Folia microbiologica最新文献

Due to their vast chemical diversity, natural products derived from medicinal plants, whether as standardized extracts or isolated compounds, hold significant promise for new drug discovery. This study focused on the application of various analytical techniques, including phytochemical screening, extraction, isolation, and characterization of bioactive constituents from Angelica glauca extracts. The antibacterial properties of these isolated compounds were evaluated using the disk diffusion method against respiratory pathogens such as Staphylococcus aureus (MTCC 1144), Streptococcus pneumoniae (MTCC 655), Streptococcus pyogenes (MTCC 442), Pseudomonas aeruginosa (MTCC 2474), and Klebsiella pneumoniae (MTCC 4030). Findings revealed that the methanolic extract of A. glauca contains three primary bioactive compounds: n-hexacosane, stigmasterol, and 6,7-dimethoxycoumarin. Additionally, the extract was rich in alkaloids, flavonoids, glycosides, steroids, saponins, and tannins. Among the isolated compounds, 6,7-dimethoxycoumarin demonstrated the strongest antibacterial activity against S. aureus (17.0 ± 0.97 mm), outperforming n-hexacosane and stigmasterol. These results highlight the therapeutic potential of these compounds in treating respiratory infections and suggest their suitability as candidates for developing new antimicrobial agents. Future research will aim to formulate novel drugs based on these promising bioactive molecules.

The wide spread of opportunistic fungal infections among several immunocompromised patients has become a major health concern. A surge in the prevalence of multi drug resistant pathogenic fungi mainly Candida and Aspergillus sp. to current antifungals has lead scientists to search for new lead compounds which can address the issues of emerging fungal infections. Majority of the antifungals used currently are less effective against these pathogens and scenario of developing resistance to azoles is also a major concern. The marine environment has become a greatest treasure house for a large number of bioactive compounds due to its extreme habitat. Several bioactive compounds have been extracted and characterized from marine sources. Nevertheless, identification of antifungal compounds from marine sources especially from marine actinobacteria is less investigated so far. The existing antifungal compounds have several limitations like toxicity, poor biocompatibility and low efficacy. Hence, the development of novel antifungal compounds from marine actinobacteria with greater potency can be an attractive solution to fight this hurdle of fungal infections. From active investigation and studies reported so far, antifungal compounds from marine actinobacteria have been addressed in this review. In addition to that, this review also focuses on actinobacteria mediated nanoparticles in the treatment of opportunistic fungal infections. Nanoparticles can be a promising approach in antifungal therapy due to their nanoscale size and surface properties which enhances treatment efficacy through disruption of fungal cell membranes. Therefore, marine antifungal compounds along with the application of nanotechnology hope to contribute better solutions to opportunistic fungal infections.

Lead (Pb) contamination is a critical environmental concern that adversely affects plant growth and development. This study investigates the potential of ZnFe₂O₄ nanoparticles (NPs) and plant growth-promoting rhizobacteria to alleviate Pb-induced phytotoxicity in Vigna radiata (mung bean). Seeds were subjected to 30 µM Pb stress alone or in combination with ZnFe₂O₄ NPs and PGPR. Germination parameters including germination percentage, mean germination time, and germination index were significantly impaired under Pb stress, whereas co-application of ZnFe₂O₄ NPs and PGPR restored these traits, resulting in improved and timely seedling emergence. Vegetative growth parameters such as shoot and root length, fresh and dry biomass, and leaf area were notably reduced under Pb exposure. However, the integrated use of ZnFe₂O₄ NPs and PGPR significantly improved plant height (by 29.4%), root length (33.8%), and leaf area (27.9%) compared to Pb-stressed plants. Similarly, fresh and dry biomass values showed marked recovery, indicating improved water and nutrient uptake efficiency in treated plants. Anatomical analysis revealed severe structural damage in Pb-stressed leaves, including reduced epidermal thickness, disrupted mesophyll tissue, and decreased stomatal dimensions. The application of ZnFe₂O₄ NPs and PGPR markedly ameliorated these anatomical deformities, enhancing epidermal integrity, vascular bundle organization, and stomatal morphology. Notably, stomatal length and guard cell dimensions were restored closer to control levels. Overall, the synergistic effect of ZnFe₂O₄ NPs and PGPR substantially mitigated Pb toxicity and promoted normal germination, vegetative development, and anatomical structure in Vigna radiata, suggesting a viable strategy for cultivating crops in contaminated soils.

Nontuberculous mycobacteria (NTM) cause difficult-to-treat pulmonary infections due to their high antimicrobial resistance. Among them, the Mycobacterium abscessus complex (MABC) is a major pathogen characterized by prolonged treatment courses and low success rates. This study investigated the combination effects of the antimicrobials bedaquiline (BDQ) and clarithromycin (CLA) with the efflux pump inhibitors (EPIs) verapamil (VP) and berberine (BER) in clinical MABC isolates. Nineteen MABC strains isolated from respiratory samples were analyzed using the checkerboard method, and fractional inhibitory concentration index (FICI) values were calculated to determine synergistic, indifferent, or antagonistic interactions. Subspecies identification and genotypic resistance profiles were assessed using the GenoType NTM-DR assay. Of the isolates, 84.2% were identified as M. abscessus subsp. abscessus, 10.5% as M. abscessus subsp. massiliense, and 5.26% as M. abscessus subsp. bolletii. While no rrl (acquired macrolide resistance) or rrs (aminoglycoside resistance) mutations were detected, a functional erm41 (inducible macrolide resistance) gene was found in 73.6% of isolates. Synergistic effects were observed at rates of 84.2% for BDQ/VP, 57.9% for CLA/VP, 5.26% for BDQ/BER, and 31.5% for CLA/BER, with no antagonism identified. The BDQ/VP combination showed significantly greater synergy than BDQ/BER (p < 0.0005) and was superior to CLA/VP (p < 0.0005). Combinations with VP demonstrated significantly lower FICI values (p < 0.0005). Median fold increases in antimicrobial activity were four-fold with VP and two-fold with BER. In conclusion, the BDQ/VP combination emerged as the most effective regimen. These results highlight the synergistic potential of EPI-antimicrobial combinations and may inform the development of new therapeutic strategies for NTM infections.

Aluminum (Al) toxicity is a major limiting factor for crop growth in acidic soils worldwide. Therefore, it is necessary to study Al-tolerance mechanisms. Cryptococcus humicola is a good candidate for Al-tolerance research due to its high ability for Al tolerance. qRT-CR analysis revealed that the expression of the RTA1 gene was upregulated approximately 18-fold in C. humicola under 50 mM Al stress. In this study, we investigated the role of the Rta1 lipid transport protein of C. humicola in acid and Al resistance. The Rta1 lipid transport protein was predicted to be a membrane protein with seven transmembrane structural domains, with low homology to other fungi but highly similar secondary structures. RTA1 mutant and transgenic yeast strains were constructed. Under normal conditions, the RTA1 mutant tended to aggregate into clusters compared with the wild type, but the clustering of the RTA1 mutant disappeared under Al stress. The growth of the RTA1 mutant and transgenic yeast on plates and in liquid culture medium revealed that the Rta1 lipid transporter protein could help C. humicola resist acidic and Al stress. After 50 mM Al treatment, the malondialdehyde content of the RTA1 mutant was greater than that of the wild type, suggesting that membrane lipid damage was more severe in the RTA1 mutant than in the wild type. The above results suggest that the Rta1 lipid transporter protein may affect cellular membrane function and thus lead to increased acid and Al tolerance in cells.

Saprobic fungi remain underexplored sources of bioactive secondary metabolites with pharmaceutical potential. This study presents the first biological evaluation of four rarely studied species, Melanographium smilacis, Helminthosporium chiangraiense, Pleopunctum thailandicum, and Pseudochaetosphaeronema chiangraiense, isolated from submerged plant material in northern Thailand. Crude ethyl acetate extracts were examined for antioxidant capacity, cytotoxicity, oxidative stress, and apoptosis-related effects. All extracts exhibited dose-dependent DPPH scavenging ranging from 47 to 89%. The strongest activity was recorded for M. smilacis and P. thailandicum, both approaching the inhibition level of ascorbic acid. Cytotoxicity assays revealed selective viability reduction in A549 lung carcinoma cells, with up to 40% inhibition at higher concentrations, while NIH3T3 fibroblasts were largely unaffected, indicating limited toxicity toward non-malignant cells. Acridine orange/ethidium bromide staining and ROS assays demonstrated oxidative stress and apoptotic features in A549 cells, particularly after treatment with M. smilacis and H. chiangraiense. Nevertheless, apoptosis induction remained quantitatively weak compared with the positive control, suggesting only preliminary pro-apoptotic potential. These findings suggest that the studied fungi harbor metabolites associated with antioxidant activity and selective cytotoxic effects. This work establishes a biological baseline for these taxa and highlights the need for bioactivity-guided fractionation, and mechanistic validation to determine their pharmacological relevance.

This study presents a comprehensive investigation of endophytic fungi isolated from Ruta graveolens (Rutaceae), evaluating the bioactivity of their extracts in terms of antimicrobial and antioxidant properties, along with preliminary mycochemical profiles. Twenty-seven isolates were identified using morphological and molecular identification (ITS-rDNA sequencing). Phylogenetic analysis classified them into Alternaria (66.7%, dominant in stems), Chaetomium (25.9%, prevalent in leaves), Achaetomium (3.7%), and Stagonosporopsis (3.7%) genera, demonstrating strong tissue specificity. Antibacterial screening (disk diffusion) of the fungal extracts revealed that 52% (14/27) were active; extracts of S4, S9, S20-2, and L11 showed inhibition against Staphylococcus aureus (inhibition zones, 14.5-15.8 mm at 100 mg/mL), while L5, L10, and L11 extracts exhibited dual activity against both S. aureus and Escherichia coli. Antifungal assays of the extracts identified strains S22, L5, and L12 as effective against phytopathogens Alternaria alternata, Pyricularia grisea, and Curvularia lunata (inhibition rates, 54.2-67.5% at 1 mg/mL). Meanwhile, antioxidant evaluation of the extracts highlighted strain L11 for remarkable DPPH and ABTS radical scavenging (IC₅₀, 8 μg/mL and 5 μg/mL, respectively). Qualitative mycochemical analysis linked ubiquitous coumarins/phenols to broad antibacterial activity. Alkaloids uniquely correlated with E. coli inhibition (L5, L10, L11), while terpenoids/steroids (S9, S20-2) specifically enhanced anti-S. aureus activity. These findings underscore R. graveolens-associated endophytes as potential sources of antimicrobial and antioxidant metabolites, suggesting possible applications for pharmaceutical development and sustainable agricultural applications.

Previous studies have predominantly focused on the pathogenic mechanisms and epidemiological investigations of pathogenic Escherichia coli (E. coli), but much remains unknown about the non-virulent and non-drug-resistant E. coli (NVNR E. coli) residing in the pig gut. In this study, 215 E. coli strains were identified from fecal samples collected from 26 healthy pigs in Guangdong Province, China. Among them, 12 NVNR E. coli strains were identified through PCR, antibiotic susceptibility tests, and genomic virulence analysis. Phylogenetic analysis revealed that 8 of these NVNR E. coli strains were located in the upstream cluster of the phylogenetic tree, which we consider as the ancestral phylogroup of porcine native E. coli. Notably, strain 2-9 showed a close evolutionary relationship with the probiotics Nissle1917 and EcAZ-1, suggesting it may also be a probiotic strain. These 9 strains (i.e., the 8 ancestral phylogroup strains and the suspected probiotic strain) were designated as evolutionarily superior strains. The 12 NVNR E. coli strains were non-hemolytic and exhibited growth rates comparable to typical E. coli strains, but they varied significantly in their tolerance to gastrointestinal conditions and adherence to IPEC-J2 cells. Most of them lacked the ability to inhibit pathogenic E. coli. Interestingly, the majority of strains exhibiting strong gastrointestinal tolerance, most of those with high adhesion capacity, and all strains possessing antibacterial ability, were found within the range of 9 evolutionarily superior strains. These findings suggest that 9 strains have shown great potential as superior porcine native E. coli strains and warrant further study.

The genus Armillaria (Basidiomycota, Agaricales, Physalacriaceae) comprises pathogenic fungi that cause root-rot disease in plants, as well as species with low pathogenicity, some of which are hosts of the fully mycoheterotrophic orchid plant Gastrodia elata (Orchidaceae). To investigate the mechanisms underlying such special interactions between Armillaria fungi and G. elata, it is crucial to establish genetic transformation platforms for the Armillaria fungi and G. elata. In this study, an Armillaria strain Arm37 was isolated from G. elata, which can form symbiosis with G. elata in axenic culture under laboratory conditions. A vector pYT-EV containing a cassette for hygromycin-resistance selection and a cassette for expressing or silencing target genes was constructed. An Agrobacterium tumefaciens-mediated transformation (ATMT) system for Arm37 was successfully developed and optimized to achieve a transformation efficiency of 32%. The ATMT system was successfully used to express the reporter genes eGFP encoding enhanced green fluorescent protein and GUS encoding β-glucuronidase and to effectively silence the endogenous gene URA3 encoding orotidine-5'-phosphate decarboxylase in Arm37. This ATMT system established for Arm37 provides an efficient genetic tool for exploring the Arm37 genes that are involved in the unique interaction between the Armillaria fungi and fully mycoheterotrophic plant G. elata.

Cells of the methylotrophic yeast Ogataea parapolymorpha have two genes encoding low-affinity phosphate transporters: PHO87, encoding the plasma membrane transporter, and PHO91, encoding a protein, which is homologous to the Saccharomyces cerevisiae vacuolar membrane transporter. Earlier, we reported that inactivation of PHO91 in O. parapolymorpha interferes with methanol utilization due to the lack of activity of methanol oxidase encoded by the MOX gene. In this work, we showed that this defect was completely suppressed by inactivating the PHO87 gene or introducing additional copies of the MOX gene into the cell. The PHO91 gene knockout decreased the level of long-chained polyphosphates only in methanol-grown cells, but not in glucose-grown cells. This effect remained even in the strain with extra copies of MOX, which rescues the ability of the mutant to grow on methanol. In contrast, the PHO87 gene knockout changed the levels of short-chained and long-chained polyphosphates in both methanol- and glucose-grown cells. Inactivation of PHO91 did not change vanadate resistance, while inactivation of PHO87 increased this resistance. Our data suggest that in O. parapolymorpha, Pho87 and Pho91 transporters have different roles in inorganic polyphosphate metabolism and adaptation to methanol consumption.