Antonie Van Leeuwenhoek International Journal of General and Molecular Microbiology最新文献

Inappropriate storage conditions make Codonopsis pilosula more susceptible to infection by harmful fungi because of moisture, which reduces the plant's therapeutic effectiveness. The volatile organic compounds (VOCs) of plant endophytes have shown great promise in recent years for managing postharvest plant diseases. This study investigates the inhibitory effects of VOCs released by Bacillus thuringiensis G-5 on two postharvest pathogenic fungi of C. pilosula: Fusarium oxysporum F-3 and Penicillium oxalicum F-5. The results revealed that the mycelial growth inhibition rates of these fungi induced by the VOCs from G-5 were 94.01% and 95.37%, respectively. Scanning electron microscopy observations and Propidium Iodide staining experiments further confirmed that these VOCs could markedly alter the morphology and structure of mycelia and spores and compromise the integrity of the cell membrane. Headspace gas chromatography-ion mobility spectrometry analysis identified 21 high-concentration volatile substances released by G-5, with 3-hepten-2-one identified as the primary antifungal component. The minimum inhibitory concentrations of 3-hepten-2-one against F-3 and F-5 were determined to be 40 μL/L and 20 μL/L, respectively. Further research indicated that 3-hepten-2-one disrupts the structural and functional integrity of the cell membrane. In vivo experiments demonstrated that 3-hepten-2-one exhibited superior efficacy in preventing and controlling C. pilosula infections compared to the VOCs produced by G-5. This study not only provides a promising new antifungal agent for managing postharvest diseases of C. pilosula but also enhances our understanding of the role of VOCs produced by G-5 in biological control.

The global oversupply of crude glycerol, a byproduct of biodiesel production, needs innovative strategies for its sustainable utilization. In this study we isolated and characterized oleaginous yeast strains from fruit surfaces in the Brazilian Cerrado biome, a biodiversity hotspot, to assess their potential for converting crude glycerol into microbial lipids suitable for biodiesel. From 150 fruits, 45 yeast strains were isolated, with six identified as oleaginous (intracellular lipids > 20% dry biomass). Molecular identification via ITS and D1/D2 sequencing analysis revealed affiliations with Rhodotorula toruloides and Pseudozyma species (P. hubeiensis, P. flocculosa, P. rugulosa). Lipid profiling showed predominant fatty acids (palmitic, oleic) aligning with biodiesel standards. Biodiesel properties derived from yeast lipids, including cetane number (58–62), viscosity (3.8–4.2 mm²/s), and density (864–902 kg/m³), complied with ASTM D6751 and EN14214 specifications, except for slightly elevated density in one strain. Rhodamine B screening demonstrated higher specificity for oleaginous yeasts compared to Nile Red. Phylogenetic analysis confirmed evolutionary relationships among isolates and type strains. These findings highlight the Cerrado’s microbial diversity as a reservoir for robust oleaginous yeasts, offering a dual solution for crude glycerol valorization and sustainable biodiesel production. The study underscores the potential of Pseudozyma spp. and R. toruloides for integrated biorefineries, combining lipid production with biosurfactant and enzyme synthesis to enhance economic viability.

Aspergillus flavus infenction of crops, which are common worldwide, are a significant threat to human and animal health. In this study, the antagonistic effects of Pantoea vagans strain BWL1 on A. flavus were analyzed. BWL1 effectively inhibited A. flavusconidial germination, vegetative growth, and sporulation. Notably, A. flavus infections and aflatoxin contents decreased in peanut and maize samples treated with BWL1. A GC–MS analysis and a two-sealed-base-plates assay showed that BWL1 can produce several antifungal volatiles, including 2,5-dimethyl-pyrazine, 2-ethyl-1-hexanol, hexamethyl-cyclotrisiloxane, phenylethyl alcohol, 2,4-di-tert-butylphenol, pentadecane, tetradecane, heptadecane, and n-hexadecanoic acid, with MICs of 0.2, 0.8, 16, 0.8, 0.2, 8, 8, 8, and 8 g/L, respectively. Among these volatiles, 2,5-dimethyl-pyrazine, 2-ethyl-1-hexanol, phenylethyl alcohol, and 2,4-di-tert-butylphenol had substantial inhibitory effects on A. flavus infection of peanuts and maize kernels. The study findings suggest that P. vagans BWL1 may be an potential biocontrol agent for the postharvest management of A. flavus in crops. This is the first report regarding the antifungal effects of P. vagans BWL1 on A. flavus.

Alternaria solani leaf spot disease (ASLS) poses a serious threat to global crop production, including peppers, resulting in notable economic losses. Bio-nanotechnology offers promising solutions for combating plant pathogens by promoting plant defenses and inhibiting pathogen growth. This study explores the effectiveness of copper oxide nanoparticles (CNPs) and copper phosphite (MAXIFOS CU®) in controlling A. solani and boosting growth and defense responses in pepper plants. CNPs were biosynthesized using Penicillium expansum first time and thoroughly characterized through various techniques. Analysis confirmed that the nanoparticles varied in shape, predominantly oval and spherical, with an average size of approximately 40.59 nm, as shown in HR-TEM images. DLS analysis indicated a mean particle size of 74.58 nm, and Zeta potential analysis at pH 7.2 revealed a negative surface charge of − 55.25 mV, attributed to the components of the fungal extract. The study demonstrated that both CNPs and MAXIFOS CU® exhibited antifungal activity against A. solani, with CNPs effectively reducing PDI by 27.5% and enhancing overall plant protection by 65.62%. Results indicated that treated plants showed improvements in photosynthetic pigments, proline content (MAXIFOS CU® 28 g/L increase by 108.3%, while CNPs 81.30%), total phenolic compounds (CNPs 80.70% increase, while MAXIFOS CU® a 68.70%), H₂O₂ levels (MAXIFOS CU® decreased 22%, whereas CNPs 9%), MDA concentration (CNPs 39% decrease in MDA, while MAXIFOS CU® 34%), and the activities of POD (increased by 53.4, and 45.1% CNPs and MAXIFOS CU®) and PPO (CNPs and MAXIFOS CU® increased by 42.8 and 31.6%) enzymes. These findings highlight the potential of an eco-friendly, dual approach using biosynthesized CNPs and Cu-phosphite for managing A. solani and enhancing pepper plant health.

An anaerobic, Gram-stain-positive and spore-forming acidophilic sulfate-reducing bacterium, designated as SYSU MS00001^T, was isolated from acidic sediments of Zhongshan Iron Mine, P.R. China. The strain was straight-rod-shaped and motile, oxidase-negative and catalase-negative, with circular, convex, regular-edged and black-pigmented colonies (1–3 mm in diameter) on the solid basal salts/yeast extract plate. Growth and proliferation occurred at 10–40 °C (optimal: 30 °C), pH 3.5–7.5 (optimal: 5.0–5.5) and NaCl concentration of 0–1.6% (optimal: 0.2%), with a doubling time of 8.2 h under the optimal conditions. The strain utilised H₂/CO₂, organic acids (fumarate, citrate, pyruvate, malate, acetate, propionate, lactate, butyrate), alcohols (glycerol), and sugars (fructose, glucose, xylose) as electron donors for sulfate reduction. Sulfate, sulfur, sulfite, thiosulfate, fumarate and nitrate were used as electron acceptors in the presence of glycerol. It also fermented ethanol and methanol without sulfate. The main polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, unidentified phospholipids, unidentified aminophospholipid, unidentified lipids and unidentified glycolipids. The major fatty acids (> 5%) were C_14:0, C_16:0 and summed features 3 (C_16:1ω7c/C_16:1ω6c). The respiratory quinones identified were MK-7 and MK-8(H₄). Phylogenetic analyses based on 16S rRNA gene and genome sequences indicated that the isolated strain should be assigned to the genus Desulfosporosinus, and the 16S rRNA gene sequence was most closely related to Desulfosporosinus acididurans M1^T with similarity of 98.34%. The genomic DNA G + C content of SYSU MS00001^T was 41.7%. The digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values between SYSU MS00001^T and D. acididurans M1^T were 50.6% and 90.95%, respectively. On the basis of phenotypic, phylogenetic and genetic characteristics, strain SYSU MS00001^T represents a novel species within the genus Desulfosporosinus, for which the name Desulfosporosinus sediminicola sp. nov. is proposed. The type strain is SYSU MS00001^T (= GDMCC 1.4736 ^T = KCTC 25900 ^T).

This study investigated the isolation and characterization of bacterial strains with enzymatic potential from cow manure undergoing a 6-day decomposition process (initial mesophilic heating). A total of 270 bacterial isolates were obtained, with 48 isolates exhibited ligninase, amylase, protease, lipase, cellulase, and xylanase activity. Morphological, biochemical and molecular characterization classified them into nine species. The enzymatic analysis revealed that Bacillus licheniformis exhibited the highest enzymatic activity for ligninase, lipase, and amylase, recording 1.13, 9.92, and 8.1 U/mL, respectively, compared to other bacterial species. Furthermore, B. subtilis exhibited the highest enzymatic activity for protease, xylanase, and cellulase, recording 3.33, 1.96, and 0.5 U/mL, respectively. Our study reported Acetobacter tropicalis and A. pasteurianus with enzymatic activity for lipase and amylase. We also identified Lactiplantibacillus plantarum with enzymatic activity for ligninase and xylanase, and Lacticaseibacillus casei with enzymatic activity for ligninase, cellulase, and xylanase. Additionally, we reported Lentilactobacillus buchneri with enzymatic activity for ligninase, amylase, protease, lipase, cellulase, and xylanase. Furthermore, our study identified Cereibacter sphaeroides with enzymatic activity for cellulase, xylanase, protease, and ligninase, and Streptomyces albidoflavus with enzymatic activity for ligninase. These findings expand the understanding of bacterial enzymatic capabilities with potential in biotechnology, waste degradation, and industrial enzyme production.

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Dengue virus (DENV) is a major global health threat, primarily transmitted by Aedes mosquitoes. It manifests in mild to severe forms, including dengue hemorrhagic fever and dengue shock syndrome, causing significant morbidity and mortality. With four serotypes (DENV-1 to DENV-4), the virus exhibits rapid genetic evolution, complicating vaccine development and disease control. This review explores the structural and genomic characteristics of DENV, emphasizing its evolutionary pressures, immune evasion mechanisms, and emerging strains. The virus’s adaptation to environmental and host factors has led to increased outbreaks, notably in tropical regions. Global warming and urbanization have exacerbated the spread, challenging current vector control strategies. Laboratory diagnosis remains complex, relying on molecular and serological techniques with varying sensitivity. The lack of effective antiviral drugs and universally protective vaccines highlights critical gaps in disease management. Ongoing genomic surveillance and integrated control strategies are crucial for mitigating the impact of new DENV variants. This review highlights the importance of investigating the effect of emerging dengue strains on society, as well as how environmental factors exacerbate their severity.

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Tetrahydrofuran (THF), as a typical recalcitrant organic pollutant, poses a serious threat to ecological security and human health due to its environmental persistence. This study aimed to systematically elucidate the metabolic pathway of THF degradation by efficient composite bacteria and develop immobilized enhancement technology to improve their degradation performance. First, the key metabolic pathway for THF degradation by the composite bacteria was analyzed using GC–MS. Second, sodium alginate-chitosan microspheres encapsulating the composite bacteria were prepared, and the preparation process parameters were systematically optimized through single-factor experiments and Box-Behnken response surface methodology. Metabolic pathway analysis revealed that THF undergoes hydroxylation-induced ring-opening catalyzed by monooxygenase, yielding 4-hydroxybutanal, which is subsequently oxidized to 4-hydroxybutyric acid, and ultimately mineralized to CO₂ and H₂O. Under varying THF initial concentrations (180–540 mg/L) and temperatures (25–40 °C), the immobilized composite bacteria demonstrated significantly higher degradation capability and environmental adaptability compared to free bacteria, with markedly improved degradation efficiency. Furthermore, the immobilized microspheres exhibited excellent reusability, maintaining efficient THF removal rates after 5 consecutive cycles. This research elucidated the metabolic mechanism of THF degradation by the composite bacteria and developed a highly efficient and stable preparation process for the immobilized bacterial agent.