ABSTRACT
Hydrogel microbeads can be used to enhance the stability of probiotics during gastrointestinal delivery and storage. In this study, the pectin-alginate hydrogel was enhanced by adding montmorillonite filler to produce microbeads for encapsulating Lactobacillus kefiranofaciens (LK). Results showed that the viscosity of biopolymer solutions with 1 % (PAMT1) and 3 % (PAMT3) montmorillonite addition was suitable for producing regular-shaped microbeads. A layered cross-linked network was formed on the surface of PAMT3 microbeads through electrostatic interaction between pectin-alginate and montmorillonite filler, and the surrounding LK with adsorbed montmorillonite was encapsulated inside the microbeads. PAMT3 microbeads reduced the loss of viability of LK when passing through the gastric acid environment, and facilitated the slow release of LK in the intestine and colonic colonization. The maximum decrease in viability among all filler groups was 1.21 log CFU/g after two weeks of storage, while PAMT3 freeze-drying microbeads only decreased by 0.46 log CFU/g, indicating that the gel layer synergized with the adsorbed layer to provide dual protection for probiotics. Therefore, filler-reinforced microbeads are a promising bulk encapsulation carrier with great potential for the protection and delivery of probiotics and can be developed as food additives for dairy products.
Subject(s)
Alginates , Lactobacillus , Probiotics , Pectins , Bentonite , Microspheres , Hydrogels , Microbial ViabilityABSTRACT
To preserve the viability of probiotics during digestion and storage, encapsulation techniques are necessary to withstand the challenges posed by adverse environments. A core-shell structure has been developed to provide protection for probiotics. By utilizing sodium alginate (SA) / Lycium barbarum polysaccharide (LBP) as the core material and chitosan (CS) as the shell, the probiotic load reached 9.676 log CFU/mL. This formulation not only facilitated continuous release in the gastrointestinal tract but also enhanced thermal stability and storage stability. The results obtained from Fourier transform infrared spectroscopy and thermogravimetric analysis confirmed that the addition of LBP and CS affected the microstructure of the gel by enhancing the hydrogen bond force, so as to achieve controlled release. Following the digestion of the gel within the gastrointestinal tract, the released amount was determined to be 9.657 log CFU/mL. The moisture content and storage stability tests confirmed that the encapsulated Lactiplantibacillus plantarum maintained good activity for an extended period at 4 °C, with an encapsulated count of 8.469 log CFU/mL on the 28th day. In conclusion, the newly developed core-shell gel in this study exhibits excellent probiotic protection and delivery capabilities.
Subject(s)
Chitosan , Drugs, Chinese Herbal , Probiotics , Alginates/chemistry , Chitosan/chemistry , Microbial Viability , Gels , Probiotics/chemistryABSTRACT
Tea polysaccharide conjugates (TPC) were used as fillers in the form of biopolymer or colloidal particles (TPC stabilized nanoemulsion, NE) for reinforcing alginate (ALG) beads to improve the probiotic viability. Results demonstrated that adding TPC or NE to ALG beads significantly enhanced the gastrointestinal viability of encapsulated probiotics when compared to free cells. Moreover, the survivability of free and ALG encapsulated probiotics markedly decreased to 2.03 ± 0.05 and 2.26 ± 0.24 log CFU/g, respectively, after 2 weeks ambient storage, indicating pure ALG encapsulation had no effective storage protective capability. However, adding TPC or NE could greatly enhance the ambient storage viability of probiotics, with ALG + NE beads possessing the best protection (8.93 ± 0.06 log CFU/g) due to their lower water activity and reduced porosity. These results suggest that TPC and NE reinforced ALG beads have the potential to encapsulate, protect and colonic delivery of probiotics.
Subject(s)
Alginates , Probiotics , Microbial Viability , Digestion , TeaABSTRACT
One of the famous traditional confectionery products is Tahini halva. The aim of this study was the production of probiotic halva using free Lactobacillus acidophilus (FLA) and microencapsulated Lactobacillus acidophilus (MLA) with sodium alginate and galbanum gum as the second layer. The survival rate of MLA and FLA during heat stress, storage time, and simulation gastrointestinal condition in Tahini halva was assessed. The survival rates of MLA and FLA under heat stress were 50.13% and 34.6% respectively. During storage in Tahini halva, the cell viability loss was 3.25 Log CFU g-1 and 6.94 Log CFU g-1 for MLA and FLA, separately. Around 3.58 and 4.77 Log CFU g-1 bacteria were reduced after 6 h of exposure in simulated gastrointestinal conditions, for MLA and FLA respectively. These results suggest that the use of alginate and galbanum gum is a promising approach to protecting L. acidophilus against harsh environmental conditions.
Subject(s)
Ferula , Probiotics , Lactobacillus acidophilus , Lactobacillus , Alginates , Microspheres , Microbial ViabilityABSTRACT
To improve the viability of Lacticaseibacillus rhamnosus ZFM231 strain in the gastrointestinal tract and exhibit better probiotic effect, an internal emulsification/gelation technique was employed to encapsulate this strain using whey protein and pectin as wall materials to fabricate the double layer microcapsules. Four key factors affecting the encapsulation process were optimized using single factor analysis and response surface methodology. Encapsulation efficiency of L. rhamnosus ZFM231 reached 89.46 ± 0.82 %, the microcapsules possessed a particle size of 172 ± 1.80 µm and ζ-potential of -18.36 mV. The characters of the microcapsules were assessed using optical microscope, SEM, FT-IR and XRD analysis. It was found that after exposure to simulated gastric fluid, the bacterial count (log (CFU g-1)) of the microcapsules only lost 1.96 units, the bacteria were released readily in simulated intestinal fluid, reaching 86.56 % after 90 min. After stored at 4 °C for 28 days and 25 °C for 14 days, bacterial count of the dry microcapsules decreased from 10.59 to 9.02 and 10.49 to 8.70 log (CFU g-1), respectively. The double layered microcapsules could significantly increase the storage and thermal abilities of bacteria. Such L. rhamnosus ZFM231 microcapsules could find applications as ingredient of the functional foods and the dairy products.
Subject(s)
Lacticaseibacillus rhamnosus , Probiotics , Whey Proteins , Pectins , Lacticaseibacillus , Capsules , Spectroscopy, Fourier Transform Infrared , Drug Compounding/methods , Microbial Viability , Probiotics/metabolismABSTRACT
Probiotic bacteria and bioactive compounds obtained from plant origin stand out as ingredients with the potential to increase the healthiness of functional foods, as there is currently a recurrent search for them. Probiotics and bioactive compounds are sensitive to intrinsic and extrinsic factors in the processing and packaging of the finished product. In this sense, the present study aims to evaluate the co-encapsulation by spray dryer (inlet air temperature 120 °C, air flow 40 L / min, pressure of 0.6 MPa and 1.5 mm nozzle diameter) of probiotic bacteria (L.plantarum) and compounds extracted from red beet stems (betalains) in order to verify the interaction between both and achieve better viability and resistance of the encapsulated material. When studying the co-encapsulation of L.plantarum and betalains extracted from beet stems, an unexpected influence was observed with a decrease in probiotic viability in the highest concentration of extract (100 %), on the other hand, the concentration of 50 % was the best enabled and maintained the survival of L.plantarum in conditions of 25 °C (63.06 %), 8 °C (88.80 %) and -18 °C (89.28 %). The viability of the betalains and the probiotic was better preserved in storage at 8 and -18 °C, where the encapsulated stability for 120 days was successfully achieved. Thus, the polyfunctional formulation developed in this study proved to be promising, as it expands the possibilities of application and development of new foods.
Subject(s)
Beta vulgaris , Lactobacillus plantarum , Probiotics , Microbial Viability , Preservation, BiologicalABSTRACT
The majority of the current regulatory practices for routine monitoring of beach water quality rely on the culture-based enumeration of faecal indicator bacteria (FIB) to develop criteria for promoting the general public's health. To address the limitations of culture methods and the arguable reliability of FIB in indicating health risks, we developed a Nanopore metagenomic sequencing-based viable cell absolute quantification workflow to rapidly and accurately estimate a broad range of microbes in beach waters by a combination of propidium monoazide (PMA) and cellular spike-ins. Using the simple synthetic bacterial communities mixed with viable and heat-killed cells, we observed near-complete relic DNA removal by PMA with minimal disturbance to the composition of viable cells, demonstrating the feasibility of PMA treatment in profiling viable cells by Nanopore sequencing. On a simple mock community comprised of 15 prokaryotic species, our results showed high accordance between the expected and estimated concentrations, suggesting the accuracy of our method in absolute quantification. We then further assessed the accuracy of our method for counting viable Escherichia coli and Vibrio spp. in beach waters by comparing to culture-based method, which were also in high agreement. Furthermore, we demonstrated that 1 Gb sequences obtained within 2 h would be sufficient to quantify a species having a concentration of ≥ 10 cells/mL in beach waters. Using our viability-resolved quantification workflow to assess the microbial risk of the beach water, we conducted (1) screening-level quantitative microbial risk assessment (QMRA) to investigate human illness risk and site-specific risk patterns that might guide risk management efforts and (2) metagenomics-based resistome risk assessment to evaluate another layer of risk caused by difficult illness treatment due to antimicrobial resistance (AMR). In summary, our metagenomic workflow for the rapid absolute quantification of viable bacteria demonstrated its great potential in paving new avenues toward holistic microbial risk assessment.
Subject(s)
Metagenomics , Nanopore Sequencing , Humans , Microbial Viability , Reproducibility of Results , Propidium , Azides , Risk Assessment , Bacteria , Escherichia coliABSTRACT
Ultraviolet-C (UV-C) irradiation is a well-recognized technology for improving blueberry postharvest quality, and previous literature indicates that it has the potential for dual-use as an antimicrobial intervention for this industry. However, the practicality and feasibility of deploying this technology in fresh blueberry fruit are significantly hindered by the shadowing effect occurring at the blossom-end scar of the fruit. The purpose of this study was to determine if treating the blueberry fruit within a chamber fitted with UV-Light Emitting Diodes (LEDs) emitting a peak UV-C at 275 nm could minimize this shadowing and result in improved treatment efficacy. Ten blueberry fruits were dip-inoculated with E. coli at a concentration of 105 CFU/mL and irradiated within the system at doses of 0, 1.617, 3.234, 9.702, and 16.17 mJ/cm2 (0, 30, 60, 180, and 300 s). Statistical analysis was performed to characterize the extent of microbial survival as well as the UV-C inactivation kinetics. A maximum of 0.91-0.95 log reduction was observed, which attenuated after 60 s of treatment. The microbial inactivation and survival were thus modeled using the Geeraerd-tail model in Microsoft Excel with the GInaFIt add-in (RMSE = 0.2862). Temperatures fluctuated between 23 ± 0.5°C and 39.5°C ± 0.5°C during treatment but did not statistically impact the treatment efficacy (P = 0.0823). The data indicate that the design of a UV-LED system may improve the antimicrobial efficacy of UV-C technology for the surface decontamination of irregularly shaped fruits, and that further optimization could facilitate its use in the industry.
Subject(s)
Blueberry Plants , Escherichia coli O157 , Fruit , Colony Count, Microbial , Microbial Viability/radiation effects , Ultraviolet RaysABSTRACT
Although both ultraviolet (UV) radiation and ultrasound (US) treatment have their capabilities in microbial inactivation, applying any one method alone may require a high dose for complete inactivation, which may affect the sensory and nutritional properties of pineapple juice. Hence, this study was intended to analyse and optimise the effect of combined US and UV treatments on microbial inactivation without affecting the selected quality parameters of pineapple juice. US treatment (33 kHz) was done at three different time intervals, viz. 10 min, 20 min and 30 min., after which, juice samples were subjected to UV treatment for 10 min at three UV dosage levels, viz. 1 J/cm2, 1.3 J/cm2, and 1.6 J/cm2. The samples were evaluated for total colour difference, pH, total soluble solids (TSS), titrable acidity (TA), and ascorbic acid content; total bacterial count and total yeast count; and the standardization of process parameters was done using Response Surface Methodology and Artificial Neural Network. The results showed that the individual, as well as combined treatments, did not significantly impact the physicochemical properties while retaining the quality characteristics. It was observed that combined treatment resulted in 5 log cycle reduction in bacterial and yeast populations while the individual treatment failed. From the optimization studies, it was found that combined US and UV treatments with 22.95 min and1.577 J/cm2 ensured a microbiologically safe product while retaining organoleptic quality close to that of fresh juice.
Subject(s)
Ananas , Malus , Malus/chemistry , Food Handling/methods , Saccharomyces cerevisiae , Fruit and Vegetable Juices , Microbial Viability/radiation effects , Ananas/chemistryABSTRACT
The use of antimicrobial photodynamic inactivation as a non-antibiotic alternative method to inactivate Acinetobacter baumannii was described in response to the ever-growing problem of antibiotic resistance. It was found that irradiation of the bacterial suspension for 10 min reduced the number of viable cells by approximately 99% and this energy fluence was considered to be sub-lethal phototherapy. The lethal dose of laser light (cell mortality about 99.9%) was 9.54 J cm-2, which corresponds to 30 min of irradiation. After a 15-fold phototherapy cycle, the tolerance to aPDT decreased, resulting in a decrease in the number of viable cells by 2.15 and 3.23 log10 CFU/ml units with the use of sub-lethal and lethal light doses, respectively. Multiple photosensitizations decreased the biofilm formation efficiency by 25 ± 1% and 35 ± 1%, respectively. No changes in antibiotic resistance were observed, whereas the cells were more sensitive to hydrogen peroxide. Metabolomic changes after multiple photosensitization were studied and 1H NMR measurements were used in statistical and multivariate data analysis. Many significant changes in the levels of the metabolites were detected demonstrating the response of A. baumannii to oxidative stress.
Subject(s)
Acinetobacter baumannii/drug effects , Energy Metabolism/drug effects , Oxidative Stress/drug effects , Photochemotherapy , Photosensitizing Agents/pharmacology , Acinetobacter baumannii/metabolism , Adenosine Triphosphate/metabolism , Drug Resistance, Bacterial , Metabolome , Metabolomics , Microbial Viability , Proton Magnetic Resonance Spectroscopy , Reactive Oxygen Species/metabolismABSTRACT
Increase in bacterial resistance to commonly used antibiotics is a major public health concern generating interest in novel antibacterial treatments. Aim of this scientific endeavor was to find an alternative efficient antibacterial agent from non-conventional plant source for human health applications. We used an eco-friendly approach for phyto-fabrication of silver nanoparticles (AgNPs) by utilizing logging residue from timber trees Gmelina arborea (GA). GC-MS analysis of leaves, barks, flowers, fruits, and roots was conducted to determine the bioactive compounds. Biosynthesis, morphological and structural characterization of GA-AgNPs were undertaken by UV-Vis spectroscopy, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDX), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffractometer (XRD). GA-AgNPs were evaluated for antibacterial, antibiofilm, antioxidant, wound healing properties and their toxicity studies were carried out. Results identified the presence of terpenoids, sterols, aliphatic alcohols, aldehydes, and flavonoids in leaves, making leaf extract the ideal choice for phyto-fabrication of silver nanoparticles. The synthesis of GA-AgNPs was confirmed by dark brown colored colloidal solution and spectral absorption peak at 420 nm. Spherical, uniformly dispersed, crystalline GA-AgNPs were 34-40 nm in diameter and stable in solutions at room temperature. Functional groups attributed to the presence of flavonoids, terpenoids, and phenols that acted as reducing and capping agents. Antibacterial potency was confirmed against pathogenic bacteria Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus by disc diffusion assay, MIC and MBC assay, biofilm inhibition assay, electron-microscopy, cell staining and colony counting techniques. The results from zone of inhibition, number of ruptured cells and dead-cell-count analysis confirmed that GA-AgNPs were more effective than GA-extract and their bacteria inhibition activity level increased further when loaded on hydrogel as GA-AgNPs-PF127, making it a novel distinguishing feature. Antioxidant activity was confirmed by the free radical scavenging assays (DPPH and ABTS). Wound healing potential was confirmed by cell scratch assay in human dermal fibroblast cell lines. Cell-proliferation study in human chang liver cell lines and optical microscopic observations confirmed non-toxicity of GA-AgNPs at low doses. Our study concluded that biosynthesized GA-AgNPs had enhanced antibacterial, antibiofilm, antioxidant, and wound healing properties.
Subject(s)
Anti-Bacterial Agents/pharmacology , Bacteria/drug effects , Biofilms/drug effects , Green Chemistry Technology , Lamiaceae , Plant Extracts/chemistry , Silver Compounds/pharmacology , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/toxicity , Bacteria/growth & development , Biofilms/growth & development , Cell Line , Cell Movement/drug effects , Cell Proliferation/drug effects , Disk Diffusion Antimicrobial Tests , Fibroblasts/drug effects , Fibroblasts/pathology , Humans , Microbial Viability/drug effects , Silver Compounds/chemistry , Silver Compounds/toxicityABSTRACT
The ethanol extracts of 155 different foodstuffs containing medicinal plants were investigated for their biofilm eradication activities against pathogenic bacteria. A combined method of a colorimetric microbial viability assay based on reduction of a tetrazolium salt (WST-8) and a biofilm formation technique on the 96-pins of a microtiter plate lid was used to screen the biofilm eradication activities of foodstuffs. The ethanol extracts of licorice (Glycyrrhiza glabra) showed potent biofilm eradication activities against Streptococcus mutans, Staphylococcus aureus, and Porphyromonas gingivalis. Among the antimicrobial constituents in licorice, glabridin had the most potent eradication activities against microbial biofilms. The minimum biofilm eradication concentration of glabridin was 25-50 µg/ml. Furthermore, the combination of glabridin with É-poly-L-lysine, a food additive, could result in broad biofilm eradication activities towards a wide variety of bacteria associated with infection, including Escherichia coli and Pseudomonas aeruginosa.
Subject(s)
Biofilms/drug effects , Flavonoids/pharmacology , Glycyrrhiza/chemistry , Isoflavones/pharmacology , Phenols/pharmacology , Plant Extracts/pharmacology , Polylysine/pharmacology , Anti-Bacterial Agents/pharmacology , Ethanol , Food Additives , Microbial Sensitivity Tests , Microbial Viability/drug effects , Porphyromonas gingivalis/drug effects , Pseudomonas aeruginosa/drug effects , Staphylococcus aureus/drug effects , Streptococcus mutans/drug effectsABSTRACT
Antimicrobial resistance is one of the greatest global threats. Particularly, multidrug resistant extended-spectrum ß-lactamase (ESBL)-producing pathogens confer resistance to many commonly used medically important antibiotics, especially beta-lactam antibiotics. Here, we developed an innovative combination approach to therapy for multidrug resistant pathogens by encapsulating cephalosporin antibiotics and ß-lactamase inhibitors with chitosan nanoparticles (CNAIs). The four combinations of CNAIs including two cephalosporin antibiotics (cefotaxime and ceftiofur) with two ß-lactamase inhibitors (tazobactam and clavulanate) were engineered as water-oil-water emulsions. Four combinations of CNAIs showed efficient antimicrobial activity against multidrug resistant ESBL-producing Enterobacteriaceae. The CNAIs showed enhanced antimicrobial activity compared to naïve chitosan nanoparticles and to the combination of cephalosporin antibiotics and ß-lactamase inhibitors. Furthermore, CNAIs attached on the bacterial surface changed the permeability to the outer membrane, resulting in cell damage that leads to cell death. Taken together, CNAIs have provided promising potential for treatment of diseases caused by critically important ESBL-producing multidrug resistant pathogens.
Subject(s)
Anti-Bacterial Agents/administration & dosage , Chitosan/chemistry , Drug Carriers/chemistry , Nanoparticles/chemistry , beta-Lactamase Inhibitors/administration & dosage , Anti-Bacterial Agents/pharmacology , Cephalosporins/pharmacology , Chemical Phenomena , Drug Combinations , Emulsions , Humans , Microbial Sensitivity Tests , Microbial Viability/drug effects , beta-Lactamase Inhibitors/pharmacologyABSTRACT
Cells that cannot synthesize one of the DNA precursors, dTTP, due to thyA mutation or metabolic poisoning, undergo thymineless death (TLD), a chromosome-based phenomenon of unclear mechanisms. In Escherichia coli, thymineless death is caused either by denying thyA mutants thymidine supplementation or by treating wild-type cells with trimethoprim. Two recent reports promised a potential breakthrough in TLD understanding, suggesting significant oxidative damage during thymine starvation. Oxidative damage in vivo comes from Fenton's reaction when hydrogen peroxide meets ferrous iron to produce hydroxyl radical. Therefore, TLD could kill via irreparable double-strand breaks behind replication forks when starvation-caused single-strand DNA gaps are attacked by hydroxyl radicals. We tested the proposed Fenton-TLD connection in both thyA mutants denied thymidine, as well as in trimethoprim-treated wild-type (WT) cells, under the following three conditions: (i) intracellular iron chelation, (ii) mutational inactivation of hydrogen peroxide (HP) scavenging, and (iii) acute treatment with sublethal HP concentrations. We found that TLD kinetics are affected by neither iron chelation nor HP stabilization in cultures, indicating no induction of oxidative damage during thymine starvation. Moreover, acute exogenous HP treatments completely block TLD, apparently by blocking cell division, which may be a novel TLD prerequisite. Separately, the acute trimethoprim sensitivity of the rffC and recBCD mutants demonstrates how bactericidal power of this antibiotic could be amplified by inhibiting the corresponding enzymes. IMPORTANCE Mysterious thymineless death strikes cells that are starved for thymine and therefore replicating their chromosomal DNA without dTTP. After 67 years of experiments testing various obvious and not so obvious explanations, thymineless death is still without a mechanism. Recently, oxidative damage via in vivo Fenton's reaction was proposed as a critical contributor to the irreparable chromosome damage during thymine starvation. We have tested this idea by either blocking in vivo Fenton's reaction (expecting no thymineless death) or by amplifying oxidative damage (expecting hyperthymineless death). Instead, we found that blocking Fenton's reaction has no influence on thymineless death, while amplifying oxidative damage prevents thymineless death altogether. Thus, oxidative damage does not contribute to thymineless death, while the latter remains enigmatic.
Subject(s)
Anti-Bacterial Agents/pharmacology , Escherichia coli/drug effects , Oxidative Stress/drug effects , Thymine/pharmacology , Trimethoprim/pharmacology , DNA Replication , DNA, Bacterial , Escherichia coli Proteins/metabolism , Gene Expression Regulation, Bacterial/drug effects , Hydrogen Peroxide , Iron/metabolism , Microbial Viability , Thymine/metabolismABSTRACT
There is a need for new antimicrobial systems due to increased global resistance to current antimicrobials. Pomegranate rind extract (PRE) and Zn (II) ions both possess a level of antimicrobial activity and work has previously shown that PRE/Zn (II) in combination possesses synergistic activity against Herpes simplex virus and Micrococcus luteus. Here, we determined whether such synergistic activity extended to other, more pathogenic, bacteria. Reference strains of methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis, Escherichia coli, and Pseudomonas aeruginosa were cultured and subjected to challenge by PRE, Zn (II), or PRE + Zn (II), in time-kill assays. Data were obtained independently by two researchers using different PRE preparations. Statistically significant synergistic activity for PRE + Zn (II) was shown for all four bacterial strains tested compared to untreated controls, although the extent of efficacy and timescales varied. Zn (II) exerted activity and at 1 h, it was not possible to distinguish with PRE + Zn (II) combination treatment in all cases. PRE alone showed low activity against all four bacteria. Reproducible synergistic bactericidal activity involving PRE and Zn (II) has been confirmed. Potential mechanisms are discussed. The development of a therapeutic system that possesses demonstrable antimicrobial activity is supported which lends itself particularly to topical delivery applications, for example MRSA infections.
Subject(s)
Escherichia coli/growth & development , Methicillin-Resistant Staphylococcus aureus/growth & development , Plant Extracts/pharmacology , Pomegranate/chemistry , Pseudomonas aeruginosa/growth & development , Staphylococcus epidermidis/growth & development , Zinc/pharmacology , Drug Synergism , Escherichia coli/drug effects , Methicillin-Resistant Staphylococcus aureus/drug effects , Microbial Sensitivity Tests , Microbial Viability/drug effects , Plant Extracts/chemistry , Pseudomonas aeruginosa/drug effects , Staphylococcus epidermidis/drug effectsABSTRACT
Given the undesirable side effects of commercially used mouth rinses that include chemically synthesized antimicrobial compounds such as chlorhexidine, it is essential to discover novel antimicrobial substances based on plant extracts. The aim of this study was to examine the antimicrobial effect of Inula viscosa extract on the initial microbial adhesion in the oral cavity. Individual test splints were manufactured for the participants, on which disinfected bovine enamel samples were attached. After the initial microbial adhesion, the biofilm-covered oral samples were removed and treated with different concentrations (10, 20, and 30 mg/mL) of an I. viscosa extract for 10 min. Positive and negative controls were also sampled. Regarding the microbiological parameters, the colony-forming units (CFU) and vitality testing (live/dead staining) were examined in combination with fluorescence microscopy. An I. viscosa extract with a concentration of 30 mg/mL killed the bacteria of the initial adhesion at a rate of 99.99% (log10 CFU value of 1.837 ± 1.54). Compared to the negative control, no killing effects were determined after treatment with I. viscosa extract at concentrations of 10 mg/mL (log10 CFU value 3.776 ± 0.831; median 3.776) and 20 mg/mL (log10 CFU value 3.725 ± 0.300; median 3.711). The live/dead staining revealed a significant reduction (p < 0.0001) of vital adherent bacteria after treatment with 10 mg/mL of I. viscosa extract. After treatment with an I. viscosa extract with a concentration of 30 mg/mL, no vital bacteria could be detected. For the first time, significant antimicrobial effects on the initial microbial adhesion in in situ oral biofilms were reported for an I. viscosa extract.
Subject(s)
Anti-Infective Agents/pharmacology , Biofilms/drug effects , Inula/chemistry , Plant Extracts/pharmacology , Anti-Bacterial Agents/pharmacology , Bacteria/drug effects , Bacterial Adhesion/drug effects , Colony Count, Microbial , Microbial Viability/drug effects , Microscopy, Fluorescence , Mouth/microbiology , MouthwashesABSTRACT
Because of the continuous rise of foodborne illnesses caused by the consumption of raw fruits and vegetables, effective post-harvest anti-microbial strategies are necessary. The aim of this study was to evaluate the anti-microbial efficacy of ozone (O3) against two common causes of fresh produce contamination, the Gram-negative Escherichia coli O157:H7 and Gram-positive Listeria monocytogenes, and to relate its effects to potential mechanisms of xenobiosis by transcriptional network modeling. The study on non-host tomato environment correlated the dose × time aspects of xenobiosis by examining the correlation between bacterial survival in terms of log-reduction and defense responses at the level of gene expression. In E. coli, low (1 µg O3/g of fruit) and moderate (2 µg O3/g of fruit) doses caused insignificant reduction in survival, while high dose (3 µg/g of fruit) caused significant reduction in survival in a time-dependent manner. In L. monocytogenes, moderate dose caused significant reduction even with short-duration exposure. Distinct responses to O3 xenobiosis between E. coli and L. monocytogenes are likely related to differences in membrane and cytoplasmic structure and components. Transcriptome profiling by RNA-Seq showed that primary defenses in E. coli were attenuated after exposure to a low dose, while the responses at moderate dose were characterized by massive upregulation of pathogenesis and stress-related genes, which implied the activation of defense responses. More genes were downregulated during the first hour at high dose, with a large number of such genes getting significantly upregulated after 2 hr and 3 hr. This trend suggests that prolonged exposure led to potential adaptation. In contrast, massive downregulation of genes was observed in L. monocytogenes regardless of dose and exposure duration, implying a mechanism of defense distinct from that of E. coli. The nature of bacterial responses revealed by this study should guide the selection of xenobiotic agents for eliminating bacterial contamination on fresh produce without overlooking the potential risks of adaptation.
Subject(s)
Anti-Bacterial Agents/pharmacology , Escherichia coli O157/drug effects , Foodborne Diseases/prevention & control , Listeria monocytogenes/drug effects , Ozone/pharmacology , Solanum lycopersicum/microbiology , Bacterial Load/drug effects , Food Microbiology , Foodborne Diseases/microbiology , Fruit/microbiology , Gene Expression Profiling , Gene Expression Regulation, Bacterial/drug effects , Microbial Viability/drug effects , Proof of Concept Study , RNA, Bacterial/genetics , RNA-Seq , Transcriptome/drug effects , Transcriptome/genetics , Vegetables/microbiologyABSTRACT
Understating how antibiotic tolerance impacts subsequent resistance development in the clinical setting is important to identifying effective therapeutic interventions and prevention measures. This study describes a patient case of methicillin-resistant Staphylococcus aureus (MRSA) bacteremia which rapidly developed resistance to three primary MRSA therapies and identifies genetic and metabolic changes selected in vivo that are associated with rapid resistance evolution. Index blood cultures displayed susceptibility to all (non-beta-lactam) antibiotics with the exception of trimethoprim/ sulfamethoxazole. One month after initial presentation, during the same encounter, blood cultures were again positive for MRSA, now displaying intermediate resistance to vancomycin and ceftaroline and resistance to daptomycin. Two weeks later, blood cultures were positive for a third time, still intermediate resistant to vancomycin and ceftaroline and resistant to daptomycin. Mutations in mprF and vraT were common to all multidrug resistant isolates whereas mutations in tagH, agrB and saeR and secondary mprF mutation emerged sequentially and transiently resulting in distinct in vitro phenotypes. The baseline mutation rate of the patient isolates was unremarkable ruling out the hypermutator phenotype as a contributor to the rapid emergence of resistance. However, the index isolate demonstrated pronounced tolerance to the antibiotic daptomycin, a phenotype that facilitates the subsequent development of resistance during antibiotic exposure. This study exemplifies the capacity of antibiotic-tolerant pathogens to rapidly develop both stable and transient genetic and phenotypic changes, over the course of a single patient encounter.
Subject(s)
Anti-Bacterial Agents/pharmacology , Bacteremia/microbiology , Bacterial Proteins/genetics , Drug Resistance, Multiple, Bacterial , Methicillin-Resistant Staphylococcus aureus/growth & development , Staphylococcal Infections/microbiology , Aged , Aminoacyltransferases/genetics , Anti-Bacterial Agents/classification , Anti-Bacterial Agents/therapeutic use , Bacteremia/drug therapy , Evolution, Molecular , Humans , Male , Methicillin-Resistant Staphylococcus aureus/drug effects , Methicillin-Resistant Staphylococcus aureus/genetics , Methicillin-Resistant Staphylococcus aureus/isolation & purification , Microbial Sensitivity Tests , Microbial Viability/drug effects , Mutation , Staphylococcal Infections/drug therapy , Transcription Factors/geneticsABSTRACT
The recent emergence of Zika virus (ZIKV) in Brazil and the increasing resistance developed by pathogenic bacteria to nearly all existing antibiotics should be taken as a wakeup call for the international authority as this represents a risk for global public health. The lack of antiviral drugs and effective antibiotics on the market triggers the need to search for safe therapeutics from medicinal plants to fight viral and microbial infections. In the present study, we investigated whether a mangrove plant, Bruguiera gymnorhiza (L.) Lam. (B. gymnorhiza) collected in Mauritius, possesses antimicrobial and antibiotic potentiating abilities and exerts anti-ZIKV activity at non-cytotoxic doses. Microorganisms Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Klebsiella pneumoniae ATCC 70603, methicillin-resistant Staphylococcus aureus ATCC 43300 (MRSA), Salmonella enteritidis ATCC 13076, Sarcina lutea ATCC 9341, Proteus mirabilis ATCC 25933, Bacillus cereus ATCC 11778 and Candida albicans ATCC 26555 were used to evaluate the antimicrobial properties. Ciprofloxacin, chloramphenicol and streptomycin antibiotics were used for assessing antibiotic potentiating activity. ZIKVMC-MR766NIID (ZIKVGFP) was used for assessing anti-ZIKV activity. In silico docking (Autodock 4) and ADME (SwissADME) analyses were performed on collected data. Antimicrobial results revealed that Bruguiera twig ethyl acetate (BTE) was the most potent extract inhibiting the growth of all nine microbes tested, with minimum inhibitory concentrations ranging from 0.19-0.39 mg/mL. BTE showed partial synergy effects against MRSA and Pseudomonas aeruginosa when applied in combination with streptomycin and ciprofloxacin, respectively. By using a recombinant ZIKV-expressing reporter GFP protein, we identified both Bruguiera root aqueous and Bruguiera fruit aqueous extracts as potent inhibitors of ZIKV infection in human epithelial A549 cells. The mechanisms by which such extracts prevented ZIKV infection are linked to the inability of the virus to bind to the host cell surface. In silico docking showed that ZIKV E protein, which is involved in cell receptor binding, could be a target for cryptochlorogenic acid, a chemical compound identified in B. gymnorhiza. From ADME results, cryptochlorogenic acid is predicted to be not orally bioavailable because it is too polar. Scientific data collected in this present work can open a new avenue for the development of potential inhibitors from B. gymnorhiza to fight ZIKV and microbial infections in the future.
Subject(s)
Anti-Bacterial Agents/pharmacology , Antifungal Agents/pharmacology , Antiviral Agents/pharmacology , Plant Extracts/pharmacology , Rhizophoraceae/chemistry , Zika Virus/growth & development , Anti-Bacterial Agents/chemistry , Antifungal Agents/chemistry , Antiviral Agents/chemistry , Brazil , Candida albicans/drug effects , Candida albicans/growth & development , Computer Simulation , Drug Synergism , Escherichia coli/drug effects , Escherichia coli/growth & development , Klebsiella pneumoniae/drug effects , Klebsiella pneumoniae/growth & development , Mauritius , Microbial Sensitivity Tests , Microbial Viability/drug effects , Plant Extracts/chemistry , Proteus mirabilis/drug effects , Proteus mirabilis/growth & development , Pseudomonas aeruginosa/drug effects , Pseudomonas aeruginosa/growth & development , Staphylococcus aureus/drug effects , Staphylococcus aureus/growth & development , Zika Virus/drug effectsABSTRACT
Essential oils (EOs) have been used in cosmetics and food due to their antimicrobial and antiviral effects. However, the applications of EOs are compromised because of their poor aqueous solubility and high volatility. Qiai (Artemisia argyi Levl. et Van. var. argyi cv. Qiai) is a traditional Chinese herb and possesses strong antibacterial activity. Herein, we report an innovative formulation of EO as nanohydrogels, which were prepared through co-assembly of Qiai EO (QEO) and Pluronic F108 (PEG-b-PPG-b-PEG, or PF108) in aqueous solution. QEO was efficiently loaded in the PF108 micelles and formed nanohydrogels by heating the QEO/PF108 mixture solution to 37 °C, by the innate thermo-responsive property of PF108. The encapsulation efficiency and loading capacity of QEO reached 80.2% and 6.8%, respectively. QEO nanohydrogels were more stable than the free QEO with respect to volatilization. Sustained QEO release was achieved at body temperature using the QEO nanohydrogels, with the cumulative release rate reaching 95% in 35 h. In vitro antibacterial test indicated that the QEO nanohydrogels showed stronger antimicrobial activity against S. aureus and E. coli than the free QEO due to the enhanced stability and sustained-release characteristics. It has been attested that thermo-responsive QEO nanohydrogels have good potential as antibacterial cosmetics.