In Silico Safety Assessment of Bacillus Isolated from Polish Bee Pollen and Bee Bread as Novel Probiotic Candidates.

Bacillus species isolated from Polish bee pollen (BP) and bee bread (BB) were characterized for in silico probiotic and safety attributes. A probiogenomics approach was used, and in-depth genomic analysis was performed using a wide array of bioinformatics tools to investigate the presence of virulence and antibiotic resistance properties, mobile genetic elements, and secondary metabolites. Functional annotation and Carbohydrate-Active enZYmes (CAZYme) profiling revealed the presence of genes and a repertoire of probiotics properties promoting enzymes. The isolates BB10.1, BP20.15 (isolated from bee bread), and PY2.3 (isolated from bee pollen) genome mining revealed the presence of several genes encoding acid, heat, cold, and other stress tolerance mechanisms, adhesion proteins required to survive and colonize harsh gastrointestinal environments, enzymes involved in the metabolism of dietary molecules, antioxidant activity, and genes associated with the synthesis of vitamins. In addition, genes responsible for the production of biogenic amines (BAs) and D-/L-lactate, hemolytic activity, and other toxic compounds were also analyzed. Pan-genome analyses were performed with 180 Bacillus subtilis and 204 Bacillus velezensis genomes to mine for any novel genes present in the genomes of our isolates. Moreover, all three isolates also consisted of gene clusters encoding secondary metabolites.

Oxolane Ammonium Salts (Muscarine-Like)-Synthesis and Microbiological Activity.

Commercially available 2-deoxy-D-ribose was used to synthesize the appropriate oxolane derivative-(2R,3S)-2-(hydroxymethyl)oxolan-3-ol-by reduction and dehydration/cyclization in an acidic aqueous solution. Its monotosyl derivative, as a result of the quaternization reaction, allowed us to obtain eight new muscarine-type derivatives containing a quaternary nitrogen atom and a hydroxyl group linked to the oxolane ring. Their structure was fully confirmed by the results of NMR, MS and IR analyses. The crystal structure of the pyridinium derivative showed a high similarity of the conformation of the oxolane ring to previously published crystal structures of muscarine. Two reference strains of Gram-negative bacteria (Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853), two reference strains of Gram-positive staphylococci (Staphylococcus aureus ATCC 25923 and Staphylococcus aureus ATCC 29213) and four reference strains of pathogenic yeasts of the genus Candida spp. (Candida albicans SC5314, Candida glabrata DSM 11226, Candida krusei DSM 6128 and Candida parapsilosis DSM 5784) were selected for the evaluation of the antimicrobial potential of the synthesized compounds. The derivative containing the longest (decyl) chain attached to the quaternary nitrogen atom turned out to be the most active.

Whole-genome sequencing and antimicrobial potential of bacteria isolated from Polish honey.

The aim of this study was the whole-genome analysis and assessment of the antimicrobial potential of bacterial isolates from honey harvested in one geographical location-the north of Poland. In total, 132 strains were derived from three honey samples, and the antimicrobial activity of CFAM (cell-free after-culture medium) was used as a criterion for strain selection and detailed genomic investigation. Two of the tested isolates (SZA14 and SZA16) were classified as Bacillus paralicheniformis, and one isolate (SZB3) as Bacillus subtilis based on their ANI and phylogenetic analysis relatedness. The isolates SZA14 and SZA16 were harvested from the same honey sample with a nucleotide identity of 98.96%. All three isolates have been found to be potential producers of different antimicrobial compounds. The secondary metabolite genome mining pipeline (antiSMASH) identified 14 gene cluster coding for non-ribosomal peptide synthetases (NRPs), polyketide synthases (PKSs), and ribosomally synthesized and post-translationally modified peptides (RiPPs) that are potential sources of novel antibacterials. The BAGEL4 analysis revealed the presence of nine putative gene clusters of interest in the isolates SZA14 and SZA16 (including the presence of six similar clusters present in both isolates, coding for the production of enterocin Nkr-5-3B, haloduracin-alpha, sonorensin, bottromycin, comX2, and lasso peptide), and four in B. subtilis isolate SZB3 (competence factor, sporulation-killing factor, subtilosin A, and sactipeptides). The outcomes of this study confirm that honey-derived Bacillus spp. strains can be considered potential producers of a broad spectrum of antimicrobial agents. KEY POINTS: • Bacteria of the genus Bacillus are an important component of honey microbiota. • Honey-derived Bacillus spp. strains are potential producers of new antimicrobials.

Hydrazinolysis Products of Selected Sugar Lactones-Crystal Structure and Microbiological Activity.

Commercially available lactones, as well as those synthesized by us, turned out to be good substrates for the synthesis of sugar hydrazides. The exception was L-ascorbic acid, whose hydrazinolysis led to the formation of a hydrazinium salt, not the hydrazide as expected. The structure of all compounds was confirmed by NMR and X-ray analyses. The lower durability of hydrazinium L-ascorbate was additionally confirmed by thermogravimetric tests. All products were tested for biological activity against Gram-negative bacteria strains Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853 and against Gram-positive Staphylococcus aureus ATCC 25923 and Staphylococcus aureus ATCC 29213. Their antifungal activity against Candida albicans SC5314, Candida glabrata DSM 11226 SM 11226, Candida krusei DSM 6128, and Candida parapsilosis DSM 5784 was also tested. The most interesting results of microbiological activity were obtained for D-gluconic acid hydrazide and hydrazinium L-ascorbate. The results of the latter encourage more extensive testing.

Antimicrobial, Cytotoxic and Mutagenic Activity of Gemini QAS Derivatives of 1,4:3,6-Dianhydro-l-iditol.

A series of quaternary diammonium salts derivatives of 1,4:3,6-dianhydro-l-iditol were synthesized, using isommanide (1,4:3,6-dianhydro-d-mannitol) as a starting material. Both aromatic (pyridine, 4-(N,N-dimethylamino)pyridine (DMAP), (3-carboxamide)pyridine; N-methylimidazole) and aliphatic (trimethylamine, N,N-dimethylhexylamine, N,N-dimethyloctylamine, N,N-dimethyldecylamine) amines were used, giving eight gemini quaternary ammonium salts (QAS). All salts were tested for their antimicrobial activity against yeasts, Candida albicans and Candida glabrata, as well as bacterial Staphylococcus aureus and Escherichia coli reference strains. Moreover, antibacterial activity against 20 isolates of S. aureus collected from patients with skin and soft tissue infections (n = 8) and strains derived from subclinical bovine mastitis milk samples (n = 12) were evaluated. Two QAS with octyl and decyl residues exhibited antimicrobial activity, whereas those with two decyl residues proved to be the most active against the tested pathogens, with MIC of 16-32, 32, and 8 µg/mL for yeast, E. coli, and S. aureus reference and clinical strains, respectively. Only QAS with decyl residues proved to be cytotoxic in MTT assay against human keratinocytes (HaCaT), IC50 12.8 ± 1.2 µg/mL. Ames test was used to assess the mutagenic potential of QAS, and none of them showed mutagenic activity in the concentration range 4-2000 µg/plate.

Quest for the Molecular Basis of Improved Selective Toxicity of All-Trans Isomers of Aromatic Heptaene Macrolide Antifungal Antibiotics.

Three aromatic heptaene macrolide antifungal antibiotics, Candicidin D, Partricin A (Gedamycin) and Partricin B (Vacidin) were subjected to controlled cis-trans→ all trans photochemical isomerization. The obtained all-trans isomers demonstrated substantially improved in vitro selective toxicity in the Candida albicans cells: human erythrocytes model. This effect was mainly due to the diminished hemotoxicity. The molecular modeling studies on interactions between original antibiotics and their photoisomers with ergosterol and cholesterol revealed some difference in free energy profiles of formation of binary antibiotic/sterol complexes in respective membrane environments. Moreover, different geometries of heptaene: sterol complexes and variations in polyene macrolide molecule alignment in cholesterol-and ergosterol-containing membranes were found. None of these effects are of the crucial importance for the observed improvement of selective toxicity of aromatic heptaene antifungals but each seems to provide a partial contribution.

Gas-phase removal of indoor volatile organic compounds and airborne microorganisms over mono- and bimetal-modified (Pt, Cu, Ag) titanium(IV) oxide nanocomposites.

The photocatalytic deactivation of volatile organic compounds and mold fungi using TiO2 modified with mono- and bimetallic (Pt, Cu, Ag) particles is reported in this study. The mono- and bimetal-modified (Pt, Cu, Ag) titanium(IV) oxide photocatalysts were prepared by chemical reduction method and characterized using XRD, XPS, DR/UV-Vis, BET, and TEM analysis. The effect of incident light, type and content of mono- and bimetallic nanoparticles deposited on titanium(IV) oxide was studied. Photocatalytic activity of as-prepared nanocomposites was examined in the gas phase using LEDs array. High photocatalytic activity of Ag/Pt-TiO2 and Cu/Pt-TiO2 in the reaction of toluene degradation resulted from improved efficiency of interfacial charge transfer process, which was consistent with the fluorescence quenching effect revealed by photoluminescence (PL) emission spectra. The photocatalytic deactivation of Penicillium chrysogenum, a pathogenic fungi present in the indoor environment, especially in a damp or water-damaged building using mono- and bimetal-modified (Pt, Cu, Ag) titanium(IV) oxide was evaluated for the first time. TiO2 modified with mono- and bimetallic NPs of Ag/Pt, Cu, and Ag deposited on TiO2 exhibited improved fungicidal activity under LEDs illumination than pure TiO2 .

Voriconazole-Based Salts Are Active against Multidrug-Resistant Human Pathogenic Yeasts.

Voriconazole (VOR) hydrochloride is unequivocally converted into VOR lactates and valinates upon reaction with silver salts of organic acids. This study found that the anticandidal in vitro activity of these compounds was comparable or slightly better than that of VOR. The Candida albicans clinical isolate overexpressing CaCDR1/CaCDR2 genes, highly resistant to VOR, was apparently more susceptible to VOR salts. On the other hand, the susceptibility of another C. albicans clinical isolate (demonstrating multidrug resistance due to the overexpression of CaMDR1) to VOR salts was comparable to that to VOR. Comparative studies on the influence of VOR and its salts on Rhodamine 6G efflux from susceptible and multidrug-resistant C. albicans cells revealed that VOR salts are poorer substrates for the CaCdr1p drug efflux pump than VOR.

The Anti-Staphylococcal Potential of Ethanolic Polish Propolis Extracts.

The principal objective of this study was to determine the anti-staphylococcal potential of ethanol extracts of propolis (EEPs). A total of 20 samples of propolis collected from apiaries located in different regions of Poland were used in the study. The two-fold broth microdilution method revealed some important differences in the antimicrobial activity of investigated EEPs. Up to the concentration of 4096 µg/mL no activity was observed against Gram-negative bacteria (E. coli and P. aeruginosa). Staphylococci exhibited much higher susceptibility. The highest efficiency observed for EEP12 and EEP20 (MIC values ranged between 32 and 256 µg/mL). However, the achievement of bactericidal effect usually required higher concentrations. In the case of clinical isolates of S. aureus MBC values for EEP12 and EEP20 ranged from 512 to 1024 µg/mL. The HPLC analysis revealed that these two products contained a higher concentration of flavonoids (flavonols, flavones, and flavanones) compared to other investigated EEPs. In checkerboard test, a synergistic anti-staphylococcal effect was observed for the action of EEP20 in combination with amikacin, kanamycin, gentamycin, tetracycline, and fusidic acid (all these antibiotics inhibit protein synthesis). Moreover, the investigated EEPs effectively eradicated staphylococcal biofilm. The obtained results clearly confirm the high anti-staphylococcal potential of propolis harvested in Polish apiaries.

Anthra[1,2-d][1,2,3]triazine-4,7,12(3H)-triones as a New Class of Antistaphylococcal Agents: Synthesis and Biological Evaluation.

The development and spread of resistance of human pathogenic bacteria to the action of commonly used antibacterial drugs is one of the key problems in modern medicine. One of the especially dangerous and easily developing antibiotic resistant bacterial species is Staphylococcus aureus. Anthra[1,2-d][1,2,3]triazine-4,7,12(3H)-triones 22-38 have been developed as novel effective antistaphylococcal agents. These compounds have been obtained by sequential conversion of 1-amino-9,10-dioxo-9,10-dihydroanthracene-2-carboxylic acid (1) and 1-amino-4-bromo-9,10-dioxo-9,10-dihydroanthracene-2-carboxylic acid (2) into the corresponding amides 5-21, followed by subsequent endo-cyclization under the influence of sodium nitrite in acetic acid. Evaluation of the antimicrobial activity of the synthesized compounds against selected species of Gram-positive and Gram-negative bacteria as well as pathogenic yeasts of the Candida genus has been carried out by the serial dilution method. It has been established that anthra[1,2-d][1,2,3]triazine-4,7,12(3H)-triones exhibit selective antibacterial activity against Gram-positive bacteria. Eight, six and seven, out of seventeen compounds tested, effectively inhibited the growth of S. aureus ATCC 25923, S. aureus ATCC 29213 and S. epidermidis ATCC12228, respectively, at a concentration equal to 1 µg/mL or lower. The high antistaphylococcal potential of the most active compounds has been also confirmed against clinical isolates of S. aureus, including the MRSA strains. However, bacteria of the Staphylococcus genus have demonstrated apparent resistance to the novel compounds when grown as a biofilm. None of the four selected compounds 3234 and 36 at a concentration of 64 µg/mL (128 or 256 × MIC-against planktonic cells) has caused any decrease in the metabolic activity of the staphylococcal cells forming the biofilm. The kinetic time-kill assay revealed some important differences in the activity of these substances. Compound 33 is bacteriostatic, while the other three demonstrate bactericidal activity.

Comparison of antimicrobial activity of selected, commercially available wound dressing materials.

OBJECTIVE: The aim of our study was to examine the antimicrobial potential of eight selected, commercially available wound dressings containing different antimicrobial agents: silver, chlorhexidine acetate, povidone-iodine, and manuka honey. METHOD: The materials were tested against four reference strains of bacteria: Staphylococcus aureus (PCM 2051), Staphylococcus epidermidis (PCM 2118), Pseudomonas aeruginosa (ATCC 27853), and Escherichia coli (K12), using the disc diffusion-like method and a time-killing assay. RESULTS: For both experiments, the highest activity against all four tested strains of bacteria was observed in the case of Mepilex Ag, which contains silver as an antibacterial agent. Incubation for four hours of a 10x10mm2 piece of this material in 10ml cells suspension (concentration: 109-1010CFU/ml) resulted in complete elimination of bacteria of all four strains tested. The same results were obtained for a povidone-iodine containing dressing, Inadine, though its activity was lower in the disc diffusion assay. Silvercel, Aquacel Ag and Melgisorb Ag, which also contain silver, also exhibited a satisfactory level of activity. In the case of Aquacel Ag, 24 hours' incubation resulted in complete elimination of the cells of both Gram-negative bacteria, Escherichia coli and Pseudomonas aeruginosa.The Escherichia coli cells were killed after only four hours' treatment. High effectiveness against Escherichia coli was also demonstrated for Silvercel. However, 24 hours' includation was required for complete elimination of the cells of this bacteria strain. High activity against all tested bacteria, but only in the disc diffusion assay, was observed for Algivon, which contains manuka honey. The Medisorb Silver Pad, containing silver, and Bactigras, which contains chlorhexidine acetate, revealed much lower antimicrobial activity, particularly noticeable in the time-killing assay. In addition, we also tested the anti-staphylococcal activity of a biopolymer material impregnated with lysostaphin. Results revealed that its activity against Staphylococcus aureus was comparable to the most active wound dressings impregnated with silver or inadine. CONCLUSION: Some important differences in the antimicrobial potential of investigated materials have been found. The presented results could be of interest to clinicians managing wounds.

Investigation of the Antifungal Activity and Mode of Action of Thymus vulgaris, Citrus limonum, Pelargonium graveolens, Cinnamomum cassia, Ocimum basilicum, and Eugenia caryophyllus Essential Oils.

The antimicrobial activity of plant oils and extracts has been recognized for many years. In this study the activity of Thymus vulgaris, Citrus limonum, Pelargonium graveolens, Cinnamomum cassia, Ocimumbasilicum, and Eugenia caryophyllus essential oils (EOs) distributed by Pollena Aroma (Nowy Dwór Mazowiecki, Poland) was investigated against a group of 183 clinical isolates of C. albicans and 76 isolates of C. glabrata. All of the oils exhibited both fungistatic and fungicidal activity toward C. albicans and C. glabrata isolates. The highest activity was observed for cinnamon oil, with MIC (Minimum Inhibitory Concentration) values in the range 0.002⁻0.125% (v/v). The MIC values of the rest of the oils were in the range 0.005% (or less) to 2.5% (v/v). In most cases MFC (Minimum Fungicidal Concentration) values were equal to MIC or twice as high. Additionally, we examined the mode of action of selected EOs. The effect on cell wall components could not be clearly proved. Three of the tested EOs (thyme, lemon, and clove) affected cell membranes. At the same time, thyme, cinnamon, and clove oil influenced potassium ion efflux, which was not seen in the case of lemon oil. All of the tested oils demonstrated the ability to inhibit the transition of yeast to mycelium form, but the effect was the lowest in the case of cinnamon oil.

Study of the Anti-Staphylococcal Potential of Honeys Produced in Northern Poland.

The antimicrobial activity of 144 samples of honeys including 95 products from apiaries located in Northern Poland was evaluated. The antibacterial activity of those natural products, their thermal stability, and activity in the presence of catalase was investigated by microdilution assays in titration plates. The MTT assay was performed for the determination of anti-biofilm activity. Spectrophotometric assays were used for the determination of antioxidant potential, total phenolic content, and ability to generate hydrogen peroxide. Some of the investigated honeys exhibited surprisingly high antimicrobial, especially anti-staphylococcal, potential, with Minimal Inhibitory Concentration (MIC) values of only 1.56% (v/v). Much higher resistance was observed in the case of staphylococci growing as biofilms. Lower concentrations of the product, up to 12.5% (v/v) stimulated its growth and effective eradication of biofilm required concentration of at least 25% (v/v). Hydrogen peroxide has been identified as a crucial contributor to the antimicrobial activity of honeys supplied by Polish beekeepers. However, some of the results suggest that phytochemicals, especially polyphenols, play an important role depending on botanical source (both positive, e.g., in the case of buckwheat honeys as well as negative, e.g., in the case of some rapeseed honeys) in their antimicrobial potential.

Isolation of Bacteriocin-producing Staphylococcus spp. Strains from Human Skin Wounds, Soft Tissue Infections and Bovine Mastitis.

A collection of 206 Staphylococcus spp. isolates was investigated for their ability to produce compounds exhibiting antistaphylococcal activity. This group included Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus xylosus strains recovered from bovine mastitis (n = 158) and human skin wounds and soft tissues infections (n = 48). Production of substances with antimicrobial activity was observed in six strains. Five of them were recovered from bovine mastitis, and one was isolated from the infected human skin wound. Three of the six antimicrobials produced by the different strains showed substantial loss of antimicrobial activity upon treatment with proteolytic enzymes, which suggests their peptidic structure. Additional studies have shown that one of the putative bacteriocins was efficiently secreted to the liquid medium, facilitating its large-scale production and isolation. The peptide produced by the M2B strain exhibited promising activity; however, against narrow spectrum of Staphylococcus spp. clinical and animal isolates. Growth inhibition was observed only in the case of 13 (including nine S. aureus, three S. xylosus and one S. epidermidis strains) out of 206 strains tested. Important advantage of the produced agent was its high thermal stability. Fifteen minutes of incubation at 90°C did not affect its antimicrobial potential. The highest efficiency of production of the agent was demonstrated in TSB medium after 24 hours at 37°C. The researches revealed that ability to production of bacteriocin among staphylococci is not very common. Only one (S. xylosus strain assigned as M2B) out of 206 strains tested produced satisfactory amounts of antistaphylococcal bacteriocin. In spite of that, we would encourage other researchers for investigation of their collections of Staphylococcus spp. isolates towards selection strains producing antimicrobial agents.

Virulence gene profiles in Staphylococcus aureus isolated from cows with subclinical mastitis in eastern Poland.

Staphylococcus aureus is arguably the most important pathogen involved in bovine mastitis. The aim of this study was to determine the virulence gene profiles of 124 Staph. aureus isolates from subclinical mastitis in cows in eastern Poland. The presence of 30 virulence genes encoding adhesins, proteases and superantigenic toxins was investigated by PCR. The 17 different combinations of adhesin genes were identified. Occurrence of eno (91·1%) and fib (82·3%) genes was found to be common. The frequency of other adhesion genes fnbA, fnbB, ebps were 14·5, 50, 25%, respectively, and for cna and bbp were 1·6%. The etA and etD genes, encoding exfoliative toxins, were present in genomes of 5·6 and 8·9% isolates, respectively. The splA and sspA, encoding serine protease, were detected in above 90% isolates. The most frequent enterotoxin genes were sei (21%), sem (19·4%), sen (19·4%), seg (18·5%) and seo (13·7%). The tst gene was harboured by 2·4% isolates. The 19 combinations of the superantigenic toxin genes were obtained and found in 35·5% of isolates. Three of them (seg, sei, sem, sen, seo; sec, seg, sei, sem, sen, seo and seg, sei, sem, sen) were the most frequent and found in 16·1% of the isolates. The most common virulotype, present in 17·7% of the isolates, was fib, eno, fnbB, splA, splE, sspA. The results indicate the variation in the presence of virulence genes in Staph. aureus isolates and considerable diversity of isolates that are able to cause mastitis in cows.

Essential Oils, Silver Nanoparticles and Propolis as Alternative Agents Against Fluconazole Resistant Candida albicans, Candida glabrata and Candida krusei Clinical Isolates.

Development of effective and safe therapeutic treatment of fungal infections remains one of the major challenge for modern medicine. The aim of presented investigation was to analyze the in vitro antifungal activity of selected essential oils, ethanolic extracts of propolis and silver nanoparticles dropped on TiO2 against azole-resistant C. albicans (n = 20), C. glabrata (n = 14) and C. krusei (n = 10) clinical isolates. Among tested essential oils, the highest activity has definitely been found in the case of the oil isolated from the bark of Cinnamomum cassia, with MIC and MFC values for all tested strains in the range of 0.0006-0.0097 % (v/v) and 0.0012-0.019 % (v/v), respectively. High activity was also observed for the Lemon, Basil, Thyme, Geranium and Clove (from buds) essential oils. Significant differences in fungicidal activity have been observed in the case of four tested propolis samples. Only one of them revealed high activity, with MFC values in the range from 0.156 to 1.25 % (v/v). Satisfactory fungicidal activity, against C. albicans and C. glabrata isolates, was also observed in the case of silver nanoparticles, however C. krusei isolates were mostly resistant. We also revealed that constituents of most of essential oils and propolis as well as silver nanoparticles are not substrates for drug transporters, which belong to the most important factors affecting resistance of Candida spp. clinical isolates to many of conventional antimycotics. To conclude, the results of our investigation revealed that essential oils, propolis and silver nanoparticles represent high potential for controlling and prevention candidiasis.

Efficient production of Staphylococcus simulans lysostaphin in a benchtop bioreactor by recombinant Escherichia coli.

Lysostaphin is an enzyme with bactericidal activity against Staphylococcus aureus and other staphylococcal species. In spite of many advantages and promising results of preliminary research, the enzyme is still not widely used in medicine, veterinary medicine, or as a food preservative. One of the most important factors limiting application of the enzyme in clinical or technological practice is the high cost of its production. In this study we have determined the optimal conditions for lysostaphin production in a 5-L batch bioreactor. The enzyme production was based on a heterologous, Escherichia coli expression system designated as pBAD2Lys and constructed earlier in our laboratory. An evident influence of physicochemical conditions of the process (areation, pH and temperature) and composition of the growing media on the amount and activity of produced enzyme was noticed. Efficiency of production of about 13,000 U/L has been achieved in the optimal conditions of the production process: low aeration (400 rpm of mechanical stirrer), pH 6, and temperature 37°C in classical LB medium. Further, about twofold improvement in the production efficiency of the enzyme was achieved as a result of modification of composition of growing media. Finally, more than 80,000 units of lysostaphin were obtained from one (batch) bioreactor with 3 L of culture of E. coli TOP10F' transformed with pBAD2Lys plasmid. To the best of our knowledge, this is the most efficient method of production of recombinant lysostaphin in E. coli expression systems described to date.

Investigation of antifungal and antibacterial potential of green extracts of propolis.

Propolis extracts have been used in traditional medicines since ages due to its advantageous complex chemical composition. However, the antibacterial and antifungal activity of poplar propolis extracts prepared in Natural Deep Eutectic Solvent (NADES) are seldom studied. This study investigates suitable alternate for ethanol as a solvent for extraction for Polish poplar propolis. It also attempts to identify suitable extraction condition for the efficient transfer of compounds from propolis to the solvents. The extraction efficiency of NADES extracts was assessed in terms of total phenolic content, antioxidant activity and antimicrobial activity. The chemical composition of the extracts was analysed using UHPLC-DAD-QqTOF-MS. Four extracts, prepared in Propylene Glycol, Choline Chloride:Propylene Glycol (1:3), Choline Chloride:Propylene Glycol (1:4) and Choline Chloride:Glycerol (1:2), demonstrated activity and properties similar to ethanolic extract and extraction at 50 °C was found the most suitable for propolis. HPLC analysis confirmed that the chemical cocktail extracted by these solvents from propolis were identical with minor variations in their concentration as compared to its ethanolic extract. Thus, extracts of propolis at 50 °C in Propylene Glycol, Choline Chloride:Propylene Glycol (1:3) and Choline Chloride:Propylene Glycol (1:4) can be alternates for ethanolic extracts.

Probiotic potential of Bacillus Isolates from Polish Bee Pollen and Bee Bread.

The main goal of this study was the evaluation of the probiotic potential of 10 Bacillus spp. strains isolated from 5 bee bread and 3 bee pollen samples. The antagonistic interaction with Staphylococcus aureus and Escherichia coli was a primary criterion for the preliminary selection of the isolates. Three out of ten strains-PY2.3 (isolated from pollen), BP20.15 and BB10.1 (both isolated from bee bread)-were found to be possible probiotic strains. All these strains are safe for humans (exhibiting [Formula: see text]-hemolytic activity) and meet all essential requirements for probiotics in terms of viability in the presence of bile salts and acid conditions, hydrophobicity, auto-aggregation, and co-aggregation with the cells of important human pathogenic bacteria. They also assimilate more than 30% of cholesterol after 24 h of incubation. These three isolates are resistant to penicillin but sensitive (or exhibit moderate resistance) to the other nine antibiotics tested herein. On the basis of whole-genome sequencing, BP20.15 and BB10.1 were classified as B. subtilis and PY2.3 as B. velezensis. Moreover, genomic analyses revealed that all these isolates are potential producers of different antimicrobial compounds, including bacteriocins and secondary metabolites. The outcomes of this study have proven that some of the Bacillus strains isolated from bee pollen or bee bread are potential probiotics.

Fatty acids as molecular carriers in cleavable antifungal conjugates.

Conjugates composed of C2-18 fatty acid (FA) residues as a molecular carrier and 5-fluorocytosine (5-FC) as an active agent, released upon the action of intracellular esterases on the ester bond between FA and "trimethyl lock" intramolecular linker, demonstrate good in vitro activity against human pathogenic yeasts of Candida spp. The minimal inhibitory concentrations (MIC) values for the most active conjugates containing caprylic (C8), capric (C10), lauric (C12), or myristic (C14) acid residues were in the 2-64 µg mL-1 range, except for these against the least susceptible Candida krusei. The least active conjugates containing C2, C16, or C18 FA were slowly hydrolyzed by esterase and probably poorly taken up by Candida cells, as found for their analogs containing a fluorescent label, Nap-NH2 instead of 5-FC.