Microbial Suspensions Research Articles

Exploring the antimicrobial potential of Leukocyte- and Platelet-Rich Fibrin - an in vitro study.

This study investigates the antimicrobial properties of leukocyte- and platelet-rich fibrin (L-PRF) against Enterococcus faecalis (ATCC 29212), Pseudomonas aeruginosa (ATCC 27853), and Candida albicans (ATCC 90028). Infections can hinder wound healing posing challenges. L-PRF's potential for regeneration and antimicrobial action has been studied. Considering the increasing concern about antibiotic resistance, assessing the antimicrobial properties of L-PRF provides valuable insights into its potential as a therapeutic agent in postoperative infections. Twenty volunteers were enrolled in the study, following ethical guidelines, and obtaining informed consent. Blood samples were collected and L-PRF was prepared. Microbial suspensions were prepared, and susceptibility testing was performed using the Kirby-Bauer agar diffusion method. The study revealed significant heterogeneity in the susceptibility to L-PRF. All L-PRF membrane samples exhibited antimicrobial activity against P. aeruginosa, with inhibition zones of 13 mm ± 3.85 SD. Enterococcus faecalis displayed inhibition diameter of 7.25 mm ± 5.15 SD. Candida albicans susceptibility to L-PRF varied among samples, with both inhibitory and non-inhibitory results. Results showed varying degrees of antimicrobial activity, particularly against P. aeruginosa, and highlight the complexity of the L-PRF-microorganism interaction. Further investigations are needed to elucidate the clinical implications and optimize the use of L-PRF.

Simultaneous enumeration of yeast and bacterial cells in the context of industrial bioprocesses

Abstract In scenarios where yeast and bacterial cells coexist, it is of interest to simultaneously quantify the concentrations of both cell types, since traditional methods used to determine these concentrations individually take more time and resources. Here, we compared different methods for quantifying the fuel ethanol Saccharomyces cerevisiae PE-2 yeast strain and cells from the probiotic Lactiplantibacillus plantarum strain in microbial suspensions. Individual suspensions were prepared, mixed in 1:1 or 100:1 yeast-to-bacteria ratios, covering the range typically encountered in sugarcane biorefineries, and analyzed using bright field microscopy, manual and automatic Spread-plate and Drop-plate counting, flow cytometry (at 1:1 and 100:1 ratios), and a Coulter counter (at 1:1 and 100:1 ratios). We observed that for yeast cell counts in the mixture (1:1 and 100:1 ratios), flow cytometry, the Coulter counter, and both Spread-plate options (manual and automatic CFU counting) yielded statistically similar results, while the Drop-plate and microscopy-based methods gave statistically different results. For bacterial cell quantification, the microscopy-based method, Drop-plate, and both Spread-plate plating options and flow cytometry (1:1 ratio) produced no significantly different results (P > 0.05). In contrast, the Coulter counter (1:1 ratio) and flow cytometry (100:1 ratio) presented results statistically different (P < 0.05). Additionally, quantifying bacterial cells in a mixed suspension at a 100:1 ratio wasn't possible due to an overlap between yeast cell debris and bacterial cells. We conclude that each method has limitations, advantages, and disadvantages.

Comparison of the Antimicrobial Efficacy of Conventional Versus Chitosan Re-inforced Heat-Polymerized Polymethylmethacrylate Dental Material: An In Vitro Study.

Polymethylmethacrylate (PMMA) is widely used in the fabrication of dentures due to its aesthetic appeal and mechanical strength. However, PMMA's susceptibility to microbial colonization often leads to oral infections such as denture stomatitis. Enhancing the antimicrobial properties of denture materials is crucial for improving patient outcomes.Chitosan, a natural biopolymer, possesses inherent antimicrobial properties and could potentially enhance the microbial resistance of PMMA. This study has investigated thepotential of chitosan-reinforced heat-polymerized PMMA denture material to reduce microbial colonization. The aim of the study was to evaluate and assess the anti-bacterial and antifungal properties of chitosan-reinforced heat-polymerized PMMA with conventional heat-polymerized PMMA Materials and methods:Chitosan-reinforced PMMA samples were fabricated with varying chitosan concentrations (0% control, 5%, 10%, and 15% by weight). The fabrication involved mixing chitosan powder with PMMA powder, adding monomer liquid, followed by mixing, packing, and curing using the conventional heat polymerization technique. The antimicrobial efficacy was assessed in vitro using two common oral pathogens: Streptococcus mutans and Candida albicans. Blood agar plates were used for S. mutans and Sabouraud agar plates were used for C. albicans. Each sample was placed on the respective agar plates inoculated with a standardized microbial suspension and incubated at 37°C for 24 hours. The number of colony-forming units (CFUs) was counted to quantify microbial growth. Statistical analyses, including linear regression analysis, one-way ANOVA test, and Pearson correlation were performed to evaluate the relationship between chitosan concentration and antimicrobial efficacy. The p-value was calculated to determine the statistical significance of the results. The chitosan-reinforced PMMA samples showed significantly greater antimicrobial efficacy compared to the conventional PMMA samples. The CFU counts for both S. mutans and C. albicans decreased with increasing chitosan concentration. Linear regression analysis indicated a strong negative correlation between chitosan concentration and CFU counts, with Pearson correlation coefficients of -0.97 for S. mutans and -0.98 for C. albicans. ANOVA analysis revealed a statistically significant difference in antimicrobial efficacy across different chitosan concentrations (p < 0.001). Incorporating chitosan into heat-polymerized PMMA significantly enhances its antimicrobial properties against S. mutans and C. albicans. The antimicrobial efficacy improves with higher concentrations of chitosan, with the 15% chitosan-reinforced samples showing the most substantial reduction in microbial growth. These results suggest that chitosan-reinforced PMMA dentures could be a superior alternative to conventional PMMA dentures, potentially reducing denture-related infections and improving oral health outcomes for denture wearers.

In Vitro Inhibitory Effects and Co-Aggregation Activity of Lactobacilli on Candida albicans

Lactobacilli are considered important probiotics for the prevention of some infections. In this study, the antifungal effect of both cells and cell-free supernatants of twenty-three strains of lactobacilli were investigated against Candida albicans by co-aggregation, agar diffusion assay, agar spot assay and co-culture assay. In all cases, a fungistatic effect was recorded. In the agar diffusion assay and agar spot assay, an effect was established primarily for heterofermentative species via the production of lactic acid. The anti-Candida effect was higher with microbial suspension than with cultural supernatants in the co-culture assay. A strain-specific reduction in the yeast growth up to 28.9% in MRS broth and up to 17.1% in BHI broth was observed. Cells of Limosilactobacillus fermentum LLF-01 and Limosilactobacillus reuteri LLR-K67 showed the highest activity in both model systems. For all strains, a lower reduction up to 9.7% was recorded with cultural supernatants. L. fermentum LLF-01 showed the highest ability of co-aggregation (64.8%) with C. albicans, followed by Lactobacillus acidophilus LLA-01, Lactobacillus gasseri LLG-V74, Lactobacillus delbrueckii subsp. bulgaricus LLB-02 and two strains of Lactobacillus delbrueckii subsp. lactis LLL-14 and LLL-F18. The present study showed the potential of several strains of lactobacilli to affect the population of C. albicans in vitro. The combination of cultures with proved anti-Candida and co-aggregation activity in a probiotic formula may have a positive effect for the prevention of yeast overgrowth in the gut and hence for the suppression of candidiasis.

Insights into the Significance of Ternary Hybrid Nanofluid Flow Between Two Rotating Disks in the Presence of Gyrotactic Microorganisms

The ecology of marine life and other biotic processes, such as septicity, are influenced by the drive of microorganism cells in the fluid. Considering the transference mechanism in nanofluids including a microbial suspension is imperative for several chemical and medical applications. This study examines the bioconvection of an Al2O3-Graphene-CNT/water ternary hybrid nanofluid between two infinitely parallel spinning disks in a porous media under the influence of heat source/sink and radiation. The Cattaneo–Christov model has been employed to inspect the transference mechanism of mass and heat. The MATLAB function “bvp4c” is used to numerically tackle the governing equations. The relationship between the most relevant variables and the motile microorganism’s density, velocity, temperature, concentration of nanoparticles and other characteristics is graphically represented. Last, figures are provided to illustrate how several important elements relate to the Nusselt and Sherwood number, and local motile microbe density number. The heat transfer rate is seen to be higher at the upper disk than at the lower disk. A rise in the volume fraction of nanoparticles causes the heat transfer rate at both disks to increase. The outcomes of this study will be useful for a wide range of architectural designs, transportation systems, oil recovery systems with microbes, medical sectors and other industries that utilize nanofluids.

Loss of microbial diversity increases methane emissions and arsenic release in paddy soils

Microorganisms are vital to the emission of greenhouse gases and transforming pollutants in paddy soils. However, the impact of microbial diversity loss on anaerobic methane (CH4) oxidation and arsenic (As) reduction under flooded conditions remains unclear. In this study, we inoculated microbial suspensions into natural As-contaminated paddy soils using a dilution approach (untreated, 10−2, 10−4, 10−6, 10−8 dilutions) to manipulate microbial diversity levels. The results revealed that the 10−4 and 10−6 dilutions resulted in the highest CH4 emissions (97.0 μmol and 102.3 μmol) compared to untreated groups (27.6 μmol). However, anaerobic CH4 oxidation was not observed in 10−4 dilution groups and higher dilutions, suggesting the loss of diversity inhibited the natural reduction of CH4. Moreover, the porewater As concentration in the dilution groups was 1.8–8.2 times greater than in the untreated groups. The loss of microbial diversity promoted the reductive dissolution of iron (Fe) minerals bearing As, leading to increased concentrations of Fe(II) and dissolved organic carbon (DOC), which further enhanced As release (Fe(II), R = 0.9, p < 0.001) (DOC, R = 0.8, p < 0.001) from soil to porewater. However, CH4-dependent As(V) reduction was almost entirely inhibited under diversity loss. The decline in microbial diversity increased the relative abundances of methanogens (e.g., Methanobacterium and Methanomassiliicoccus), Fe(III)/As(V)-reducing bacteria (e.g., Bacillus, Clostridium_sensu_stricto_10, and Geobacter), and the related functional genes (i.e., mcrA and Geo). These findings suggest that microbial diversity is critical for specialized soil processes, highlighting the detrimental effects of biodiversity loss on CH4 emissions and As release in As-contaminated paddies.

The Combination Between Super Absorbent Polymers (SAPs) and Biofertilizers Could be an Ecofriendly Approach for Soil Chemical Properties Improving and Sustainable Wheat (Triticum Sativum) Production in Sandy Loam Soil

Sustainable agriculture aims to provide food needs while improving soil health and protecting it from degradation and contamination from excessive chemical fertilizer use. Sandy-textured soils have low fertility and water-holding capacity. This study assessed the integrated impact of super absorbent polymers (SAPs) and biofertilizer application on the soil chemical characteristics and wheat growth parameters in sandy loam soil. Two super absorbent polymers (SAPs) included Barbary plant G3 (P1) and Aqua Gool polymer (P2), and four microbial inoculations (Trichoderma harzianum (T), Actinomycetes (Streptomyces rochei and Streptomyces atrovirens) (AC1 and AC2), and Bacillus subtilis (B)) as biofertilizers were used in our pot experiment. The SAPs were applied to soil at a level of 0.2% (w/w), while biofertilizers were applied in the form of microbial cell suspensions (50 ml per pot) in addition to treating wheat seed with these suspensions during cultivation. Wheat plants were irrigated every 8 days to field capacity level. Amending soil with super absorbent polymers and microbes either individually or in combination significantly reduced pH and EC, increased organic matter level, and the availability of macro- and micronutrients in soil. Wheat growth metrics, including shoot length, tiller number, biomass accumulation, leaf area, and grain yield, exhibited considerable enhancements relative to the plants of the control treatment. The interaction between P1 polymer and Streptomyces atrovirens (AC2) showed the highest performance in improving the almost studied parameters. The application of SAPs with microbial biofertilizers offers a promising eco-friendly method for enhancing soil health and wheat yield.

Potential of artificial soil preparation for vegetation restoration using red mud and phosphogypsum

Red mud and phosphogypsum have long been a focus and challenge in global industrial waste management, and their low-cost and large-scale utilization technology has always been an urgent need. This study is based on the strong acid-base neutralization reaction between red mud and phosphogypsum, which contain an elemental composition similar to that of natural soil, red mud itself has characteristic of clay minerals, and other auxiliary materials (i.e. rice husk powder, bentonite, fly ash, polyacrylamide flocculant and microbial suspension) were added, so as to explore the potential of synergistically prepared artificial soil for vegetation restoration. The results showed that the artificial soils exhibited physicochemical characteristics (e.g., pH, moisture content, cation exchange capacity) similar to those of natural soil, along with abundant organic matter, nitrogen, phosphorus, and potassium contents, meeting the growth requirements of plants. The artificial soils were able to support favorable growth of suitable plants (e.g., sunflower, wheat, rye grass), accumulating high levels of diverse enzymatic activities, comparable to those in natural soils (e.g., catalase, urease, phosphatase), or even surpassing natural soils (e.g., sucrase), and rich microorganism communities, such as Cyanobacteria, Proteobacteria, Actinobacteria in the bacteria domain, and Ascomycota in the fungi domain, were initially developed. It's suggested that preparing 1 ton of artificial soil entails synergistic consumption of 613.7 kg of red mud and 244.6 kg of phosphogypsum, accounting for mass proportions of 61.4 % and 24.5 %, respectively. In future, more evaluations on the leaching loss of nutrients and alkalinity and the environmental risks of heavy metals should be conducted to more references for the artificial soil application. In summary, the preparation of artificial soil is a very simple, efficient, scalable and low-cost collaborative resource utilization scheme of red mud and phosphogypsum, which has great potential for vegetation restoration in some places such as tailings field and soil-deficient depression.

Carbohydrate structural complexity modulates the formation, composition and functionality of microbial flocs and its impact on gut microbiota and growth of Pacific white shrimp

The addition of carbohydrate into the culture water to facilitate the growth of heterotrophic bacteria is a common practice in shrimp grow out culture. The present study aimed to evaluate the effect of carbohydrate structural complexity on the formation, composition and functionality of microbial flocs, and how it impacts the gut microbiome and growth of Pacific white shrimp (Litopenaeus vannamei). Pacific white shrimp juveniles (1.07 ± 0.01 g) were randomly distributed in 12 indoor fiber tanks (50 cm × 50 cm × 100 cm) and maintained for 30 days at stocking density 107 ind.m−3 (20 ind per tank). Three different carbohydrate sources were added according to the treatments, that is dextrose (Dx) representing simple carbohydrate, potato starch (St) representing starch polysaccharide, and cellulose (Cl) representing complex non-starch polysaccharide. Settleable solids level and particle size of microbial flocs in Dx treatment were consistently higher than those of St and Cl treatments (P < 0.05). Amino acids concentrations were not significantly different amongst the treatments (P > 0.05), however essential amino acid index relative to shrimp requirement was the lowest in the Dx treatment (P < 0.05). Shannon diversity index level in the microbial flocs with Cl as the carbohydrate sources was higher compared to Dx and St. T6SS2 and ExsA gene expressions in the co-culture of Vibrio parahaemolyticus and the microbial floc suspension was highly upregulated in Dx treatment. Accordingly, differences in the shrimp gut microbiome was also observed amongst the treatments. The highest growth performance was demonstrated by the shrimp cultured with cellulose as the carbohydrate source. In conclusion, carbohydrate structural complexity could significantly affect the characteristics of microbial flocs suspended in the culture water and could ultimately affect the shrimp growth performance.

Exploring polyphosphates in soil: presence, extractability, and contribution to microbial biomass phosphorus

Polyphosphates (Poly-P) are known to fulfil several important physiological functions. Many microorganisms can accumulate large amounts of Poly-P in their biomass. Regardless of these facts, systematic research on Poly-P in soil is missing, probably due to the absence of any method of direct Poly-P quantification. In this study, we attempted to unequivocally prove the presence of Poly-P in the biomass of soil microorganisms and quantify their extractability and contribution to microbial biomass phosphorus. To do so, we combined several approaches that can indicate Poly-P presence in soil microbial biomass indirectly, i.e. growth of soil inoculum on media without phosphorus, associated with measurement of changes in the microbial biomass stoichiometry, and the colour of the microbial suspension stained by the Neisser method. All soil microbial communities exhibited growth on media without phosphorus. As the growth on this media depleted Poly-P content, the biomass carbon to phosphorus and nitrogen to phosphorus ratio increased and the colour of the microbial suspension stained by the Neisser method changed predictively. The associated Poly-P addition experiment indicated that the recovery of added Poly-P from soil in form of soluble reactive phosphorus in sodium bicarbonate extract may reach up to 93% mainly due to abiotic depolymerization. Using a simple stoichiometric model applied to measured data, we calculated that the Poly-P content of microbial biomass in our soils may be up to 45 or 70% of total microbial biomass phosphorus depending on the assumptions applied regarding parameter values. We discuss the magnitude of error associated with the measurement of soil microbial phosphorus due to the high extractability of Poly-P.

ИЗУЧЕНИЕ ВЛИЯНИЯ РАЗЛИЧНЫХ ДОЗ ЛУЧЕВОГО ВОЗДЕЙСТВИЯ НА УРОВЕНЬ МИНЕРАЛИЗАЦИИ В РАЗНЫХ УЧАСТКАХ ТВЕРДЫХ ТКАНЕЙ ЗУБОВ МЕТОДОМ РАМАН-ФЛЮОРЕСЦЕНЦИИ

Subject. Changes in the mineralization of hard tissues of teeth under the influence of radiation factor. Objectives. To study the effect of radiation factor on the level of mineralization of hard dental tissues by Raman fluorescence. Methodology. The study was conducted at the Department of Orthopedic Dentistry and Orthodontics of the SUSMU. The study was conducted on clinically removed teeth. All teeth were divided into three groups depending on the amount of radiation exposure (2 Gy, 70 Gy, 110 Gy). The main research method was the study of raman fluorescence of tooth sections on the hardware and software complex "InSpectr" with diagnostic sensitivity for the integral concentration of aerobic-anaerobic microbial suspension up to 109 CFU/ml. Teeth were examined in three areas (neck, equator, cutting edge) before and after radiation exposure. Results. Raman fluorescence diagnostics of the tooth surface made it possible to visually see the difference in mineralization in digitized indicators. For example, according to the indicators before and after exposure to the radiation factor, it is clear that the mineralization indicators, regardless of the dose, had no significant differences. At the same time, there are significant differences in the level of mineralization in the area of different tooth settings (equator, cervical region, cutting edge). Conclusion. In different areas of the tooth surface, the level of mineralization of hard tissues differs. The smallest is observed in the area of the neck of the teeth (incisors, y = 145 ± 1.5, x = 963 cm-1, canines, y = 141 ± 1.1, x = 963 cm-1, premolars, y = 142 ± 1.8 , x = 963 cm-1, molars, y = 143 ± 1.3, x = 963 cm-1), middle, in the area of the cutting edge and occlusal surface (incisors, y = 374 ± 1.7, x = 963 cm-1, canines, y = 377 ± 1.3, x = 963 cm-1, premolars, y = 375 ± 1.2, x = 963 cm-1, molars, y = 375 ± 1.1, x = 963 cm-1), and maximum, in the equator region (incisors, y = 413 ± 1.1, x = 963 cm-1, canines, y = 414 ± 1.9, x = 963 cm-1, premolars, y = 415 ± 1.7, x = 963 cm-1, molars, y = 419 ± 1.6, x = 963 cm-1). The method of Raman-fluorescence diagnostics makes it possible to detect changes in mineralization due to the potential difference in the areas of hard tooth tissues in various areas (neck, equator, cutting edge) of all functional groups of teeth (incisors, canines, premolars, molars) both before and after direct radiation exposure, direct radiation exposure does not significantly change the level of mineralization of hard dental tissues, regardless of the dose applied in all functional groups (incisors, canines, premolars, molars), in all areas of the teeth (equator, cutting edge, cervical region).

A mesoscale non-dimensional lattice Boltzmann model for self-sustained structures of swimming microbial suspensions

A new mesoscale two-phase flow non-dimensional lattice Boltzmann model (NDLBM) is developed for dynamical simulations of emergence and dispersion of self-sustained vortex and energy structures in microbial suspensions. Microbial fluids are treated as two-phase fluids with interaction forces between the biofluid phase and the base fluid phase, and the bioforces are based on transient local relative velocities. Microbial concentrations, sizes, shapes, densities, viscosities, surface tensions, active indexes, self repelling coefficients, and the nonlinear drag between the two phases are included in the present model. Base fluid properties and temperatures are also included. Both macroscopic and mesoscopic governing parameters are expressed with physical means for each coefficient. Compared to previous single-phase fluid mixture absolute velocity based models, the present two-phase fluid model based on the relative velocity shows faster convergence and more stable results. Parametric studies have been performed for intensities and group sizes of active flow structures in wide ranges of physical properties and governing parameters. Vorticity and energy structure patterns and scales are illustrated to show the underlying mechanism.

The effect of low-intensity laser radiation on the sensitivity of Staphylococcus aureus to some halogen-containing azaheterocycles

The rapid rate of acquisition and spread of resistance to antibiotics by microorganisms leads to the search and investigation of new ways of combating infectious agents. Being a modern, minimally invasive method with an almost complete absence of side effects, the use of low-intensity laser radiation can be considered as one of the alternatives to traditional antibiotic therapy. At the same time, the search for new chemical compounds with pronounced antimicrobial activity is also promising. The impact of low-intensity laser of the red spectrum (λ = 660 nm) on the sensitivity of a clinical isolate of Staphylococcus aureus to newly synthesized halogen- and chalcogen-halogen-containing derivatives of the quinazoline and benzothiazole series was studied using the serial microdilutions method with the determination of minimal inhibitory and minimal bactericidal concentrations. To evaluate the antimicrobial properties of the investigated substances in dynamic, we investigated their activity two months after the synthesis with subsequent comparison to freshly synthesized compounds. The research results indicate that the most pronounced antimicrobial effect was shown by trichlorotelluromethylthiazoloquinazolinium chloride and propargylthiobenzothiazolium hexachlorotellurate. Evaluating the dynamics of the activity of the studied compounds, it was noted that the absolute majority of substances retained their properties, which indicates their stability. When evaluating the effect of irradiation of microbial inoculum with low-intensity laser radiation on the susceptibility to chemical compounds, an increase in the sensitivity of irradiated microorganisms to some investigated chemicals was noted compared to similar non-irradiated microbial suspensions. In the case of 2 out of 9 studied chemical compounds we noted a 2- to 4-fold decrease in the minimal inhibitory concentration for irradiated microbial suspensions. A decrease in the minimal bactericidal concentration after irradiation was noted for one of the substances. In the cases of butynylthiobenzothiazolium hexabromotellurate, and tribromotelluromethylthiazoloquinazolinium bromide, decrease of both minimal inhibitory and minimal bactericidal concentrations in the irradiated inoculum was observed. The above shows that low-intensity laser radiation under certain parameters increases the susceptibility of microorganisms to antimicrobial agents.

Antimicrobial efficacy of newly prepared nano-tricalcium silicate-58s bioactive glass-based endodontic sealer

ABSTRACT Objectives: Endodontic sealers with antimicrobial impact are considered relevant to prevent re-infection and ensure healing of damaged periapical tissue. Hence, this study aimed to assist the antimicrobial effect of newly developed nano-tricalcium silicate-58s bioactive glass (BG)-based endodontic sealer (C3S-BG-P), and compare its results with Nishika Canal Sealer BG and BioRoot™ root canal sealer (RCS). Materials and Methods: The antimicrobial impact of endodontic sealers was evaluated by both agar diffusion test (ADT) and direct contact test (DCT) against Enterococcus faecalis and Candida albicans. In ADT, the diameter of inhibition zones was measured after 1, 2, and 3 days of incubation using Digimizer software program. In DCT, the sealers were allowed to set for 1, 7, and 14 days and then exposed to the microbial suspension for 24 h. The colony-forming unit was counted using ImageJ software program. The data were analyzed with ANOVA and Tukey’s tests. Results: In ADT, all the tested sealers showed antimicrobial effect after 3 days, with no significant difference after 1 day, but the impact of C3S-BG-P and Nishika significantly higher than that of BioRoot after 2 and 3 days. In DCT, C3S-BG-P and Nishika had an antimicrobial effect against both isolates even after 14 days of their setting, whereas BioRoot had an effect for 7 days of its setting and lost its impact after 14 days. Conclusions: C3S-BG-P explored antimicrobial impact superior to that of BioRoot and nearly comparable to that of Nishika against E. faecalis and C. albicans, which last even after 14 days of its setting.

The study on the development of the composition of chewable lozenges with probiotic properties. 1. Substantiation of the active substance

In recent times, a new understanding of the concept of probiotics has emerged – the use of their metabolites instead of living cells of microorganisms. They can both inhibit the development of pathogenic bacteria and effectively stimulate the reproduction of indigenous microflora. It is possible that metabiotics will be more effective than traditional live probiotics. Taking into account the prospects of new-generation probiotic drugs and the rapid growth of interest of pharmaceutical market entities in such a new dosage form as lozenges, we have proposed to create chewable lozenges containing Lactobacillus exometabolites, which pharmacological action is aimed at preventing and treating an imbalance of the oral cavity microflora.Aim. To theoretically and experimentally substantiate the choice of the exometabolite complex of lactobacilli as the active substance of a medicinal product with probiotic properties in the form of chewable lozenges.Materials and methods. The exometabolite complex of the Lactobacillus plantarum UCM-2693 strain was used as the study object. Acidity, the lactic acid content, the optical density of a microbial suspension, as well as the quantitative count of lactobacilli were determined in accordance with the generally accepted methods specified in the State Pharmacopoeia of Ukraine (SPhU).Results and discussion. The bacteriotropic effect of the exometabolite complex of L. plantarum UCM-2693 was detected on lactobacilli of the probiotic drug “Lactobacterin-Biopharma” when cultured on a medium with exometabolites compared to the control sample. This technique has a stimulating effect on the acid formation, proliferation of probiotic microorganisms, changes the characteristics of their growth phases, namely reduces the lag phase, accelerates the exponential phase, which can accelerate the onset of the therapeutic effect, and is the proof of the feasibility of using this active substance in the composition of chewable lozenges with probiotic properties.Conclusions. The choice of the exometabolite complex of lactobacilli as the active substance of a new drug from the group of metabiotics in the form of chewable lozenges has been substantiated. The exometabolite complex of lactobacilli has been obtained, and its bacteriotropic effect has been studied.

Improved production strain maintenance technique for Burkholderia mallei 5584 (Master seed) used for glander diagnostic agent production

One of the aspects important for strain collection maintenance is the optimization of existing methods and development of new techniques for microbial strain preservation, that is why the improvement of previously developed methods for authentic strain preservation is an urgent task. The article provides information on the maintenance of Burkholderia mallei 5584 (Master seed) using previously developed technique, which was supplemented with new stages in accordance with modern requirements for strain collections of highly dangerous disease agents. The previous strain maintenance technique involved its storage in its native state, which facilitated accumulation of genetic mutations and, ultimately modification of bacterial cell properties. To extend the storage time of this strain and to ensure the stability of its biological properties, the freeze-drying method was used. Skimmed milk was used as a cryoprotectant. Freeze-drying was performed under selected conditions. This technique allows for the strain sub-culturing on sensitive models once every 5 years, which is more expedient and safe from an economic and biological point of view. For safe handling of Burkholderia mallei 5584 production strain, an inactivation technique using gamma rays at 30 kGy was developed, which allowed to achieve microbial suspension sterility and preserve the bacterial cell structure. When comparing the previously developed and supplemented techniques, it was found that the improved technique of Burkholderia mallei 5584 (Master seed) maintenance makes it possible to avoid the loss of its biological properties needed for the production of high-quality laboratory diagnostic agents used for timely disease detection in susceptible animals by diagnostic tests.

In vitro photoinactivation effectiveness of a portable LED device aimed for intranasal photodisinfection and a photosensitizer formulation comprising methylene blue and potassium iodide against bacterial, fungal, and viral respiratory pathogens.

Antimicrobial photodynamic therapy (aPDT) can be a viable option for management of intranasal infections. However, there are light delivery, fluence, and photosensitizer-related challenges. We report in vitro effectiveness of an easily fabricated, low-cost, portable, LED device and a formulation comprising methylene blue (MB) and potassium iodide (KI) for photoinactivation of pathogens of the nasal cavity, namely, methicillin-resistant Staphylococcus aureus, antibiotic-resistant Klebsiella pneumoniae, multi-antibiotic-resistant Pseudomonas aeruginosa, Candida spp., and SARS-CoV-2.In a 96-well plate, microbial suspensions incubated with 0.005% MB alone or MB and KI formulation were exposed to different red light (~ 660 ± 25nm) fluence using the LED device fitted to each well. Survival loss in bacteria and fungi was quantified using colony-forming unit assay, and SARS-CoV-2 photodamage was assessed by RT-PCR.The results suggest that KI addition to MB leads to KI concentration-dependent potentiation (up to ~ 5 log10) of photoinactivation in bacteria and fungi. aPDT in the presence of 25 or 50mM KI shows the following photoinactivation trend; Gm + ve bacteria > Gm - ve bacteria > fungi > virus. aPDT in the presence of 100mM KI, using 3- or 5-min red light exposure, results in complete eradication of bacteria or fungi, respectively. For SARS-CoV-2, aPDT using MB-KI leads to a ~ 6.5 increase in cycle threshold value.The results demonstrate the photoinactivation effectiveness of the device and MB-KI formulation, which may be helpful in designing of an optimized protocol for future intranasal photoinactivation studies in clinical settings.

Microbiological studies of juniper extract to determine sensitivity to strains of microorganisms

Juniper is a widely used resource in the food, cosmetic, and medical industries. However, its application in veterinary medicine represents a less researched area. Literature studies confirm the presence of terpenoid compounds, tannins, ketones, sugars, organic acids, and flavonoids in juniper. Determination of the chemical composition of juniper essential oil revealed the prevalence of terpenes such as α-pinene, β-pinene, ocimene, and α-limonene, with variations depending on the species and habitat of the plant. Analysis of the literature data highlights the significant importance of α-pinene, serving as the primary and most studied terpene in juniper essential oil with notable diuretic properties. Furthermore, juniper essential oil possesses antibacterial, antifungal, anti-inflammatory, and deodorizing properties. The aim of the study was to reassess the antimicrobial and antifungal properties of the extract obtained from common juniper fruits through extraction. The research used extracts of essential oils obtained from common juniper fruits and tested them for antibiotic activity against microorganisms of various taxonomic groups. The experiment was conducted in accordance with sanitary and epidemiological requirements and federal clinical recommendations. The research methodology included serial dilutions, preparation of microbial suspensions, inoculation of nutrient media, incubation, and result assessment.

Microfluidic-based spatiotemporal control of oxygen concentration in bacteria suspension culture from bulk to the single cells

Oxygen plays a crucial role in microbial growth and metabolism. However, the detailed bacterial responses and regulatory mechanisms toward the change of oxygen are still not completely understood partly due to the lack of real-time measurement and control of dissolved oxygen (DO). Here, we present a novel platform for spatiotemporal and real-time controls of oxygen concentrations by a simple microfluidic design in bacteria suspension culture on chip. The DO concentrations are precisely controlled or flexibly tuned in bioreactor arrays in nanoliter scale. Multiple bioreactor groups with diverse DO control strategies are integrated on a single chip. With our platform, adequate oxygen existed in the microfluidic culture channels and may be the critical factor for the fast growth during bacteria suspension culture. Notably, we extend our platform to mimic the DO oscillation environment and monitor the growth of bulk and single bacterium for many generations. This microfluidic platform exhibits the unique capability of spatiotemporal gas control and detection for microbial suspension culture in nanoliter scale, which can be applied for screening, studying, and culturing the industrial or niche-specific environmental microbiome, at bulk, single cell, or consortia level, responding to oxygen or other gas environment, such as carbon dioxide, ammonia, etc.

In Vitro Comparative Evaluation of the Efficacy of Antimicrobial Photodynamic Therapy, Chlorhexidine, Sodium Fluoride, and Hydrogen Peroxide for Acrylic Resin Disinfection.

Introduction: Plaque accumulation on the surface of removable orthodontic appliances could lead to dental caries, periodontitis, and fungal infections. This study evaluated the effectiveness of antimicrobial photodynamic therapy (aPDT), chlorhexidine (CHX), sodium fluoride (NaF), and hydrogen peroxide (H2O2) for the disinfection of acrylic resin. Methods: In this in vitro experimental study, 100 acrylic resin specimens were randomly divided into five groups (n=20 each): Enterococcus faecalis, Streptococcus mutans, Streptococcus salivarius, Streptococcus sanguinis, and Lactobacillus acidophilus. Each group was immersed separately in 5 mL of microbial suspension. They were then incubated until biofilm formation on their surface. Of each microorganism, one biofilm sample in phosphate-buffered saline was considered as negative control, and other biofilm samples (n=80) were subjected to aPDT with curcumin, 0.12% CHX (positive control), 1% H2O2, and 0.2% NaF. Finally, the number of colonies was counted. Data were analyzed by the Kruskal-Wallis and Mann-Whitney tests, two-way ANOVA, and Bonferroni adjustment at a significance level of 0.05. Results: The interaction effect of the treatment modality and type of microorganism was significant on the microbial count (effect size: 0.91, P<0.05). Maximum bacterial proliferation was noted in the following combinations: NaF/E. faecalis, H2O2/E. faecalis, and H2O2/S. salivarius. Microorganisms had no or insignificant growth and proliferation in the aPDT and CHX groups. Conclusion: The results supported the optimal antimicrobial efficacy of PDT which was comparable to that of CHX. aPDT showed superior antimicrobial efficacy to NaF and H2O2 for the disinfection of acrylic resin.