Inhibition Halos Research Articles

Optimized Incorporation of Silver Nanoparticles onto Cotton Fabric Using k-Carrageenan Coatings for Enhanced Antimicrobial Properties.

The incorporation of bactericidal properties into textiles is a widely sought-after aspect, and silver nanoparticles (AgNPs) can be used for this. Here, we evaluate a strategy for incorporating AgNPs into a cotton fabric. For this purpose, a bactericidal textile coating based on a composite of AgNPs and kappa-carrageenan (k-CA) was proposed. The composite was obtained by heating the silver precursor (AgNO3) directly in k-CA solution for green synthesis and in situ AgNPs stabilization. Cotton substrates were added to the heated composite solution for surface impregnation and hydrogel film formation after cooling. Direct synthesis of AgNPs on a fabric was also tested. The results showed that the application of a coating based on k-CA/AgNPs composite can achieve more than twice the silver loading on the fabric surface compared to the textile subjected to direct AgNPs incorporation. Furthermore, silver release tests in water showed that higher Ag+ levels were reached for k-CA/AgNPs-coated cotton. Therefore, inoculation tests with the bacteria Staphylococcus aureus (SA) using the agar diffusion method showed that samples covered with the composite resulted in significantly larger inhibition halos. This indicated that the use of the composite as a coating for cotton fabric improved its bactericidal activity against SA.

Crystal Structure, Photophysical Properties and Antibacterial Activity of a Cd(II) Complex with Trans-2,3,4-Trimethoxycinnamic Acid and 4,4'-Bipyridine Ligands.

A new coordination polymer {[Cd(C12H13O5)2(4,4'-bpy)(H2O)2]}n (Cd-Tmca-bpy) was constructed with trans-2,3,4-Trimethoxycinnamic acid (HTmca) and 4,4'-Bipyridine (4,4'-bpy) ligands. This complex was structurally characterized on the basis of elemental analysis, infrared (IR) spectroscopy, powder X-ray diffraction and thermogravimetric analyses. X-ray crystallography revealed that the complex was monoclinic, space group C2/c. The Cd(II) ion in the complex was six coordinated, adopting an octahedron geometry. The neighboring Cd(II) ions linked linear ligand 4,4'-bpy molecules to form an infinite 1D chain. The 1D chain was further interlinked by O-H···O and C-H···O hydrogen bonds, resulting in a 3-D supramolecular framework. Meanwhile, the photoluminescence spectrum of the Cd(II) complex at room temperature exhibited an emission maximum at 475 nm. Using the time-dependent density functional theory (TD-DFT) method, the electronic absorption spectra of the Cd(II) complex was predicted. A good agreement was achieved between the predicted spectra and the experimental data. Bioactivity studies showed that the complex exhibited significant inhibition halos against Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus).

Evaluation of the antimicrobial properties of natural extracts of Ganoderma lucidum

There is a growing importance of alternative anticancer and anti-inflammatory treatments. Current interest lies in natural medicine and secondary metabolites present in plants, particularly focusing on triterpenes. Ganoderma lucidum is a fungal species of significant commercial interest due to its therapeutic and medicinal properties resulting from secondary metabolites such as polysaccharides and triterpenes. These compounds exhibit antitumor activity and bolster the immune system. The study aimed to assess the antimicrobial activity of G. lucidumextracts, both commercial and wild. The content of ganoderic acids in all extracts showed a slight difference in concentration between commercial and wild extracts. However, no bacterial inhibition halos were observed in any of the strains used. The presence of varying concentrations of ganoderic acids among treatments underscores the importance of optimizing and standardizing a comprehensive strategy for extracting secondary metabolites, focusing on producing high-quality supplements and pharmaceutical products. Furthermore, preserving the stability of the obtained triterpenes is necessary due to their importance in the medicinal properties of the fungus.

Study the Effect of Mango Peel Extract on Pathogenic Bacteria Isolated From Urinary Tract Infection

Objective: Urinary tract infection is an infection that affects any part of the urinary system. The urinary system includes the kidneys, ureters, bladder, and urethra. Most infections affect the lower part of the system, the bladder and urethra. The infection may reach the kidneys and develop into kidney failure. This study aimed to find a new natural extract against the germs that cause the disease to help reduce the large number of patients suffering from the disease. Methods: This study included plant extraction for mango peels by used ethanol 70% in soxhlet apparatus. Urine samples were collected from dogs, and samples containing inflammatory cells were isolated and cultured. The cultured bacteria were identified by used morphology of colony, Gram stain and biochemical tests. Biofilm made by used microliter plate method, activity of mango peels extract (MPE) was measured by well agar diffusion method, the concentration of minimal inhibitory (MIC), and the concentration of minimal bactericide (MBC) was measured by broth dilution method, Statistical analysis was used to determine the effectiveness of the extract. Results: Diagnosis for isolated pathogenic bacteria of urine samples which contained inflammatory cells staph aureus, E.coli, pseudomonas. The best Biofilm formation of staph aureus (91.7)% followed by E.coli ( 83.4), pseudomonas (16.7). The highest effectiveness of mango peels extract activity was recorded against staph aureus (22-26) mm zone of inhibition and (17-19)mm of E.coli ciprofloxacin gave (22-25)mm zone of inhibition of S.aureus and (18-22)mm E.coli . The concentration of minimal inhibitory (2mg/ml) of staph aureus and (4mg/ml) E.coli The concentration of minimal bactericide (4mg/ml) of staph aureus and (8mg/ml) E.coli. The Statistical analysis of inhibition halos of staph aureus (24 ± 0.6 ) highest than E.coli (18 ± 0.2) of MPE and the Statistical analysis of inhibition halos of staph aureus(23± 0.2) and(20± 0.6 ) E.coli of ciprofloxacin. Conclusion: Mango peels extract have antibacterial effect against both gram positive and gram negative pathogenic bacteria isolated from UTI. Use of extract is help in treating patients with urinary tract infection, MPE contributing and limiting the progression of the condition.

Optimization of fermentation temperature and time for production of an antifungal extract from Bacillus amyloliquefaciens B17

Background/Objective. Species of Bacillus are currently gaining interest because its ability to produce secondary metabolites with antifungal properties against various plant pathogenic fungi. The objective of this study was to optimize fermentation temperature and time for antifungal extract production by Bacillus amyloliquefaciens B17 and to verify its activity against plant pathogenic fungi Gilbertella persicaria, Choanephora cucurbitarum, Colletotrichum asianum, and Botrytis cinerea. Materials and Methods. A central composite design (CCD) with two factors and five levels (fermentation temperature: 23.7, 25, 28, 31, and 32.2 °C and fermentation time: 25, 46, 95, 144, and 164. 3 h) was used. Thirteen combinations of temperature and fermentation time were randomly performed. The thirteen crude extracts of B. amyloliquefaciens B17 were obtained from the cell-free fermentation broth by acid precipitation followed by alkaline solubilization. The response variable was the diameter of the inhibition halos generated by placing drops of the different crude extracts onto the medium already inoculated with a suspension of Gilbertella persicaria spores. Results. The optimal conditions for the production of the extract with the greatest antifungal activity in B. amyloliquefaciens B17 were 26.8 °C and 158.6 h. Conclusion. The optimized crude extract from B. amyloliquefaciens B17 exhibited a strong ability to inhibit mycelial growth and spore germination of Gilbertella persicaria, Choanephora cucurbitarum, Colletotrichum asianum, and Botrytis cinerea.

Lippia origanoides and Thymus vulgaris Essential Oils Synergize with Ampicillin against Extended-Spectrum Beta-Lactamase-Producing Escherichia coli.

(1) Background: Could compounds such as monoterpenes and sesquiterpenes present in essential plant oils inhibit bacterial growth as an alternative to help mitigate bacterial resistance? The purpose of this study is evaluating the in vitro antibacterial effect of Lippia organoides EO (LEO) and Thymus vulgaris EO (TEO), individually and in combination with ampicillin, against extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli strains; (2) Methods: Experimental in vitro design with post-test. The EOs were obtained by hydrodistillation and were analyzed by GC. ESBL-producing E. coli strains used were selected from urine cultures and the blaCTX-M and blaTEM resistance genes were identified by end point PCR. The disk diffusion method was used for the susceptibility tests. The MICs and MBCs were determined by microdilution test. Finally, the interaction effect was observed by checkerboard assay; (3) Results: A 39.9% decrease in the growth of the strain thymol in TEO and 70.4% in carvacrol in LEO was shown, observing inhibition halos of 32 mm for both EOs. MICs of 632 and 892 μg/mL for LEO and 738 and 940 μg/mL for TEO were determined. Finally, it was observed that, at low doses, there is a synergistic effect between TEO + LEO and EOs + ampicillin; (4) Conclusions: The findings demonstrate that TEO and LEO have an inhibitory effect on ESBL-producing E. coli, suggesting that they are candidates for further studies in the formulation of antibiotics to reduce bacterial resistance to traditional antibiotics.

Development of superhydrophilic ZnOX/TiO2 with visible light-induced self-cleaning and antibacterial properties

Many studies aimed to improve the antibacterial ability and applicability of antibacterial surface materials by altering their chemical composition and structure. In this study, we successfully prepared a multifunctional ZnOX/TiO2 (0<X ≤ 2) nanocomposites by a sol-gel method, which exhibits visible light responsive self-cleaning, antibacterial adhesion, and antimicrobial properties. In the comparison of the three zinc sources, it was found that the ZnOX/TiO2 prepared with zinc sulfate doping had a water contact angle of only 1.7°, with enhanced hydrophilicity, and exhibited the best photocatalytic activity under visible light, with a removal rate of up to 90.2% of methylene orange (MO). Antibacterial tests revealed the average diameters of the inhibition halos for Escherichia coli and Staphylococcus aureus were 10 and 12 mm, respectively, thereby showing excellent antibacterial activity under visible light. The low photogenerated electron-hole recombination and the high rates of ·OH and ·O2- generation through photo-induced interface charge transfer in ZnOX/TiO2 composite, which is the main reason for enhancing the photocatalytic antibacterial activity under visible light irradiation. Release of Zn2+ species, resulting in significant antibacterial performance even under dark conditions. This study combines doping and surface modification, introduce abundant surface hydroxyl groups to endow the composite material surface with superhydrophilicity, anti-bacterial adhesion, and antibacterial properties that can meet the needs of clean and antibacterial surfaces in medical.

FLORES: VERDADEIRO RESERVATÓRIO DE ANTIBIÓTICOS E RESINAS ANTIMICROBIANAS

Microbial resistance is the versatility of microorganisms not to succumb to the harsh environment and to maintain themselves in all environmental compartments, organisms and living cells. This phenomenon is a mechanism of acquired adaptation that directly impacts humans and animals, as these organisms have disharmonious relationships with them, causing several practically intractable pathologies, leading to the death of the host. The World Health Organization points out, every year, the increase of microorganisms resistant to drugs, both for domestic and hospital use, publishing in its reports, the frightening reality of organisms resistant to all commercialized drugs, being called Pan-resistant. Therefore, the objective of the study is to investigate in fresh, freshly picked flowers, a new substance with antimicrobial and/or bactericidal power against Enterobacteria. Of the 66 flowers studied, 29 showed some promising antibiotic/bactericidal effect, with passion fruit and mallow being the ones that stood out the most, followed by dahlia and munguba. The hexane extract of the passion fruit flower showed a halo of formation greater than Gentamicin and Amikacin, of 22 mm with only 0.5 g of the flower. Several studies describe the complexity of substances found in passion fruit flower, making it difficult to indicate a possible organic group or the combination of mixed organic compounds with synergistic effects. The mallow flower, which has the coumarin malvina and the terpenoid malvona exclusively, presented an inhibition halo comparable to antibiotic discs already used in drug therapies, with an effect on all three Enterobacteriaceae studied, Salmonella serotype thyphimurium NCTC® 12023, multiresistant Escherichia coli, and the pan-resistant bacterium kpcKlebsiella planticola2019, being a great antimicrobial potential. For a similar bacteriostatic effect of propolis, 22 flowers expressed a glutinous, expansive and resinous effect, in order to immobilize and prevent an aggressive and pathogenic agent from expressing its metabolism or life cycle, with the highlight being azalea, presenting the largest halo.Thus, it is possible to infer that the production of propolis by bees is the sum of the harvesting of resins from several species of flowers, both exotic and native, in the manufacture of the best resin to protect their hives. Finally, the trend of phytotherapy combined with modern biotechnological science may be the key to success against highly specialized parasites. This study falls under SDG 13 (quality health) and SDG 15 (life on land) of the development goals.

Vaginal Ovule Loaded with Bismuth Lipophilic Nanoparticles and Cetylpyridinium Chloride Inhibits Human Cervical Carcinoma and Candida albicans Growth.

Bismuth lipophilic nanoparticles (BisBAL NPs) and cetylpyridinium chloride (CPC) are antineoplastic and antimicrobial in vitro. As a next pre-clinical step, a clinically viable dosage form for vaginal application was developed. Compendial pharmacopeial tests (mass uniformity, disintegration, and compressive mechanics) and inductively coupled plasma optical emission spectroscopy were conducted on in-house developed glycerinated gelatin (60:15 v/w) vaginal ovules containing BisBAL NP-CPC. The antimycotic activity of BisBAL NP-CPC vaginal ovules was analyzed using disk diffusion and cell viability XTT assays. The antitumor properties of BisBAL NP-CPC vaginal ovules were assessed by cell viability MTT tests. BisBAL NP-CPC and drug-free vaginal ovules deposited into ex vivo porcine vaginas disaggregated without signs of adverse cytotoxicity within the timespan of clinical efficacy. BisBAL NP-CPC vaginal ovules demonstrated antifungal efficacy comparable to miconazole: C. albicans growth inhibition haloes in diffusion tests were 23 ± 0.968 mm (n = 3) for BisBAL NP-CPC and 20.35 ± 0.899 mm (n = 3) for miconazole. Likewise, BisBAL NP-CPC vaginal ovules reduced HeLa cell growth by 81%, outperforming the clinical reference of 500 μM 5-fluouracil, which induced a 70% growth inhibition. BisBAL NP-CPC incorporated into glycerinated gelatin vaginal ovules constitute an innovative drug delivery system for topical antimycotic and anti-cervical carcinoma treatments.

Studying the pathogenic Streptomyces strains responsible for causing potato common scab in Iran and assessing the efficacy of native S. fimicarius-ghR and S. rochei-FsG in reducing scab lesion development in both potato and radish hosts in vivo

ABSTRACT Potato common scab an important widespread disease caused by Streptomyces species, usually can diminish the market value of tubers. None of the disease management methods is considered efficient. Non-pathogenic Streptomyces species owing to their source of bioactive compounds can alleviate scab severity and strengthen plant vigour. During our survey, three pathogenic strains with atypical composition of Pathogenicity Island (PAI) marker genes prevented radish seed germination by ≥98% and exhibited coalescing superficial, raised or mild pitted lesions in pot trials. Based on 16S rRNA and rpoB sequencing, Streptomyces sp. (FG1 and AAb) and S. rochei-HGs were identified. Our research findings have led us to identify S. rochei-HGs as a novel scab-causing species of potato. In addition, two beneficial Streptomyces strains obtained from potato rhizosphere and soil, including S. fimicarius-ghR and S. rochei-FsG, inhibited streptomyces sp.-FG1 growth with the inhibition halo ≥30 mm on agar plates, alleviated the lesion severity index and showed the control efficacy of 88.88 ± 6.41% and 83.33 ± 16.94% on potato, respectively under greenhouse conditions. Both of them can produce siderophore, IAA and solubilise phosphate. By measuring the plant growth attributes, the application of ghR and FsG strains in pathogen-infected soil showed enhancement in potato root and shoot length as well as radish compared with the controls. Evaluation of the inhibitory compounds of studied antagonists by chemistry methods is ongoing. The disease suppressiveness of strains and their plant growth induction should also be validated at the field level.

The antibacterial, antioxidant, and insecticidal activities of essential oils from Thymus vulgaris L., Salvia officinalis L., and Ocimum basilicum L.

AbstractThe essential oils from Thymus vulgaris, Salvia officinalis, and Ocimum basilicum were extracted by hydrodistillation, characterized by gas chromatography/mass spectrometry, and quantified by gas chromatography/flame ionization detector. The principal constituents were thymol, ρ‐cymene and carvacrol (T. vulgaris); camphor, β‐pinene, and 1,8‐cineole (S. officinalis); and (E)‐anethole, linalool, and 1,8‐cineole (O. basilicum). The essential oil from T. vulgaris was the most effective, forming inhibition halos of 46.16 ± 0.16 and 26.38 ± 0.33 mm, respectively, for Salmonella choleraesuis and Listeria monocytogenes. This essential oil was also more effective against S. choleraesuis, with a minimum inhibitory concentration of 8.85 mg mL−1, and a minimum inhibitory concentration of 17.71 mg mL−1 for L. monocytogenes. No bactericidal activity against S. choleraesuis and L. monocytogenes was observed for the essential oils from S. officinalis, and O. basilicum. Scanning electron micrographs showed that the addition of essential oils left the bacterial cells damaged and deformed. Significant 2,2‐diphenyl‐1‐picrylhydrazyl free radical scavenging capacity and lipid substrate protection were observed in the β‐carotene bleaching assay for the essential oil from T. vulgaris, with IC50 of 231.13 ± 0.53 and 15.25 ± 0.38 μg mL−1, respectively. A dose‐dependent relationship between antioxidant activity and concentrations was observed in the tests. Toxicities of LC50 = 1.24, 3.51 and 1.19 mg mL−1 against Drosophila suzukii flies, respectively, were observed for the essential oils from T. vulgaris, S. officinalis, and O. basilicum. Results suggest that essential oils can be promising antioxidant agents, insecticides, and inhibitors of pathogenic bacteria.

Francisella salimarina infection in farmed cobia (Rachycentron canadum) and dusky grouper (Epinephelus marginatus) in Brazil: A case report.

This study aimed to identify and characterize isolates of Francisella salimarina associated with an outbreak on a marine fish farm in Brazil and to analyse their genetic variability and antimicrobial susceptibility. In 2021, diseased cobias (Rachycentron canadum, n = 10) and dusky groupers (Epinephelus marginatus, n = 10) were sampled and subjected to bacteriological and pathological examinations. The isolates obtained were morphologically and biochemically characterized and identified by matrix-assisted laser desorption/ionization-time of flight (MALDI-ToF) and 16S rRNA gene sequencing. The genetic diversity of these isolates was analysed using repetitive extragenic palindromic-polymerase chain reaction (REP-PCR). Antimicrobial susceptibility was assessed using the disk diffusion technique. Macroscopically, the fish presented skin ulcerations, ocular lesions, hepatomegaly and splenomegaly. A pleomorphic, gram-negative, catalase- and oxidase-positive bacterium was isolated from seven cobias and two groupers. The 16S rRNA gene sequences showed >99% coverage and identity with other deposited sequences of F. salimarina. The results of the biochemical analysis corresponded to these bacterial species. Histologically, granulomas were observed in the spleen, liver and heart of the cobias (n = 6), and necrotizing and fibrinous dermatitis and myositis were identified in some groupers (n = 2). The isolates exhibited the same banding pattern when REP-PCR was performed, indicating that they were clonally related. Finally, the antibiogram test, no inhibition halo was observed for amoxicillin and trimethoprim-sulfamethoxazole. To our knowledge, this is the first report of F. salimarina infection in cobias and dusky groupers.

Antibacterial and antiviral PA6-AgNPs microfibers for application as a filter element in facial respirators

Polymeric microfibers are very interesting materials that can be associated with other nanomaterials aiming to obtain specific properties and be used in a wide range of applications. In this study, we prepared different formulations of polyamide 6 (PA6) containing silver nanoparticles (AgNPs) and produced microfibers by solution blow spinning technique for its use as a filter element in a face respirator. The obtained samples were then characterized by field emission gun-scanning electron microscopy (FEG-SEM), energy dispersion spectroscopy (EDS), ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS), water contact angle (WCA), thermogravimetric analysis (TGA), and respirability and antibacterial, antiviral and cytotoxicity assays. In general, the microfibers were well dispersed and the AgNPs were evenly distributed throughout the samples, reflecting a hydrophilic character and good thermal stability, with a maximum weight loss of 2.9 % attributed to the evaporation of water molecules. The sample produced with a concentration of 10 mmol/L of silver nitrate presented acceptable levels of resistance to respiration. Concerning the microbiological analyses, the results showed that samples evidenced antibacterial effect against Escherichia coli and Staphylococcus aureus, forming inhibition halos of up to 4 mm in disk diffusion assays and inhibiting bacterial growth in liquid medium assays, as well as antiviral effect against betacoronavirus MHV-3, promoting a reduction of up to 99.9 % of viral particles. Moreover, the samples presented cytotoxicity on the first and second days, whereas on the seventh day some of the extracts did not show cytotoxic activity, indicating that the cells adapted to the culture medium. Considering the data set and the simple process of obtaining the microfibers, it was possible to conclude that this material can be applied as a filter element in a face respirator as well as in a variety of products with antibacterial and antiviral purposes.

Reliability of a Screening Method Using Antibiotic Disks to Detect Carbapenemases in Glucose-Nonfermenting Gram-Negative Microorganisms From Clinical Samples of a Regional Hospital in Southeastern Spain.

Infections by glucose-nonfermenting gram-negative bacilli (NFGNB) pose a major public health problem due to multiresistance to beta-lactam antibiotics, especially plasmid-borne carbapenemases. Their detection by microbiology laboratories is challenging, and there is a need for easy-to-use and reliable diagnostic techniques. Our objective was to evaluate an in-house screening method to presumptively detect carbapenemases in NFGNB in a simple and clinically useful manner. The study included 175 NFGNB isolates from urinary, respiratory, and rectal samples. In a triple assay, isolates were incubated at 37°C for 24 h on three solid-culture media: MacConkey II Agar, 5% Sheep Blood Columbia Agar and Mueller Hinton II Agar; meropenem (MEM) and cefepime (FEP) disks were employed for screening. Studies were then performed on the inhibition halo diameter, scanning effects, and the appearance of mutant colonies, which were compared with those observed using the colorimetric Neo-Rapid CARB Kit and immunochromatography (NG5-Test Carba and K-Set for OXA-23). Receiver operating characteristic curves were constructed for these data. Carbapenemases were expressed by 79/175 (45.1%): 19 Pseudomonas aeruginosa and 60 Acinetobacter baumannii. Optimal inhibition halo diameter cutoffs to detect this resistance on 5% sheep blood agar were as follows: 6 mm (MEM) and 6.5 mm (FEP) for P. aeruginosa (in the absence of scanning effects and mutations) and 10.5 mm (MEM) and 16 mm (FEP) for A. baumannii (even in the presence of scanning effects). The combined utilization of MEM and FEP antibiotic disks in 5% sheep blood agar, measuring their inhibition haloes, offers an effective method to predict the presence of carbapenemases as resistance mechanism in P. aeruginosa and A. baumannii.

The Antibacterial Activity of Novel Bacteriophages and the Emergence of Bacterial Resistance to Phage Infections: An In Vitro Study

The emergence of bacteria resistant to bacteriophage (phage) infection may compromise the success and effectiveness of phage therapy. The aim of this study was to evaluate the in vitro antibacterial activity of five novel phages, as well as the emergence of bacterial resistance to phage infections. The antibacterial activity of lytic phages was evaluated against standard strains of Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC 25927), Enterococcus faecalis (ATCC 29212) and Staphylococcus aureus (ATCC 6538). Phages were initially grown in the presence of host bacteria in an exponential growth phase, then purified and titrated. In a second exposure, 20 μL of each phage was inoculated with 106 CFU/mL of P. aeruginosa/E. coli/E. faecalis/S. aureus, separately. In a third exposure, resistant colonies were isolated, cultivated and exposed again to the phages. Bacterial colonies resistant to phage infection after the third exposure were evaluated for their susceptibility profile to different antibiotics via the diffusion disk technique. The diameters of the inhibition halos were evaluated with Image J software (version 1.54g) and the definition of the susceptibility profile to antibiotics was determined according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria. In addition, fourteen cocktails with different phages were formulated to evaluate the emergence of a bacterial resistance to phage infections. The phages exhibited specificity for P. aeruginosa and did not infect E. coli, E. faecalis and S. aureus. The presence of bacterial colonies resistant to phage infection in the three successive exposures was identified, and the bacterial resistance to phage infection was confirmed in all phages titrated at 108 PFU/mL, in four phages titrated at 1010 PFU/mL and in one phage titrated at 1013 PFU/mL. The development of a resistance to infection by phages (~108 PFU/mL) did not change the susceptibility profile of P. aeruginosa to antibiotics and, when evaluating the emergence of a resistance to infection by phage cocktails (~108 PFU/mL, ~1010 PFU/mL, ~1013 PFU/mL), bacterial resistance to phage infection was confirmed in all cocktails with phages titrated at 108 PFU/mL, in ten cocktails with phages titrated at 1010 PFU/mL and in seven cocktails with phages titrated at 1013 PFU/mL. In conclusion, the presence of resistant P. aeruginosa colonies to phage infection after successive exposures was evidenced, although some phages at title ~1010 PFU/mL and ~1013 PFU/mL were effective in inhibiting the growth of resistant colonies. The development of resistance did not change the susceptibility profile of P. aeruginosa to antibiotics. Variants of P. aeruginosa that were resistant to phage infection were isolated and their resistance to infection via the phage cocktail was demonstrated regardless of the viral titer, although some cocktails at title ~1010 PFU/mL and ~1013 PFU/mL were effective in inhibiting the growth of resistant colonies. Despite the emergence of bacterial variants resistant to phage infection, new studies involving the applicability of phages in the control of infections must be conducted.

Antibacterial Screening of Lippia origanoides Essential Oil on Gram-negative Bacteria

Essential oils (EO) are extracted from different plant species and can be present in different plant organs. Rosemary-pepper EO is composed of around 50% to 70% thymol, a phenolic compound proven to be active against fungi and bacteria. The active components present in these compounds can affect the vital functionality of bacterial cells, leading to protein denaturation and cell lysis. Therefore, the present study aims to evaluate in vitro the antibacterial potential of Lippia origanoides EO against gram-negative bacteria. This is an exploratory study, with a technical-experimental procedure, with a quantitative approach, carried out at the Federal University of Campina Grande. The strains used were Pseudomonas aeruginosa ATCC 27853, Proteus mirabilis ATCC 25933, and Escherichia coli ATCC 25922, using concentrations of 1024, 512, 256, and 128 μg/ml using the disc diffusion method in triplicate. After the incubation period, the formation of halos of bacterial growth inhibition was not observed. There are possible causes for the lack of antibacterial activity of the EO concerning the strains of gram-negative bacteria used in the study, including the possibility of not containing components with antibacterial properties in concentrations sufficient for the expected activity at the concentrations tested. Based on the results obtained, the Rosemary-Pepper EO (Lippia organoids) did not demonstrate antimicrobial activity against the gram-negative bacteria used in the study. Therefore, the development of new research with Lippia origanoides essential oil with gram-positive bacteria is suggested.

Synthesis and Characterization of Cassava Gum Hydrogel Associated with Chlorhexidine and Evaluation of Release and Antimicrobial Activity.

Hydrogels from natural sources are attracting increasing interest due to their ability to protect biologically active molecules. Starch extracted from cassava tubers is a promising material for synthesizing these hydrogels. Copolymerization of cassava gum and incorporation of chlorhexidine digluconate (CLX) into the hydrogels is confirmed by changes in the crystallographic profile, as observed through X-ray diffraction, and a shift in the 1000 cm-1 band in the Fourier-transform infrared spectroscopy spectrum. The differential scanning calorimetry reveals changes in the decomposition temperature of the synthesized hydrogels related to CLX volatility. Micrographs illustrate the material's porosity. Release tests indicate a constant linear release over 72 h, while antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Candida albicans is satisfactory, with 100% effectiveness from 0.5% CLX and the formation of inhibition halos. Toxicity and biocompatibility studies show no cytotoxicity. The continuous release of chlorhexidine is promising for components of biomedical implants and applications as it can ensure antimicrobial action according to specific therapeutic needs.

Insect protein-based composite film incorporated with E. purpurea-based nanoparticles augmented the storage stability of parmesan cheese

The objective of this study was to prepare an insect protein-based composite film containing plant extract-based nanoparticles to augment the lipid and microbial stability of cheese. An ultrasonication-mediated green method of synthesis was followed to develop the nanoparticles using E. purpurea flower extract (EP-NPs). The film was developed using locust protein (Loc-Pro) and different levels of EP-NPs [2.0% (T3), 1.5% (T2), 1.0% (T1), and 0.0% (T0)]. It was characterised and evaluated for efficacy using parmesan cheese (Par-Che) as a model system stored for 90 days (4 ± 1 °C). The addition of EP-NPs markedly enhanced the antioxidant and antimicrobial activities of the Loc-Pro-based film as indicated by the results of radical-scavenging activity (ABTS and DPPH), total-flavonoid and total-phenolic contents, ion-reducing potential (FRAP), and inhibitory halos (mm). It also increased (P < 0.05) the density (g/ml), redness (a*), and yellowness (b*) and reduced (P < 0.05) the WVTR (mg/m2t), transparency (%) and lightness (L*) of the Loc-Pro-based film. The film incorporated with EP-NPs showed a marked desirable impact on protein oxidation, lipid stability, microbial quality and antioxidant potential of Par-Che during 90 days of storage. While cheese samples without any film showed mean values of 2.24 mg malondialdehyde/kg, 0.79% oleic acid, 1.22 nm/mg protein, 2.52 log CFU/g and 1.24 log CFU/g on day 90 for TBARS, FFA, total carbonyl content, total plate count and psychrophilic count, samples within T3 films showed significantly lower values of 1.82, 0.67, 0.81, 2.15, and 0.81, respectively. A positive impact of the Loc-Pro-based film was found on the sensory characteristics of Par-Che. Both the Loc-Pro-based film and the digestion simulation improved the radical-scavenging activity and ion-reducing potential of the Par-Che. Our results indicate the potential of Loc-Pro-based film as a means to enhance the storage quality of cheese.

ANTIBACTERIAL ACTIVITY OF CLOVE ESSENTIAL OIL (SYZYGIUM AROMATICUM) AGAINST STRAINS OF ESCHERICHIA COLI, PSEUDOMONAS AERUGINOSA, AND SALMONELLA SSP

Background: The Clove (Syzygium aromaticum), a member of the Myrtaceae family, is cultivated in various countries across Asia, Africa, and the West. Eugenol, its primary volatile phenolic compound, imparts characteristic aroma and flavor, as well as possessing bactericidal properties. Objective: This study evaluated the antibacterial activity of clove essential oil (Syzygium aromaticum) against Escherichia coli, Pseudomonas aeruginosa, and Salmonella spp, isolated from food and water. Methods: To achieve this, the essential oil was extracted from the dried floral buds of cloves using the hydrodistillation method, using a Clevenger system. The susceptibility assessment of the strains took place using the disc diffusion method. Results: Escherichia coli and Salmonella, isolated from food, demonstrated sensitivity to the essential oil, with inhibition halos of 16 and 18 mm, respectively. The gram-negative strains Salmonella spp. and Salmonella isolated from sururu (Mytella guyanensis) were also sensitive to the oil, and the pattern with inhibition halos was 15 mm. However, strains of Pseudomonas aeruginosa, isolated from water, did not show activity against the essential oil. Discussion: The essential oil extracted from Syzygium aromaticum, known as clove, demonstrated a high level of antibacterial activity against two of the three tested bacterial strains (Escherichia coli and Salmonella spp), while exhibiting moderately effective activity against Pseudomonas aeruginosa. Conclusions: The microbiological study revealed that clove essential oil exhibited good antibacterial activity against the tested strains, with eugenol being the main compound responsible for this efficacy.

Sustainable Filters with Antimicrobial Action from Sugarcane Bagasse: A Novel Waste Utilization Approach

Sugarcane bagasse (SCB) is a waste product from Mexico’s sugar industry that is generally burned or discarded. It contains around 48% cellulose, representing a significant source of this component from industrial waste. Eugenol is found in clove oil; it has been used for its medicinal and antimicrobial benefits in the food and pharmaceutical industries. This study aims to develop a filtering material using sugarcane bagasse (SCB) and encapsulated eugenol as an antimicrobial agent. The study involves extracting cellulose from SCB using alkaline hydrolysis with ultrasound, followed by forming composite materials encapsulated in alginate with eugenol concentrations from 0 to 1% v/v. These materials were characterized and tested for antimicrobial efficacy. The findings indicate that the cellulose–eugenol–alginate composite displays high eugenol encapsulation efficiency and effective short-term release. In well-diffusion assays, the material showed inhibition halos up to 20.47 mm against S. aureus, suggesting its potential as an eco-friendly alternative to traditional antimicrobial agents in filter materials.