Antimicrobial Characteristics Research Articles

Genomic Comparative of Pseudomonas aeruginosa Small Colony Variant, Mucoid and Non-mucoid Phenotypes Obtained from a Patient with Cystic Fibrosis During Respiratory Exacerbations.

Pseudomonas aeruginosa, the most prevalent opportunistic pathogen in chronic obstructive pulmonary disease, associated with high morbidity and mortality in patients with cystic fibrosis (CF), is practically impossible to be eradicated from the airways in chronicity. Its extraordinary genomic plasticity is possibly associated with high antimicrobial resistance, virulence factors, and its phenotypic diversity. The occurrence of P. aeruginosa isolates promoting airway infection, showing mucoid, non-mucoid, and small colony variant (SCV) phenotypes, was observed simultaneously, in the present study, in sputum cultures obtained from a male CF young patient with chronic pulmonary infection for over a decade. The isolates belonged to a new ST (2744) were obtained in two moments of exacerbation of the respiratory disease, in which he was hospitalized. Genetic background and phenotypic analysis indicated that the isolates exhibited multi- and pan-antimicrobial resistant profiles, as well as non-susceptible to polymyxin and predominantly hypermutable (HPM) phenotypes. Whole genome sequencing showed variations in genome sizes, coding sequences and their determinants of resistance and virulence. The annotated genomes were compared for antimicrobial resistance, hypermutability, and SCV characteristics. We highlight the lack of reported genetic determinants of SCV emergence and HPM phenotypes, which can be explained in part due to the very short time between collections of isolates. To the best of our knowledge, this is the first report of genome sequencing of P. aeruginosa SCV from a CF patient in Brazil.

Bioactive Peptides Derived from Whey Proteins for Health and Functional Beverages

Milk serves as a crucial source of natural bioactive compounds essential for human nutrition and health. The increased production of high-protein dairy products is a source of whey—a valuable secondary product that, along with other biologically valuable substances, contains significant amounts of whey proteins and is often irrationally used or not utilized at all. Acid whey, containing almost all whey proteins and approximately one-quarter of casein, presents a valuable raw material for generating peptides with potential health benefits. These peptides exhibit properties such as antioxidant, antimicrobial, anti-inflammatory, anticarcinogenic, antihypertensive, antithrombotic, opioid, mineral-binding, and growth-stimulating activities, contributing to improved human immunity and the treatment of chronic diseases. Bioactive peptides can be produced by enzymatic hydrolysis using a variety of proteolytic enzymes, plant extracts, and microbial fermentation. With the participation of plant enzymes, peptides that inhibit angiotensin-converting enzyme are most often obtained. The use of enzymatic hydrolysis and microbial fermentation by lactic acid bacteria (LAB) produces more diverse peptides from different whey proteins with α-lactalbumin and β-lactoglobulin as the main targets. The resulting peptides of varying lengths often have antimicrobial, antioxidant, antihypertensive, and antidiabetic characteristics. Peptides produced by LAB are promising for use in medicine and the food industry as antioxidants and biopreservatives. Other beneficial properties of LAB-produced, whey-derived peptides have not yet been fully explored and remain to be studied. The development of whey drinks rich in bioactive peptides and based on the LAB proteolytic activity is underway. The strain specificity of LAB proteases opens up broad prospects for combining microorganisms to obtain products with the widest range of beneficial properties.

Investigating the synergistic effects of apple vinegar and deep eutectic solvent as natural antibiotics: an experimental and COSMO-RS analysis

ABSTRACT The present investigation examines the antimicrobial and antifungal characteristics of natural deep eutectic solvents (NADES) and apple vinegar in relation to a diverse array of bacterial and fungal strains. The clinical bacterial strains, including gram-negative and gram-positive, and the fungal pathogen Candida albicans, were subjected to solid medium diffusion to determine the inhibitory effects of these compounds. The results show that NADES has superior antimicrobial and antifungal action compared to apple vinegar. The observed inhibitory zones for apple vinegar and NADES varied in length from 16.5 to 24.2 and 16 to 52.5 mm, respectively. The results obtained indicate that no synergy is observed for this mixture (50% AV + 50% NADES). The range of values for bactericidal concentrations (MBC) and minimal inhibitory concentrations (MIC) was 0.0125 to 0.2 and 0.0125 to 0.4 µl/ml, respectively. Antibacterial and antifungal chemicals may be found in apple vinegar and NADES, with NADES offering environmentally safe substitutes for traditional antibiotics. Additional investigation is suggested to refine these compounds for a wide range of bacteria, which could create antimicrobial solutions that are both highly effective and specifically targeted, thereby offering extensive potential in medicine and the environment.

Temporal evolution of bacterial species and their antimicrobial resistance characteristics in wound infections of war-related injuries in Ukraine from 2014 to 2023

This study continues surveillance of antimicrobial resistance associated with combat injuries in Ukraine. To compare species composition, antibiotic resistance profiles, and emergence of new resistance genes between 2014-2020 and 2022-2023. Retrospective multicentre microbiological survey in Ukrainian hospitals. Antibiotic susceptibility, whole genome sequencing, and MLST typing were conducted on 154 organisms obtained from 125 casualties from 2022-2023. The data reveals a predominance of gram-negative bacteria, particularly Acinetobacter baumannii (35.7%), Pseudomonas aeruginosa (14.9%), and Klebsiella pneumoniae (20.7%). High levels of carbapenem resistance was observed among A. baumannii (meropenem 72,2% [(39/54) 95% CI 58.4-83.5], imipenem 66.7% [(36/54) 95% CI 52.5-78.9]), Klebsiella (meropenem 90.6% [(29/32) 95% CI 75.0-98.0], imipenem 81.2% [(26/32) 95% CI 63.6-92.8]), and P. aeruginosa (meropenem 47.8% [(11/23) 95% CI 26.8-69.4], imipenem 60.8% [(14/23) 95% CI 38.5-80.3]) strains. A. baumannii ST-78 and ST-400 were prevalent from 2014 to 2020, while 5 strains of ST-1077 were newly identified. Pseudomonas aeruginosa strains showed diversity across 16 sequence types (STs), with ST-773 increasing in frequency and new STs emerging, but lacking carbapenemase genes. K. pneumoniae exhibited increased genetic diversity over time, with three STs from 2014 to 2020 and six new STs, including blaNDM-1, blaOXA-48, and blaKPC2 carriers, in recent years. There is a growing prevalence of multidrug resistant isolates from globally distributed sequence types.

Multifunctional skin dressings synthesized via one‐pot photopolymerization: Advancing wound healing and infection prevention strategies

AbstractIn the field of wound healing treatment, the development of new materials is essential to cover multiple functions, such as acceleration of the healing process, prevention of infection and response to stimuli, especially if they present lower costs or are easier to manufacture. These properties are of great importance to prompt skin cicatrization. In this work, new multifunctional skin dressings for wound healing and infection prevention are developed based on new hydrogel materials. The dressings are produced via a straightforward and environmentally friendly one‐pot photopolymerization manufacturing process utilizing vitamin B2 aqueous solutions as sensitizer, and energy‐efficient blue light sources. These dressings exhibit a high swelling capacity, pH and temperature responsiveness, biocompatibility, antimicrobial activity in the absence of conventional antibiotics, and are capable of promoting wound healing. The formulation is based on the combination of three monomers: 2‐((methacryloyloxy)ethyl)trimethylammonium chloride, methacrylic acid and N‐vinyl caprolactam. Collagen, hyaluronic acid, and essential oil of hop are added to enhance antimicrobial properties and stimulate regenerative cellular processes. In vivo experiments have demonstrated that pristine dressings are superior in promoting collagen and fibroblast regeneration and accelerating cicatrization as compared to dressings containing natural products. The dressing embedded with hop also displayed antimicrobial characteristics. The preparation and testing of these new efficient wound dressings are described. This study is distinctive in its integration of environmentally conscious manufacturing techniques with innovative material formulations, resulting in superior wound dressings that are both cost‐effective and highly functional. By achieving enhanced healing and infection prevention without the employment of conventional antibiotics, this work represents a substantial advancement in sustainable and effective wound care management.

Zebrafish do not have calprotectin.

The protein heterodimer calprotectin and its component proteins, S100A8 and S100A9, play important antibacterial and proinflammatory roles in the mammalian innate immune response. Gaining mechanistic insights into the regulation and biological function of calprotectin will help facilitate patient diagnostics and therapy and further our understanding of the host-microbe interface. Recent literature has identified zebrafish s100a10b as zebrafish calprotectin based on sequence similarity, genomic context, and transcriptional upregulation during the immune response to bacterial infections. The field would benefit from expanding the breadth of calprotectin studies into a zebrafish innate immunity model. Here, we carefully evaluated the possibility that zebrafish possess a calprotectin. We found that zebrafish do not possess an ortholog of mammalian S100A8 or S100A9. We then identified four zebrafish s100 proteins- including s100a10b-that are expressed in immune cells and upregulated during the immune response. We recombinantly expressed and purified these proteins and measured the antimicrobial and proinflammatory characteristics. We found that none of the zebrafish proteins exhibited activity comparable to mammalian calprotectin. Our work demonstrates conclusively that zebrafish have no ortholog of calprotectin, and the most plausible candidate proteins have not convergently evolved similar functions.

Optimization of antimicrobial nanocomposite films based on carboxymethyl cellulose incorporating chitosan nanofibers and Guggul gum polysaccharide

The present study utilized response surface methodology (RSM) to investigate the impact of varying concentrations of carboxymethyl cellulose (CMC: 0.75–1.75 wt%), Commiphora mukul polysaccharide (CMP: 0–1 wt%), and Chitosan Nanofiber (CHNF: 0–1 wt%) on the physical and antimicrobial characteristics of nanocomposite films based on CMC. The optimization process aimed to enhance ultimate tensile strength (UTS), strain at break (SAB), and antibacterial activity, while minimizing water vapor permeability (WVP), solubility, swelling, moisture content, opacity, and total color difference (ΔE). The results revealed that both CMP and CHNF had a positive influence on reducing moisture content, WVP, and increasing UTS. However, higher concentrations of CMP and CHNF had a divergent effect on SAB, ΔE, and swelling. The incorporation of CMP led to increased opacity and solubility, while the inclusion of CHNF resulted in decreased opacity and solubility. Notably, only CHNF addition significantly improved the antibacterial properties of the films. By applying the optimization procedure utilizing RSM, the formulation containing CMC (1.5 wt%), CMP (0.25 wt%), and CHNF (0.75 wt%) demonstrated superior physical, mechanical, and antibacterial properties in the biodegradable film matrix. These findings highlight the potential of utilizing these components to enhance the performance of CMC-based nanocomposite films.

Antioxidant and antimicrobial characteristics of mangosteen peel extract and synergistic capacity in beef burger preservation

SummaryThis study aimed to investigate the efficiency of mangosteen peel extract (MPE) in preservation of beef burgers. MPE was first evaluated for its total phenolic content (TPC), total flavonoid content (TFC) and antioxidant and antimicrobial activities. Subsequently, beef burgers were prepared with different MPE amounts (0–1%) and stored for 1 day, 3 days and 5 days. The synthetic antioxidant 2,6‐di‐tert‐butyl‐4‐methyl phenol (BHT) and synthetic antimicrobial sodium benzoate (SB) were used for comparison. The changes of burgers in physicochemical parameters (moisture, cooking loss, storage loss and pH), lipid and protein oxidation (peroxide value, PV; thiobarbituric acid reactive substances, TBARS and carbonyl content), microbiological (total viable count, TVC) and sensory characteristics were assessed. The results revealed that MPE contained a high TPC of 128.93 mg gallic acid equivalent g−1 dry extract and TFC of 62.98 mg rutin equivalent g−1 dry extract. These bioactive compounds rendered MPE with its antioxidant activity approximately equivalent to ascorbic acid and antimicrobial activities against Escherichia coli and Staphylococcus aureus comparable with SB. MPE‐combined burger samples had higher moisture and cooking loss (P < 0.05) but almost equal storage loss and pH value compared with the control samples (P > 0.05). However, the incorporation of MPE into beef burgers did not affect the sensory attributes and preferences of consumers (P > 0.05). The burger with 1% MPE had lower values of PV, TBARS and carbonyl content than all other samples (P < 0.05), including the one added with BHT, indicating the strong potential of MPE as natural antioxidant alternative to prevent the oxidation of lipids and proteins. Through the TVC test, 1% MPE was demonstrated to result in the safe preservation of burgers up to 5 days of storage, equivalent to SB (P > 0.05). Therefore, MPE could become a natural synergistic alternative to both synthetic antioxidant and antimicrobial in the preservation of meat and meat products.

Investigate the Effect of Coating Concentration and Coating Thickness on the Anti-microbial Properties of Polycarbonate Sheet

This paper investigates the effect of coating concentration (ppm), and coating thickness (µm) on the anti-microbial properties of polycarbonate sheets using a variety of anti-microbial agents (Cu-infused Mg(OH)2, Mg(OH)2, Cu(OH)2, MgO, CuCl2.2H2O, and ZnO). In addition, a complete analysis was performed for all agents to rank the best agent in terms of the highest anti-microbial performance against E. coli K-12 MG1655 in two time intervals (4 and 24 hours). The coating concentration (ppm) was found to be a significant factor in the anti-microbial characteristics for Cu-infused Mg(OH)2, Mg(OH)2, Cu(OH)2, MgO, CuCl2.2H2O, and ZnO (p = 0.004, p < 0.0001, p < 0.0001, p = 0.0297, p = 0.0011, and p = 0.0130 respectively). The coating thickness (µm), on the other hand, was found to be a major contributor to the anti-microbial properties of Cu-infused Mg(OH)2, Mg(OH)2, Cu(OH)2, MgO, and CuCl2.2H2O (p < 0.0001, p = 0.0004, p = 0.0011, p = 0.0310, and p < 0.0001 respectively). The analysis determined that the coating did not influence the anti-microbial properties of ZnO. The interaction between the coating concentration (ppm), and the coating thickness (µm) was found to be a significant factor for Cu-infused Mg(OH)2, Cu(OH)2, MgO, CuCl2.2H2O, and ZnO (p < 0.0001, p = 0.0001, p = 0.0004, p < 0.0001, and p < 0.0001 respectively), however, this was not a significant factor for Mg(OH)2. Highlights • The anti-microbial activity of the inorganic material is dependent on the particle shape and size. • Particles with sharp edges will provide additional physical injuries to the microorganisms. • Smaller particle size will provide higher surface area therefore better interaction with microorganisms. • The coating concentration and coating thickness will be crucial to the anti-microbial activity. • The thermal embossing techniques demonstrate good adhesion to the surface.

Preparation and performance evaluation of a novel orthodontic adhesive incorporating composite dimethylaminohexadecyl methacrylate-Polycaprolactone fibers.

This study addressed enamel demineralization, a common complication in fixed orthodontic treatment, by evaluating a novel orthodontic adhesive with DMAHDM-PCL composite fibers. These fibers, produced through electrospinning, were incorporated into orthodontic adhesive to create experimental formulations at different concentrations and a control group. The study assessed antimicrobial properties, biosafety, and mechanical characteristics. New orthodontic adhesive exhibited significant bacteriostatic effects, reducing bacterial biofilm activity and concentrations. Incorporating 1% and 3% DMAHDM-PCL did not affect cytocompatibility. Animal tests confirmed no inflammatory irritation. Shear bond strength and adhesive residual index results indicated that antimicrobial fibers didn't impact bonding ability. In conclusion, orthodontic adhesives with 3% DMAHDM-PCL fibers are potential antimicrobial bonding materials, offering a comprehensive solution to enamel demineralization in orthodontic patients.

The potential effect of silver nanoparticles to inhibit microbial activity in orthodontic adhesive appliances: A literature review

Silver nanoparticles have been the focus of research in various areas of dentistry, including orthodontics. Orthodontic treatment requires a long period of time, so the brackets are in the oral cavity for a long time. This can potentially trigger the formation of white spot lesions because plaque sticks more easily to the surrounding enamel. Using silver nanoparticles mixed with orthodontic adhesives has been reported to increase antibacterial and antimicrobial characteristics. This literature review aims to investigate the effect of adding silver nanoparticles to orthodontic adhesive devices in inhibiting antimicrobial activity. This study method was carried out by searching the online electronic databases PubMed, Science Direct, and Google Scholar with the keywords "silver nanoparticles AND antimicrobial", "silver nanoparticles AND orthodontic adhesive", "silver nanoparticles AND composite resin", which is an original article published the year 2019- 2023. The results of research from 10 articles that met the inclusion criteria showed that orthodontic adhesives with silver nanoparticles effectively inhibited microbial activity, such as Streptococcus mutans (S.mutans), Lactobacillus acidophilus (L.acidophilus), Streptococcus sanguinis (S.sanguinis) and Candida albicans through increased release of Ag+ ions. Silver has been known to have effects, including producing minimal bacterial resistance compared to antibiotics. Even though it results in a decrease in the shear bond strength (SBS), the decrease level is still within clinically tolerable limits. It can be concluded that research needs to continue to be developed to obtain the right concentration and composition of the addition of silver nanoparticles so that an orthodontic adhesive material is obtained that is not only superior in its antibacterial properties but also in its mechanical properties.

Metabolic Composition of Methanolic Extract of the Balkan Endemic Species Micromeria frivaldszkyana (Degen) Velen and Its Anti-Inflammatory Effect on Male Wistar Rats.

Extracts from medicinal plants are widely used in the treatment and prevention of different diseases. Micromeria frivaldszkyana is a Balkan endemic species with reported antioxidant and antimicrobial characteristics; however, its phytochemical composition is not well defined. Here, we examined the metabolome of M. frivaldszkyana by chromatography-mass spectrometry (GC-MS), ultra-performance liquid chromatography-mass spectrometry (UPLC-MS-MS), and inductively coupled plasma mass spectrometry (ICP-MS). Amino acids, organic acids, sugars, and sugar alcohols were the primary metabolites with the highest levels in the plant extract. Detailed analysis of the sugar content identified high levels of sucrose, glucose, mannose, and fructose. Lipids are primary plant metabolites, and the analysis revealed triacylglycerols as the most abundant lipid group. Potassium (K), magnesium (Mg), zinc (Zn), and calcium (Ca) were the elements with the highest content. The results showed linarin, 3-caffeoil-quinic acid, and rosmarinic acid, as well as a number of polyphenols, as the most abundant secondary metabolites. Among the flavonoids and polyphenols with a high presence were eupatorin, kaempferol, and apigenin-compounds widely known for their bioactive properties. Further, the acute toxicity and potential anti-inflammatory activity of the methanolic extract were evaluated in Wistar rats. No toxic effects were registered after a single oral application of the extract in doses of between 200 and 5000 mg/kg bw. A fourteen-day pre-treatment with methanolic extract of M. frivaldszkyana in doses of 250, 400, and 500 mg/kg bw induced anti-inflammatory activity in the 1st, 2nd, and 3rd hours after carrageenan injection in a model of rat paw edema. This effect was also present in the 4th hour only in the group treated with a dose of 500 mg/kg. In conclusion, M. frivaldszkyana extract is particularly rich in linarin, rosmarinic acid, and flavonoids (eupatorin, kaempferol, and apigenin). Its methanolic extract induced no toxicity in male Wistar rats after oral application in doses of up to 5000 mg/kg bw. Additionally, treatment with the methanolic extract for 14 days revealed anti-inflammatory potential in a model of rat paw edema on the 1st, 2nd, and 3rd hours after the carrageenan injection. These results show the anti-inflammatory potential of the plant, which might be considered for further exploration and eventual application as a phytotherapeutic agent.

Physicochemical and antimicrobial characteristics of polypropylene-based nanocomposite containing SiO2-Ag nanoparticles prepared by gamma irradiation

This article evaluates the physicochemical and antimicrobial properties when silver-coated silica (SiO2-Ag) nanoparticles as active nanofiller are incorporated into the polypropylene (PP) thermoplastic matrix. The silica (SiO2) nanoparticles were prepared by precipitation method using sodium silicate. After that, silver-coated silica (SiO2-Ag) nanoparticles were synthesized by gamma radiation technique. X-ray diffraction (XRD), Infrared spectroscopy analysis (FTIR) and Transmission electron microscopy (TEM) analysis clarified the formation of SiO2-Ag nanoparticles. SiO2-Ag nanoparticles has a particle size with an average of 70 nm. The melt mixing procedure operated to fabricate PP thermoplastic nanocomposites with various ratios of 1.0, 2.0, and 3.0 part per hundred resin (phr) of the SiO2-Ag nanoparticles. To examine the effect of ionizing radiation on the prepared PP/SiO2-Ag nanocomposites, the samples were exposed to 20 kGy of gamma-irradiation. FTIR, XRD, mechanical analysis, thermogravimetric analysis (TGA), and scanning electron microscope (SEM) were utilized to characterize the physico-chemical alterations of the PP when loaded with SiO2-Ag nanoparticles. It is found that PP/1.0 phr SiO2-Ag nanocomposite revealed superior physico-chemical characteristics than the other two components. The irradiated specimens revealed superior tensile strength (TS) and elastic modulus (EM) over unirradiated ones, whereas inverse effects were predominant in case elongation at break (E%). Tmax of the native PP increased from 335°C to nearly 370°C of PP/1.0 phr SiO2-Ag nanocomposite. It is established that the fabricated PP/SiO2-Ag nanocomposites exhibited potent antimicrobial activity and can be a good candidate for food packaging applications.

Tissue engineered multifunctional chitosan-modified polypropylene hernia mesh loaded with bioactive phyto-extracts

Surface modified tissue engineered polypropylene / PP hernia meshes were fabricated by incorporating Bacterial cellulose / BC and chitosan / CS and phytochemical extracts. Under current practice, hernia and other traumatic injuries to the abdominal organs are clinically treated with surgical meshes. Often the foreign body reaction and infections result in relapse in patients which dictates additional reparative surgical procedures and pain. To improve the outcome of clinical restorative procedures new biomaterials with improved characteristics are required. The functionalized meshes were physically and chemically characterized using SEM, mechanical testing, FTIR and XRD. The antimicrobial activity was qualitatively and quantitatively tested using E. coli and S. aureus strains of bacteria. In vitro biocompatibility and wound healing effect of the modified meshes were performed using NIH3T3 fibroblast cell lines. Furthermore, tissue engineering potential of the meshes was evaluated using confocal fluorescent microscopy. In vivo implantation of the meshes was performed in male wistar rats for 21 days. Therefore, PP meshes with sustained drug delivery system augmented with anti-inflammatory and anti-microbial characteristics were developed. The coatings hereby not only increased the tensile strength of meshes but also prevented the modified meshes from causing infection. Current study resulted in CS-BC bioactive PP meshes loaded with phytochemicals which showed anti-inflammatory, antibacterial and wound healing potential. These meshes can be valuable to lessen the post-surgical complications of implanted PP mesh and thus reduce rejection and recurrence.

Genetic, virulence, and antimicrobial resistance characteristics associated with distinct morphotypes in ST11 carbapenem-resistant Klebsiella pneumoniae

ABSTRACT ST11 is the most common lineage among carbapenem-resistant Klebsiella pneumoniae (CRKP) infections in Asia. Diverse morphotypes resulting from genetic mutations are associated with significant differences in microbial characteristics among K. pneumoniae isolates. Here, we investigated the genetic determinants and critical characteristics associated with distinct morphotypes of ST11 CRKP. An ST11-KL47 CRKP isolate carrying a pLVPK-like virulence plasmid was isolated from a patient with a bloodstream infection; the isolate had the “mcsw” morphotype. Two distinct morphotypes (“ntrd” and “msdw”) were derived from this strain during in vitro passage. Whole genome sequencing was used to identify mutations that cause the distinct morphotypes of ST11 CRKP. Transmission electron microscopy, antimicrobial susceptibility tests, growth assays, biofilm formation, virulence assays, membrane permeability assays, and RNA-seq analysis were used to investigate the specific characteristics associated with different morphotypes of ST11 CRKP. Compared with the parental mcsw morphotype, the ntrd morphotype resulted from mutation of genes involved in capsular polysaccharide biosynthesis (wza, wzc, and wbaP), a result validated by gene knockout experiments. This morphotype showed capsule deficiency and lower virulence potential, but higher biofilm production. By contrast, the msdw morphotype displayed competition deficiency and increased susceptibility to chlorhexidine and polymyxin B. Further analyses indicated that these characteristics were caused by interruption of the sigma factor gene rpoN by insertion mutations and deletion of the rpoN gene, which attenuated membrane integrity presumably by downregulating the phage shock protein operon. These data expand current understanding of genetic, virulence, and antimicrobial resistance characteristics associated with distinct morphotypes in ST11 CRKP.

Gamma Irradiation-Mediated Alterations in Chemical Composition and Antimicrobial Efficacy of Zubaidi, a Wild Edible Desert Truffle (Terfezia boudieri), with Implications for Pharmaceutical Applications

In exploring the impact of γ-radiation on the biochemical makeup and antimicrobial attributes of Zubaidi truffle (Terfezia boudieri), this study delved into the nuanced interplay between irradiation doses, chemical components, and antimicrobial efficacy. This research scrutinized the influence of γ-radiation on the chemical constitutes and antimicrobial characteristics of Zubaidi truffle (Terfezia boudieri). By applying four distinct doses of γ-radiation (2.5, 5.0, 7.5, and 10 kGy), the study assesses various parameters, including phenols, flavonoids, total and reduced soluble sugars, crude and soluble protein, total amino acids, antioxidant activity, and the susceptibility of examined strains to irradiated and non-irradiated truffle extracts in comparison to standard antibiotics. The findings elucidate that γ-irradiation induces moderate adjustments in the chemical composition, coupled with a dose-dependent escalation in antioxidant activity. Remarkably, irradiated truffle extracts highlight antibiotic efficacy comparable to standard antibiotics, unveiling a nuanced correlation influenced by both radiation dosage and bacterial strain.

High intragenomic, intergenomic, and phenotypic diversity in pulcherrimin-producing Metschnikowia yeasts indicates a special mode of genome evolution

In molecular systematics, the delimitation of yeast species is based on the notion that the barcode differences are smaller within species than between them. The most widely used barcodes are segments of the chromosomal repeats coding for ribosomal RNAs that are homogenised in yeasts. The analysis of these segments of the type strains of ten species recently merged in Metschnikowia pulcherrima and 37 new isolates demonstrated that this is not the case in this species. The intragenomic diversity significantly exceeded the threshold gaps used to differentiate related yeast species. Large segments of the D1/D2 domains were not diverse within the genomes and could therefore be used to determine the taxonomic affiliation of the isolates. The genome structures of the isolates were compared by RAPD and the RFLP of the mitochondrial DNA. Both patterns were highly heterogeneous. The sequence analysis of the PUL4 gene (a member of the PUL gene cluster involved in pulcherrimin production) revealed very high intragenomic differences, suggesting that the genomes may be chimerised. Three phenotypic traits related to the antimicrobial antagonism characteristic of the species were also highly diverse and prone to reversible segregation resembling epigenetic processes (silencing and reactivation of regulators) rather than mutations and back-mutations. These features make M. pulcherrima unique among yeasts and indicate that it evolves in a non-standard way.

Streptococcus suis serotype 4: a population with the potential pathogenicity in humans and pigs

ABSTRACT Streptococcus suis is a major bacterial pathogen in pigs and an emerging zoonotic pathogen. Different S. suis serotypes exhibit diverse characteristics in population structure and pathogenicity. Surveillance data highlight the significance of S. suis serotype 4 (SS4) in swine streptococcusis, a pathotype causing human infections. However, except for a few epidemiologic studies, the information on SS4 remains limited. In this study, we investigated the population structure, pathogenicity, and antimicrobial characteristics of SS4 based on 126 isolates, including one from a patient with septicemia. We discovered significant diversities within this population, clustering into six minimum core genome (MCG) groups (1, 2, 3, 4, 7-2, and 7-3) and five lineages. Two main clonal complexes (CCs), CC17 and CC94, belong to MCG groups 1 and 3, respectively. Numerous important putative virulence-associated genes are present in these two MCG groups, and 35.00% (7/20) of pig isolates from CC17, CC94, and CC839 (also belonging to MCG group 3) were highly virulent (mortality rate ≥ 80%) in zebrafish and mice, similar to the human isolate ID36054. Cytotoxicity assays showed that the human and pig isolates of SS4 strains exhibit significant cytotoxicity to human cells. Antimicrobial susceptibility testing showed that 95.83% of strains isolated from our labs were classified as multidrug-resistant. Prophages were identified as the primary vehicle for antibiotic resistance genes. Our study demonstrates the public health threat posed by SS4, expanding the understanding of SS4 population structure and pathogenicity characteristics and providing valuable information for its surveillance and prevention.

Advancements in developing biomaterials for 3D printing photosensitive resins containing quaternary ammonium molecules for enhanced oral healthcare

In this study, we investigated the development of biomaterials tailored for UV-cured 3D printing technology in oral healthcare. Traditionally, 3D-printed oral healthcare products have exhibited imperfections in antimicrobial and anti-pollution properties, limiting their utility. To address this challenge, we synthesised antimicrobial agents incorporating quaternary ammonium groups through a combination of isophorone diisocyanate (IPDI), hydroxyethyl methacrylate (HEMA), and choline chloride. These agents were then blended with diluents, resins, and photoinitiators to create raw materials suitable for UV-curing 3D printing photosensitive resins. Subsequently, the resins were subjected to digital light processing (DLP) 3D printing for curing. The resulting 3D-printed material underwent rigorous mechanical and antimicrobial testing. Our findings demonstrate that the 3D printed compounds, cured through this process, exhibited exceptional hardness, tensile properties, antimicrobial characteristics, and long-lasting antimicrobial durability. These developments promise widespread adoption and application within the oral healthcare field.

Gelatin/sodium alginate-based biodegradable films functionalized by persimmon pectin/ovalbumin-stabilized neem essential oil Pickering emulsion: Application for cherry tomato preservation

This work aims to develop a biodegradable film with enhanced mechanical, water-barrier, and antimicrobial characteristics for the preservation of cherry tomatoes. Here, a persimmon pectin/ovalbumin (PN/OVA) stabilized-neem essential oil Pickering emulsion (NOPE) was added into the gelatin/sodium alginate-based blend matrix (GS). Even the biodegradability and transmittance of NOPE-rich film were decreased as compared to the control film, its flexibility, oxygen-barrier, and water-barrier performances significantly (P < 0.05) increased by 45.23 %, 32.32 %, and 37.02 %, respectively. The NOPE-loaded films destroyed the hyphal structure and reduced spore germination of Botrytis cinerea through slow-releasing neem essential oil (NO), in turn inhibiting the growth of B. cinerea. Finally, the prepared films were applied for cherry tomato preservation. Compared with the control, 2.0 wt%-loaded GS films greatly reduced the weight loss and disease incidence of cherry tomatoes by 57.33 and 72.4 %, respectively, owing to their excellent water resistance and slow-released properties. Thus, the addition of 2.0 wt% NOPE into GS film is of particular interest in the design of active biodegradable packaging films for fruit preservation.