus aureus var. bovis 1491f conventional methods. The following phages were isolated and labeled: Phage SAvB07, Phage SAvB08, Phage SAvB12, Phage SAvB14. To determine the effect of temperature and pH, aliquots after the action of these factors were sown by the double agar method at regular intervals. The study found that phage lytic activity was temperature dependent. Thus, under the influence of temperature 45 °C after 30 minutes of action, it decreased by 3.0–3.4 times for bacteriophages Phage SAvB07, Phage SAvB08, Phage SAvB12 and after one hour was 2.4–12.6%. Phage SAvB14 strain was more resistant to temperature. Its activity decreased by only 67.6% during the analyzed period. With higher temperatures (55–65 °C), the intensity of phage infection decreased significantly, but remained stable. The most resistant to the effects of temperature was Phage SAvB14 – its activity was on average higher by 15.6–33.9% compared with other phages taken in the experiment. The results of our studies on the effect of pH on the reproduction of phages showed that the maximum number of phage virions was observed at pH 6 7. However, the most resistant to acidity was the phage strain Phage SAvB14, compared with other strains taken in the experiment. Therefore, the bacteriophage Phage SAvB14 exhibited the greatest stability and has considerable potential for in vivo use in the treatment of mastitis of cows caused by Staphylococcus aureus.

scholarly journals Characterization of MazFSa, an Endoribonuclease from Staphylococcus aureus

2007 ◽  
Vol 189 (24) ◽  
pp. 8871-8879 ◽  
Author(s):  
Zhibiao Fu ◽  
Niles P. Donegan ◽  
Guido Memmi ◽  
Ambrose L. Cheung
Keyword(s):  
Staphylococcus Aureus ◽  
Environmental Stress Response ◽  
Binding Studies ◽  
Cell Growth Arrest ◽  
Consensus Sequences ◽  
E Coli ◽  
Endoribonuclease Activity

ABSTRACT The mazEF homologs of Staphylococcus aureus, designated mazEFsa , have been shown to cotranscribe with the sigB operon under stress conditions. In this study, we showed that MazEF Sa , as with their Escherichia coli counterparts, compose a toxin-antitoxin module wherein MazF Sa leads to rapid cell growth arrest and loss in viable CFU upon overexpression. MazF Sa is a novel sequence-specific endoribonuclease which cleaves mRNA to inhibit protein synthesis. Using ctpA mRNA as the model substrate both in vitro and in vivo, we demonstrated that MazF Sa cleaves single-strand RNA preferentially at the 5′ side of the first U or 3′ side of the second U residue within the consensus sequences VUUV′ (where V and V′ are A, C, or G and may or may not be identical). Binding studies confirmed that the antitoxin MazE Sa binds MazF Sa to form a complex to inhibit the endoribonuclease activity of MazF Sa . Contrary to the system in E. coli, exposure to selected antibiotics augmented mazEFsa transcription, akin to what one would anticipate from the environmental stress response of the sigB system. These data indicate that the mazEF system of S. aureus differs from the gram-negative counterparts with respect to mRNA cleavage specificity and antibiotic stresses.

scholarly journals Characterization of the Bacteriophage-Derived Endolysins PlySs2 and PlySs9 with In Vitro Lytic Activity against Bovine Mastitis Streptococcus uberis

Antibiotics ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 621
Author(s):  
Niels Vander Elst ◽  
Sara B. Linden ◽  
Rob Lavigne ◽  
Evelyne Meyer ◽  
Yves Briers ◽  
...  
Keyword(s):  
Bovine Mastitis ◽  
Binding Activity ◽  
Lytic Activity ◽  
Economic Losses ◽  
Therapeutic Measure ◽  
Cell Wall Binding ◽  
Streptococcus Uberis ◽  
Major Loss

Bovine mastitis, an infection of the cow’s mammary gland, is frequently caused by Streptococcus uberis and causes major economic losses in the dairy industry. The intramammary administration of antibiotics currently remains the predominant preventive and therapeutic measure. These antimicrobial compounds, of which some are considered critical in human health care, are frequently applied as dry therapy resulting in their consistent overuse. Therefore, the use of antibiotics in the dairy sector is being questioned. We here identified two endolysins, i.e., PlySs2 and PlySs9, respectively derived from Streptococcus suis serotype-2 and -9 prophages, with lytic activity against S. uberis in an in vitro setting. Both endolysins gave clear lysis zones in spot-on-plate assays and caused a reduction of the optical density in a turbidity reduction assay. In depth characterization identified PlySs9 as the more potent endolysin over PlySs2 with a lower MIC value and about one additional log of killing. PlySs2 and PlySs9 were challenged to a panel of subclinical and clinical S. uberis milk isolates and were both able to lyse all strains tested. Molecular dissection of these endolysins in catalytic and cell wall binding subdomains resulted in major loss of killing and binding activity, respectively. Taken together, we here propose PlySs2 and PlySs9 as candidate compounds to the current antimicrobial arsenal known against bovine mastitis-causing S. uberis as future add-on or replacement strategy to the currently used intramammary antibiotics.

Selection and characterization of potential probiotic Lactobacilli spp isolated from chicken feces may be used as a potent antibacterial agent

2016 ◽  
Vol 35 (1) ◽  
Author(s):  
Nazila Aazami ◽  
Enayatollah Kalantar ◽  
Helen Poormazaheri ◽  
Nassimeh Setayesh vali Pour ◽  
Gholamreza Salehi Jouzan
Keyword(s):  
Antibacterial Activity ◽  
Antibiotic Resistance ◽  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Acid Tolerance ◽  
Resistance Test ◽  
Effect Of Temperature ◽  
Rdna Sequencing

<italic>Lactobacillus</italic> strains commonly used as probiotics which possess some properties such as resistance to gastric acidity and bile salts, production of antimicrobial compounds, the ability to modulate immune responses, and adhesion to gut tissues. This study aimed to isolate, identify, production and characterization of the probiotic strains. Total of 10 digestive tracts of chickens fed without antibiotics for presence of <italic>Lactobacillus spp</italic> was evaluated. All isolates were grown with different conditions like effect of temperature, pH, pepsine, bile, sodium chloride tolerance, aggregation, adhesion and antibiotic resistance test tested and then antibacterial activity was determined.In this study, 34 lactic acid bacteria were investigated as putative probiotic candidates. Based on the molecular identification using 16S rDNA sequencing the isolates belonged to <italic>Lactobacillus</italic> species. The strains showed potent antibacterial activity. The results on acid tolerance showed that all the strains tested survived at pH 2.0 to 5.5. <italic>L. agilis</italic> strain M18, <italic>L. salivarius</italic> strain M10, <italic>L.vaginalis</italic> strains M8 and M19, and <italic>L. crispatus</italic> strains Or2 and M10 showed the lowest sensitivity to pepsine. All the studied Lactobacillus strains were able to grow at both 15 and 45°C . Five Lactobacillus strains adhered well to the Caco-2 cells. The result of antibiotic resistance test of 34 lactic acid bacteria showed that most of them were resistant or intermediate. Based on 34 <italic>Lactobacillus</italic> strains, <italic>L. vaginalis</italic> strain M8 and <italic>L. reuteri</italic> strain M6 were selected for the further in vivo assays and possible eventual use as prophylactic and therapeutic agent.

scholarly journals Characterization of Andean Blueberry in Bioactive Compounds, Evaluation of Biological Properties and in vitro Bioaccessibility

2020 ◽  
Author(s):  
Nieves Baenas ◽  
Jenny Ruales ◽  
Diego A. Moreno ◽  
Daniel Alejandro Barrio ◽  
Carla M. Stinco ◽  
...  
Keyword(s):  
Antioxidant Capacity ◽  
Bioactive Compounds ◽  
Biological Activities ◽  
In Vitro Digestion ◽  
Biological Properties ◽  
Wide Range ◽  
Zebrafish Embryogenesis

Andean blueberries are wild berries grown and consumed in Ecuador which contain high values of bioactive compounds, mainly anthocyanins, with powerful antioxidant activity. The aim of this study was to evaluate the profile and contents of (poly)phenols and carotenoids in Andean blueberry by HPLC-DAD-MSn and determine a wide range of its biological activities. The antioxidant capacity of this fruit was evaluated in vitro by three different methods and in vivo using the zebrafish animal model, also the toxicity effect was determined by the zebrafish embryogenesis test. Besides, the antimicrobial activity and the capacity of Andean blueberry to produce hemagglutination in blood cells were evaluated. Finally, the bioaccessibility of (poly)phenols and related antioxidant capacity were determined in the different phases of an in vitro digestion. The global results indicated no toxicity of Andean blueberry, weakly bacteriostatic activity, and high contents of anthocyanins and antioxidant capacity, which were partially bioaccesible in vitro (~ 50 % at the final intestinal step), contributing to the knowledge of its health benefits for consumers and its potential use in the food and pharmaceutical industry as functional ingredient.

Skeletal muscle fatigue in vitro is temperature dependent

1986 ◽  
Vol 61 (2) ◽  
pp. 660-665 ◽  
Author(s):  
S. S. Segal ◽  
J. A. Faulkner ◽  
T. P. White
Keyword(s):  
Effect Of Temperature ◽  
Isometric Contractions ◽  
Temperature Dependent ◽  
Temperature Optimum ◽  
Constant Frequency ◽  
Protocol Development ◽  
Effects Of Temperature ◽  
The Relationship ◽  
Bell Shaped Curve

Our purpose was to determine the effect of temperature on the fatigability of isolated soleus and extensor digitorum longus (EDL) muscles from rats during repeated isometric contractions. Muscles (70–90 mg) were studied at 20–40 degrees C in vitro. Fatigability was defined with respect to both the time and number of stimuli required to reach 50% of the force (P) developed at the onset of the fatigue test. Fatigue was studied during stimulation protocols of variable [force approximately 70% of maximum force (Po)] and constant frequency (28 Hz). Results for soleus and EDL muscles were qualitatively similar, but fatigue times were longer for soleus than for EDL muscles. During the variable-frequency protocol, development of approximately 70% of Po required an increase in stimulation frequency as temperature increased. During stimulation at these frequencies, fatigue time shortened as temperature increased. For both fatigue protocols, the relationship between temperature and the number of stimuli required to reach fatigue followed a bell-shaped curve, with maximum values at 25–30 degrees C. The temperature optimum for maximizing the number of isometric contractions to reach fatigue reflects direct effects of temperature on muscle function.

scholarly journals Characterization of ligand binding and processing by bombesin receptors in an insulin-secreting cell line

1987 ◽  
Vol 247 (3) ◽  
pp. 731-738 ◽  
Author(s):  
S L Swope ◽  
A Schonbrunn
Keyword(s):  
Islet Cells ◽  
Scatchard Analysis ◽  
Dependent Manner ◽  
Temperature Dependent ◽  
Single Class ◽  
Relative Potencies ◽  
Stimulate Insulin Release ◽  
Bombesin Receptors

Bombesin is a tetradecapeptide which stimulates insulin secretion in vivo by isolated islets and by HIT-T15 cells, a clonal line of hamster pancreatic-islet cells. In the present study we have used [125I-Tyr4]bombesin to characterize bombesin receptors in HIT-T15 cells. [125I-Tyr4]Bombesin binding was time- and temperature-dependent: maximum binding occurred after 45 min, 90 min and 10 h at 37, 22 and 4 degrees C respectively. Thereafter, cell-associated radioactivity declined at 37 degrees C and 22 degrees C but not at 4 degrees C. Scatchard analysis of [125I-Tyr4]bombesin binding measured at 4 degrees C showed that HIT-T15 cells contain a single class of binding sites (approximately equal to 85000/cell) with an apparent Kd of 0.9 +/- 0.11 nM. Structurally unrelated neuropeptides did not compete for [125I-Tyr4]bombesin binding. However, the relative potencies of bombesin and four bombesin analogues in inhibiting the binding of [125I-Tyr4]bombesin correlated with their ability to stimulate insulin release. Receptor-mediated processing of [125I-Tyr4]bombesin was examined by using an acid wash (0.2 M-acetic acid/0.5 M-NaCl, pH 2.5) to dissociate surface-bound peptide from the cells. Following [125I-Tyr4]bombesin binding at 4 degrees C, more than 85% of the cell-associated radioactivity could be released by acid. When the temperature was then increased to 37 degrees C, the bound radioactivity was rapidly (t1/2 less than 3 min) converted into an acid-resistant state. These results indicate that receptor-bound [125I-Tyr4]bombesin is internalized in a temperature-dependent manner. In fact, the entire ligand-receptor complex appeared to be internalized, since pretreatment of cells with 100 nM-bombesin for 90 min at 37 degrees C decreased the subsequent binding of [125I-Tyr4]bombesin by 90%. The chemical nature of the cell-associated radioactivity was determined by reverse-phase chromatography of the material extracted from cells after a 30 min binding incubation at 37 degrees C. Although 70% of the saturably bound radioactivity was co-eluted with intact [125I-Tyr4]bombesin 90% of the radioactivity subsequently dissociated from cells chromatographed as free iodide. At least some of the degradation of receptor-bound [125I-Tyr4]bombesin appeared to occur in lysosomes, since chloroquine increased the cellular accumulation of [125I-Tyr4]bombesin at 37 degrees C and slowed the release of radioactivity.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals EFFECT OF TEMPERATURE AND SODIUM CHLORIDE CONCENTRATION ON GROWTH OF Staphylococcus aureus MUTANTS

2019 ◽  
Vol 17 (72) ◽  
pp. 117-129
Author(s):  
Hiba Muneer Al-Khafagi
Keyword(s):  
Staphylococcus Aureus ◽  
Chloride Concentration ◽  
Antibiotic Sensitivity ◽  
Effect Of Temperature ◽  
Temperature Sensitive ◽  
Sensitivity Pattern ◽  
Nacl Concentration ◽  
Mutant Strains ◽  
Strain Number

The study included the identification of Staphylococcus aureus (wild type and mutant) isolates. All these isolates were identified as coagulase and catalase positive and able to ferment mannitol. Strain number 24 was chosen & undergone mutation with NTG to isolate temperature sensitive osmotically fragile (TOF) mutants. TOF mutants were successfully isolated by exposing the cell suspension to 200 Mg/ml of NTG for 75 minutes. The results of characterization of TOF mutants, showed that these mutants were identical to their mother strain morphologically and biochemically. The result of this mutation is to make the lysozyme able to lyse the cell wall of the TOF mutants in pattern similar to lysostaphin . Antibiotic sensitivity pattern was demonstrated for all the isolates and multiple resistance of some isolates were detected. The obtained results showed that the two mutant isolates were resistant to Methicillin, Benzathin, Penicillin, Cloxacillin Sodium and Lincomycin, wherease these isolates were sensitive to Amoxicillin, Cefotaxine Sodium, Cephalexin Sodium and Tetracyclin but intermediate in resistance to Clindamycin. The effect of different temperature showed that the growth of the mother strain (strain No.24) increased with the increase of temperature.The mutant strains (3M,10M) are not stable in the different temperature and their growth is very low at 40C. The effect of different NaCl concentration showed that the growth of the mother strain (strain No.24) and the 2 mutant strain (3M,10M) would increase with the increase of the NaCl concentration but decrease at NaCl concentration = 1.5 M .

scholarly journals New method of evaluating specific bacteriophage activity using HLE-3 cell culture

2020 ◽  
Vol 3 (32) ◽  
pp. 16-18
Author(s):  
Yu. A. Zakharova ◽  
O. S. Fedotova ◽  
N. A. Shmelyova
Keyword(s):  
Cell Culture ◽  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Acinetobacter Baumannii ◽  
Lytic Activity ◽  
New Method ◽  
Acinetobacter Baumanii ◽  
Specific Bacteriophage

In the presented study, we evaluated the efficacy of specific bacteriophage activity in vivo for resolution of infections caused by Staphylococcus aureus, Pseudomonas aeruginosa and Acinetobacter baumanii. Pseudomonas aeruginosa, Acinetobacter baumannii. It was demonstrated that administration of a specific bacteriophage with high lytic activity in an hour leads to a decrease in the adhesive activity of the microorganisms. The duration of the experiment was one hour.

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