Coli ATCC Research Articles

Interplay between IncF plasmids and topoisomerase mutations conferring quinolone resistance in the Escherichia coli ST131 clone: stability and resistance evolution.

The Escherichia coli ST131 H30-Rx subclone vehicles CTX-M-15 plasmids and mutations in gyrA and parC conferring multidrug resistance successfully in the clinical setting. The aim of this study was (1) to investigate the relationship of specific topoisomerase mutations on the stability of IncF (CTX-M producing) plasmids using isogenic E. coli mutants and (2) to investigate the impact of the IncF-type plasmids present in the E. coli clone ST131 on the evolution of quinolone resistance. E. coli ATCC 25922 (background strain) and derived mutants encoding specific QRDR substitutions were used. Also, NGS-characterized IncFIA and IncFIB plasmids (encoding CTX-M genes) were included. Plasmid stability was evaluated by sequential dilutions into Luria broth medium without antibiotics for 7days. Mutant frequency to ciprofloxacin was also evaluated. Moderate differences in the IncF plasmids stability were observed among E. coli ATCC 25922 and isogenic mutants. Under our experimental conditions, the fluctuation of bacteria harboring plasmids was less than 0.5-log(10) in all cases. In the mutant frequency tests, it was observed that the presence of these IncF plasmids increased this value significantly (10-1000-fold). Quinolone resistance substitutions in gyrA or parC genes, frequently found associated with E. coli clone ST131, do not modify the stability of ST131-associated IncFIA and IncFIB plasmids under in vitro conditions. IncF-type plasmids present in E. coli clone ST131 facilitate the selection of resistance to quinolones. These results are consistent with the clinical scenario in which the combination of resistance to quinolones and beta-lactams is highly frequent in the E. coli clone ST131.

INVESTIGATION OF ANTIMICROBIAL EFFECT OF DECASAN CHLORHEXIDINE AND IODOPHORAM ON STANDARD MICROBIAL STRAINS

The problem of treatment and prevention of infectious-inflammatory post extraction complications in modern surgical dentistry are still challenging, despite the great advances in this field. Many etiological factors are identified as contributing to the development of such complications, but at present scientists are paying much attention to the infectious factor, which is associated with the microflora of the tooth socket after tooth removal. According to the literature, the most common post-extraction complication during an outpatient surgical appointment is alveolitis, which accounts for 1-35% of all cases of tooth extraction. To combat an infectious etiological factor of alveolitis, dental surgeons apply topical antiseptics with a broad spectrum of action such as iodoform and chlorhexidine. As a topical antiseptic drug in the treatment and prevention of oral infectious and inflammatory complications, a domestic antiseptic, Decasan, based on decamethoxine, is becoming more widely applied. Previous studies have shown that this antiseptic has antimicrobial effect against gram-positive and gram-negative, aerobic and anaerobic bacteria; this requires further in-depth studies of its properties, which could be applied in the dental surgical practice to treat and prevent infectious-inflammatory post extraction complications. Chlorhexidine bigluconate is a cationic biguanide. Penetrating into the intracellular membranes of bacteria, it impedes the oxygen consumption and leads to the death of bacterial cells. This antiseptic is widely used in dental practice. Treatment of alveolitis is carried out by using the standard method, namely by using iodoform tamponade of the tooth socket in combination with other medicines. Iodoform (triiodomethane) is a yellow crystalline substance with a strong characteristic odor, practically insoluble in water. In dentistry, this drug is used as an antiseptic in powder form, or combined pastes. The purpose of this in vitro study is to investigate the antimicrobial properties of Decasan, chlorhexidine and iodoform against museum microbial strains. Materials and methods. Museum strains of Staphylococcus aureus ATCC 25923, Staphylococcus epidermidis ATCC 14990, Enterococcus faecalis ATCC 29212, Esherichia coli ATCC 25922, Candida albicans ATCC 10231, obtained from L.V. Gromashevsky Institute of Epidemiology and Infectious Diseases, National Academy of Medical Sciences of Ukraine, were used as studied cultures of microorganisms. The antimicrobial effect of decasan, chlorhexidine and iodoform was assessed by quantitative method of serial dilutions in broth and agar according to the order №167, dated 5.04.2007 On approval of guidelines “Determination of sensitivity of microorganisms to antibacterial drugs". Conclusion. According to the data obtained, decasan and chlorhexidine demonstrate higher bacteriostatic and bactericidal effect on the studied museum microbial strains at a concentration thousands of times lower than the concentration of iodoform.

Silver/poly(vinyl alcohol)/graphene hydrogels for wound dressing applications: Understanding the mechanism of silver, antibacterial agent release

AbstractLong‐term wound healing and chronic wound care represent significant challenges for biomaterials science and engineering with many diverse requirements for the wound dressing properties, as well as antibacterial efficacy and antibacterial agent release to prevent and treat persistent infections. Silver nanoparticles, as a wide‐spectrum antibacterial agent that does not induce bacterial resistance, are very convenient for use as an active component in antibacterial hydrogel wound dressing materials with the controlled release ability. In this work, we aim to perform a comprehensive analysis of silver release from poly(vinyl alcohol)‐based hydrogels with electrochemically synthesized antibacterial silver nanoparticles (AgNPs), aimed for wound dressing applications. Different AgNPs concentrations were loaded in hydrogel matrices using the green electrochemical reduction method, and thus synthesized nanocomposite hydrogels were characterized by different techniques (scanning electron microscopy, Fourier‐transform infrared and Raman spectroscopy, and differential scanning calorimetry), in order to assess their physico‐chemical and thermal properties. Silver release was monitored for 28 days in physiologically‐relevant conditions (phosphate buffered medium, pH 7.4, 37°C). The obtained experimental data were evaluated against several theoretical release models (Korsmeyer‐Peppas, Higuchi, Makoid‐Banakar, Kopcha, and early‐time approximation), which confirmed the predominantly diffusion‐controlled mechanism of release. Finally, AgNP‐loaded hydrogels were assessed for antibacterial activity againstStaphylococcus aureusTL andEscherichia coliATCC25922 bacterial strains, to prove their strong potential for wound dressing applications.

ANTIMICROBIAL PROPERTIES OF RABBIT COLLAGEN GLUE-CHITOSAN BIOMATERIAL LOADED WITH CYMBOPOGON FLEXUOSUS ESSENTIAL OIL

One approach to develop innovative antimicrobial wound dressing materials is to use natural polymers loaded with antimicrobial agents. The valorisation of animal proteins as biomaterials with antimicrobial properties is a new concern for development of wound healing. Plant esssential oils (EO) also indicate a potential approach for new wound dressing materials able to replace the synthetic antymicrobial agents. In this paper, plant-polymeric film was prepared by casting film-forming emulsion based on lemongrass (Cymbopogon flexuosus) essential oil/Tween 80 dispersed into rabbit collagen glue hydrolysate– chitosan biomaterial. The effect of biomaterial film composition on Staphylococcus aureus ATCC 6538 and Escherichia coli ATCC 10536 standard bacteria, and Candida albicans ATCC 10231 pathogenic fungus was studied according to European Pharmacopoeia 10/2020 as compared with biomaterial film without essential oil. The in vitro antibacterial tests against three bacterial strains showed that the rabbit collagen glue hydrolysate–chitosan biomaterial inhibited all the three microorganisms. The rabbit collagen hydrolysate glue-chitosan film loaded with lemongrass essential oil exhibits antimicrobial activity towards tested microorganisms but lower as compared with control. The explanation could be due to the short time of investigation, or maybe some active compounds constituents of EO, which favour the cellular proliferation. Preparation of rabbit collagen glue hydrolysate-chitosan biomaterial loaded with lemongrass essential oil is an environmentally friendly solution, which may contribute to the development of wound healing materials as an alternative to topical antimicrobial agents.

Functionalization of PMMA/TiO2 nanocomposites: Synthesis, characterization and their antioxidant and antibacterial evaluation

AbstractThe present work reports the functionalization of PMMA and its nanocomposites were synthesized via simple solution mixing method. Functionalization of PMMA with different amino containing groups, that is, ethylene diamine (ED) and 4‐amino benzoic acid (PA) and used with low dosage (1 wt% and 3 wt%) of TiO2 nanoparticles (NPs) to form nanocomposites. The morphology was determined by SEM, average particle size (50 nm) of TiO2 NPs was measured by TEM. The pore radius (14.47 A°) and specific surface area (157.89 m2/g) of TiO2 NPs were measured by BET analysis. FT‐IR and NMR analysis confirms the functionalization of PMMA. The antioxidant activity of functionalized PMMA and its nanocomposites have been analyzed by using 2,2 diphenyl‐1‐picryhydrazyl (DPPH) assay. The antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) of functionalized polymer nanocomposites were investigated. The result revealed that functionalized PMMA (PMPA) shows maximum antioxidant activity. The increase in concentration of TiO2 NPs efficiently augments the bacterial inhibition against Gram‐negative and Gram‐positive bacteria. The maximum zone of inhibition (ZOI) was recorded against E. coli ATCC 25922 (30 mm) and S. aureus ATCC 29213 (31 mm) and minimum inhibitory concentration (MIC) over E. coli (64 μg/ml) and S. aureus (32 μg/ml) by PMPA2. The synthesized functionalized PMMA nanocomposites can be considered as promising material for biological applications.

Biotransformation of Flavonoids Improves Antimicrobial and Anti-Breast Cancer Activities In Vitro.

Coarse cereals are rich in flavonoids, which are bioactive substances with a wide range of functions. Biotransformation is considered an emerging approach to methylate flavonoids, displaying prominent regio- and stereoselectivity. In the current study, liquiritigenin, naringenin, and hesperidin flavonoids were biotransformed using O-methyltransferases that were heterologously expressed in Saccharomyces cerevisiae BJ5464-NpgA. Nuclear magnetic resonance (NMR) spectroscopy was used together with high-resolution mass spectroscopy analysis to determine the structures of the resulting methylated transformants, and their antimicrobial and antiproliferation activities were also characterized. Among the five methylated flavonoids obtained, 7-methoxy-liquiritigenin had the strongest inhibitory effect on Candida albicans SC5314 (C. albicans SC5314), Staphylococcus aureus ATCC6538 (S. aureus ATCC6538), and Escherichia coli ATCC25922 (E. coli ATCC25922), which increased 7.65-, 1.49-, and 0.54-fold in comparison to the values of their unmethylated counterparts at 200, 250, and 400 μM, respectively. The results suggest that 3′-methoxyhesperetin showed the best antiproliferative activity against MCF-7 cells with IC50 values of 10.45 ± 0.45 µM, which was an increase of more than 14.35-fold compared to that of hesperetin. These results indicate that methylation enhances the antimicrobial activities and antiproliferative effects of flavonoids. The current study provides an experimental basis for further research on flavonoids as well as flavonoid-containing crops in the development of antimicrobial and anti-breast cancer drugs in addition to supplementary and health foods. The biotransformation method is ideal, as it represents a means for the sustainable production of bioactive flavonoids.

Study of Antimicrobial Activity of Vegetable Alcoholic Extracts Obtained from Vinca Minor L.

Abstract Important natural antimicrobial compounds derived from Vinca minor L. plant contain a wide variety of secondary metabolites which are useful for brain health (increasing blood circulation in the brain, supporting brain metabolism, preventing memory loss and problems with concentration and premature aging of the cell), and externally they play a role in tissue repair and skin lesion healing. The testing of the antimicrobial activity of the alcoholic plant extracts obtained from Vinca minor plant was performed on two types of pathogenic germs: a Gram-positive strain, Staphylococcus aureus ATCC 25923 and a Gram-negative strain, Escherichia Coli ATCC 25922, as well as on a yeast strain pathogenic, Candida albicans ATCC 900288. Quantitative evaluation of antimicrobial activity was performed by a variant of the Kirby-Bauer diffusimetric method, a simple and fast method that allows the determination of the spectrum of sensitivity / resistance to antibiotics of the microorganism. Experimental studies have shown that all samples of alcoholic extract of 70% concentration, in volumes of 7µL, exerted a total antibacterial inhibitory action against the reference strains E. coli ATCC 25922 and C. albicans ATCC 10231 and moderate against the strain S. aureus ATCC 25923, results that agree with the literature. Regarding the alcoholic plant extracts with a concentration of 40% ethyl alcohol, obtained from the leaf and stem of Vinca minor plant, they did not show antimicrobial activity, which suggests that 40% ethyl alcohol does not extract bioactive compounds with antimicrobial activity.

Effective degradation of norfloxacin on Ag3PO4/CNTs photoanode: Z-scheme mechanism, reaction pathway, and toxicity assessment

The removal of antibiotics was a concerned issue for human, while photoelectrocatalytic (PEC) technology displayed excellent degradation efficiency. Ag3PO4/carbon nanotubes (CNTs) was synthesized for PEC degradation of norfloxacin (NOR) in this work. The effects of applied bias voltage, Ag3PO4 content, pH, initial concentration of NOR, and supporting electrolyte concentration on the degradation efficiency of NOR were investigated. Under the optimal experimental conditions, the degradation efficiency of NOR could reach up to 93% within 30 min. Compared with photocatalytic (30%) and electrocatalytic (76%) degradation within 120 min, PEC degradation (100%) exhibited the highest degradation efficiency and a significant synergetic effect (74.9%). The prepared Ag3PO4/CNTs photoanode showed appropriate stability as the degradation efficiency of NOR remained 82% after 5 cycles. The excellent degradation efficiency of Ag3PO4/CNTs photoanode was explained based on the Z-scheme mechanism, which significantly promoted the separation of electron-hole pairs. During the degradation process, the contribution of h+ and ·O2– was the most major to oxidize NOR. Moreover, three degradation pathways were proposed by analysis of mass spectrometry. The toxicity of NOR and intermediates was approximately reduced 100% for Escherichia coli ATCC25922 (E. coli ATCC25922) in the PEC degradation process within 120 min. Based on the ecological structure–activity relationship (ECOSAR) program, some intermediates with higher toxicity generated compared with the parent compound in the PEC degradation process. Nevertheless, the PEC system showed low ecotoxicological risk according to the calculated result of ECOSAR. This work provided a Z-scheme mechanism for Ag3PO4/CNTs, which could degrade NOR and reduce its toxicity efficiently.

In vitro biological activity of liposomal-containing antimony trioxide

Antimonials are used as chemotherapy for leishmaniasis, but have limited results due to their toxicity and broad resistance already acquired by the parasites. Nanotechnology offers an alternative to reduce these effects through the use of biocompatible nanocarriers, which can be vectorized to the target site. In addition, the redirection of molecules, already developed for the treatment of other pathologies, has the advantage of being already approved for therapy by regulatory agencies. The present study addresses the production of liposomal vesicles containing antimony trioxide (LC Sb2O3), as well as the evaluation of activity against tumor and bacterial cells. We produce liposomes in order of nanometric size, polydispersity index (PDI <0.3), pH value close to physiological (7.2), and zeta potential (anionic). Cytotoxicity was evaluated in 24 and 72 hours, in the HepG2, T98G, and U87MG tumor cell lines, by the method (3-4.5 dimethylthiazole-2.5 diphenyltetrazolium bromide) (MTT). The minimum inhibitory concentration (MIC) was tested on three bacterial strains (American Type Culture Collection – ATCC-Escherichia coli ATCC 35218, Staphylococcus aureus ATCC 29213 and Enterococcus faecalis ATCC 29212) and mandatory (Staphylococcus aureus and Klebsiella pneumoniae). The liposomes were more cytotoxic than Sb2O3 in the free form, for all tested cell lines. This effect was stronger after 72 hours incubation. Antimony trioxide in both free and liposomal forms showed low antibacterial activity. Based on our results, we suggest that liposomes containing antimony trioxide have the potential for the repositioning of drugs addressing anticancer therapy.

Cationic Lignin-Based Hyperbranched Polymers to Circumvent Drug Resistance in Pseudomonas Keratitis.

The rise of antimicrobial-resistant bacteria strains has been a global public health concern due to their ability to cause increased patient morbidity and a greater burden on the healthcare system. As one of the potential solutions to overcome such bacterial infections, hyperbranched copolymers with cationic charges were developed. These copolymers were assessed for their antimicrobial efficacy and their bactericidal mechanisms. They were found to be potent against mobile colistin-resistant 1 strains, which was significant as colistin is known to be the last-resort antibiotic against Gram-negative bacteria. Furthermore, there was no sign of mutational resistance developed by E. ColiATCC 25922 and MCR 1+E. Coli against the copolymer even up to 20 passages. The ability to evade inducing resistance would provide invaluable insights for future antibiotic development. Our studies suggest that the bactericidal efficacy comes from the ability to target the outer membrane efficaciously. In vivo study using a Pseudomonas keratitis model showed that the copolymer was compatible with the eye and further supported that the copolymer treatment was effective for complete bacteria elimination.

Antibacterial and Mode of Action of Extracts from Endophytic Fungi Derived from Terminalia mantaly, Terminalia catappa, and Cananga odorata.

Emerging drug-resistant bacteria creates an urgent need to search for antibiotics drugs with novel mechanisms of action. Endophytes have established a reputation as a source of structurally novel secondary metabolites with a wide range of biological activities. In the present study, we explore the antibacterial potential of endophytic fungi isolated from different tissues of Terminalia mantaly, Terminalia catappa, and Cananga odorata. The crude ethyl acetate extracts of 56 different endophytic fungi were screened against seven bacterial strains using the broth microdilution method. The antibacterial modes of action of the most active extracts (04) were evaluated using E. coli ATCC 25922 and H. influenzae ATCC 49247 strains. Both the DPPH and FRAP assays were used to investigate their antioxidant activity, and their cytotoxicity against the Vero cell line was evaluated using the MTT assay. Out of the 56 crude extracts tested, about 13% were considered very active, 66% partially active, and 21% nonactive against all tested bacterial strains with MIC values ranging from 0.32 μg/mL to 25 μg/mL. The four more potent extracts (MIC <5 μg/mL) (from Aspergillus sp. N454, Aspergillus sp. N13, Curvularia sp. N101, and Aspergillus sp. N18) significantly lysed the bacteria cells, increased outer membrane permeability, reduced salt tolerance, and inhibited bacterial catalase activity. They exhibited a DPPH free radical scavenging activity with IC50 ranging from 150.71 to 936.08 μg/mL. Three of the four potent extracts were noncytotoxic against the Vero cells line (CC50 > 100 μg/mL). Results from this investigation demonstrated that endophytes from Cameroonian medicinal plants might content potent antibacterial metabolites. The bioguided fractionation of these potent extracts is ongoing to isolate and characterise potential active ingredients.

Fabrication of Paper Sheets Coatings Based on Chitosan/Bacterial Nanocellulose/ZnO with Enhanced Antibacterial and Mechanical Properties.

Here, we designed paper sheets coated with chitosan, bacterial cellulose (nanofibers), and ZnO with boosted antibacterial and mechanical activity. We investigated the compositions, with ZnO exhibiting two different sizes/shapes: (1) rods and (2) irregular sphere-like particles. The proposed processing of bacterial cellulose resulted in the formation of nanofibers. Antimicrobial behavior was tested using E. coli ATCC® 25922™ following the ASTM E2149-13a standard. The mechanical properties of the paper sheets were measured by comparing tearing resistance, tensile strength, and bursting strength according to the ISO 5270 standard. The results showed an increased antibacterial response (assigned to the combination of chitosan and ZnO, independent of its shape and size) and boosted mechanical properties. Therefore, the proposed composition is an interesting multifunctional mixture for coatings in food packaging applications.

How Bacteria Change after Exposure to Silver Nanoformulations: Analysis of the Genome and Outer Membrane Proteome.

Objective: the main purpose of this work was to compare the genetic and phenotypic changes of E. coli treated with silver nanoformulations (E. coli BW25113 wt, E. coli BW25113 AgR, E. coli J53, E. coli ATCC 11229 wt, E. coli ATCC 11229 var. S2 and E. coli ATCC 11229 var. S7). Silver, as the metal with promising antibacterial properties, is currently widely used in medicine and the biomedical industry, in both ionic and nanoparticles forms. Silver nanoformulations are usually considered as one type of antibacterial agent, but their physical and chemical properties determine the way of interactions with the bacterial cell, the mode of action, and the bacterial cell response to silver. Methods: the changes in the bacterial genome, resulting from the treatment of bacteria with various silver nanoformulations, were verified by analyzing of genes (selected with mutfunc) and their conservative and non-conservative mutations selected with BLOSUM62. The phenotype was verified using an outer membrane proteome analysis (OMP isolation, 2-DE electrophoresis, and MS protein identification). Results: the variety of genetic and phenotypic changes in E. coli strains depends on the type of silver used for bacteria treatment. The most changes were identified in E. coli ATCC 11229 treated with silver nanoformulation signed as S2 (E. coli ATCC 11229 var. S2). We pinpointed 39 genes encoding proteins located in the outer membrane, 40 genes of their regulators, and 22 genes related to other outer membrane structures, such as flagellum, fimbria, lipopolysaccharide (LPS), or exopolysaccharide in this strain. Optical density of OmpC protein in E. coli electropherograms decreased after exposure to silver nanoformulation S7 (noticed in E. coli ATCC 11229 var. S7), and increased after treatment with the other silver nanoformulations (SNF) marked as S2 (noticed in E. coli ATCC 11229 var. S2). Increase of FliC protein optical density was identified in turn after Ag+ treatment (noticed in E.coli AgR). Conclusion: the results show that silver nanoformulations (SNF) exerts a selective pressure on bacteria causing both conservative and non-conservative mutations. The proteomic approach revealed that the levels of some proteins have changed after treatment with appropriate SNF.

Rapid Screening of Essential Oils as Substances Which Enhance Antibiotic Activity Using a Modified Well Diffusion Method.

Antimicrobial resistance is recognized as one of the major global health challenges of the 21st century. Synergistic combinations for antimicrobial therapies can be a good strategy for the treatment of multidrug resistant infections. We examined the ability of a group of 29 plant essential oils as substances which enhance the antibiotic activity. We used a modified well diffusion method to establish a high-throughput screening method for easy and rapid identification of high-level enhancement combinations against bacteria. We found that 25 essential oils possessed antibacterial activity against Escherichia Coli ATCC 25922 and methicillin-resistant Staphylococcus aureus (MRSA) 43300 with MICs that ranged from 0.01% to 2.5% v/v. We examined 319 (11 × 29) combinations in a checkerboard assay with E. Coli ATCC 25922 and MRSA 43300, and the result showed that high-level enhancement combinations were 48 and 44, low-level enhancement combinations were 214 and 211, and no effects combinations were 57 and 64, respectively. For further verification we randomly chose six combinations that included orange and Petitgrain essential oils in a standard time-killing assay. The results are in great agreement with those of the well diffusion assays. Therefore, the modified diffusion method was a rapid and effective method to screen high-level enhancement combinations of antibiotics and essential oils.

Biosynthesis of silver nanoparticles using Bacillus subitilis and its antibacterial activity

Background: Silver nanoparticles (AgNPs) have recently been extensively investigated because of their superior physical, chemical, and biological characteristics, and their superiority is primarily due to the size, shape, composition, crystallinity, and structure of AgNPs compared to their bulk forms. Objective: The current study aimed to investigate the antibacterial activity of silver nanoparticles (AgNPs) synthesized intracellular by using standard strain Bacillus subitilis ATCC 6633 against reference strains Escherichia coli ATCC 2592 and Staphylococcus aureus ATCC 29737. Results: The synthesized AgNPs showed potent antibacterial activities against the two tested bacterial strains with inhibition zones ranged from 42 -52mm and MIC 27.2 µg / ml. The silver nanoparticles were characterized with particle size ≃ 100 nm and zeta potential -19. There was deformation in both tested strains upon treatment with AgNPs which was observed by Scanning Electron Microscopy (SEM). Conclusion: The results indicated that AgNPs could be used as an effective antibacterial agent.

High-pressure supercritical carbon dioxide uses to inactivate Escherichia coli in pumpkin puree

Coli ATCC 25922 inactivation was studied to determine the effect of high-pressure carbon dioxide (HPCD) process on pumpkin puree. Experiments were performed using a batch HPCD system at three conditions of pressure (7.5 MPa, 17.5 MPa and 27.5 MPa) at 32 °C. Afterwards, at the best experimental condition (27.5 MPa – 275 bar), a kinetic was performed to assess inactivation of microorganisms over time (from 1 to 8 h). The physicochemical characteristics (pH, total soluble solids – TSS, titratable acidity – TA, total carotenoids, total reducing sugars – TRS, moisture and optical microscopy) of the pumpkin puree were also evaluated. HPCD with acidification increases bacterial efficacy of treatments, as well as significant changes in physicochemical parameters. HPCD treatment reduced the microbial load moderately in all experiments, by a maximum of approximately 3.17 log cycles in 8 h of process at 27.5 MPa (275 bar). Optical microscopy showed no difference in cell wall, just in starch which was expected by cooking.

Microalgal Bioprocess Toward the Production of Microalgal Oil Loaded Bovine Serum Albumin Nanoparticles.

Microalgal biotechnology has increased rapidly owing to have high value bioactive compounds and numerous consumer products that can be utilized from microalgae. With the development of novel cultivation and processing methods, microalgal biotechnology can meet the high demands of food, energy and pharmaceutical industries. In this context, especially for food and pharmaceutical applications, encapsulation of microalgal bioactive compounds is carried out to protect the compound from oxidation and degradation. In this study, a microalgal production process was carried out and microalgal oil loaded bovine serum albumin (BSA) nanoparticle production using glucose as cross-linking agent was investigated. The influences of different process parameters such as initial BSA concentration, glucose concentration and desolvation temperature on the size of BSA nanoparticles were investigated to achieve very small size nanoparticles. Furthermore, data obtained from the experiments were assessed statistically to model the process. It was found that the obtained nanoparticles showed spherical shape with the mean particle size of around 200-300nm with zeta potential of about - 23mV. Also, stability test showed that, there was not any change in particle size for one month storage and nanoparticle structure enhance the protection of microalgae oil from oxidation. At last, antibacterial effect of nanoparticles was presented against E. coli ATCC 8739 and L. monocytogenes ATCC 13932. In here, we demonstrated a microalgal bioprocess which consists of microalgae production to obtain microalgal oil riched in bioactive and, encapsulation of microalgal oil to protect it from environmental conditions.

ANTIMICROBIAL EFFECT OF IODOFORM AND CHLORHEXIDINE ON MUSEUM STRAINS OF MICROORGANISMS

Surgical tooth extraction can result in a number of complications. Alveolitis is an infectious and inflammatory process in the walls of a tooth socket that may occur after tooth extraction during at the oral surgery outpatient appointment. This condition is characterized by a partial or complete absence of a blood clot, called as "dry socket", and pain syndrome. There are various factors, which can contribute to the development of this process, but the most common are traumatic and infectious ones. For the local treatment of alveolitis, a number of drugs are used to eliminate inflammatory manifestations and pain syndrome. During an outpatient appointment for the treatment of alveolitis, antiseptic drugs as iodoform and chlorhexidine are most often used. Iodoform is an antiseptic widely used locally in oral surgery and in endodontics. Chlorhexidine is also widely used in dentistry as an antiseptic. The aim of this in vitro study is to investigate the antimicrobial properties of iodoform and chlorhexidine using museum strains of microorganisms. Materials and methods. Museum strains of Staphylococcus aureus ATCC 25923, Staphylococcus epidermidis ATCC 14990, Enterococcus faecalis ATCC 29212, Esherichia coli ATCC 25922, Candida albicans ATCC 10231 were used the studied cultures of microorganisms. The antimicrobial effect of iodoform and chlorhexidine was determined by a quantitative method of serial dilutions in broth and agar. For this purpose, we used iodoform suspension, which corresponded to 200.0 mg / ml of the working concentration of the agent. A 0.05% solution of chlorhexidine bigluconate was used that corresponded to 500 μg / ml of the working concentration of the agent. Results and discussion. Iodoform as powder in the studied concentrations caused an insignificant static effect on museum strains of E. faecalis, E. coli, but did not exhibit a bactericidal effect against them. In relation to the C. albicans strain, iodoform demonstrated fungiostatic properties. The S. epidermidis and S. aureus strains were resistant to iodoform. Chlorhexidine caused both inhibitory and microbicidal action on all studied strains of microorganisms.

ANTISEPTIC PROPERTIES OF CITRATE BUFFER

The antiseptic properties of endodontic materials are used for microbial control in root canals. Decrease in microfloria is known as one of key demands for root canal therapy. The aim of this work is to study the sensitivity of reference strains of microorganisms to citrate buffer and its combination with the antibiotic «Amoxiclav». We used the museum strains of E. coli ATCC 25922, S. aureus ATCC 25923, S. epidermidis ATCC 14990, E. faecalis ATCC 29212, M. lysodeicus ATCC 4698 and C. albicans ATCC10231 to solve this task. The disk-diffusion method for assessing the sensitivity of standard strains of microorganisms was used. We used chlorhexidine digluconate 0.05% as a control. Citrate buffer has high antibacterial activity. The combination of citrate buffer with antibiotic increases the sensitivity of all reference strains. E. coli ATCC 25922 demonstrates a moderate sensitivity to citrate buffer. This combination with an antibiotic increases the antibacterial effect in 2.3 times (p &lt; 0.05). The sensitivity of enterococci increases towards the direction of chlorhexidine – citrate buffer – citrate buffer + «Amoxiclav». When comparing the results obtained using citrate buffer, its combination with antibiotic and chlorhexidine as a control, we should stress on the lower activity of chlorhexidine to strains of transient and normal oral microflora, which are E. coli ATCC 25922 and M. lysodeisticus ATCC 4698. On the contrary, we have revealed more pronounced action of experimental compositions against strains of pathogenic and opportunistic microorganisms, staphylococci, enterococci and yeast-like fungi that points out the advantage of citrate buffer and its combination with antibiotic «Amoxiclav» in terms of their use in the treatment of complicated caries.

Synergistic effect of Ceftriaxone and diclofenac against Escherichia Coli

Background: The emergence of resistant strains of bacteria has rendered many useful antibiotics ineffective. The researchers areforced to try combination of two or more antibiotics, or addition of a non- antibacterial to them. Ceftriaxone, a third-generationcephalosporin agent is used to treat many infectious diseases, especially those caused by members of Enterobacteriaceae family.We tested the efficacy of ceftriaxone, alone and in combination with various concentrations of diclofenac sodium, againstEscherichia coli.Objective: To study the synergistic effect of ceftriaxone and its combination with non-antibiotic drug diclofenac sodium againstEscherichia coli ATCC 25922 isolate.Material and Methods: Agar well diffusion technique was applied. 30 µl of solutions of ceftriaxone, and its combination withdifferent concentrations of diclofenac sodium and DMSO were transferred aseptically into the wells. Agar plates were placed in incubator at 37°C for 24 hours. Mean zone of inhibition of each drug was calculated.Results: Ceftriaxone 30µg formed a zone of inhibition of 35 mm. Its combination with 25µg and 50µg of diclofenac sodium formedzone of inhibition of 37.5mm while its combination with 100µg diclofenac sodium formed a zone of inhibition of 38.6mm and formed39.8mm zone of inhibition when combined with 200µg diclofenac sodium.Conclusion: Ceftriaxone activity increased when combined with different concentrations of diclofenac sodium drug showing asynergistic effect of their combination.Key words: ceftriaxone, Diclofenac sodium, E. coli, Synergism