High Levels Of Antimicrobial Activity Research Articles

Evaluation of the long-term protection conferred by an organosilicon-based disinfectant formulation against bacterial contamination of surfaces.

The aim of this work was to evaluate the efficacy of an organosilicon-based, commercially available antimicrobial formulation in the My-shield® product line against bacterial surface contamination. The antimicrobial product was tested in vitro for its long-term persistence on surfaces and effectiveness against Staphylococcus aureus biofilms in comparison to 70% ethanol and 0.1% or 0.6% sodium hypochlorite. Field testing was also conducted over 6 weeks at a university athletic facility. In vitro studies demonstrated the log reductions achieved by the test product, 70% ethanol, and 0.1% sodium hypochlorite were 3.6, 3.1, and 3.2, respectively. The test product persisted on surfaces after washing and scrubbing, and pre-treatment with this product prevented S. aureus surface colonization for up to 30 days. In comparison, pre-treatment with 70% ethanol or 0.6% sodium hypochlorite was not protective against S. aureus biofilm formation after seven days. The field test demonstrated that weekly applications of the test product were more effective at reducing surface bacterial load than daily applications of a control product. The test product conferred greater long-term protection against bacterial growth and biofilm formation by S. aureus than ethanol and sodium hypochlorite. Even with less frequent applications, the test product maintained a high level of antimicrobial activity.

Phytosynthesis via wasted onion peel extract of samarium oxide/silver core/shell nanoparticles for excellent inhibition of microbes

The aqueous onion peel extract (OPE) was used to synthesize silver nanoparticles (Ag-onion), samarium oxide nanoparticles (Sm2O3-onion), and silver/samarium oxide core/shell nanoparticles (Ag@Sm2O3-onion). The produced nanoparticles were characterized by thermal gravimetric analysis (TGA), infrared spectra (FT-IR), absorption spectra (UV–Vis), energy band gap, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), zeta potential, and transmission electron microscopy (TEM). OPE and NPs were tested for the disinfection of some water microbes. XRD analysis exhibited an amorphous structure of samarium oxide in both Sm2O3-onion and Ag@ Sm2O3-onion. The isolated bacteria from the water sample were Bacillus subtilis (OQ073500) and Escherichia coli (MW534699), while the isolated fungi were Alternaria brassicae (MZ266540), Aspergillus flavus (MT550030), Aspergillus penicillioides (MW957971), Pythium ultimum (MW830915), Verticillium dahlia (MW830379), Fusarium acuminatum (MZ266538), Candida albicans (MW534712), and Candida parapsilosis (MW960416). High levels of antimicrobial activity were seen in both the nanoparticles and the aqueous onion peel extract. Based on experimental results, Ag@Sm2O3 demonstrated the highest activity as an effective disinfectant, indicating the effectiveness of the modification process.

In silico identification of novel antimicrobial peptides from the venom gland transcriptome of the spider Argiope bruennichi (Scopoli, 1772).

As the emergence and prevalence of antibiotic-resistant strains have resulted in a global crisis, there is an urgent need for new antimicrobial agents. Antimicrobial peptides (AMPs) exhibit inhibitory activity against a wide spectrum of pathogens and can be utilized as an alternative to conventional antibiotics. In this study, two novel AMPs were identified from the venom transcriptome of the spider Argiope bruennichi (Scopoli, 1772) using in silico methods, and their antimicrobial activity was experimentally validated. Aranetoxin-Ab2a (AATX-Ab2a) and Aranetoxin-Ab3a (AATX-Ab3a) were identified by homology analysis and were predicted to have high levels of antimicrobial activity based on in silico analysis. Both peptides were found to have antibacterial effect against Gram-positive and -negative strains, and, in particular, showed significant inhibitory activity against multidrug-resistant Pseudomonas aeruginosa isolates. In addition, AATX-Ab2a and AATX-Ab3a inhibited animal and vegetable fungal strains, while showing low toxicity to normal human cells. The antimicrobial activity of the peptides was attributed to the increased permeability of microbial membranes. The study described the discovery of novel antibiotic candidates, AATX-Ab2a and AATX-Ab3a, using the spider venom gland transcriptome, and validated an in silico-based method for identifying functional substances from biological resources.

Probiotic-Bacteria (Lactobacillus fermentum)-Wrapped Zinc Oxide Nanoparticles: Biosynthesis, Characterization, and Antibacterial Activity

Recently, fabricated nanoparticles (NPs), which can efficiently penetrate biological systems, have found increased usage in the health and hygiene industries. Microbial enzymes and proteins have recently shown their potential to act as reducing agents for the production of NPs, thereby providing an alternative to physical and chemical methods. Not only is this approach efficient and cost-effective, but it also produces a minimal ecological footprint. In this study, zinc oxide nanoparticles (ZnO NPs) were synthesized using probiotic bacteria (Lactobacillus fermentum) as the reducing and capping agent. Several analytical methods, including Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), ultraviolet–visible spectroscopy (UV–Vis), and atomic force microscopy (AFM), were used to analyze the produced ZnO NPs. The SEM analysis confirmed the spherical form of the nanoparticles and estimated their average size to be between 100 and 120 nm. FT-IR analysis verified that the ZnO NPs’ surfaces contained many functional groups. X-ray diffraction examination evidenced that the biogenically produced nanoparticles were crystalline. AFM analysis revealed that the nanoparticles’ size was about 90–100 nm. The maximum absorption peak, determined via a UV–visible spectrophotometer, was 510 nm. The synthesized ZnO NPs’ antimicrobial activity against various bacterial strains was tested, and the highest level of antimicrobial activity was noted against a Vibrio harveyi strain. The maximum concentration, namely, 20 mM of ZnO NPs, showed the highest antimicrobial activity. These observations indicate that the synthesized ZnO NPs possess remarkable antimicrobial potency. This method is an efficient, environmentally friendly, cost-effective approach for producing ZnO NPs that are useful for various biomedical applications.

Natural day–night temperature variations driving pyrocatalytic wastewater treatment and CO2 reduction based on room-temperature rhombohedral–tetragonal phase transition of lead-free ferroelectric BZT-0.5BCT fibers

Environmental remediation approaches in terms of wastewater treatment and CO2 reduction using environmental energy are highly desirable for an industrialized society. Herein, the pyrocatalytic performance of electrospun lead-free ferroelectric Ba(Ti0.8Zr0.2)O3-x(Ba0.7Ca0.3)TiO3 (BZT-xBCT, x = 0.2, 0.3, 0.4, 0.5, 0.6) micro-nano fibers is investigated, and BZT-0.5BCT is identified as an efficient pyrocatalyst for water pollutants decomposition driven by rhombohedral–tetragonal (R-T) phase transition. Phase changes can induce high pyroelectric coefficients. In response to 0–60 °C thermal cycles, the decomposition ratio of Rhodamine B (RhB) by BZT-0.5BCT fibers after nine thermal cycles is approximately 70%. Moreover, under outdoor day-night temperature fluctuations, about 76% of RhB and 95% of methylene blue (MB) can be degraded after 10 and 7 days respectively because BZT-0.5BCT has an R-T phase change point of around 30 °C. For Cr(VI) (potassium dichromate) and tetracycline (TE), the fibers also show good pyrocatalytic degradation ability. Due to destruction of bacterial cell membranes by superoxide groups, high levels of antimicrobial activity could also be achieved against Escherichia coli (99.99%) and Staphylococcus aureus (92.83%). Furthermore, the pyrocatalytic reduction of CO2 to acetaldehyde by BZT-0.5BCT can reach approximately 382.47 μmol g−1 after 20 thermal cycles of 0–60 °C. Therefore, such outstanding catalytic performance of pyroelectric BZT-0.5BCT fibers enables pyroelectric catalysis as a potential approach for both all-round wastewater treatment and CO2 reduction.

Analysis and Evaluation of the Flagellin Activity of Bacillus amyloliquefaciens Ba168 Antimicrobial Proteins against Penicillium expansum.

Blue mold caused by Penicillium expansum is one of the most common apple diseases, and it is becoming a serious threat in apple production. The strain Bacillus amyloliquefaciens Ba168 showed high levels of antimicrobial activity in our previous study. To analyze the antimicrobial protein of Ba168, a high-resolution LC-MS/MS proteomic analysis was performed. A total of 1155 proteins were identified from 5233 unique peptides. A total of 16 potential antimicrobial-activity-related proteins were identified; 10 of these proteins have direct antimicrobial effects, while 6 of these proteins are associated with the formation of antimicrobial substances. Then, an antifungal protein of Ba168 was isolated and purified by the sequential chromatography of DEAE Bio-sep FF anion exchange and Sephadex G-75. The single protein, named BP8-2, showed antifungal activity towards Penicillium expansum. The peptide mass fingerprinting of the protein band of BP8-2 had a high similarity with the amino acid sequences of flagellin protein. The results showed that BP8-2 significantly inhibited the growth of P. expansum and slowed the spread of apple blue mold. The results indicated that flagellin is one of the important antimicrobial substances from Ba168.

Antimicrobial and Aging Properties of Ag-, Ag/Cu-, and Ag Cluster-Doped Amorphous Carbon Coatings Produced by Magnetron Sputtering for Space Applications.

Inside a spacecraft, the temperature and humidity, suitable for the human crew onboard, also creates an ideal breeding environment for the proliferation of bacteria and fungi; this can present a hazard to human health and create issues for the safe running of equipment. To address this issue, wear-resistant antimicrobial thin films prepared by magnetron sputtering were developed, with the aim to coat key internal components within spacecrafts. Silver and copper are among the most studied active bactericidal materials, thus this work investigated the antibacterial properties of amorphous carbon coatings, doped with either silver, silver and copper, or with silver clusters. The longevity of these antimicrobial coatings, which is heavily influenced by metal diffusion within the coating, was also investigated. With a conventional approach, amorphous carbon coatings were prepared by cosputtering, to generate coatings that contained a range of silver and copper concentrations. In addition, coatings containing silver clusters were prepared using a separate cluster source to better control the metal particle size distribution in the amorphous carbon matrix. The particle size distributions were characterized by grazing-incidence small-angle X-ray scattering (GISAXS). Antibacterial tests were performed under both terrestrial gravity and microgravity conditions, to simulate the condition in space. Results show that although silver-doped coatings possess extremely high levels of antimicrobial activity, silver cluster-doped coatings are equally effective, while being more long-lived, despite containing a lower absolute silver concentration.

Analysis of the resistance of clinical isolates of Escherichia coli to antimicrobial agents in single-centre study

The aim of this research is to assess the phenotypic resistance to antimicrobial agents of clinical isolates of Escherichia coli from patients undergoing treatment in various departments of the oncological clinic in Minsk. In this work, 34 clinical isolates of Escherichia coli were studied. Species identification and determination of sensitivity to antibiotics was performed on a Vitek2Compact analyzer (BioMerieux). The resistance / sensitivity of clinical bacterial isolates to antiseptics was determined by the agar dilution method. The profiles of phenotypic resistance / sensitivity of 34 clinical E. coli isolates to 15 antibiotics and 8 antiseptics were determined. Based on the results of a comparative analysis, 5 bacterial isolates were assigned to one sensitivity profile. 80-100% of the studied bacterial isolates were susceptible to amoxicillin/clavulanic acid, ertapenem, imipenem, meropenem, amikacin, gentamicin, fosfomycin, nitrofurantoin. 26-42% of the E. coli isolates showed resistance to cefotaxime, ceftazidime, cefepime, ciprofloxacin and norfloxacin. Multiple resistance (to 4 antibiotics or more) was characteristic for 35.3% of the studied isolates of microorganisms. One strain of E. coli isolate was resistant to 11 studied antibiotics. Analysis of the resistance of clinical E. coli isolates to antiseptics showed that iodinol, iodiskin, septomyrin were ineffective in inhibiting bacterial growth on an agar plate. A high level of antimicrobial activity against E. coli was found in the antiseptic agents chlorhexidine bigluconate and hydrogen peroxide. High efficacy of amoxicillin/clavulanic acid, ertapenem, imipenem, meropenem, amikacin, gentamicin, fosfomycin, nitrofurantoin and low efficacy of cefotaxime, ceftazidime, cefepime, ciprofloxacin, norfloxacin against clinical isolates of E. coli circulating in the oncological clinic of Minsk was revealed. A phenotypic resistance of E. coli to pharmaceutical forms of antiseptics iodinol, iodiskin and septomyrin was established.

Probiotic Characterization of Indigenous Kocuria flava Y4 Strain Isolated from Dioscorea villosa Leaves.

This aim of the study was to isolate and screen potential probiotics from Dioscorea villosa leaves. The potential isolate Y4 was obtained from the Dioscorea villosa leaves, and its ability to grow in a medium containing high NaCl concentrations (2-10%) indicated its negative hemolytic activity. Furthermore, Y4 demonstrated inhibitory activity against human pathogens, such as Klebsiella pneumonia, Staphylococcus aureus, Citrobacter koseri, and Vibrio cholerae, as well as towards a plant pathogen isolate OR-2 (obtained from Citrus sinensis). Some biologically important functional groups of Y4 metabolites, such as sulfoxide; aliphatic ether; 1, 2, 3-trisubstituted, tertiary alcohol: vinyl ether; aromatic amine; carboxylic acid; nitro compound; alkene mono-substituted; and alcohol, were identified through FTIR analysis. The 16S rRNA sequencing and subsequent phylogenetic tree analysis indicated that Y4 and OR-2 are the closest neighbors to Kocuria flava (GenBank accession no. MT773277) and Pantoea dispersa (GenBank accession no. MT766308), respectively. The potential isolate Y4 was found to exhibit adhesion, auto-aggregation, co-aggregation, and weak biofilm activity. It also exhibited a high level of antimicrobial activity and antibiotic susceptibility. The safety of K. flava Y4 isolate, which is proposed to be a probiotic, was evaluated through acute oral toxicity test and biogenic amine production test. Moreover, the preservation potential of isolate Y4 was assessed through application on fruits under different temperatures. Thus, our results confirmed that Kocuria flava Y4 is a prospective probiotic and could also be used for the preservation of fruits.

Effects of Green Tea Powder, Pomegranate Peel Powder, Epicatechin and Punicalagin Additives on Antimicrobial, Antioxidant Potential and Quality Properties of Raw Meatballs

Alternative technologies, which have been developed in order to meet the consumers’ demand for nourishing and healthy meat and meat products, are followed by the food industry. In the present study, it was determined, using the HPLC method, that green tea contains a high level of epicatechin (EP) under optimal conditions and that pomegranate peel contains a high level of punicalagin (PN). Green tea, pomegranate peel, EP and PN were added to meatballs at different concentrations in eight groups. The antioxidant capacities of extracts were measured. The antimicrobial activity was examined for 72 h using three different food pathogens. The highest level of antimicrobial activity was achieved in the 1% punicalagin group, whereas the minimum inhibition concentration (L. monocytogenes, S. typhimurium) was found to be 1.87 mg/mL. A statistically significant decrease was found in FFA, POV and TBARS levels of meatballs on different days of storage (p < 0.05). When compared to the control group, the bioactive compounds preserved the microbiological and chemical properties of meatballs during storage at +4 °C (14 days). It was concluded that the extracts with high EP and PN concentrations can be used as bio-preservative agents for meat and meat products.

Antimicrobial activitiy of oak honey (Quercus spp.) on the biofilm microorganisms

Objective: The aim of this study is to determine antimicrobial properties of oak honey on biofilm microorganisms and its potential usage. Material and Methods: The oak honey was collected in 2 years from the same region (OHPH/OHSH). Susceptibility patterns of clinical strains of three bacteria (Escherichia coli-ATCC 35218), (Staphyllococcus aureus-ATCC 29213) , (Pseudomonas aeruginosa -ATCC 27853) and one yeast (Candida albicans -ATCC 10231) strains that can form biofilm communities to oak honey were assessed by the disc diffusion method. Results: The results revealed that oak honey has high level of antimicrobial activity to the pathogens. The antifungal activity against C. albicans was not measured clearly though, bacteriostatic effect showed itself as a secondary zone. Conclusion: Oak honey might have a big potential for its antimicrobial properties in near future.

Effect-Directed Profiling of 17 Different Fortified Plant Extracts by High-Performance Thin-Layer Chromatography Combined with Six Planar Assays and High-Resolution Mass Spectrometry.

An effect-directed profiling method was developed to investigate 17 different fortified plant extracts for potential benefits. Six planar effect-directed assays were piezoelectrically sprayed on the samples separated side-by-side by high-performance thin-layer chromatography. Multipotent compounds with antibacterial, α-glucosidase, β-glucosidase, AChE, tyrosinase and/or β-glucuronidase-inhibiting effects were detected in most fortified plant extracts. A comparatively high level of antimicrobial activity was observed for Eleutherococcus, hops, grape pomace, passiflora, rosemary and Eschscholzia. Except in red vine, black radish and horse tail, strong enzyme inhibiting compounds were also detected. Most plants with anti-α-glucosidase activity also inhibited β-glucosidase. Green tea, lemon balm and rosemary were identified as multipotent plants. Their multipotent compound zones were characterized by high-resolution mass spectrometry to be catechins, rosmarinic acid, chlorogenic acid and gallic acid. The results pointed to antibacterial and enzymatic effects that were not yet known for plants such as Eleutherococcus and for compounds such as cynaratriol and caffeine. The nontarget effect-directed profiling with multi-imaging is of high benefit for routine inspections, as it provides comprehensive information on the quality and safety of the plant extracts with respect to the global production chain. In this study, it not only confirmed what was expected, but also identified multipotent plants and compounds, and revealed new bioactivity effects.

Derivatisation of metronidazole enhances cytotoxic effect against Acanthamoeba genotype T4 isolates and leads to cytomorphological changes in trophozoites

Amoebae of the genus Acanthamoeba are worldwide distributed causative agents of serious human infections such as granulomatous amoebic encephalitis (GAE) and Acanthamoeba keratitis (AK). To date, treatment of these infections is non-uniform and frequently unsuccessful. Recently, the phosphonium salts were studied for their high levels of antimicrobial activity. This work was aimed to investigate the cytotoxic effect of metronidazole and two phosphonium salts (PS1, PS2) on two clinical Acanthamoeba isolates. The isolates showed distinctly higher susceptibility to both phosphonium salts than to metronidazole. The highest susceptibility was noted to PS1 after 48 h of incubation. Metronidazole derivate PS2 showed higher susceptibility than metronidazole. The values of EC50 of PS2 were approximately twenty times lower than EC50 of metronidazole for Acanthamoeba lugdunensis strain and sixteen times lower for Acanthamoeba quina strain after 48 h. Although the therapeutic effect of metronidazole in Acanthamoeba infections is usually insufficient, its derivatisation can result in a significantly higher amoebicidal effect. Cytomorphological changes of trophozoites after exposure to tested compounds included rounding up of the cells, damage of membrane integrity, presence of pathological protrusions, elongation of the cells or pseudocyst-like stages. Obtained results indicate possible therapeutic potential of studied phosphonium salts.

Characterization of bacteriocin related genes discovered in a novel probiotic isolate Enterococcus faecium W1

Aims: To isolate and characterize the bacteriocin activity identified by the genomic analysis of a novel enterococcal isolate, Enterococcus faecium W1 Methods and Results: Culture fermentates of a novel E. faecium isolate, W1 showed high levels of antimicrobial activity against Listeria monocytogenesisand a variety of other Gram+ve and Gram-ve bacteria. Ammonium sulphate precipitation of the fermentates followed by hydrophobic interaction chromatography showed bactericidal activity correlated with fractions containing only low molecular weight proteins. The same fractions had activity on human cancer cell line HT-29 measured by cytotoxicity assay (MTT) and apoptosis induction. Whole-genome sequencing of E. faecium W1 revealed five bacteriocin related gene clusters, a lack of virulence factors and lack of antibiotic resistance genes. To confirm that antimicrobial activity was correlated with the bacteriocin genes identified, selected bacteriocin genes were cloned and expressed as His-tagged proteins in E. coli. Bactericidal activity against L. monocytogenes was associated with protein purified by metal affinity chromatography. A structure-function analysis to investigate the role of key residues in activity is ongoing. Conclusion: E. faecium W1 is a promising candidate for use as a probiotic supplement or in food preservation. The bacteriocin related genes are functional and could be improved for future use as antimicrobial and cancer cell therapeutics. Significance and Impact of the Study: There is a need for new approaches to the growing problem of antibiotic resistance. Expression of bacteriocins identified in E. faecium W1 could contribute to this endeavour in addition to its use as a probiotic organism.

The Antibacterial Effect of Silver Nanoparticles on Staphylococcus epidermidis Strains with Different Biofilm-Forming Ability.

Among many infectious diseases, infections caused by pathogens of Staphylococcus species exert a substantial influence upon human health, mainly due to their continuous presence on human skin and mucous membranes. For that reason, an intensive search for new, effective anistaphyloccocal agents can currently be observed worldwide. In recent years, there has been growing interest in nanoparticles, as compounds with potential antibacterial effect. The antibacterial activity of silver containing substances has been well recognized, but thoughtful studies focused on the effect of silver nanoparticles on bacterial biofilm are scarce. The aim of this study was to assess the influence of silver nanoparticles (AgNPs) with particle sizes in the range between 10 and 100 nm, and a concentration range from 1 to 10 µg/mL, upon Staphylococcus epidermidis strains with different biofilm-forming abilities (BFAs). The studies revealed the highest level of antimicrobial activity for AgNPs in relation to S. epidermidis strains with BFA, and what is more, the observed effect was proportional to the increasing particles’ size, and strains not forming biofilm were more susceptible to silver nanoparticles with the smallest examined size, which was 10 nm.

Functional antimicrobial coatings for application on microbiologically contaminated surfaces

ABSTRACT Increases in diseases caused by pathogenic microorganisms and their growing resistances to antibiotics rise the need for the development of new antimicrobial materials. Silver nanoparticles exhibit high levels of antimicrobial activity. Compositions based on poly (vinyl alcohol) with different nanosilver contents were obtained and analysed. Materials differed in both the content of functional substances and their preparation parameters Research techniques, including spectrophotometry (UV-Vis) dynamic light scattering (DLS), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and transmission electron microscopy with an energy-dispersive X-ray spectrometer (TEM-EDX), were applied. The rheological properties of the compositions were tested. They may qualify as non-Newtonian, pseudoplastic fluids. Analyses of the forces needed to tear the adhesives were used to assess the adhesion properties. The antimicrobial properties against an Aspergillus niger strain are discussed. Concerning the bioavailability, the results revealed that, when the composition contacted amodel dermal membrane, the nanoparticles were unable to penetrate it.

Synthesis and antibacterial activity of a series novel 5,7-diisoprenyloxyflavone derivatives

In the present study, a series of novel 5,7-diisoprenyloxyflavone derivatives were designed, synthesized, and evaluated for their antibacterial activity. Most of these compounds displayed significant antibacterial effects against Gram-positive bacteria, especially against strains of multidrug-resistant clinical isolates. Compounds 4c, 4g, 4i, 4j, 4k, 4l, 4n, 4q and 4t showed high levels of antimicrobial activity against Staphylococcus aureus RN4220 with minimum inhibitory concentrations of 4.0-20 µM. Compound 4k showed the most potent activity among these compounds against all multidrug-resistant clinical isolates tested. Unfortunately, none of the compounds were active against Gram-negative bacteria at the doses of 24-164 µM.

Antibacterial mechanism of Tetrapleura tetraptera extract against Escherichia coli and Staphylococcus aureus and its application in pork

AbstractThe antibacterial activity and the mechanism of Tetrapleura tetraptera root extract against Escherichia coli and Staphylococcus aureus were investigated. The mechanism of action of T. tetraptera on tested bacterial species was predominantly characterized by the study of transmission electron microscopy, which revealed severe damage on the primary target which affected the cell integrity and cell membrane permeability. The loss of soluble proteins studied by bacterial protein sodium dodecyl sulfate–polyacrylamide gel electrophoresis analysis and the decreased adenosine triphosphate and DNA contents confirmed the leakage of cell wall. In addition, the studies revealed that the root extract of T. tetraptera could also disrupt the respiratory metabolism by inhibiting the bacteria through the Embden–Meyerhof–Parnas and the hexose monophosphate pathways. T. tetraptera extract possessed a high level of antimicrobial activity in pork, which significantly reduced total viable bacterial population. This study clearly indicates that the T. tetraptera could be a potential source of new antimicrobial agent which has proven effective activity against antibiotic‐resistant strains of pathogens.Practical ApplicationsTetrapleura tetraptera is a flowering plant native to Africa with a wide range of applicability in local cuisines and traditional medicine. The T. tetraptera root extract possesses high antimicrobial activity against both gram‐positive and gram‐negative bacteria. This study could contribute to the better understanding of antibacterial mechanism of T. tetraptera. As a natural food preservative, it has broad prospect to be utilized in the meat industry.

Characterization and antimicrobial mechanism of CF-14, a new antimicrobial peptide from the epidermal mucus of catfish

In this study, we identified a novel antibacterial peptide, RIVELTLPRVSVRL-NH2 (named CF-14), derived from the epidermal mucus of catfish and characterized its antimicrobial activity. Analysis of antimicrobial activity and hemolytic activity of CF-14 revealed broad spectrum, high levels of antimicrobial activity and low toxicity to eukaryotic cells. CF-14 remained stable at pH values ranging from 4.0 to 12.0 and remained bioactive when exposed to high temperature. CD analysis indicated that CF-14 forms a random coil in PBS buffer and an α-helical conformation in the membrane-mimetic 2.5% SDS micelle. Additionally, the antibacterial mechanism of CF-14 against Shewanella putrefaciens was investigated. Membrane permeability experiments confirmed that CF-14 could increase cell wall membrane permeability and cause nucleotide leakage. Moreover, observations performed using scanning electron and confocal microscopy indicated that CF-14 could penetrate into the cell membranes of S. putrefaciens and accumulate in bacterial cells, but did not break down cell membranes. Further, electrophoresis analysis demonstrated that CF-14 possesses DNA-binding affinity. The results provide a substantial basis for future application of CF-14, a novel cell-penetrating peptide (CPP) derived from catfish.

Evaluation of anti-microbial activity of filtrates of Lactobacillus rhamnosus and Saccharomyces boulardii against antibiotic-resistant gram-negative bacteria

The article presents the results of the first study on the influence of biologically active substances Lactobacillus rhamnosus GG ATCC 53103 and Saccharomyces boulardii, obtained according to the author`s method, on growth of gram-negative bacteria with broad medical resistance: Pseudomonas aeruginosa PR, Klebsiella pneumoniae PR, Lelliottia amnigena (Enterobacter amnigenus) PR using the spectrophotometric method. Disintegrates of L. rhamnosus GG and S. boulardii were obtained using low-frequency ultrasound processing of suspension of probiotic strains, and metabolites – through cultivation of lactobacteria and saccharomycetes in disintegrates of probiotic microorganisms. To samples of test-cultures with studied filtrates of disintegrates or metabolites we added growth medium and cultivated them (period of monitoring was 5- and 24-hours). Results of the studies were expressed as the percentage of inhibition of increment in polyresistant gram-negative bacteria under the impact of biologically active substances of probiotic microorganisms. Five-hour incubation of test-strains with the studied samples of lactobacteria led to inhibition of their growth properties by 85.6–96.7%. Growth of bacteria under the impact of substances of saccharomycetes was inhibted by 45.1–92.5%. Twenty-four hour exposure of the test-cultures in filtrates of L. rhamnosus GG and S. boulardii caused 100% inhibition of P. aeruginosa and L. amnigena polyresistant strains. Temporal interval of cultivation directly proportionally affected the extent of inhibition of growth of microorganisms: we determined direct correlation dependence within 0.789–0.991. Maximum inhibition of increment of the studied pathogens was observed under the influence of metabolites of lactobacteria, obtained by cultivating primary producers in their disintegrate. We determined a high level of anti-microbial activity of metabolites from L. rhamnosus GG and S. boulardii obtained by cultivation of probiotics in disintegrates against bacteria resistant to a broad range of preparations, which allows us to consider these substances as promising for development of anti-microbial preparations of a new generation against etiologically significant antibiotic-resistant gram-negative microorganisms.