Minimum Bactericidal Concentration Research Articles

Supercritical CO2 Fluid Extraction and Microencapsulation of Oil from Anchovy (Engraulis mordax) By-Products.

Fish by-products are discarded as waste, which has a significant impact on the environment. They have no economic value, but there are many opportunities to turn them into high value products. Due to significant quantities generated internationally and the continuous expansion of the market for ω-3 and ω-6 fatty acids as nutraceuticals, innovative technological approaches are needed to transform this waste into marketable products with added value, while limiting the risk of environmental pollution. In this study, two temperatures (40 and 60 °C) at a constant pressure during the extraction of anchovy by-products with supercritical CO2 fluid were used to determine extraction yield, fatty acid, tocopherol and phytosterol composition, followed by microencapsulation with two matrices based on the transglutaminase-mediated crosslinking reaction between whey protein isolates and casein. Before microencapsulation, the binding parameters were estimated using quenching studies. The results showed a higher content of total fatty acids when extracted at 40 °C, resulting in two fractions on a dry mass basis of (712±12) mg/g in the fraction obtained in the separator with code S40 and (732±10) mg/g in the fraction obtained in the separator with code S45, respectively. The monounsaturated (MUFAs) and polyunsaturated fatty acids (PUFAs) accounted for 40-44 %. The extracts showed a higher mass fraction of eicosapentaenoic acid ((28.7±1.0) mg/g) in fraction S45 when extracted at 60 °C. A minimum inhibitory and bactericidal concentration of 0.66 μg/mL against Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923 was found for all fractions. Higher binding constants were found for palmitoleic and oleic acids than for palmitic acid. The control variant, without crosslinking, enabled the microencapsulation of a higher amount of fatty acids, while in both powders the sum of MUFAs and PUFAs was 40 %. The approaches used in our study open up new opportunities for adding value to the fish by-products through extraction and microencapsulation, extending their potential use to food, cosmetics and nutraceuticals.

Engineered extracellular vesicles coated with an antimicrobial peptide for advanced control of bacterial sepsis.

Alarming sepsis-related mortality rates present significant challenges to healthcare services globally. Despite advances made in the field, there is still an urgent need to develop innovative approaches that could improve survival rates and reduce the overall cost of treatment for sepsis patients. Therefore, this study aimed to develop a novel multifunctional therapeutic agent for advanced control of bacterial sepsis. Extracellular vesicles (EVs) isolated from lipopolysaccharide (LPS) induced HepG2 (hepatocellular carcinoma cells) (iEV) displayed an average particle size of 171.63±2.77nm, a poly dispersion index (PDI) of 0.32±0.0, and a zeta potential (ZP) of -11.87±0.18mV. Compared to HepG2 EV, LPS induction significantly increases the EV protein concentration, PDI and ZP, reduces the average size and promotes cell proliferation and cytoprotective effects of the isolated EVs (iEVs) against LPS-induced cytotoxicity. Coating of iEV with a cationic antimicrobial peptide (AMP) to form PC-iEV slightly changed their physical properties and shifted their surface charge toward neutral values. This modification improved the antibacterial activity (2-fold lower minimum bactericidal concentration [MBC] values) and biocompatibility of the conjugated peptide while maintaining iEV cytoprotective and anti-inflammatory activities. Our findings indicate the superior anti-inflammatory and antibacterial dual activity of PC-iEV against pathogens associated with sepsis.

A Comparative Study on Antibacterial Activities of Alcohol Disinfectants and α-Mangostin Extract

Background A green and efficient process, free from toxic solvents, was employed to prepare an α-mangostin-rich extract. Conventional techniques like maceration and heat reflux extraction are recognized for their time-intensive nature, as well as the requirement for significant quantities of organic solvents. This innovative process not only reduces energy consumption but also streamlines production steps, providing a more sustainable alternative in herbal medicine preparation. Purpose The purpose of the study was to compare the antibacterial activities of alcohol disinfectants and α-mangostin extract-containing disinfectants against tested microorganisms. Methods The α-mangostin-rich extract was obtained from dried powders of Garcinia mangostana pericarps utilizing the microwave-assisted extraction method with polyethylene glycol 400 (PEG 400). The α-mangostin content in the resultant extract was determined through the high-performance liquid chromatography (HPLC) method. Additionally, a broth microdilution method was utilized to investigate the minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of each compound against methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus pseudintermedius. Results According to a microdilution method, the disinfectant comprising isopropanol (50% and 70%) with 1% α-mangostin extract demonstrated antibacterial effectiveness against both MRSA and S. pseudintermedius. The MICs and MBCs were observed within dilutions ranging from 1:64 to 1:512 and 1:64 to 1:256, respectively. Ethanol (50% and 70%) plus 1% α-mangostin extract disinfectant exhibited antibacterial activity with MICs and MBCs at dilutions of 1:32–1:512 and 1:16–1:128, respectively. Moreover, isopropanol and ethanol (30%) with 1% α-mangostin extract disinfectant demonstrated antibacterial activity with MICs and MBCs at dilutions of 1:16–1:256 and 1:4–1:128, respectively. However, isopropanol (50% and 70%) and ethanol (50% and 70%) disinfectants showed weaker antibacterial activity than α-mangostin extract-containing alcohol solutions. Although isopropanol (30%) disinfectant demonstrated antibacterial activity (MICs and MBCs at dilutions of 1:16–1:32), the 30% ethanol solution did not show any activity against either bacterium. In addition, α-mangostin extract exhibited stronger antibacterial activity (MICs and MBCs at dilutions of 1:625–1:5,000) than all alcohol solutions. Conclusion The combination of isopropanol and ethanol disinfectants with α-mangostin-rich extract exhibited significant antibacterial effectiveness against MRSA and S. pseudintermedius. The enhancement of efficacy by α-mangostin-rich extract suggests promising opportunities for enhancing disinfection approaches.

Evaluation of the antibacterial effect of (R)-(+)-Limonene against Enterococcus faecalis and Enterobacter cloacae strains isolated from food

The aim of this study was to evaluate the potential antibacterial and anti-adherent activities of the monoterpene (R)-(+)-limonene, as well as its synergistic potential with synthetic antimicrobials against strains of Enterococcus faecalis and Enterobacter cloacae. The antibacterial properties of (R)-(+)-limonene were assessed using the broth microdilution technique to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Additionally, the infusion disc method was employed to explore the association of the compound with antimicrobials, and the test tube method was used to determine the minimum inhibitory concentration of adherence (MICA). It was observed that the MIC for (R)-(+)-limonene was 1000 μg mL-1 for five of the six E. faecalis strains tested, while for E. cloacae, the MIC exceeded 1000 μg mL-1 for all strains tested. Identical values were recorded for the MBC in E. faecalis. In terms of its combination with synthetic antimicrobials, (R)-(+)-limonene demonstrated a synergistic effect with gentamicin and ciprofloxacin for most strains. Regarding the MICA, both (R)-(+)-limonene and 0.12% chlorhexidine digluconate failed to inhibit biofilm formation at the tested concentrations. Given the need for new therapeutic alternatives for treating bacterial infections, this study revealed that the tested monoterpene exhibited moderate bactericidal effects against E. faecalis strains and no antibacterial effect against E. cloacae strains. However, when combined with various classes of antimicrobials, (R)-(+)-limonene showed synergistic effects with gentamicin and ciprofloxacin for most strains. This suggests that (R)-(+)-limonene holds promise for enhancing the treatment of bacterial infections and could support conventional therapies. Nonetheless, further in vitro, ex vivo, and in vivo studies are necessary to confirm and elucidate its efficacy and mechanisms.

A Novel Combination of Zinc Oxide with Two Essential Oils Exerts Antimicrobial Effect against Endodontic Pathogens In Vitro.

Evaluating the antimicrobial efficacy of the novel combinations of zinc oxide mixed with ajwain oil (ZNOA) and combination of ajwain and eugenol (ZNOAE) vs conventionally used zinc oxide eugenol (ZNOE) against endodontic pathogens like Escherichia coli and Enterococcus faecalis. The pure cultures of E. coli (MTCC 443) and E. faecalis (MTCC 439) were revived and grown on selective cultural media. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the test materials were determined correspondingly through sequential dilution and agar well diffusion methods, as per Clinical and Laboratory Standard Institute (CLSI) guidelines. The data values were presented as mean ± standard deviation (SD). The comparisons among groups were completed through the one-way analysis of variance (ANOVA) test, whereas intragroup pairwise comparisons were completed using the unpaired t-test (p < 0.05). Minimum inhibitory concentration values against E. coli and E. faecalis of ZNOE were 250 and 500 µg/mL, ZNOA was 250 µg/mL, and ZNOAE were 125 and 250 µg/mL, correspondingly. MBC values in the form of inhibition zone against E. coli by ZNOE were 21.33 ± 1.53 mm, ZNOA 18.67 ± 1.53 mm, and ZNOAE 20.33 ± 1.53 mm. The E. faecalis inhibition zone for ZNOE was 14.33 ± 2.08 mm, ZNOA 18.67 ± 2.08 mm, and ZNOAE 24.33 ± 1.53 mm. All test materials demonstrated good antibacterial efficacy. However, between the novel combinations of test materials, ZNOA showed better antimicrobial efficacy against resistant endodontic pathogens than ZNOE. Dahake PT, Joshi SS, Kale YJ, et al. A Novel Combination of Zinc Oxide with Two Essential Oils Exerts Antimicrobial Effect against Endodontic Pathogens In Vitro. Int J Clin Pediatr Dent 2024;17(S-1):S11-S16.

Evaluation of banana peel extract (Musa sapientum L.) as a natural antimicrobial for livestock farming

AbstractIntroductionOne of the primary objectives of managing microbial content in livestock farming is to control diseases in the respective animals. Nevertheless, the pervasive development of drug‐resistant bacteria is a consequence of the high levels of antibiotic use that are necessary to achieve this objective. This situation exacerbates animal disease and poses a threat to human health. The purpose of this study was to investigate alternative microbial control methods in livestock farming using banana peel extract.Materials &amp; MethodsThe antioxidant and antimicrobial activities of peel extracts from unripe and ripe cultivated bananas were examined and compared.ResultsThe results are notable because they show that the unripe banana peel extracts exhibited significantly better antioxidant activity than the ripe banana peel extracts in 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH), 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid (ABTS), and ferric reducing antioxidant power (FRAP) tests. Furthermore, the unripe banana peels showed significant antimicrobial activity in vitro against four bacteria that are commonly found in swine and poultry houses, including Staphylococcus epidermidis, Exiguobacterium indicum, Bacillus cereus, Bacillus siamensis, Bacillus altitudinis, Pantoea ananatis, and Bacillus megaterium. This activity was probably due to their high levels of total phenolic content and total flavonoid content. Then, the spray formulation loaded with the concentrated unripe banana peel extract that was five times higher than the minimum bactericidal concentration was developed and tested. Ethanol, sodium benzoate, tween 80, and glycerine were applied as additives in the spray formulation to increase the extract's solubility and stability. It was found that the developed spray formulation effectively inhibited the growth of S. epidermidis.ConclusionThese research outcomes show that the possible application of banana peel extract is an excellent approach because it is an eco‐friendly alternative to control microorganisms undesired microbial growth in farm animals.

Effects of antimicrobials over sessile and planktonic microbiota associated with an industrial cooling water system

The bacterial community from a cooling water system was investigated through culture-dependent and independent strategies, and the responses of planktonic and sessile bacteria (grown in glass slides and stainless-steel coupons) to antimicrobials of industrial and clinical use were assessed. The morphotypes with higher biofilm-forming potential were Pseudoxanthomonas sp., Rheinheimera sp., Aeromonas sp. and Staphylococcus sp., and the first also exhibited lower susceptibility to all antibiotics and biocides tested. 16S rRNA high throughput sequencing indicated that Pseudomonadota (77.1% on average, sd 11.1%), Bacteroidota (8.4, sd 5.7%), and Planctomycetota (3.0, sd 1.3%) were the most abundant phyla. KEGG orthologs associated with antibiotics and biocide resistance were abundant in all samples. Although the minimum inhibitory and bactericidal concentrations were generally higher for biofilms, morphotypes in planktonic form also showed high levels of resistance, which could be associated with biofilm cells passing into the planktonic phase. Overall, monochloramine was the most effective biocide.

Influence of critical micelle concentration of choline-based long chain fatty acid soaps on their antibacterial activity against Methicillin resistant Staphylococcus aureus

HypothesisAntimicrobial resistance (AMR) is a pressing global health concern. ESKAPEE pathogens, such as Methicillin-resistant Staphylococcus aureus (MRSA) are notable of concern in healthcare settings due to their resistance to critical antibiotics. To combat AMR, the development of alternatives such as bacterial membrane-active agents is crucial. Fatty acids (FAs) have emerged as a sustainable, antibiotic-free solution with inherent antibacterial activity. However, long chain saturated fatty acids (LCFAs) sodium soaps exhibit poorly antibacterial properties in comparison to short chain FAs, believed to be linked to limited solubility in aqueous media. ExperimentsWe employed choline as a chaotropic organic counter-ion to enhance the solubility of LCFAs and investigated their antibacterial effects against MRSA. The optimal medium conditions for micelle formation for LCFAs was first investigated. Then, we determined the critical micelle concentration (CMC), micellar morphology, and aggregation number through surface tension measurements and small angle neutron scattering experiments. Antimicrobial activity was assessed using minimum bactericidal concentration (MBC) assays and time-kill experiments. FindingsWe have identified conditions where LCFAs are effective against MRSA for the first time, providing valuable insights for developing new antibacterial agents to fight AMR. LCFAs need to be used above their Krafft temperatures and CMC to exhibit antibacterial efficacy.

Chitosan-coated PLGA microemulsion loaded with tannic acid against Escherichia coli in vitro and in vivo

The overuse of antibiotics has resulted in a surge of drug-resistant bacteria, making the pursuit of natural antimicrobials an urgent and significant trend. Encapsulation and nanoparticulation are effective ways to enhance the antibacterial properties of natural drugs. In this study, we encapsulated tannic acid (TA) with chitosan (CS) and poly (lactide-co-glycolide) (PLGA) using the emulsion-solvent evaporation method to enhance the antimicrobial effect of TA. We prepared a bilayer membrane spherical nanoemulsion of TA-PLGA-CS (TPC) with uniform size of 559.87 ± 1.16 nm, and zeta potential of 59.53 ± 1.07 mV. TPC could be stably stored for 90 days at 4°C without affecting the properties of the emulsion, and the minimum bactericidal concentration against four strains of Escherichia coli (E. coli) remained unchanged for 60 d. The results indicated that TPC enhanced the inhibitory effect of TA against E. coli. Scanning electron microscope images revealed that TPC treatment caused damage to the bacterial cell membrane. In addition, in vivo experiments indicated that TPC exhibited a superior therapeutic effect on artificial colibacillosis in chickens infested with Avian pathogenic Escherichia coli, as evidenced by the changes in body weight and a reduction bacterial load in heart. Furthermore, TPC reversed the down-regulation of catalase, glutathione peroxidase1 (GPX1), and GPX7 gene expression levels in intestinal tissues. Compared to the model group, TPC treatment elevated serum glutathione peroxidase activities and lowered myeloperoxidase and lactate dehydrogenase levels, offering antioxidant protection that was slightly better than that of doxycycline hydrochlorid group. In summary, we prepared a novel TA antimicrobial preparation with significant antioxidant potential and inhibitory effect against E. coli both in vitro and in vivo.

Prokaryotic Expression, Purification, and Biological Properties of a Novel Bioactive Protein (PFAP-1) from Pinctada fucata.

Pinctada fucata meat is the main by-product of the pearl harvesting industry. It is rich in nutrition, containing a lot of protein and peptides, and holds significant value for both medicine and food. In this study, a new active protein was discovered and expressed heterogeneously through bioinformatics analysis. It was then identified using Western blot, molecular weight, and mass spectrometry. The antibacterial activity, hemolysis activity, antioxidant activity, and Angiotensin-Converting Enzyme II (ACE2) inhibitory activity were investigated. An unknown functional protein was screened through the Uniprot protein database, and its primary structure did not resemble existing proteins. It was an α-helical cationic polypeptide we named PFAP-1. The codon-optimized full-length PFAP-1 gene was synthesized and inserted into the prokaryotic expression vector pET-30a. The induced expression conditions were determined with a final isopropyl-β-d-thiogalactoside (IPTG) concentration of 0.2 mM, an induction temperature of 15 °C, and an induction time of 16 h. The recombinant PFAP-1 protein, with low endotoxin and sterility, was successfully prepared. The recombinant PFAP-1 protein exhibited strong antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) in vitro, and the diameter of the inhibition zone was 15.99 ± 0.02 mm. Its minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were 37.5 μg/mL and 150 μg/mL, respectively, and its hemolytic activity was low (11.21%) at the bactericidal concentration. The recombinant PFAP-1 protein significantly inhibited the formation of MRSA biofilm and eradicated MRSA biofilm. It also demonstrated potent 1,1-diphenyl-2-picryl-hydrazyl radical (DPPH) scavenging activity with a half-maximal inhibitory concentration (IC50) of 40.83 μg/mL. The IC50 of ACE2 inhibition was 5.66 μg/mL. Molecular docking results revealed that the optimal docking fraction of PFAP-1 protein and ACE2 protein was -267.78 kcal/mol, with a confidence level of 0.913. The stable binding complex was primarily formed through nine groups of hydrogen bonds, three groups of salt bridges, and numerous hydrophobic interactions. In conclusion, recombinant PFAP-1 can serve as a promising active protein in food, cosmetics, or medicine.

Multidrug-Resistance of Vibrio Species in Bivalve Mollusks from Southern Thailand: Isolation, Identification, Pathogenicity, and Their Sensitivity toward Chitooligosaccharide-Epigallocatechin-3-Gallate Conjugate.

Vibrio spp. is a Gram-negative bacteria known for its ability to cause foodborne infection in association with eating raw or undercooked seafood. The majority of these foodborne illnesses are caused by mollusks, especially bivalves. Thus, the prevalence of Vibrio spp. in blood clams (Tegillarca granosa), baby clams (Paphia undulata), and Asian green mussels (Perna viridis) from South Thailand was determined. A total of 649 Vibrio spp. isolates were subjected to pathogenicity analysis on blood agar plates, among which 21 isolates from blood clams (15 isolates), baby clams (2 isolates), and green mussels (4 isolates) showed positive β-hemolysis. Based on the biofilm formation index (BFI) of β-hemolysis-positive Vibrio strains, nine isolates exhibited a strong biofilm formation capacity, with a BFI in the range of 1.37 to 10.13. Among the 21 isolates, 6 isolates (BL18, BL82, BL84, BL85, BL90, and BL92) were tlh-positive, while trh and tdh genes were not detected in all strains. Out of 21 strains, 5 strains showed multidrug resistance (MDR) against amoxicillin/clavulanic acid, ampicillin/sulbactam, cefotaxime, cefuroxime, meropenem, and trimethoprim/sulfamethoxazole. A phylogenetic analysis of MDR Vibrio was performed based on 16s rDNA sequences using the neighbor-joining method. The five MDR isolates were identified to be Vibrio neocaledonicus (one isolate), Vibrio fluvialis (one isolate) and, Vibrio cidicii (three isolates). In addition, the antimicrobial activity of chitooligosaccharide-epigallocatechin gallate (COS-EGCG) conjugate against MDR Vibrio strains was determined. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of COS-EGCG conjugate were in the range of 64-128 µg/mL. The antimicrobial activity of the conjugate was advocated by the cell lysis of MDR Vibrio strains, as elucidated by scanning electron microscopic images. Vibrio spp. isolated from blood clams, baby clams, and Asian green mussels were highly pathogenic, exhibiting the ability to produce biofilm and being resistant to antibiotics. However, the COS-EGCG conjugate could be used as a potential antimicrobial agent for controlling Vibrio in mollusks.

Wild Vitis Species as Stilbenes Sources: Cane Extracts and Their Antibacterial Activity against Listeria monocytogenes.

Grapevines (Vitis spp.) produce several valuable polyphenol-type secondary metabolites including various stilbenoids. Although the potential application of stilbenes may offer alternative solutions to food safety or health challenges, only little information is available on their antibacterial activity against foodborne pathogens. In this work, high-performance liquid chromatography was used to analyze the stilbenoid profile of various wild Vitis species, including V. amurensis, V. davidii, V. pentagona, and V. romanetii, selected from the gene bank for grapes at the University of Pécs, Hungary. We found that the stilbene profile of cane extracts is strongly genotype-dependent, showing the predominant presence of ε-viniferin with a wide concentration range ≈ 320-3870 µg/g dry weight. A novel yet simple and efficient extraction procedure was developed and applied for the first time on grape canes, resulting in ε-viniferin-rich crude extracts that were tested against Listeria monocytogenes, an important foodborne pathogen. After 24 h exposure, V. pentagona and V. amurensis crude extracts completely eliminated the bacteria at a minimum bactericidal concentration of 42.3 µg/mL and 39.2 µg/mL of ε-viniferin, respectively. On the other hand, V. romanetii extract with 7.8 µg/mL of ε-viniferin resulted in 4 log reduction in the viable bacterial cells, while V. davidii extract with 1.4 µg/mL of ε-viniferin did not show significant antibacterial activity. These findings indicate that the ε-viniferin content was directly responsible for the antibacterial effect of cane extract. However, pure ε-viniferin (purity > 95%) required a higher concentration (188 µg/mL) to eradicate the bacteria under the same conditions, suggesting the presence of other antibacterial compounds in the cane extracts. Investigating the onset time of the bactericidal action was conducted through a kinetic experiment, and results showed that the reduction in living bacterial number started after 2 h; however, the bactericidal action demanded 24 h of exposure. Our results revealed that the canes of V. pentagona and V. amurensis species are a crucial bio-source of an important stilbene with antimicrobial activity and health benefits.

Controlling Staphylococcus aureus Biofilm on Food Contact Surfaces: The Efficacy of Oliveria decumbens Essential Oil and its Implications on Biofilm-Related Genes.

This study aimed to investigate the effect of Oliveria decumbens essential oil (Od-EO) on the phenotypic properties and gene expression of Staphylococcus aureus biofilm on commonly used food contact surfaces. The minimum inhibitory concentration and minimum bactericidal concentration of Od-EO on Staphylococcus aureus ATCC25923 were determined to be 0.5 and 1µl/mL, respectively. Crystal violet staining, scanning electron microscopy (SEM), biofilm metabolic activity evaluation and Real-time PCR analysis were used to assess the anti-biofilm properties of Od-EO. The results demonstrated that Od-EO exhibited significant anti-biofilm properties against S. aureus and effectively reduced the metabolic activity of biofilm cells. Furthermore, the inhibitory effects of Od-EO on biofilm formation were more pronounced on Stainless Steel (SS) compared to High Density Polyethylene (HDPE) surfaces. Real-time PCR analysis revealed that Od-EO downregulated the expression of biofilm-related genes (icaA, icaD, clfA, clfB, FnbA, FnbB, hld) in S. aureus grown on SS, while the expression levels of all studied genes except hld in the biofilm formed on HDPE remained unchanged or increased. One of the main anti-biofilm mechanisms of the Od-EO on the HDPE is related to the disturbance in the QS of the cells. These findings highlight the potential of Od-EO as an effective agent for controlling and inhibiting S. aureus biofilm in the food industry and its potential use in disinfectant compounds.

Postbiotic mediators derived from Lactobacillus species enhance riboflavin-mediated antimicrobial photodynamic therapy for eradication of Streptococcus mutans planktonic and biofilm growth

BackgroundStreptococcus mutans has been implicated as a primary causative agent of dental caries and one of its important virulence properties is an ability to form biofilm on tooth surfaces. Thus, strategies to prevent and control S. mutans biofilms are requested. The present study aimed to examine the eradication of S. mutans planktonic and biofilm cells using riboflavin (Rib)-mediated antimicrobial photodynamic therapy (aPDT) enhanced by postbiotic mediators derived from Lactobacillus species.Materials and methodsMinimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of Rib and postbiotic mediators were determined. The antimicrobial and anti-biofilm effects of Rib-mediated aPDT (Rib plus blue light), Rib-mediated aPDT in combination with postbiotic mediators derived from Lactobacillus casei (LC) (aPDT+ LC), and Rib-mediated aPDT in combination with postbiotic mediators derived from Lactobacillus plantarum (LP) (aPDT+ LP) were evaluated. The anti-virulence potential of Rib-mediated aPDT, aPDT+ LC, and aPDT+ LP were assessed by measuring the expression of the gtfB gene using quantitative real-time polymerase chain reaction (qRT-PCR) at the highest concentrations of Rib, LC, and LP, at which the S. mutans had proliferation as the same as in the control (non-treated) group.ResultsAccording to the results, the MIC doses of LC, LP, and Rib were 64 µg/mL, 128 µg/mL, and 128 µg/mL, respectively, while the MBC values of LC, LP, and Rib were 128 µg/mL, 256 µg/mL, and 256 µg/mL, respectively. Rib-mediated aPDT, aPDT+ LP, and aPDT+ LC showed a significant reduction in Log10 CFU/mL of S. mutans compared to the control group (4.2, 4.9, and 5.2 Log10 CFU/mL, respectively; all P < 0.05). The most destruction of S. mutans biofilms was observed after treatment with aPDT+ LC followed by aPDT+ LP and Rib-mediated aPDT (77.5%, 73.3%, and 67.6%, respectively; all P < 0.05). The concentrations of 31.2 µg/mL, 62.5 µg/mL, and 62.5 µg/mL were considered as the highest concentrations of LC, LP, and Rib, respectively, at which S. mutans replicates as same as the control group and were used for gtfB gene expression assay using qRT-PCR during Rib-mediated aPDT, aPDT+ LP, and aPDT+ LC treatments. Gene expression results revealed that aPDT+ LP and aPDT+ LC could decrease the gene expression level of gtfB by 6.3- and 5.7-fold, respectively (P < 0.05), while only 5.1-fold reduction was observed after Rib-mediated aPDT (P < 0.05).ConclusionOur findings indicate that aPDT+ LP and aPDT+ LC hold promise for use as a treatment to combat S. mutans planktonic and biofilms growth as well as anti-virulence as a preventive strategy to inhibit biofilms development via reduction of gtfB gene expression.

Antibacterial and antioxidant activities of Chlorella vulgaris and Scenedesmus incrassatulus using natural deep eutectic solvent under microwave assisted by ultrasound

Microalgae are increasingly recognized as promising sources of natural bioactive compounds. However, traditional extraction methods using volatile organic solvents (VOCs) pose environmental risks. This study explores renewable deep eutectic solvents (DES) as sustainable alternatives for extracting bioactive compounds from microalgae biomass, focusing on Chlorella vulgaris and Scenedesmus incrassatulus. Four DES systems, comprising choline chloride (ChCl) and glycerol, citric acid, urea, and glucose, were compared with three conventional solvents (ethanol, methanol, and water). Extraction efficiency was assessed based on total phenolic content (TPC), flavonoid content, and tannin content, followed by antioxidant activity evaluation using DPPH, CAT, and FRAP assays. Additionally, antibacterial activity of the DES extracts was determined against Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), Staphylococcus aureus (ATCC 29213), and Bacillus subtilis (ATCC 3366) using disc diffusion and microplate dilution methods to determine minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Results reveal that DES, particularly choline chloride: citric acid, outperform conventional solvents in terms of polyphenol extraction efficiency, antioxidant activity, and antibacterial activity against both Gram-negative and Gram-positive bacteria. For instance, the citric acid-based DES (SIDES2) showed a TPC of 4.98 mg/g, while the conventional solvent ethanol exhibited a TPC of 3.27 mg/g. Additionally, SIDES2 exhibiting the highest DPPH scavenging activity of 75 %, compared to 60 % for ethanol. Furthermore, SIDES2 showed an MIC of 0.5 mg/ml against Staphylococcus aureus. This study underscores the potential of DES for sustainable extraction of natural antioxidants from microalgae biomass, contributing to the development of environmentally friendly extraction processes in various industries.

Phytofabrication, characterization of silver nanoparticles using Hippophae rhamnoides berries extract and their biological activities.

Fabrication of plant-based metal nanoparticles has yielded promising results, establishing this approach as viable, sustainable, and non-toxic in the biomedical sector for targeted drug delivery, diagnostic imaging, biosensing, cancer therapy, and antimicrobial treatments. The present work demonstrates the suitability of Hippophae rhamnoides berries for the instant green synthesis of silver nanoparticles to check their antioxidant, lipid peroxidation, and antimicrobial potential. The preliminary characterization of Hippophae rhamnoides-mediated AgNPs was validated by monitoring the color shift in the solution from pale yellow to reddish brown, which was further confirmed by UV-vis spectroscopy and the plasmon peaks were observed at 450 nm. Field Emission Scanning Electron Microscopy (FESEM) and X-ray diffraction (XRD) were used to evaluate the surface topography and structure of AgNPs. Herein, the antioxidant potential of synthesized AgNPs was investigated using DPPH free radical assay and the antimicrobial efficacy of similar was checked against E. coli and S. aureus by following MIC (minimum inhibitory concentration) and MBC (Minimum bactericidal concentration) assay. Along with the inhibitory percentage of lipid peroxidation was analysed by following TBARS (Thiobarbituric acid reactive species) assay. The results revealed that the AgNPs were spherical in shape with an average size distribution within the range of 23.5-28 nm and a crystalline structure. Negative zeta potential (-19.7 mV) revealed the physical stability of synthesized AgNPs as the repulsive force to prevent immediate aggregation. The bioactive functional moieties involved in reducing bulk AgNO3 into AgNPs were further validated by FTIR. TBARS was adapted to test lipid peroxidation, and Hippophae rhamnoides-mediated AgNPs showed a 79% inhibition in lipid peroxidation compared to Hippophae rhamnoides berries extract as 65%. Furthermore, the antibacterial tests showed 37 ± 0.01 mm and 35 ± 0.0132 mm, zones of inhibition against E. coli MTCC 1698 and S. aureus MTCC 3160 with MIC and MBC values of 1 mg/mL, respectively.

Green Synthesis of Silver Nanoparticle Using Black Mulberry and Characterization, Phytochemical, and Bioactivity.

Synthesis of silver nanoparticles (AgNPs) using plant extracts has been proposed as a more advantageous and environmentally friendly alternative compared to existing physical/chemical methods. In this study, AgNPs were synthesized from silver nitrate using black mulberry (BM) extract. The biosynthesized AgNPs were characterized through an UV-visible spectrometer, X-ray diffraction, and transmission electron microscopy. Additionally, BM-AgNPs were subjected to antioxidant, antibacterial, anti-inflammatory, and anticancer activities. AgNPs biosynthesized from BM extract were dark brown in color and showed a strong peak at 437 nm, confirming that AgNPs were successfully synthesized. The size of AgNPs was 170.17 ± 12.65 nm, the polydispersity index was 0.281 ± 0.07, and the zeta potential value was -56.6 ± 0.56 mV, indicating that the particles were stable. The higher total phenol, flavonoid, and anthocyanin content of BM-AgNPs compared to BM extract indicates that the particles contain multiple active substances due to the formation of AgNPs. The DPPH and ABTS assays showed decreased IC50 values compared to BM extract, demonstrating improved antioxidant activity. AgNPs inhibited the growth of S. aureus and E. coli at 600 μg/mL, with minimum bactericidal concentrations determined to be 1000 and 1200 μg/mL, respectively. The anti-inflammatory activity was 64.28% at a BM-AgNPs concentration of 250 μg/mL. As the concentration increased, the difference from the standard decreased, indicating the inhibitory effect of AgNPs on bovine serum albumin denaturation. The viability of MCF-7 cells treated with BM-AgNPs was found to be significantly lower than that of cells treated with BM extract. The IC50 value of BM-AgNPs was determined to be 96.9 μg/mL. This study showed that BM-AgNPs have the potential to be used in the pharmaceutical industry as antioxidant, antibacterial, anti-inflammatory, and anticancer agents.

Nanobiological synthesis of silver oxide-doped titanium oxide bionanocomposite targeting foodborne and phytopathogenic bacteria

Fungi possess remarkable capabilities for metal speciation, dissolution, and mineral formation, which contribute to the production of mycogenic nanostructures. This study explores a green chemistry approach for synthesizing silver oxide-doped titanium oxide (Ag2O-doped TiO2) bionanocomposite utilizing Trichoderma virens. The light yellowish fungal filtrate transformed into a dark brownish colloidal suspension after reacting with silver nitrate and rutile titanium (IV) oxide. X-ray diffractometry (XRD) unveiled the crystalline structure of Ag2O-doped TiO2 bionanocomposite (22.15 nm), showing the coexistence of cubic and rutile tetragonal phases of Ag2O and TiO2, respectively. Fourier-transform infrared spectroscopy (FTIR) showed the presence of functional groups of alcohols, phenols nitro compounds, and aromatic amines derived from the cultural filtrate of T. virens. Raman analysis revealed vibrational modes corresponding to Ag2O and TiO2 nanoparticles. Distinct sharp emission peaks characteristic to Ti, Ag, and O were depicted using energy dispersive X-ray analysis (EDX) analysis. X-ray photoelectron spectroscopy (XPS) confirmed the presence of elemental valence states and binding energies of Ag, Ti, and O in the mycogenic nanocomposite. Field emission scanning electron microscopy (FESEM) revealed aggregation of polydispersed Ag2O-doped TiO2 bionanocomposite, displaying spherical- and cuboctahedron-shaped nanostructures with rough surfaces. High-resolution transmission electron microscopy (HRTEM) showed the presence of circular-, semi-spherical-, hexagonal-, and polygonal-shaped monodispersed Ag2O NPs, with defined boundaries. The Ag2O NPs were obviously deposited on the sheet-like TiO2 NPs. Selected area electron diffraction pattern implied the polycrystallinity of the as-synthesized bionanocomposite. A broad antibacterial spectrum of the prepared bionanocomposite was attained against foodborne pathogenic bacteria; Escherichia coli (12.05 mm), Salmonella enterica (11.26 mm), and Staphylococcus aureus (11.44 mm) and phytopathogenic bacteria; Clavibacter michiganensis subsp. michiganensis (15.72 mm), C. michiganensis subsp. capsici (10.80 mm), streptomycin-sensitive and -resistant Xanthomonas citri pv. citri (14.11 and 14.53 mm, respectively), and streptomycin-sensitive and -resistant Pectobacterium carotovorum subsp. carotovorum (11.36 and 11.07 mm, respectively) using in vitro Kirby-Bauer method. Minimum inhibitory and minimum bactericidal concentrations were determined via a broth micro-dilution assay. FESEM revealed significant morphological alterations in bacterial cells upon treatment with the Ag2O-doped TiO2 bionanocomposite, including deformed shape, rough surface, cell thinning, wrinkled cell wall, protrusions, cavitations, and cracks. These findings signify the successful mycosynthesis of Ag2O-doped TiO2 bionanocomposite, which acted a potent antibacterial agent against a variety of foodborne and phytopathogenic bacteria, which could be employed for environmental, biomedical, agricultural, food bio-processing applications.

Chirality and pH Influence the Self-Assembly of Antimicrobial Lipopeptides with Diverse Nanostructures.

Chirality plays a crucial role in the self-assembly of biomolecules in nature. Peptides show chirality-dependent conformation and self-assembly. Lipidation of peptides occurs in vivo and has recently been exploited in designed conjugates to drive self-assembly and enhance bioactivity. Here, a library of pH-responsive homochiral and heterochiral lipidated tripeptides has been designed. The designed lipopeptides comprise homochiral C16-YKK or C16-WKK (where all the amino acids are l-isomers), and two heterochiral conjugates C16-Ykk and C16-Wkk (where the two lysines are d-isomers). The self-assembly of all the synthesized lipopeptides in aqueous solution was examined using a combination of spectroscopic methods along with cryogenic-transmission electron microscopy (cryo-TEM) and small-angle X-ray scattering (SAXS). Interestingly, it was observed that at acidic pH all the lipopeptides self-assemble into micelles, whereas at basic pH the homochiral lipopeptides self-assemble into nanofibers, whereas the heterochiral lipopeptides self-assemble into nanotapes and nanotubes. A pH switch was demonstrated using a thioflavin T fluorescence probe of β-sheet structure present in the extended structures at pH 8. We demonstrate that both chirality and pH in lipopeptides influence the self-assembly behavior of the model tripeptides, which also show promising bioactivity. Good cytocompatibility is observed in hemolytic assays and antimicrobial activity against both Gram-negative and Gram-positive bacteria is shown through the determination of minimum inhibition concentration (MIC) and minimum bactericidal concentration (MBC) values and live/dead bacteria staining assay.

5-aminolevulinic acid photodynamic therapy for chronic wound infection in rats with diabetes

Recent research indicated that ulcers and peripheral vascular disease resulting from drug-resistant bacterial infections are the main causes of delayed healing in chronic diabetic wounds. 5-Aminolevulinic acid (ALA) is a second-generation endogenous photosensitizer. The therapeutic effect and mechanism of ALA-mediated photodynamic therapy (ALA-PDT) on methicillin-resistant Staphylococcus aureus (MRSA)-infected wounds in diabetic rats were investigated in this study. The results revealed the promising antibacterial effects of ALA-PDT MRSA in vitro, with a minimum inhibitory concentration and minimum bactericidal concentration of 250 and 500 μM, respectively. ALA-PDT also changed the permeability and structural integrity of bacterial cell membranes by producing reactive oxygen species. Meanwhile, ALA-PDT accelerated wound healing in MRSA-infected diabetic rats, with 5 % ALA-PDT achieving complete sterilization in 14 days and wound closure in 21 days. Treatment with 5 % ALA-PDT additionally improved the histopathological appearance of skin tissue, as well as fibrosis, inflammatory cytokine release, and angiogenesis-related protein expression. These findings indicated that ALA-PDT significantly promoted the healing of MRSA-infected wounds in diabetic rats by eliminating bacteria, inhibiting inflammation, generating granulation tissues, promoting neovascularization, and restoring damaged nerves. In addition, the healing mechanism was related to the activation of inflammatory and angiogenesis pathways through the regulation of tumor necrosis factor-alpha and interleukin-6 expression and upregulation of CD206, CD31, and VEGF. These findings underscored the potential role of ALA-PDT in promoting the healing of chronic diabetic wounds.