Search

In this study, we have evaluated the effects of previously characterized bacteriocins produced by E. faecium strains ST651ea, ST7119ea, and ST7319ea, against biofilm formation and biofilms formed by L. monocytogenes ATCC15313 and vancomycin-resistant E. faecium VRE19. The effects of bacteriocins on the biofilms formed by L. monocytogenes ATCC151313 were evaluated by crystal violet assay and further confirmed by quantifying viable cells and cell metabolic activities through flow cytometry and TTC assay, respectively, indicating that bacteriocin activities required to completely eradicate biofilms are at least 1600 AU mL−1, 3200 AU mL−1, and 6400 AU mL−1, respectively for each bacteriocin evaluated. Furthermore, bacteriocins ST651ea and ST7119ea require at least 6400 AU mL−1 to completely eradicate the viability of cells within the biofilms formed by E. faecium VRE19, while bacteriocin ST7319ea requires at least 12800 AU mL−1 to obtain the same observations. Assessment of synergistic activities between selected conventional antibiotics (ciprofloxacin and vancomycin) with these bacteriocins was carried out to evaluate their effects on biofilm formation and pre-formed biofilms of both test microorganisms. Results showed that higher concentrations are needed to completely eradicate metabolic activities of cells within pre-formed biofilms in contrast with the biofilm formation abilities of the strains. Furthermore, synergistic activities of bacteriocins with both ciprofloxacin and vancomycin are more evident against vancomycin-resistant E. faecium VRE19 rather than L. monocytogenes ATCC15313. These observations can be further explored for possible applications of these combinations of antibiotics as a possible treatment of clinically relevant pathogens.

There is almost a century since discovery of penicillin by Alexander Fleming, a century of enthusiasm, abuse, facing development of antibiotic-resistance and clear conclusion that the modern medicine needs a new type of antimicrobials. Bacteriocins produced by Gram-positive and Gram-negative bacteria, Archaea and Eukaryotes were widely explored as potential antimicrobials with several applications in food industry. In last two decades bacteriocins showed their potential as promising alternative therapeutic for the treatment of antibiotic-resistant pathogens. Bacteriocins can be characterised as highly selective antimicrobials and therapeutics with low cytotoxicity. Most probably in order to solve the problems associated with the increasing number of antibiotic-resistant bacteria, the application of natural or bioengineered bacteriocins in addition to synergistically acting preparations of bacteriocins and conventional antibiotics, can be the next step in combat

Ten novel Schiff-base functionalized nickel nano-systems were synthesized to investigate the capping ability of the ligands as well as the stability of the resulting nanoparticles. All four ligands employed were found to be capable and comparable stabilizers to produce monodispersed nanoparticles. These nanoparticles were further evaluated as catalysts in the polymerization of norbornene, using MAO or MMAO as a co-catalyst. All ten nanomaterials were active polymerization catalysts, resulting in the first ever reported nanoparticle-assisted polymerization processes. It was shown that the nano-catalyst can facilitate either oligomerization or polymerization depending on the co-catalyst employed. Other than vinyl polynorbornene, hydroxy functionalized oligomer stabilized nanocomposite products were also obtained. The oligomers could be cleaved from the nanoparticle surface, depending on its intended application. The vinyl polymers obtained gave high molecular weights and low polydispersity indices, whereas the hydroxy oligomers gave low molecular weight oligomers that were monodispersed. It was shown that the metal to ligand concentration, i.e. the extent of the nanoparticle surface stabilization, has little influence on the catalytic activity but rather influenced the polymer selectivity. A higher ligand to metal ratio resulted in higher molecular weight polymers with lower polydispersity indices compared to the lower metal to ligand ratio analogues. The effect of the type of ligand employed, is also investigated.

Strain ST182Gu, isolated from fresh guava fruit, was identified as Enterococcus casseliflavus on the basis of biochemical tests, sugar fermentation reactions (API20Strip), PCR with genus-specific primers, and 16S rRNA sequencing. This appears to be the first documentation of the presence of this species in guava. E. casseliflavus ST182Gu was shown to produce a 4.8 kDa class IIa bacteriocin, active against various lactic acid bacteria including Enterococcus spp. and Streptococcus spp., and Staphylococcus aureus, and different serotypes of Listeria spp. The activity of the peptide was reduced by treatment with 0.1 mg/mL proteolytic enzymes, but not by α-amylase, catalase, lipase, and 1% (w/v) sodium dodecyl sulphate (SDS), Tween-20, Tween-80, urea, NaCl, and EDTA. No change in activity was recorded after adjustment to pH values of between 2.0 and 12.0 for 2 h, and after treatment at 100 °C for 120 min or 121°C for 20 min, compared with non-treated antimicrobial peptide. The mode of action against representative susceptible bacteria was shown to be bactericidal and associated with cell lysis and enzyme- and DNA-leakage. These susceptible bacteria, Listeria ivanovii subsp. ivanovii ATCC 19119, Listeria monocytogenes ATCC 15313, and Enterococcus faecalis ATCC 19443 differed however in their sensitivity to bacteriocin ST182Gu (6,553,600 AU/mL, 102,400 AU/mL, and 51,200 AU/mL, respectively). No significant differences were detected in cell growth and bacteriocin production when strain ST182Gu was grown in MRS broth at 26 °C, 30 °C, and 37 °C for 24 h. Bacteriocin ST182Gu recovery from the surface of the producer cells showed different activity, dependent of the applied test organisms (3200, 800 and 400 AU/mL, evaluated versus L. ivanovii subsp. ivanovii ATCC 19119, L. monocytogenes ATCC 15313 and E. faecalis ATCC 19443, respectively), however, with proportional values with the activity recorded in cell free supernatant versus same test microorganisms. When bacteriocin ST182Gu was combined with sublethal doses of ciprofloxacin, synergistic inhibition of L. ivanovii subsp. ivanovii ATCC 19119 was demonstrated. This increase in ciprofloxacin sensitivity may be due to the dissipation of the proton gradient in the cell membrane of the target organism associated with exposure to bacteriocin ST182Gu. Apart from reducing the MIC of classical therapeutic antibiotics, bacteriocins such as ST182Gu may also play an important role in the treatment of multidrug resistant strains.

In this study evaluation of the beneficial properties and survival for eight LAB putative probiotic strain was conducted including their ability to survive at different ox-bile concentrations and in the models representing different parts of digestive tract, ability to produce diacetyl, GABA and specific enzymes. The survival rates and release rates of the cells under the SSDP and AOS models were evaluated by encapsulation using sodium alginate. Interaction between studied LAB and the pathogen in the artificial oral saliva was evaluated. Str. salivarius ST48HK, ST59HK, ST61HK and ST62HK generated positive results for gadL and only L. gasseri ST16HK for gadP, genes associated with GABA production. According to biochemical approach in the evaluation of GABA production, strains Str. salivarius ST48HK, ST59HK, and L. sakei ST69HK can be considered as the most promising producers, even if other evaluated strains showed levels of assimilation of sodium glutamate. Overall, tests for the beneficial properties, survival rate for the planktonic and encapsulated strains under different ox-bile conditions, SSDP, AOS models, indicates that the studied strains can be promising candidates for oral probiotics application. Evaluation of probiotic properties of new strains is a complex process, with essential basic requirement – survival in the different parts of digestive tract, stability for the extended storage time, expression of beneficial properties and safety characteristics. We have evaluated Str. salivarius ST48HK, ST59HK, ST61HK, and ST62HK, L. plantarum ST63HK and ST66HK, L. sakei ST69HK, and L. gasseri ST16HK as putative probiotics, promising candidates for complementary animals’ studies and future human applications.

The aim of this project was to screen for bacteriocinogenic Bacillus strains with activity versus Staphylococcus spp. with future application in formulation of pharmaceutical antimicrobial preparations. Putative bacteriocinogenic strains, isolated and pre-identified as Bacillus spp. were selected for future study and differentiated based on repPCR and identified as Bacillus subtilis for strains ST826CD and ST829CD, Bacillus subtilis subsp. stercoris for strain ST794CD, Bacillus subtilis subsp. spizizenii for strain ST824CD, Bacillus velezensis for strain ST796CD, and Bacillus tequilensis for strain ST790CD. Selected strains were evaluated regarding their safety/virulence, beneficial properties, and potential production of antimicrobials based on biomolecular and physiological approves. Expressed bacteriocins were characterized regarding their proteinaceous nature, stability at different levels of pH, temperatures, and the presence of common chemicals applied in bacterial cultivation and bacteriocin purification. Dynamic of bacterial growth, acidification, and cumulation of produced bacteriocins and some aspects of the bacteriocins mode of action were evaluated. Based on obtained results, isolation and application of expressed antimicrobials can be realistic scenario for treatment of some staphylococcal associated infections. Appropriate biotechnological approaches need to be developed for cost effective production, isolation, and purification of expressed antimicrobials by studied Bacillus strains.

The application of LAB in various sectors, including in the biotechnical and food industry, in human and veterinary practice, and in health-promoting practices and cosmetics, has been the subject of intensive research across the globe, with a range of traditional and innovative methods currently being explored [...]

Cancer is one of the leading causes of human death worldwide, being one of the most serious problems faced by mankind. For the diagnosis, Magnetic Resonance Imaging (MRI), through effective contrast agents (Cas), has greatly helped in the diagnosis at the initial stages. However, it is necessary to include new compounds more effective and selective for cancer diagnosis. The complexes with Mn

nach Beobachtungen gesammlet und herausgegeben von Friedrich Wilhelm Heinrich von Trebra, Königl. Großbritt. und Churfürstl. Braunschweig-Lüneburgschen Vice-Berghauptmanne ..., Exlibrisetikette: "Legat von Herrn Bergrath Stockar-Escher" 002228821_0002 Exemplar der ETH-BIB, Exlibrisstempel 990023199790205503_0001 Exemplar der ETH-BIB, Exlibrisstempel: "BA" 990023199790205503_0002 Exemplar der ETH-BIB

This study aimed to select beneficial strains from the oral cavity of healthy volunteers and to evaluate these as potential oral probiotic candidates. The selection process was based on the isolation, differentiation, identification, and safety assessment of LAB strains, followed by a series of experiments for the selection of appropriate candidates with beneficial properties. In the screening procedure, 8 isolates from the oral cavity of a Caucasian volunteers were identified as Streptococcus (Str.) salivarius ST48HK, ST59HK, ST61HK, and ST62HK; Lactiplantibacillus plantarum (Lb.) (Lactobacillus plantarum) ST63HK and ST66HK; Latilactobacillus sakei (Lb.) (Lactobacillus sakei) ST69HK; and Lactobacillus (Lb.) gasseri ST16HK based on 16S rRNA sequencing. Physiological and phenotypic tests did not show hemolytic, proteinase, or gelatinase activities, as well as production of biogenic amines. In addition, screening for the presence of efaA, cyt, IS16, esp, asa1, and hyl virulence genes and vancomycin-resistant genes confirmed safety of the studied strains. Moreover, cell-to-cell antagonism indicated that the strains were able to inhibit the growth of tested representatives from the genera Bacillus, Enterococcus, Streptococcus, and Staphylococcus in a strain-specific manner. Various beneficial genes were detected including gad gene, which codes for GABA production. Furthermore, cell surface hydrophobicity levels ranging between 1.58% and 85% were determined. The studied strains have also demonstrated high survivability in a broad range of pH (4.0-8.0). The interaction of the 8 putative probiotic candidates with drugs from different groups and oral hygiene products were evaluated for their MICs. This is to determine if the application of these drugs and hygiene products can negatively affect the oral probiotic candidates. Overall, antagonistic properties, safety assessment, and high rates of survival in the presence of these commonly used drugs and oral hygiene products indicate Str. salivarius ST48HK, ST59HK, ST61HK, and ST62HK; Lb. plantarum ST63HK and ST66HK; Lb. sakei ST69HK; and Lb. gasseri ST16HK as promising oral cavity probiotic candidates.

Highlights • Bacteriocinogenic Enterococcus faecium strains were evaluated for their beneficial and safety properties. • Safety of the strains were evaluated based on phenotypic and bio-molecular approaches. • The beneficial properties of the strains were demonstrated. • High survivability under simulated GIT conditions and inhibition of Listeria spp. were demonstrated. • The strains were found to carry genes coding for GABA production., Enterococcus spp., known for their wide ecological distribution, have been associated with various fermented food products of plant and animal origin. The strains used in this study, bacteriocinogenic Enterococcus faecium previously isolated from artisanal soybean paste, have shown strong activity against Listeria spp. and vancomycin-resistant enterococci. Although their antimicrobial activity is considered beneficial, the potential application of enterococci is still under debate due to concerns about their safety for human and other animal consumption. Therefore, this study not only focuses on the screening of potential virulence factors, but also the auxiliary beneficial properties of the strains Ent. faecium ST651ea, ST7119ea, and ST7319ea. Phenotypic screening for gelatinase, hemolysin, and biogenic amine production showed that the strains were all safe. Furthermore, the antibiogram profiling showed that all the strains were susceptible to the panel of antibiotics used in the assessment except for erythromycin. Yet, Ent. faecium ST7319ea was found to carry some of the virulence genes used in the molecular screening for safety including hyl, esp, and IS16. The probiotic potential and other beneficial properties of the strains were also studied, demonstrating high aggregation and co-aggregation levels compared to previously characterized strains, in addition to high survivability under simulated gastrointestinal conditions, and production of numerous desirable enzymes as evaluated by APIZym, indicating diverse possible biotechnological applications of these strains. Additionally, the strains were found to carry genes coding for γ-aminobutyric acid (GABA) production, an auxiliary characteristic for their probiotic potential. Although these tests showed relatively favorable characteristics, it should be considered that these assays were carried out in vitro and should therefore also be assessed under in vivo conditions., Graphical abstract Image, graphical abstract

Antibiotics have been one of the most important discoveries in the area of applied medical microbiology; however, as a result of various factors, we are currently facing a dramatic and relatively dangerous increase in the number of cases of antibiotic resistance, and the need for new types of antimicrobials continues to grow. New approaches are needed to combat antibiotic-resistant pathogens. Bacteriocins, as part of the group of antimicrobial peptides, can be considered as alternatives and/or complements to known antibiotics. Their narrow spectra of activity can be explored for the control of various pathogens, such as vancomycin-resistant enterococci (VRE), as single therapies or in combination with known antibiotics. In the present study, we isolated bacteriocins from different lactic acid bacteria (LAB) strains, including Enterococcus and Pediococcus, and explored the possible synergistic inhibition of growth by bacteriocins and vancomycin. It was observed in the growth dynamics with previously selected VRE strains that the bacteriocins had a high specificity and a promising inhibitory effect against the VRE strains, and these results were validated by a propidium iodide viability test using flow cytometry. The data obtained indicate that the selected bacteriocins can be used to control VRE in the food industry or even as an alternative treatment to combat infections with antibiotic-resistant bacteria.

Preservation of probiotics by lyophilization is considered a method of choice for developing stable products. However, both direct consumption and reconstitution of dehydrated probiotic preparations before application “compromise” the survival and functional characteristics of the microorganisms under the stress of the upper gastro-intestinal tract. We evaluated the impact of different food additives on the viability, mucin adhesion, and zeta potential of a freeze-dried putative probiotic, Lactiplantibacillus (Lp.) plantarum HAC03. HAC03-compatible ingredients for the formulation of ten rehydration mixtures could be selected. Elevated efficacy was achieved by the B-active formulation, a mixture of non-protein nitrogen compounds, sugars, and salts. The survival of Lp. plantarum HAC03 increased by 36.36% compared rehydration with distilled water (4.92%) after passing simulated gastro-intestinal stress conditions. Cell viability determined by plate counting was confirmed by flow cytometry. B-active formulation also influenced Lp. plantarum HAC03 functionality by increasing its adherence to a Caco-2 cell-line and by changing the bacterial surface charge, measured as zeta potential.Hydrophobicity, mucin adhesion and immunomodulatory properties of Lp. plantarum HAC03 were not affected by the B-active formulation. The rehydration medium also effectively protected Lp. plantarum ATCC14917, Lp. plantarum 299v, Latilactobacillus sakei (Lt.) HAC11, Lacticaseibacillus (Lc.) paracasei 532, Enterococcus faecium 200, and Lc. rhamnosus BFE5263.

Three out of one hundred eighty putative LAB isolates from Korean traditional fermented soybean paste were identified to be unique and bacteriocinogenic strains. Based on phenotypic and 16S rRNA sequencing analysis, selected strains were identified as Enterococcus faecium ST651ea, E. faecium ST7119ea and E. faecium ST7319ea. The bacteriocinogenic properties of the studied strains were evaluated against Listeria monocytogenes ATCC15313, Listeria innocua ATCC33090 and vancomycin-resistant E. faecium VRE19 of clinical origin. The strains E. faecium ST651ea, ST7119ea and ST7319ea expressed bacteriocins with an activity of 12,800 AU/mL, 25,600 AU/mL and 25,600 AU/mL, respectively, recorded against L. monocytogenes ATCC15131. According to the PCR-based screening of bacteriocin-related genes, which was further confirmed through amplicon sequencing, showed that strain E. faecium ST651ea carries entB and entP genes, whereas both E. faecium ST7119ea and ST7319ea strains harbor entA and entB genes. The molecular size of expressed bacteriocins was estimated by tricine-SDS-PAGE showing an approximative protein size of 4.5 kDa. The assessment of the spectrum of activity of bacteriocins ST651ea, ST7119ea and ST7319ea showed strong activity against most of clinical VRE isolates, majority of other Enterococcus spp. and Listeria spp. Bacteriocins ST651ea, ST7119ea and ST7319ea were partially purified by combination of 60% ammonium sulfate precipitation and hydrophobic chromatography on the SepPakC18 column. Challenge test with semi-purified (60% 2-propanol fraction) bacteriocins resulted in a significant reduction of viable cells for all test organisms. Thus, indicating that all the bacteriocins evaluated can be used as potential biocontrol in food and feed industries as well as an alternative treatment for VRE-related infections in both veterinary and clinical settings.

Die vorliegende Arbeit nimmt sich den organisationalen Narrativen an, die entlang ausgesandter Steuerungsmaßnahmen und -impulse neu entstehen bzw. auf bestehende Narrative zugreifen und diese weiterentwickeln. Dabei ist auch ihre Wechselwirkung zu unterschiedlichen Steuerungsformen und -maßnahmen von Interesse. Die Arbeit teilt sich dazu in einen theoretischen ersten Teil, der verschiedene Aspekte rund um organisationale Narrative sowie verschiedene Steuerungsformen ausleuchtet und einen empirischen zweiten Teil, der mit Hilfe einer Fallstudie weitere Erkenntnisse erbringt. eingereicht von Mag. Wilhelm Pedak Universität Linz, Dissertation, 2021 (VLID)6538935

Gastric inflammation is an indication of gastric ulcers and possible other underlying gastric malignancies. Epidemiological studies have revealed that several Asian countries, including South Korea, suffer from a high incidence of gastric diseases derived from high levels of stress, alcoholic consumption, pyloric infection and usage of non-steroidal anti-inflammatory drugs (NSAIDs). Clinical treatments of gastric ulcers are generally limited to proton pump inhibitors that neutralize the stomach acid, and the application of antibiotics for Helicobacter pylori eradication, both of which are known to have a negative effect on the gut microbiota. The potential of probiotics for alleviating gastrointestinal diseases such as intestinal bowel syndrome and intestinal bowel disease receives increasing scientific interest. Probiotics may support the amelioration of disease-related symptoms through modulation of the gut microbiota without causing dysbiosis. In this study the potential of Lactobacillus plantarum APSulloc 331261 (GTB1TM), isolated from green tea, was investigated for alleviating gastric inflammation in an alcohol induced gastric ulcer murine model (positive control). Treatment with the test strain significantly influenced the expression of pro-inflammatory and anti-inflammatory biomarkers, interleukin 6 (IL6) and interleukin 10 (IL10), of which the former was down- and the latter up-regulated when the alcohol induced mice were treated with the test strain. This positive effect was also indicated by less severe gastric morphological changes and the histological score of the gastric tissues. A significant increase in the abundance of Akkermansia within the GTB1TM treated group compared to the positive control group also correlated with a decrease in the ratio of acetate over propionate. The increased levels of propionate in the GTB1TM group appear to result from the impact of the test strain on the microbial population and the resulting metabolic activities. Moreover, there was a significant increase in beta-diversity in the group that received GTB1TM over that of the alcohol induced control group.

Olenitic tourmaline with high amounts of tetrahedral B (up to 2.53 [4] B pfu) has been synthesized in a piston-cylinder press at 4.0 GPa, 700 °C, and a run duration of 9 days. Crystals are large enough (up to 30 × 150 μm) to allow for reliable and spatially resolved quantification of B by electron microprobe analysis (EMPA), single-crystal X-ray diffraction, and polarized single-crystal Raman spectroscopy. Tourmalines with radial acicular habit are zoned in [4] B-concentration [core: 2.53(25) [4] B pfu; rim: 1.43(15) [4] B pfu], whereas columnar crystals are chemically homogeneous [1.18(15) [4] B pfu]. An amount of 1.4(1) [4] B pfu was found in the columnar tourmaline by single-crystal structure refinement (SREF) ( R = 1.94%). The EMPA identify [T] Si −1 [V,W] O −1 [T] B 1 [V,W] (OH) 1 as the main and [X] □ −1 [T] Si −1 [X] Na 1 [T] B 1 as minor exchange vectors for [4] B-incorporation, which is supported by the SREF. Due to the restricted and well-defined variations in chemistry, Raman bands in the OH-stretching region (3000–3800 cm −1 ) are unambiguously assigned to a specific cation arrangement. We found the sum of the relative integrated intensity ( I rel ) of two low-frequency bands at 3284–3301 cm −1 (ν1) and 3367–3390 cm −1 (ν2) to positively correlate with the [4] B concentrations: [4] B [pfu] = 0.03(1) × [ I rel (ν1) + I rel (ν2)]. Hence, those bands correspond to configurations with mixed Si/B occupancy at the T site. Our semi-quantitative correlation also holds for well-characterized natural [4] B-bearing tourmaline from the Koralpe, Austria. This work shows the potential for Raman spectroscopy as a non-destructive method for the chemical classification of (precious) natural tourmaline, and as a tool to rapidly characterize chemical zonation of tourmalines in thin section.