Number Of Viable Bacterial Cells Research Articles

Photocatalytic Degradation of Paracetamol and Antibacterial Activity of La-Modified TiO2 Obtained by Non-Hydrolytic Sol–Gel Route

The current study aims to synthesize and analyze both pure and La-doped TiO2, and evaluate the photocatalytic and antibacterial activity of as-prepared samples. Doped and undoped samples were prepared by the non-hydrolytic sol–gel method from titanium(IV) chloride, benzyl alcohol, and lanthanum(III) nitrate followed by thermal treatment. Lanthanum content in synthesized samples was 0.4, 1, and 5 mol%. The resulting nanopowders’ structure and morphology were described using XRD, IR, and UV–Vis analysis. The average particle sizes of pure and doped TiO2 were about 6–15 nm and anatase was found to be a dominant crystalline phase in the samples. It was observed that particle sizes decreased on increasing La content. The photocatalytic activity of the pure and La-doped sol–gel powders was estimated in the decomposition of paracetamol in distilled water using ultraviolet light illumination. Doping with lanthanum ions has been shown to increase the photocatalytic properties on the degradation of paracetamol. Furthermore, the annealed catalysts (pure and La3+ doped) showed increased photocatalytic activity and degradation of the analgesic in comparison with non-annealed materials. In both cases, the highest photocatalytic efficiency is observed at the optimal La3+ (1 mol%) concentration. The antimicrobial activity of 1 mol% La/TiO2 was tested against a reference strain E. coli in the presence of ultraviolet light and in dark conditions. The number of viable bacterial cells was determined by a spread plate method, and kill curves were performed. The results showed that photoactivated 1 mol% La/TiO2 exhibited a strong bactericidal effect, and in concentration, 1 mg/mL efficiently killed bacteria at an initial cell density of about 105 colony forming units in 1 mL within 15 min.

Enhancing heavy metal phytoremediation in landfill soil by Chrysopogon zizanioides (L.) roberty through the application of bacterial-biochar pellets

This work investigated the performance of bacterial-biochar pellets (BBP) on promoting heavy metal phytoremediation by Chrysopogon zizanioides (L.) Roberty planted in landfill soil. Micrococcus sp. MU1, an indole-3-acetic acid (IAA)-producing bacterium, was incorporated into biochar pellets (MU1-BBP). MU1-BBP contained a high number of viable bacterial cells with 90 % viability after storage at 4°C for two months. In addition, it had a greater survival capability in heavy metals-contaminated landfill soil than MU1-free cells. The application of MU1-BBP significantly promoted the growth performance and chlorophyll synthesis of C. zizanioides planted in landfill soil. Cd, Cu, Pb and Zn were mostly retained in the roots relative to the shoots of C. zizanioides. The accumulation of Cd, Cu, Pb, and Zn in the roots of C. zizanioides were significantly boosted by MU1-BBP inoculation. Plants with MU1-BBP inoculation enhanced the accumulation coefficient (AC) of all four heavy metals. The values of AC values of Cd, Cu, and Zn in C. zizanioides with MU1-BBP inoculation were greater than 1.0. However, translocation factors of all four metals were low. The findings suggest C. zizanioides may be a good heavy metal phytostabilizer. The findings support the potential of bacterial-biochar pellets to enhance the efficiency of heavy metal phytostabilization of C. zizanioides in landfill sites.

Comparison of the Antibacterial Efficacy of Bamboo Shoot Ethanol Extract With Chlorhexidine Mouth Rinse Against Salivary Streptococcus mutans and Lactobacillus acidophilus: An Ex Vivo Study.

Background Dental caries is the most prevalent polymicrobial oral infectious disease tormenting individuals' healthy lifestyles and presents a significant public health problem. The objective of this study was to evaluate and compare the antibacterial properties of different concentrations of bamboo shoot ethanol extract with chlorhexidine mouth rinse on isolates of salivary Streptococcus mutans (S. mutans) and Lactobacillus acidophilus (L. acidophilus). Materials and methods Non-stimulated salivary samples from 30 young adults were treated ex vivo with bamboo shoot ethanolic extract at concentrations of 30 µg/ml, 40 µg/ml, 50 µg/ml, and 60 µg/ml. The colony-forming units were quantified by measuring the number of viable bacterial cells. Inhibition zones were evaluated using the agar diffusion method. One-way ANOVA and post-hoc test were used to analyze the significant difference between variables using SPSS version 22.0 (IBM Corp., Armonk, NY). Results The mean zone of inhibition with bamboo shoot ethanolic extract against salivary S. mutans (23.00 ± 0.816) and L. acidophilus (22.00 ± 0.816) total counts was closest to the control chlorhexidine (S. mutans =22.00 ± 0.876 and L. acidophilus =21.10 ± 0.876). A greater activity against S. mutans and L. acidophilus is seen in the zone of inhibition of the 60 µg/ml experimental concentration of bamboo shoot ethanolic extract, with a significant difference in the disc diffusion assay. Conclusion The treatment with bamboo shoot extract was equivalent effective in the mentioned bacterial species. Clinical relevance It can be assured that preventive measures like mouth rinse and dentifrices compromising bamboo shoots, a potential dental biomaterial, would be optimistic agents for caries control, including the cariostatic effect.

Bionanotechnology of Selenite Ions Recovery into Nanoselenium by Probiotic Strains of Lactobacteria and Tolerance of Lactobacteria to Sodium Selenite

Green synthesis of nanoparticles (NPs) using living cells is a promising and new tool in bionanotechnology. Chemical and physical methods are used to synthesize NPs, but biological methods are preferred because of their environmentally friendly, clean, safe, cost-effective, simple, and efficient sources for high productivity and purity. Aim. To investigate the processes of bioreduction of selenite ions into nanoselenium by probiotic strains of lactobacilli Lactobacillus plantarum IMV B-7679 and L. casei IMV B-7280. Methods. Cultivation of lactobacilli L. plantarum IMV B-7679 and L. casei IMV B-7280 was carried out in vials (500 cm3) on a rotary shaker (220 rpm) at 30 °C for 2 days on the Man, Rogosa, and Sharpe (MRS) broth nutrient medium. Sodium selenite was additionally added to the environment in different concentrations from 1 to 30 ppm by Se. The number of viable bacterial cells in 1 mL of suspension was determined by the method of limiting dilutions in the case of sowing aliquots on a nutrient medium containing 0.2% agar-agar. Cultures of L. plantarum IMV B-7679 or L. casei IMV B-7280 were grown in the liquid MRS broth medium with low pH in the presence or absence of Na2SeO3. The concentration of sodium selenite ranged from 1 to 30 ppm by Se level. The number of microorganisms was determined by inoculation (0.1 mL of suspension) in dense media on cups with MRS agar medium, and the seeding dose was 107 cells/Petri dish. The tolerance of lactobacilli to the selenite ions was evaluated by the decrease in the number of CFU when sowing aliquots taken from culture samples grown in the presence or absence of selenite. The results of the experiments were presented in CFU and transferred to Log CFU/cm3. The characteristics of Nano-Se were studied using transmission electron microscopy (TEM). Results. It was found that after 48 h incubation in an MRS medium with the addition of sodium selenite from 1 to 30 ppm, the culture of L. plantarum IMV В-7679 was the most resistant. Thus, enrichment of the culture medium with 30 ppm of Se in the Na2SeO3 composition led to a decrease in the number of L. plantarum IMV B-7679 to 5.17 ± 0.09 Log CFU/cm3 against 4.41 ± 0.11 Log CFU/cm3 for L. casei IMV B-7280 in the control. The use of lower concentrations (1—3 ppm of Se in Na2SeO3) did not affect the change in morphology and cultural properties of L. plantarum IMV B-7679. The ability of L. casei IMV B-7280 and L. plantarum IMV B-7679 cultures to grow on MRSA nutrient medium in the presence of 3 ppm Se was shown. Higher tolerance to sodium selenite was found for L. plantarum IMV B-7679. Thus, increasing the concentration to 30 ppm of Se in the form of Na2SeO3 led to a decrease in the viability of only the culture of L. casei IMV B-7280. That is, the studied lactobacilli showed different ability to grow in the presence of selenite ions. The formation of round electron-dense granules sizing from 30 nm to 250 nm was observed using TEM. Both probiotic strains showed the ability to restore selenite ions with the accumulation of intracellular Nano-Se and the release of Nano-Se into the culture medium, which was accompanied by color shifts from yellowish to red-brown. The partial destruction of L. casei IMV B-7280 cells under the influence of oxyanions was revealed, which was accompanied by the release of culture-synthesized electron-dense Nano-Se particles. Conclusions. The optimal conditions for the growth of L. plantarum IMV B-7679 and L. casei IMV B-7280 in the presence of Na2SeO3 were established, and it was proved that lactobacilli have different abilities to grow in the presence of selenite ions. The obtained data indicate that the investigated probiotic strains showed the ability to restore selenite ions along with the accumulation of intracellular Nano-Se and the release of Nano-Se into the culture medium.

Enhancing the Activity of Surface Immobilized Antimicrobial Peptides Using Thiol-Mediated Tethering to Poly(ethylene glycol).

Considering the need for versatile surface coatings that can display multiple bioactive signals and chemistries, the use of more novel surface modification methods is starting to emerge. Thiol-mediated conjugation of biomolecules is shown to be quite advantageous for such purposes due to the reactivity and chemoselectivity of thiol functional groups. Herein, the immobilization of poly(ethylene glycol) (PEG) and antimicrobial peptides (AMPs) to silica colloidal particles based on thiol-mediated conjugation techniques, along with an assessment of the antimicrobial potential of the functionalized particles against Pseudomonas aeruginosa and Staphylococcus aureus is investigated. Immobilization of PEG to thiolated Si particles is performed by either a two-step thiol-ene "photo-click" reaction or a "one-pot" thiol-maleimide type conjugation using terminal acrylate or maleimide functional groups, respectively. It is demonstrated that both immobilization methods result in a significant reduction in the number of viable bacterial cells compared to unmodified samples after the designated incubation periods with the PEG-AMP-modified colloidal suspensions. These findings provide a promising outlook for the fabrication of multifunctional surfaces based upon the tethering of PEG and AMPs to colloidal particles through thiol-mediated biocompatible chemistry, which has potential for use as implant coatings or as antibacterial formulations that can be incorporated into wound dressings to prevent or control bacterial infections.

Supercharged MPNs? Automated Determination of High-Throughput Most Probable Number (htMPN) Using Chip-Based 3D Digital PCR.

Surface plating on agar and most probable number (MPN) are the standard methods for determining bacterial viability but both have limitations. Here we present a novel cell count method, high-throughput MPN (htMPN), that uses a chip-based digital PCR instrument to accelerate and to improve the quantification of viable or sublethally injured cells. This method tracks growth of up to 20,000 individual bacterial cells on a single chip. Single cells were grown in the individual wells of the chip at their optimal temperature until the cell density was high enough to detect the fluorescent signal with cell-permeant or cell-impermeant DNA-intercalating fluorescent dyes. This method based on microfluidic devices implemented in digital PCR equipment was equivalent to surface plating in determining cell counts of Escherichia coli, Salmonella enterica serovar Typhimurium, Fructilactobacillus sanfranciscensis, Pseudomonas putida, and vegetative cells but not spores of Bacillus subtilis. Viable E. coli could be enumerated within 7 h. Culture of strict aerobes was restricted to strains that are capable of nitrate respiration; organisms requiring complex media that also contain double-stranded DNA were detected after treatment of growth media with DNase before inoculation. Our approach not only monitors the frequency distribution of bacterial growth and determines cell counts with high reliability but also detected heat-injured cells of S. Typhimurium that escaped detection by the surface plating. Overall, the method accelerates detection of viable bacterial cells, facilitates automation, and offers new possibilities for the analysis of individual bacterial cells. IMPORTANCE htMPN uses chip-based fluorescence acquisition and is a simple and compact tool for automatic viable cell enumeration with applications in microbiological research. This method applies to a wide range of anaerobic or facultative anaerobic species and improves accuracy by reducing the number of pipetting steps. In addition, the method offers an additional tool for single-cell microbiology. The single cell time-to-detection times have been used as an important criterion for the physiological state of bacterial cells after sublethal stress, and htMPNs support the acquisition of such data with an unprecedented number of cells. In particular, htMPN provides an anaerobic environment and enables a long incubation time to increase the recovery rate of sublethally injured cells. Given its reproducibility and reliability, our approach can potentially be applied to quantify viable cells in samples from environmental, clinical, or food samples to reduce the risk of underestimation of the number of viable bacterial cells.

Self-locomotive, antimicrobial microrobot (SLAM) swarm for enhanced biofilm elimination

Biofilm is a major cause of infections and infrastructure deterioration, largely due to molecular diffusion restrictions that hamper the antimicrobial activity of traditional antibiotics and disinfectants. Here, we present a self-locomotive, antimicrobial microrobot (SLAM) swarm that can penetrate, fracture, and detach biofilm and, in turn, nullify bacterial resistance to antibiotics. The SLAM is assembled by loading a controlled mass of manganese oxide nanosheets on diatoms with the polydopamine binder. In hydrogen peroxide solution, SLAMs produce oxygen bubbles that generate thrust to penetrate the rigid and dense Pseudomonas aeruginosa biofilm and self-assemble into a swarm that repeatedly surrounds, expands, and bursts oxygen bubbles. The resulting cavities continue to deform and fracture extracellular polymeric substances from microgrooved silicone substrates and wounded skin explants while decreasing the number of viable bacterial cells. Additionally, SLAM allows irrigating water or antibiotics to access the residual biofilm better, thus enhancing the synergistic efficacy in killing up to 99.9% of bacterial cells.

The antimicrobial effect of Rosmarinus officinalis extracts on oral initial adhesion ex vivo

ObjectiveIn the last few decades, there has been a growing worldwide interest in the use of plant extracts for the prevention of oral diseases. The main focus of this interest lies in the identification and isolation of substances that limit the formation of microbial biofilm which plays a major role in the development of caries, periodontitis, and peri-implantitis. In this clinical ex vivo study, we investigated the antimicrobial effects of Rosmarinus officinalis extract against oral microorganisms within in situ initial oral biofilms.Materials and methodsInitial in situ biofilm samples (2 h) from six healthy volunteers were treated ex vivo with R. officinalis extract at concentrations of 20 mg/ml and 30 mg/ml. The number of viable bacterial cells was determined by counting the colony-forming units. All surviving bacteria were isolated in pure cultures and identified using MALDI-TOF and biochemical testing procedures. Additionally, live/dead staining in combination with epifluorescence microscopy was used for visualizing the antimicrobial effects in the initial biofilms.ResultsThe number of colony-forming units in the R. officinalis–treated biofilms was significantly lower than in the untreated controls (p < 0.001). The reduction range of log10 was 1.64–2.78 and 2.41–3.23 for aerobic and anaerobic bacteria, respectively. Regarding the bacterial composition, large intra- and interindividual variability were observed. Except for Campylobacter spp., the average amount of all bacterial taxa was lower after treatment with R. officinalis than in the untreated biofilms. A total of 49 different species were detected in the untreated biofilms, while only 11 bacterial species were detected in the R. officinalis–treated biofilms. Live/dead staining confirmed that the R. officinalis–treated biofilms had significantly lower numbers of surviving bacteria than the untreated biofilms.ConclusionsThe treatment with R. officinalis extract has a significant potential to eliminate microbial oral initial biofilms.Clinical relevanceThe results of this study encourage the use of R. officinalis extracts in biofilm control and thus in the treatment of caries and periodontitis as a herbal adjuvant to synthetic substances.

Synergetic effects of Lactobacillus plantarum and Rhizopus oryzae on physicochemical, nutritional and antioxidant properties of whole-grain oats (Avena sativa L.) during solid-state fermentation

In this study, Lactobacillus plantarum strains, namely 70810, B1-6, and ZR were used to confirm the synergetic effects of co-inoculation with Lactobacillus and Rhizopus oryzae on whole-oat solid state fermentation (SSF). The results indicated that number of viable bacterial cells increased more quickly (10.72–11.23-fold higher) during co-inoculated SSF than that during pure Lactobacillus fermentation. Fungal ergosterol content reached slightly less during co-inoculation (137.04–155.12 mg/kg) than that during R. oryzae fermentation (193.64 mg/kg). However, compared to R. oryzae, R. oryzae combined with Lactobacillus produced more obvious hydrolysis of macromolecules and accelerated more water transformation from confined to free form. As for co-inoculated SSF of oat, the reducing sugar content reached the highest at 41.09–47.42 g/100g and then dropped, and free amino acid nitrogen content varied gradually until 40.66–41.67 mg/100g. Fermented oats (FOs) had higher total phenolic content than unfermented oat (UO) (2.56–2.72-fold, FO vs. UO), and their DPPH radical scavenging activity, ferric reducing capacity, and hydroxyl scavenging activity were increased 2.04-, 2.10-, and 1.99-fold at maximum (FO vs. UO), respectively. The Lactobacillus showed strain dependence during co-inoculated SSF, among which B1-6 displayed the best to enhance oat's overall quality.

The biofilm inhibition activity of a NO donor nanosilica with enhanced antibiotics action

Nitric oxide (NO) has emerged as a promising antibacterial agent, where NO donor compounds have been explored. Here, we investigated the role of a silica nanoparticle containing nitroprusside (MPSi-NP) as a NO donor agent against methicillin-sensitive (ATCC 25,923 and ATCC 12228) and methicillin-resistant (ATCC 700,698 and ATCC 35984) Staphylococcus strains. Biofilm inhibition was studied along with antibiotic activity in combination with standard antibiotics (ampicillin and tetracycline). MPSi-NP exhibited thermal release of 63% of NO within 24 h, while free nitroprusside released only 18% during a dialysis assay, indicating an assisted release of NO mediated by the nanoparticles. This nanomaterial showed only a moderate activity in blocking biofilm production, but exhibited a significant decrease in the number of viable bacterial cells (over 600-fold for Staphylococcus aureus ATCC 700,698 and Staphylococcus epidermidis ATCC 35984). Remarkably, even using MPSi-NP at concentrations below any antibacterial action, its combination with ampicillin promoted a significant decrease in MIC for resistant strains of S. aureus ATCC 700,698 (2-fold) and S. epidermidis ATCC 35,984 (4-fold). A carbopol-based gel formulation with MPSi-NP (0.5% w/w) was prepared and showed a zone of inhibition of 7.7 ± 0.6 mm for S. epidermidis ATCC 35984. Topical use of MPSi-NP in combination with antibiotics might be a manageable strategy to prevent and eventually treat complicated resistant bacterial infections.

The study of biotechnological potential of &lt;i&gt;Lactobacillus sakei&lt;/i&gt; LSK-103

Lactic acid bacteria play an important role in the production of food. Bacterial cultures widely used in the food industry often have a set of characteristics that ensure the stability of the production. The biotechnological properties of Lactobacillus sakei LSK-103 have been studied in the present work. Lactobacillus sakei LSK-103 has shown high biochemical activity on MRS medium. It has been found that after 16 h of cultivation at the end of the exponential growth phase, the number of viable bacterial cells reaches 10 CFU/cm. The study of the effect of different concentrations of sodium chloride on biomass accumulation has shown that Lactobacillus sakei LSK-103 is highly resistant to salt. Increase in NaCl concentration from 2 to 10 % leads to decrease in cell survival from 96.8 to 91.2 %, and in number of bacteria to 10 CFU/cm. Morphological studies indicate that an increase in the concentration of sodium chloride in the medium is accompanied by cell cohesion, the formation of cell conglomerates. Cohesion intensifies intercellular contacts and increases the resistance of Lactobacillus sakei LSK-103 to osmotic stress. The high survival rate of Lactobacillus sakei LSK-103 has been shown in the presence of bile, phenol (0.4 %), high (pH 8.3) and low (pH 3.5) values of active acidity of the medium indicating its probiotic properties. The results of research have shown that the Lactobacillus sakei LSK-103 has high biotechnological potential and can be used as part of bacterial preparations for the production of fermented fish products.

The Effect of the Addition of Chokeberry Fiber on the Quality of Sheep's Milk Fermented by Lactobacillus rhamnosus and Lactobacillus acidophilus.

The global market for sheep's milk and its products is increasing due to higher demand for cheese and traditional dairy products, and as a novelty, sheep's milk is an ingredient in infant formulas and nutraceuticals. The aim of this study was to determine the properties of fermented sheep's milk, which combines probiotic benefits with increased dietary fiber content. The influence of the applied dose of chokeberry fiber on the growth of living cells of Lactobacillus acidophilus and Lactobacillus rhamnosus in fermented sheep's milk was also evaluated. Sheep milk with the addition of 0% (control sample), 1.5%, and 3.0% chokeberry fiber was fermented by two different probiotic monocultures L. acidophilus and L. rhamnosus. In the fermented milk, pH value, syneresis (%), color, and texture were determined. Furthermore, the microbiological analysis and an organoleptic evaluation were performed. With the increasing dose of chokeberry fiber, the pH value decreased already before the fermentation process. After fermentation, the milk's pH values with fiber were still lower than those in the control sample. Presumably, more acidic metabolites were produced by L. acidophilus, causing a more intense reduction of the pH value than L. rhamnosus both in control milk and in milk with the addition of fiber. The addition of chokeberry fiber affected the stimulation of the growth of both types of bacteria. In the milk sample without fiber addition, a more significant number of viable cells were counted for L. acidophilus by 0.5 log CFU g−1 more than the milk fermented with L. rhamnosus. Furthermore, in milk fermented by L. acidophilus with 1.5% chokeberry fiber (LA1), the number of viable bacterial cells was higher than that in milk fermented by L. rhamnosus with the same addition of fiber (LR1). However, in sample LA3, the number of viable bacterial cells was lower than that in sample LR3. Tested fermented sheep milk met the Recommendation of the International Dairy Federation's requirements regarding the number of live bacterial cells for dairy probiotics. The addition of chokeberry fiber increased syneresis in each fermented milk group, regardless of the bacteria used for fermentation. Moreover, the use of fiber caused a significant reduction in brightness L∗, an increase of red color, and a decrease of yellow color. Milk fermented with L. acidophilus was characterized by a harder gel, compared to their analogues fermented with L. rhamnosus. The addition of fiber intensified the sour taste and the taste of the additive in both types of fermented sheep milk.

Formation of biofilms by representatives of the oral microflora on the surfaces of basic materials

The aim of the work is to conduct a comparative analysis of the biofilm formation by representatives of the oral microflora on the surfaces of basic materials. Materials and methods. The process of biofilm formation was examined on 7 types of basic plastic samples: Polyan, Breflex, Nylon, Protakryl, Vinakryl, Biocryl, which were used for the manufacture of removable prosthetic basis constructions, and SYNMA, which was used for comparison. Biofilm formation was analyzed by the method Y. Zhang (2017) with minor modifications. The test sample was placed in a test tube with 2.0 ml of nutrient broth Brain Heart Infusion to model the biofilm growth of microorganisms (HiMedia Laboratories Pvt. Ltd., India) supplemented with 1 % glucose, pre-inoculated with test strains at a final concentration of 1 × 104 CFU/ml. The strains were cultivated for 24 hours at a temperature of 37 °C under continuous stirring in a shaker MR-1 (SIA BIOS AN, Latvia) at 20 rpm. Evaluation of the biofilm massiveness was performed after gentian violet staining followed by elution of the stain with ethanol and registration of the eluent optical density (OD). The OD was measured with a Synergy™ HTX S1LFTA microplate multimode photometer (BioTek Instruments, Inc., USA) at 595 nm wavelength using Gen5™ Data Analysis Software. The number of viable bacterial cells in the formed biofilms was determined by the method of ten-fold serial dilutions. The obtained results were converted per unit area of the sample tested. Processing of the results was performed using a two-sample t-test with the software package Statistica 13.0 and Microsoft Office Excel, the differences were considered statistically significant at a P value of &lt; 0.05. Statistical analysis of the obtained data was presented as mean values of measurements ± standard deviation for three independent experiments. Results. According to the microbiological analysis results it was found that α-hemolytic streptococci S. oralis and S. sanguinis showed the ability to form biofilms on the surfaces of basic materials, namely Protacryl and Vinacryl, the total biomass of S. sanguinis biofilms was 47.7 % (P &lt; 0.01) and 14.7 % (P &gt; 0.05) greater, respectively, in comparison to a glass slide. Inhibition of biofilm formation processes was observed on the surfaces of Nylon and Biocryl basic materials. S. oralis and S. gordonii showed the highest ability to survive in biofilms. The intensity of C. albicans biofilms formation on Biocryl basic materials, comparative plastics SINMA and Breflex basic materials was greater than on glass slides by 48.3 %, 43.0 % and 34.9 % (P &lt; 0.01), respectively. The least massive C. albicans biofilms were formed on Breflex surfaces and SINMA comparative plastics in comparison to glass slides by 33.6 % and 24.8 % (P &lt; 0.01), respectively. Both Candida strains had the highest level of fungal viability in biofilms on Breflex, Polyan and Protacryl basic materials (P &lt; 0.01), and C. tropicalis biofilms on Biocryl and Vinacryl basic materials (P &lt; 0.05). Integral coefficients indicated the inhibition of the oral microflora ability to form biofilms on the surfaces of basic materials. Conclusions. Oral α-hemolytic and β-hemolytic streptococci have the ability to intensive biofilm growth on the surfaces of the basic materials Protacryl and Vinacryl. Oral Candida albicans form massive biofilms on the surfaces of Biocryl and Vinacryl basic materials and comparative SYNMA plastics. The basic materials Breflex, Nylon and comparative plastics SYNMA are the most inert to biofilm formation by the oral microflora representatives.

DIAZOTROPH ACTIVITY REGULATING STRATEGY UNDER THEIR INTRODUCTION IN AGROCENOSES

Objective. Investigate approaches to managing the activity of soil diazotrophs and propose a strategy for its regulation. Methods. Theoretical, vegetation and field experiments, microbiological, gas chromatographic, mathematical and statistical. Results. The activity of beneficial soil microorganisms can change under the action of temperature, humidity, chemical compounds of various origin, and other microorganisms. It was established that, taking into account a significant variety of factors, it is necessary to develop a set of specific ways to increase the growth and functional activity of nitrogen-fixing bacteria, as well as their viability. It has been proved that the combination of diazotrophs forms an effective symbiotic leguminous-rhizobial system, which provides additional biological nitrogen in agrocenoses. At the same time, there was an increase in plant mass, chlorophyll content in the leaves, protein and oil content in the products. The combined use of diazotrophs increases the yield, in particular, soybeans by 9–16 % compared with inoculation by pure bacterial culture. Conclusion. Based on the analysis and generalization of the obtained research results, a strategy for regulating the activity of diazotrophs for their effective introduction into agrocenoses is proposed, which consists in combining bacteria of different species, selecting conditions for their co-cultivation and application upon stabilisation of the number of viable bacterial cells. The proposed strategy involves solving the problem by obtaining an inoculant, which is characterized by a high titre and a stable number of viable cells, which allows to obtain an effective nitrogen-fixing system. The strategy is tried-and-tested on the example of regulating the growth and functional activity of soybean nodule bacteria by combining diazotrophs of different species, substantiating the conditions of their co-cultivation and application to ensure positive interaction in the form of commensalism, as well as by regulating viability of diazotrophs by adding stabilisers to the medium.

Viability and phenotypic heterogeneity of Rhodococcus Rhodochrous CNMN-AC-05 in the presence of fullerene C60

Introduction. In recent years, due to wide applications of nanotechnologies in various fields, the safety of nanomaterials has become a pressing issue. Fullerene C60 is not an exception. Research on the activity of microorganisms and their interaction with nanoparticles is of major importance, both for microorganisms and for the ecosystem as a whole.&#x0D; Material and methods. Fullerene C60 powder was purchased from Sigma-Aldrich. The object of study was R. rhodochrous CNMN-Ac-05 strain. The number of viable bacterial cells was estimated by colony-forming units (CFU). The morphological features of the rhodococci colonies have been described according to the usual microbiological method.&#x0D; Results. It was established that fullerene C60 in concentrations of 1-25 mg/L fullerene C60 stimulated the growth of R. rhodochrous by 2.4-2.8 times. As the concentration of fullerene C60 increased up to 50-100 mg/L, the multiplication and growth of rhodococci decreased by 29.5% and 38% respectively. In the presence of 1-10 mg/L fullerene C60 the rhodococci population remained homogeneous, being composed of 100% S type colonies. The increase of fullerene C60 concentration led both to the decrease in the CFU number and to the appearance of R type colonies, up to 1.3% of population.&#x0D; Conclusions. Fullerene C60 in concentrations 1-100 mg/L had no obvious toxic effect on the rhodococci strain. The optimum concentration is 10 mg/L. The concentrations higher than 25 mg/L led to the dissociation of rhodococcal population and diminution in the CFU counts, but not to the total inhibition.

Cobalt-Chromium Alloy Has Superior Antibacterial Effect Than Titanium Alloy: In Vitro and In Vivo Studies.

In vitro and in vivo laboratory studies. This study aimed to compare bacterial survival on titanium alloy (Ti) and cobalt-chromium alloy (CC) using in vitro and in vivo experiments. Spinal implants are frequently manufactured from Ti and CC. These foreign materials are thought to be susceptible to biofilm formation that contributes to the development of surgical site infections. Certain metals (i.e., silver, cobalt) are known to have antibacterial properties. In the in vitro study, discs made of Ti or CC were incubated with one of two common bacteria: Staphylococcus aureus (S. aureus) and Propionibacterium acnes (P. acnes). After incubation, discs were assessed to determine the number of viable bacterial cells. In the in vivo study, the discs that were made of CC or Ti were implanted into the subcutaneous layer of BALB/c mice. After skin closure, a suspension including either S. aureus or P. acnes was directly inoculated on the implanted discs. The discs were retrieved and analyzed to determine the number of viable bacteria at 0.5, 1, and 3 days after inoculation. The number of viable S. aureus cultured from the CC discs was 0.9 ± 0.2 × 103 CFU/disc, which was significantly lower than the cultured Ti discs (114.8 ± 18.3 × 103 CFU/disc). Moreover, a significantly lower mean number of P. acnes were cultured with CC (1.9 ± 1.2 × 103 CFU/disc) compared with the Ti (180.0 ± 72.1 × 103 CFU/disc). The in vivo infection model testing against S. aureus or P. acnes showed a significantly lower number of viable S. aureus or P. acnes on CC discs than Ti discs. The result was seen at all measured time points. CC suppressed S. aureus and P. acnes proliferation compared with Ti in vitro and in an in vivo infection model.Level of Evidence: N/A.

Specific Features of Biocorrosion of the Circulation Cooling System in the Petrochemical Industry

The circulating water of the cooling systems of petrochemical enterprises has a number of special features: the temperature of cooling water is in the range of 14-28 °С all year round, the evaporation of water in cooling towers increases the concentration of dissolved salts. Inevitable ingress of hydrocarbons, dosing of corrosion inhibitors, scaling, reagents for dispersing and softening of the water creates favorable conditions for micro- and macroorganisms development. Existing standards stipulate that the number of viable bacterial cells in planktonic form should not exceed 10 cells/ml, the number of bacteria in the adhered form is not regulated, nevertheless these organisms in particular lead to biocorrosion. During the assessing of the biological degradation of water cycle equipment materials, it was studied the micro- and macroorganisms that populate the surface of steel samples 20. Studies of the effect of this bacteria on the corrosion of steel 20 showed that this whole complex of micro- and macroorganisms, releasing metabolites into the water, also indirectly affects the processes of corrosion, and when choosing protection methods, it is necessary to take into account not only the presence and types of bacteria, but also the entire local biocenosis.

Dual role of splenic mononuclear and polymorphonuclear cells in the outcome of ciprofloxacin treatment of Salmonella enterica infections.

To determine the immune cell populations associated with Salmonella enterica serovar Typhimurium before and after ciprofloxacin treatment using a murine model of systemic infection. The effect of depletion of immune cells associating with Salmonella on treatment outcome was also determined. We infected mice with a Salmonella enterica serovar Typhimurium strain expressing GFP and used multicolour flow cytometry to identify splenic immune cell populations associating with GFP-positive Salmonella before and after treatment with ciprofloxacin. This was followed by depletion of different immune cell populations using antibodies and liposomes. Our results identified CD11b+CD11chi/lo (dendritic cells/macrophages) and Ly6G+CD11b+ (neutrophils) leucocytes as the main host cell populations that are associated with Salmonella after ciprofloxacin treatment. We therefore proceeded to test the effects of depletion of such populations during treatment. We show that depletion of Ly6G+CD11b+ populations resulted in an increase in the number of viable bacterial cells in the spleen at the end of ciprofloxacin treatment. Conversely, treatment with clodronate liposomes during antimicrobial treatment, which depleted the CD11b+CD11chi/lo populations, resulted in lower numbers of viable bacteria in the tissues. Our study identified host cells where Salmonella bacteria persist during ciprofloxacin treatment and revealed a dual and opposing effect of removal of Ly6G+CD11b+ and CD11b+CD11chi/lo host cells on the efficacy of antimicrobial treatment. This suggests a dichotomy in the role of these populations in clearance/persistence of Salmonella during antimicrobial treatment.

Establishment and application of a novel fluorescence-based analytical method for the rapid detection of viable bacteria in different samples.

A rapid method for readily detecting the total numbers of viable bacterial cells in numerous samples (including surface water, solid inoculants, and soil samples) is reported using a newly developed hand-held fluorometer and a fluorescent dye Calcein UltraGreen™ AM. Compared to the traditional plate counting method that requires 48 hours of cultivation, the newly established method does not require any incubation time, making the detection method faster and more convenient. The portable rapid detection fluorometer has a wide dynamic range of relative fluorescence intensity from 45 to 30 133. It can detect bacterial concentration ranging from 105 to 1010 cells per mL. This newly established method has good applicability for accurately and quickly detecting the cell number of viable bacteria in various samples. The results of the fluorescence-based method were compared with those of the traditional plate counting method, and it was found that the relative standard deviation was less than 6%. This new rapid measurement system provides a robust method for the rapid on-site detection of viable bacteria.

Antimicrobial activity of Titanium dioxide and Zinc oxide nanoparticles supported in 4A zeolite and evaluation the morphological characteristic

In this study, the antimicrobial activity of titanium dioxide (TiO2), zinc oxide (ZnO), and TiO2/ZnO nanoparticles supported into 4A zeolite (4A z) was assessed. Based on antimicrobial experiments, minimum inhibitory concentration (MIC90), minimum bactericidal concentration (MBC), fractional inhibitory concentration (FIC) and disc diffusion test were determined after 24 h of contact with the prepared nanocomposites. These results are in agreements with the results of disc diffusion test. During the experiments, the numbers of viable bacterial cells of Staphylococcus aureus, Pseudomonas fluorescens, Listeria monocytogenes and Escherichia coli O157:H7 decreased significantly. The crystallinity and morphology of nanoparticles were investigated by X-ray diffraction patterns (XRD), elemental mapping at the microstructural level by scanning electron microscopy (SEM) with energy dispersive X-ray spectrometry (EDS), and transmission electron microscopy (TEM). As a result, it was demonstrated that TiO2/ZnO nanoparticles supported in 4A zeolite could lead to an optimum activity as antimicrobial agents.