Search Results (223)

Chemical investigation of the marine sponge-derived Streptomyces xiamenensis 1310KO-148 afforded six polycyclic tetramate macrolactams (PTMs), including three known compounds (1–3) and three previously undescribed chlorohydrin-containing analogues, chlokamycins B–D (4–6). Their planar structures were elucidated by extensive analysis of 1D and 2D NMR spectra and HR-ESIMS data, while the relative configurations were assigned using NOESY correlations. The absolute configurations were further confirmed by electronic circular dichroism (ECD) calculations. Compounds 3–6 exhibited significant cytotoxic activity against 14 human cancer cell lines (GI₅₀ = 2.68–24.92 μM) and antibacterial activity against Staphylococcus aureus (MIC = 16.00–32.00 μg/mL) and Micrococcus luteus (MIC = 4.00–32.00 μg/mL) among six tested bacterial strains. Full article

Backgrouınd/Objectives: Edible fungi are increasingly regarded as important natural reservoirs of secondary metabolites exhibiting a wide range of biological activities. The present study aimed to molecularly identify Rhizopogon roseolus collected from Türkiye and to systematically evaluate its bioactive properties. Methods: The antimicrobial and antioxidant activities of methanolic, ethanolic, and aqueous extracts were evaluated. The phenolic profile and the fatty acid composition of the species were characterized using HPLC-DAD and GC–MS respectively. Results: All extracts showed noticeable antimicrobial activity against several pathogenic microorganisms, including Bacillus subtilis, Micrococcus luteus, Bacillus cereus and Pseudomonas aeruginosa. In addition, the extracts displayed remarkable antioxidant potential. The methanolic extract of R. roseolus demonstrated DPPH and ABTS radical scavenging activities of 651.44 ± 15.02 mg TE/g and 162.71 ± 8.11 mg TE/g, respectively. Its ferric reducing antioxidant power was determined as 724.33 ± 12.23 mg AAE/g DW, while the cupric reducing antioxidant capacity reached 952.45 ± 4.35 mg TE/g DW. These strong antioxidant effects were closely associated with the high phenolic content (9.89 ± 0.08 mg GAE/g DW) of the extracts. GC–MS analysis indicated that palmitoleic, oleic, and linoleic acids were the major fatty acids, while HPLC-DAD revealed that gallic acid and pyrocatechol were major phenolic compounds present in R. roseolus, suggesting a nutritionally beneficial metabolite composition. Conclusions: Taken together, the findings demonstrate that R. roseolus represents a promising natural source of antimicrobial and antioxidant compounds with potential applications. Full article

Lactic acid bacteria (LAB) are widely used in food systems; among them, bacteriocin-producing strains have attracted attention for their potential in the biopreservation of dairy products. This study started from the detection of bacteriocin-encoding genes in eight probiotic Leuconostoc mesenteroides subsp. mesenteroides strains, previously isolated, identified, and characterized for antimicrobial activity. Results confirmed the presence of bacteriocin genes across the strains, with Ln.F5 harboring both mesB and lcnA genes, and three other strains, including the Ln.M14 strain, exclusively carrying the lcnA gene. The two strains, Ln.F5 and Ln.M14, were used, in single and mixed cultures, for the first time, as adjunct cultures in a model cheese. Their impact against Listeria spp., Staphylococcus aureus, Escherichia coli, Micrococcus luteus, and Brochothrix thermosphacta, and on volatile organic compounds (VOCs), during ripening and storage, was evaluated. Results showed high viability (9.2 Log CFU/g) of Leuconostoc spp. in model cheese, up to 60 days of storage, and Pulsed-Field Gel Electrophoresis (PFGE) profiles of the re-isolated bacteria confirmed the survival of the added strains. Furthermore, results indicated the inhibition of E. coli and Listeria spp. started from the 15th day of ripening in samples differently inoculated with the two Leuconostoc strains. Listeria spp. was completely inhibited starting from 15 days by Ln.M14, in single culture. The complete inhibition of S. aureus, M. luteus, and B. thermosphacta was detected after 30 days of ripening in samples differently inoculated with Ln.F5 and Ln.M14. The VOC analyses revealed more complex aromatic profiles in samples inoculated with Leuconostoc strains, which, along with the development of cheese eyes, confirmed the effect of the Leuconostoc strains in enhancing quality traits of cheeses. Full article

The human skin microbiome has gained considerable attention as a resource for the development of innovative probiotics for cosmetic purposes or promoting skin health. However, the evaluation of new probiotic strains to ensure their “generally recognized as safe” (GRAS) status remains challenging. Here, we have subjected the annotated draft genome sequences of four human skin-derived bacterial strains, namely Bacillus subtilis MBF10-19J, Micrococcus luteus MBF05-19J, Staphylococcus hominis MBF12-19J, and Staphylococcus warneri MBF02-19J, to bioinformatic analyses to detect the genes associated with important probiotic traits, as well as undesirable characteristics such as antibiotic resistance, virulence factors, and toxic metabolites. Each bacterium harbors at least one type of adhesin-encoding gene, while only S. hominis MBF12-19J and S. warneri MBF02-19J contain the putative genes encoding enzymes for metabolism improvement. In vitro assays, including antibiotic susceptibility and antimicrobial activity testing, revealed strain-specific safety characteristics that complement the genomic findings. With regard to antibiotic resistance determinants, S. hominis MBF12-19J showed the most favorable profile, S. warneri MBF02-19J and M. luteus MBF05-19J appeared suitable when used with appropriate caution, and B. subtilis MBF10-19J exhibited amoxicillin resistance, i.e., warrants careful evaluation. Further in vivo validation is needed to determine whether these strains do indeed comply with GRAS evaluation frameworks. Full article

Tomato leafminer (Tuta absoluta) significantly affects tomato (Solanum lycopersicum) and eggplant (Solanum melongena) crops worldwide, with its feeding patterns being closely associated with its gut microbiota. We aimed to compare the cultivable gut bacteria of T. absoluta larvae fed on tomato and eggplant to investigate their role in host adaptation. Gut bacteria were cultivated on Luria–Bertani broth, nutrient agar, and Brain Heart Infusion media under different temperature conditions, followed by morphology- and 16S rRNA-based identification. Notably, both feeding groups revealed distinct gut bacterial community structures. Tomato-fed larvae harbored bacteria spanning eight species, five genera, four families, and two phyla. In contrast, eggplant-fed larvae exhibited greater microbial diversity, encompassing 15 species, 10 genera, 9 families, and 3 phyla, including unique genera such as Pseudomonas and Pectobacterium, which was attributed to the host plant contribution. Enterococcus mundtii was the most dominant bacterium, and species such as Bacillus wiedmannii and Micrococcus luteus were most thermotolerant. Overall, these findings highlight the importance of multi-condition culture approaches for thoroughly characterizing insect gut microbiota and underscore the role of host plants in pest adaptability by modulating gut microbial communities, providing new insights for developing sustainable control strategies utilizing “plant–insect–microorganism” interactions. Full article

Antibacterial thin-film coatings are of increasing interest for enhancing hygiene in controlled environments such as commercial greenhouses. Phytopathogens including Pseudomonas syringae, and human pathogens such as Escherichia coli, Micrococcus luteus, and Staphylococcus aureus, frequently contaminate greenhouse environments. The present study aimed to develop and evaluate multifunctional magnetron-sputtered glass coatings with strong antimicrobial performance, deposited by physical vapor deposition to achieve precise control of film composition and uniform coverage of large substrates (≥0.25 m²), ensuring industrial-scale applicability. Thin films were fabricated by magnetron sputtering using multi-alloy targets composed of Cu, Sn, Zn, Al, Ni, Fe, Ti, Mn, Nb, or Co. Fourteen distinct coating compositions were characterized using high-resolution transmission electron microscopy, scanning transmission electron microscopy, and energy-dispersive X-ray spectroscopy. Antibacterial performance was evaluated against the following strains: E. coli (PCM 2560), M. luteus (PCM 525), S. aureus (PCM 2602), and P. syringae pv. tomato (IOR2146). Coatings prepared from 90%Cu-10%Sn, 90%Cu-10%Zn, and 80%Cu-20%Ti targets exhibited one of the highest antibacterial efficiencies. These coatings also showed strong mechanical durability and corrosion resistance. Our results indicate that coatings obtained from Cu-based multi-alloy targets by magnetron sputtering are promising candidates for use as durable, antimicrobial inner glass surfaces in future greenhouse applications. Full article

Intense training loads alter the skin microbiome and defence mechanisms in athletes, yet adaptation profiles remain insufficiently characterised. This study evaluated the relationships between skin bacterial microbiome structure, antimicrobial activity, dermcidin levels, and acne severity in male professional hockey players compared with amateur athletes and non-athletes. One hundred men (18–57 years) were examined and allocated to six subgroups by exercise intensity and acne status. Microbiota composition was assessed by culture-based methods and MALDI-TOF identification, antimicrobial activity measured spectrophotometrically, dermcidin quantified by ELISA, and sweat proteome characterised by HPLC-MS. Staphylococcus epidermidis and Micrococcus luteus predominated in all groups. Exercise intensity, rather than acne, was the main determinant of total bacterial colonisation, which increased approximately tenfold from non-athletes to professional hockey players. In non-athletes, higher antimicrobial activity correlated with greater acne severity, whereas in professionals this relationship was absent and dermcidin levels showed an inverse association with acne severity. Proteomic analysis identified 17 polypeptides; dermcidin and prolactin-inducible protein were dominant in all groups, and calprotectin (S100-A8/A9) was detected exclusively in healthy professionals. Full article

Multidrug-resistant (MDR) pathogens and biofilm-associated infections represent a major global health concern, particularly in the context of medical devices such as catheters, tubing, and blood sampling devices. Biofilms, responsible for up to 85% of human infections, confer a high level of microbial resistance and compromise device performance and patient safety. In this study, the antibiofilm potential of Syzygium aromaticum (clove) essential oil was investigated through an in vitro assay. GC–MS analysis revealed eugenol (72.77%) as the predominant compound, accompanied by β-caryophyllene (14.72%) and carvacrol (2.09%). The essential oil exhibited notable antimicrobial activity, producing inhibition zones of 30.5 ± 4.5 mm against Staphylococcus aureus, 24.5 ± 0.5 mm against Micrococcus luteus, 16.0 ± 2.0 mm against Escherichia coli, 13.0 ± 1.0 mm against Pseudomonas aeruginosa, 23.5 ± 1.5 mm against Candida albicans, and 24.0 ± 2.0 mm against C. glabrata. A marked reduction in biofilm biomass observed on polyvinyl chloride (PVC) surfaces. The application of clove essential oil as a coating for PVC-based medical devices remains a future possibility that requires formulation and in vivo testing. This strategy is proposed as potentially eco-safe, although environmental toxicity and biocompatibility have not yet been evaluated. It could contribute to the prevention of biofilm formation in arterial sampling systems and other healthcare-related materials, thereby enhancing device safety and longevity. Full article

Atopic dermatitis (AD) is associated with microbial dysbiosis and impaired skin barrier function. Topical therapies, such as moisturisers and antimicrobial fragrance compounds, may modulate the skin microbiome and support disease management. The objective was to evaluate how a moisturiser and a fragrance compound (farnesol) influence skin microbiome composition in individuals with AD and healthy controls. In a randomised, controlled, operator-blinded study, 15 AD patients and 15 healthy controls applied a moisturiser, farnesol, moisturiser + farnesol, or no treatment to defined skin areas over 7 days. Microbiome composition, alpha/beta diversity, and core taxa were analysed using shotgun metagenomics. At baseline, AD patients exhibited distinct microbial profiles, including elevated Staphylococcus aureus and Micrococcus luteus. Neither moisturiser nor farnesol significantly altered richness, beta diversity, or core taxa in either AD patients or controls. However, moisturiser use in healthy individuals modestly increased Shannon diversity, reflecting improved microbial evenness. Despite clear microbiome differences between AD and healthy skin, short-term topical treatment did not markedly shift microbial composition. The observed stability underscores the resilience of the skin microbiome and suggests that longer interventions or more targeted formulations may be necessary to influence microbial dysbiosis in AD. Full article

Fruits of the Laurocerasus officinalis Roem., known as cherry laurel, are found in the Black Sea region. This study examines the phytochemical characterization, antioxidant properties, and antimicrobial potential of cherry laurel’s fruits, variety Novita, cultivated in Southern Bulgaria. The study is significant since it examines the phytochemical profile of this variety’s fruits for the first time. The carbohydrate composition of the fruit was identified. The total polyphenols and flavonoids of five fruit extracts (96% ethanol, 70% ethanol, 50% ethanol, 80% methanol, and water) were determined. The antioxidant potential of these five extracts was evaluated by three methods: DPPH, ABTS, and FRAP. We found that the 96% ethanol extract had the highest content of polyphenols and flavonoids and the highest antioxidant activity values by all three methods. A correlation was established between the content of polyphenols, flavonoids, and antioxidant activity based on the calculated correlation coefficient. The antimicrobial potential of methanolic and aqueous extracts of the fruit of the laurel cherry was evaluated against twenty microorganisms. It was found that the methanolic extracts exhibited moderate to high sensitivity against both Gram-positive and Gram-negative strains, yeast Saccharomyces cerevisiae, and five fungi, while water extracts had moderately sensitive activity against Micrococcus luteus only. Based on the results, we can conclude that the fruits demonstrate good antioxidant and antimicrobial potential. Full article

In the current research a series of new copper(II) complexes with novel acylhydrazone ligands were synthesized and their antibacterial and anticancer activities were determined. The complexes were characterized by molecular spectroscopy (FT-IR and UV-Vis) and conductivity measurements. Additionally, their structure was confirmed by single-crystal X-ray analysis. The crystallographic data revealed that all compounds are mononuclear Cu(II) species. The Cu(II) ion is four-coordinated by the ONO donor set from mono-deprotonated hydrazone ligand and one Cl^¯ anion, forming distorted square-planar geometry. The biological studies revealed that the compounds exhibit high antimicrobial activity, especially against Gram-positive bacteria, in some cases greater than the reference substances, and better activity than free ligands. The tested complexes possessed the lowest MIC and MBC values towards Staphylococcus epidermidis ATCC 12228 and Micrococcus luteus ATCC 10240. Furthermore, they showed no toxicity towards normal cell lines. Full article

The emergence of multidrug-resistant microbes presents a serious public health threat that requires new antimicrobial methods. A potential solution to combat resistance involves using metal nanoparticles that possess improved biological characteristics. The researchers have synthesized gold nanoparticles (Au-NPs) using gamma irradiation of Polyacrylamide (PAM) at 5, 10, and 15 kGy doses and through Au/chitosan nanocomposite production methods. They have also assessed the antimicrobial and anticancer functions of the produced nanomaterials by testing them on various microorganisms and cancer cell lines. Gold nanoparticles exhibited strong antibacterial effects against multiple Gram-positive bacterial strains, including Bacillus subtilis, Micrococcus luteus, Staphylococcus epidermidis, Staphylococcus aureus, and Streptococcus mutans, as well as methicillin-resistant Staphylococcus aureus (MRSA). Escherichia coli showed a significant inhibition zone of 23 mm, and Salmonella spp. showed similar inhibition. The inhibition zone for Klebsiella pneumoniae ATCC 13883 revealed resistance. The Au-NPs/chitosan composite showed moderate antifungal effectiveness against Syncephalis racemosum and Aspergillus niger alongside Candida albicans and several other tested fungi. Au-NPs showed cytotoxicity to breast MCF-7 cells, as well as liver HepG-2 cells and colon HCT-116 cells. The combination of Au-NPs with chitosan demonstrated limited effectiveness in countering hepatitis A virus (HAV-10) and herpes simplex virus type 1 (HSV-1). The combination of gamma-irradiated Au-NPs with biopolymers like chitosan demonstrates significant promise in antimicrobial and anticancer biomedical applications. Full article

Bacteriocins from lactic acid bacteria have attracted considerable attention as natural alternatives to conventional antimicrobial agents. Weissellicin LM85, a bacteriocin purified from Weissella confusa LM85, has been less extensively studied in terms of its mechanism of action and potential applications. In this study, purified weissellicin LM85 exhibited potent inhibitory effects against Gram-positive bacteria, with minimum inhibitory and bactericidal concentrations determined against Micrococcus luteus MTCC106. Time-kill assays and fluorescence staining indicated a concentration-dependent reduction in cell viability, accompanied by membrane disruption. Further analyses revealed potassium ion efflux, dissipation of membrane potential (Δψ) and pH gradient (ΔpH), genomic DNA fragmentation, and pronounced morphological alterations in target cells. These findings are strongly suggestive of membrane-targeted bactericidal activity, likely involving pore-forming effects. In addition, weissellicin LM85 inhibited both growth and biofilm formation of Salmonella enterica subsp. enterica serovar Typhimurium ATCC13311 and Staphylococcus aureus subsp. aureus ATCC25923. Mechanistic analyses revealed the disruption of cell membrane integrity, leakage of potassium ions, cytoplasmic contents, and non-specific DNA degradation, indicating a multifaceted antibacterial mode of action. These findings highlight weissellicin LM85 as a promising natural antimicrobial with potential applications in food preservation and the control of foodborne pathogens and biofilm-associated infections. Further studies on cytotoxicity and in vivo efficacy are required to advance its practical application. Full article

Marine actinomycetes constitute a vigorous source of bioactive compounds with potential anti-tumor activity. This study investigates the antitumor activity and classification of actinomycetes isolated from 32 marine soil samples collected across four seasons from Tyr City Beach, Lebanon. A total of 80 morphologically diverse isolates were recovered and characterized, with dominant genera including Streptomyces, Kocuria, and Micrococcus. Among these, three promising strains—Kocuria rosea, Micrococcus luteus, and Streptomyces longisporoflavus—were selected for further analysis. Crude extracts were tested against human colorectal adenocarcinoma (Caco-2) and human hepatocellular carcinoma (HepG-2) cancer cell lines using MTT and Western blot assays. At the highest concentration (8 µg/µL), the extracts reduced cell viability to 24–37% in Caco-2 and 12–25% in HepG-2. The IC₅₀ values ranged from 1.72 to 3.53 µg/µL, depending on the extract and cell line. Western blot analysis showed dose-dependent increases in the Bax/Bcl-2 ratio, with fold changes reaching 4.35 (Kocuria), 11.39 (Micrococcus), and 14.25 (Streptomyces) in HepG-2 cells. The p53 protein expression also increased significantly, with fold changes up to 7.79 in Caco-2 and 3.0 in HepG-2 cells. These results indicate that marine actinomycetes from the Lebanese coastline hold strong potential as a source of antitumor agents targeting apoptosis pathways. Full article

Subclinical mastitis is an udder infection and inflammation in dairy animals that causes no visible changes in the milk or udder, making it hard to detect. Animal welfare and health are negatively impacted by dairy cow mastitis, which also severely impairs the dairy industry’s financial standing. This study was carried out in the three local Municipalities of Free State Province, South Africa, sought to determine bacterial contamination of raw milk of cows infected with subclinical mastitis using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and 16S rRNA Sanger sequencing. From subclinical mastitic samples, our MALDI-TOF results revealed coliform bacteria such as Pseudomonas oryzihabitans with 25/71 (32.21%) as a dominant species, followed by Pseudomonas aeruginosa, Escherichia coli, Pantoea agglomerans and Enterobacter kobei at 9/71 (12.67%), 8/71 (11.27%), 6/71 (8.45%) and 6/71 (8.45%), respectively. Finally, Enterococcus faecalis, Enterococcus faecium, Micrococcus luteus, Routella ornithinolytica were detected at 3/71 (4.22%) each and 1 sample with mixed species of Routella platicola 1/71 (1.40%) and Routella ornithinolytica at 1/71 (1.40%). The most frequent microbes causing dairy cow mastitis can be identified using MALDI-TOF MS, a technique that is strong, quick, and accurate. With the inclusion of new species, the database can be enhanced and expanded over time. Full article