MicrobiologyOpen最新文献

On the basis of gut microbiota and short-chain fatty acids (SCFAs), this study aims to identify diagnostic biomarkers for damp-heat diarrhea and cold-damp diarrhea. Rat models of damp-heat diarrhea and cold-damp diarrhea were established. Changes in body weight, body temperature, food intake, water consumption, and the diarrhea index were recorded. ELISA was employed to detect levels of IL-6, IL-1β, TNF-α, and IL-10. Histological evaluations were conducted using H&E staining and AB-PAS staining techniques. Transmission electron microscopy was utilized to observe ultrastructural changes in the colonic epithelium, while Western blot analysis was performed to assess the expression of Occludin, Claudin1, Claudin5, GPR41, GPR43, GPR109A, and NLRP3 in colon tissues. GC–MS analysis was carried out to determine the content of SCFAs in the cecal contents of rats; additionally, 16S rRNA sequencing was performed to analyze the composition of gut microbiota in these animals. Differential analysis methods were applied to evaluate similarities and differences in SCFAs profiles and gut microbiota between damp-heat diarrhea and cold-damp conditions. The body weight and food intake of rats with induced damp-heat diarrhea or cold-damp diarrhea significantly decreased over time as their diarrheal symptoms progressively worsened. However, following treatment with appropriate prescriptions tailored for each condition resulted in an improvement in diarrheal symptoms among the affected rats. In accordance with the “prescription-based syndrome differentiation” theory, the rat experimental animal models of damp-heat diarrhea and cold-dampness diarrhea were successfully established. The models exhibited characteristic diarrheal symptoms alongside increased levels of inflammatory factors indicative of severe histopathological damage; there was also a notable reduction in tight junction protein expression observed across all models studied. Furthermore, the Firmicutes/Bacteroidota ratio showed a significant decrease. Interestingly, differences between damp-heat diarrhea and cold-damp diarrhea manifested as follows: Both modeling groups showed an increase in the relative abundance of Lachnoclostridium and Marvinbryantia. In the damp-heat diarrhea group, the levels of Lachnoclostridium and Marvinbryantia were relatively low; however, these levels gradually increased after successful treatment. In contrast, in the cold-damp diarrhea group, the trends of Lachnoclostridium and Marvinbryantia were opposite. Mucosal color has the potential for clinical diagnosis of damp-heat diarrhea and cold-damp diarrhea. Moreover, Lachnoclostridium and Marvinbryantia are potential biomarkers for distinguishing between damp-heat diarrhea and cold-damp diarrhea. However, the diagnostic basis and accuracy of Lachnoclostridium and Marvinbryantia biomarkers still need to be further validated.

Shewanella algae, a marine-origin opportunistic pathogen, has shown a significant increase in non-coastal infections, yet its environmental adaptability and synergistic pathogenic mechanisms with Epstein-Barr virus (EBV) coinfection remain unclear. This study reports a clinical case of S. algae bloodstream infection complicated by EBV reactivation leading to septic shock in Sichuan Province, China, and elucidates the molecular mechanisms through genomic analysis. Pathogen identification was performed via blood culture, antibiotic susceptibility testing, and genomic annotation. The strain harbored resistance genes (acrB, tolC, tet(35), golS) and virulence factors (bplL/bplF, clpC/clpP, tonB). Phylogenetic analysis indicated the highest genetic affinity to freshwater-derived Shewanella chilikensis, while pan-genome analysis identified 1412 unique genes, including transmembrane transporters and carbohydrate-active enzyme genes, suggesting freshwater adaptive evolution. Metagenomic next-generation sequencing (mNGS) detected a high EBV load. The patient succumbed to multi-organ failure. This study reveals that S. algae may evolve freshwater adaptability to cause inland infections, and EBV coinfection accelerates septic shock through immunosuppression and inflammatory cascades. Genomic analysis provides critical insights for precision diagnosis and treatment of polymicrobial infections.

Coinfection of Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) is frequently observed. Our previous study demonstrated that S. aureus-derived extracellular vesicles (SaEVs) promote P. aeruginosa pathogenicity by increasing lipopolysaccharide (LPS) production, promoting biofilm formation and decreasing the uptake of P. aeruginosa by macrophages. Proteomic analysis revealed that SaEVs enhance the production of PslE, an exopolysaccharide biosynthetic protein in P. aeruginosa, but the role of Psl exopolysaccharide polymerization on SaEV-mediated P. aeruginosa pathogenicity is unclear. In this study, a pslE-deletion mutant of P. aeruginosa (PaΔpslE) was constructed, and the effect of SaEVs on the pathogenicity of this mutant was evaluated. Our results showed that SaEVs significantly increased the expression of pslA, E, J, K, and L genes in the psl cluster of P. aeruginosa wildtype (PaWT), and this effect was abolished in PaΔpslE. In addition, LPS production and biofilm formation were reduced in PaΔpslE compared to PaWT. SaEVs significantly enhanced LPS production and biofilm formation in PaWT. On the other hand, the effects of SaEVs on the production of lipid A and LPS core and biofilm formation in PaΔpslE were abolished. Invasion of PaWT and PaΔpslE into HaCaT human epithelial cells was not significantly different and the effect of SaEVs on these bacterial cell invasions was not found. However, the uptake of SaEV-treated PaWT by macrophages significantly reduced compared to nontreated PaWT, whereas SaEVs did not alter the uptake of PaΔpslE. These results suggest that PslE is required for SaEV-mediated P. aeruginosa pathogenicity. SaEVs upregulate pslE gene as well as other exopolysaccharide polymerization-related genes, increase LPS production and biofilm formation, and affect the uptake of P. aeruginosa by macrophages.

Crustose coralline algae (CCA) comprise hundreds of different species and are critical to coral reef growth, structural stability and coral recruitment. Despite their integral role in reef functioning, little is known about the diversity and structure of bacterial communities associated with CCA. We address this knowledge gap by characterising the surface microbial communities of 15 Indo-Pacific CCA species across eight different families from the Great Barrier Reef, using 16S rRNA amplicon sequencing. CCA microbial community composition was distinct and found to primarily differentiate by algal host species. When looking at the core bacterial communities, divergence across CCA microbiomes was additionally correlated to host phylogeny. CCA from similar light environments and depths also had more similar microbial communities, suggesting the potential role of environmental parameters in influencing microbial community organisation. The fundamental descriptions of CCA bacterial communities for a wide range of Indo-Pacific species presented here provide essential baseline information to further inform CCA microbial symbiosis research.

Rice blast disease, caused by Pyricularia oryzae Cavara, is the most threatening rice pathogen in Italy. The development of resistant cultivars is a sustainable approach to mitigate yield losses. However, P. oryzae genomic plasticity often allows rapid adaptation to host resistance. Understanding the population structure of plant pathogens is crucial for assessing their genetic diversity and implementing durable management strategies. Despite first attempts from Piotti et al. (2005) to study the Italian P. oryzae population, a gap in current local P. oryzae genetic variability still needs to be addressed. Here, the population structure of a large set of P. oryzae isolates from diseased rice panicles, collected in five different Italian regions between 2011–2012 and 2020–2022, was characterized using SSR genotyping. Mating type was determined to investigate the occurrence of sexual reproduction in Italy. The integration of different cluster analyses of 200 unique multilocus genotypes allowed to identify five distinct genetic clusters. Analysis of molecular variance and of genetic divergence revealed a limited influence of geographic origin and time on population structure. A strong positive correlation was detected between climatic variables and allelic diversity in Piedmont, the most evenly sampled region in this study. The gradual disappearance over time of a genetic cluster could be linked to lower virulence on a susceptible rice cultivar. This study provides new insights into the genetic dynamics of Italian P. oryzae population, supporting the strategic deployment of resistance genes in rice breeding programs.

Oral coinfections involving herpes simplex virus (HSV) and Candida albicans can potentially interact and exacerbate each other. Starting from bibliographical investigation, this study aimed to examine the effectiveness of some essential oils (EOs), and their commercial formulations, both against C. albicans and HSV-1, identifying their antimicrobial, anti-inflammatory and allergenic potential. A preliminary review examined essential oils' efficacy against HSV-1. Broth microdilution tested 14 EOs, a commercial formulation (LA), and a homemade one (MIX) against three fungal strains. The quality of LA, MIX and single EOs was assessed by Solid Phase Microextraction (SPME) sampling coupled with gas chromatography-mass spectrometry (GC-MS) analysis. To assess the allergenic activity of MIX, LA, and single EOs a Basophil Activation Test (BAT) was standardized. ELISA tests were done to evaluate the anti-inflammatory activity. The bibliographic search highlighted seven EOs active against HSV-1. Four EOs showing strong antifungal activity were blended, following IFRA lip-application limits, to create a formulation (MIX) for comparison with a commercial herpes treatment (LA). Formulations were active against HSV-1, able to modulate the expression of pro (TNF-α_LA = −29.7% and TNF-α_MIX = −33.6%) and anti-inflammatory (IL-1β _LA = −50.0% and IL-1β _MIX = −25.0%) cytokines and no allergenic. MIX reinforces target cells and blocks viral entry, while LA also limits intracellular replication. EO-based formulations show promise for managing HSV-1 and Candida co-infections, offering antiviral, antifungal, and anti-inflammatory effects. BAT results indicate no basophil activation at tested concentrations, supporting their safety.

Patulin (PAT) is a toxic secondary metabolite produced by certain species of Penicillium and Aspergillus on pome fruits. In this study, we isolated Rhodosporidiobolus ruineniae (R. ruineniae) and Meyerozyma guilliermondii (M. guilliermondii) from a peach and an apple as candidates for PAT degradation, respectively, and investigated the effects of three key parameters (incubation time and temperature, and initial PAT concentration) on PAT removal rates, and the mechanism involved in PAT degradation by the yeast strains. The PAT degradation rate by the yeast strains was dependent on the three key parameters. Both yeast strains were able to degrade 1 μg mL⁻¹ of PAT to below the regulatory limit (50 µg L⁻¹) at 60 h when they were incubated at 35°C. The PAT removal by the yeast strains was not due to either binding onto yeast cell walls or degradation by extracellular fractions of the yeast culture among three yeast cell fractions (cell walls, extracellular, or intracellular fractions). The use of spheroplast or intracellular enzymes confirmed that PAT degradation occurred inside the yeast cells. Moreover, the PAT degradation ability was inducible in M. guilliermondii. LC/MS/MS analysis showed that (E)-ascladiol is the sole PAT biodegradation product from both yeast strains. Our data demonstrated that both yeast strains were able to degrade PAT and produce (E)-ascladiol, a less toxic product. These results could be exploited for practical applications to efficiently control PAT on fruits such as apples and peaches.

The Cape Floristic Region, a biodiversity hotspot in South Africa, is characterised by acidic, nutrient-poor soils and distinctive fynbos vegetation. Despite the ecological importance and metabolic versatility of Acidobacteriota, their diversity and functional roles in fynbos soils remain poorly understood. This study investigated the diversity and abundance of Acidobacteriota in two nature reserves, Jonkershoek and Kogelberg, and the influence of soil abiotic factors and enzyme activities on their distribution and composition at the subdivision (SD) level. A total of 26 bulk soil samples were collected, and the V1–V9 regions of the 16S rRNA gene were sequenced using the Oxford Nanopore platform. The mean relative abundance of Acidobacteriota ranged from 1.5% to 36.25%. Subdivision 1 was the most dominant, with relative abundances of 66.96 ± 8.96% in Kogelberg Nature Reserve and 30.35 ± 0.15% in Jonkershoek Nature Reserve (p = 0.001). Other prevalent SDs included SDs 2, 3, and 5, with this study being the first to report the presence of SDs 22 and 17 in fynbos soils. Beta-diversity analysis revealed distinct community compositions between the two reserves, driven by soil pH, moisture content, available phosphate, electrical conductivity, and enzyme activities (p = 0.001). Several positive and negative correlations between Acidobacteriota SDs and soil properties were also identified. Overall, this study highlights the high diversity of Acidobacteriota in fynbos soils and their close associations with soil abiotic properties, underscoring the need for cultivation-based research to elucidate their ecological roles in these oligotrophic environments.

This systematic review and meta-analysis compared bacterial semi-quantification of respiratory samples from the BIOFIRE FILMARRAY Pneumonia (PN) Panels with quantitative and semi-quantitative culture methods (qCMs). Fourteen studies comprising 1,654 samples were included. Across both bronchoalveolar lavage-like and endotracheal aspirate-like specimens, the BIOFIRE PN Panel reported consistently higher bacterial loads than qCMs, with pooled mean differences of 1.17 and 0.95 log, respectively. Discrepancies decreased as culture-reported bacterial burden increased. The concordance rate in identifying the predominant pathogen was 94%, supporting the panel's clinical relevance. However, differential reporting at lower bacterial loads suggests that existing culture-based thresholds may not translate directly to molecular diagnostics. These findings highlight the need for pathogen- and method-specific interpretive thresholds to optimize the diagnostic utility of semi-quantitative molecular results and inform antimicrobial stewardship decisions.

The present study reports the isolation and molecular identification of Streptomyces sp. strain WSN-2 using 16S rRNA gene sequencing and BLASTn analysis (GenBank Accession No. MN128377), followed by its application in the green synthesis of silver nanoparticles (AgNPs). Biomass filtrate of Streptomyces sp. WSN-2 efficiently reduced silver ions to form stable AgNPs, confirmed by a characteristic UV-Vis surface plasmon resonance (SPR) peak at 423 nm. Structural and morphological characterization using FTIR, SEM, TEM, and EDX revealed spherical nanoparticles with a smooth texture and well-dispersed arrangement. TEM analysis indicated particle size predominantly between 50 and 60 nm (overall range 0.83–100 nm), while the zeta potential of –22.9 mV confirmed moderate colloidal stability. EDX spectra displayed strong elemental silver absorption peaks at 3-4 keV, indicating crystalline Ag formation. The biosynthesized AgNPs exhibited strong antimicrobial activity against wide range of pathogenic microbes. Maximum antibacterial growth inhibition zones were observed against S. typhi (24 ± 1.53 mm), followed by E. coli (23 ± 1.25 mm), B. subtilis (23 ± 1.73 mm), and P. aeruginosa (22 ± 1.53 mm). Antifungal assays revealed highest antifungal activity against A. flavus (16 ± 1.15 mm), and notable inhibition of A. niger (16 ± 1.25 mm), A. fumigatus (15 ± 1.70 mm), and F. oxysporum (14 ± 1.53 mm). MIC values ranged from 8.00 ± 0.05 µg/mL for P. aeruginosa to 18.000.07 µg/mL for A. fumigatus. The AgNPs also demonstrated remarkable antioxidant potential, achieving 65.2% H₂O₂ scavenging activity at 50 µg/mL, surpassing L-ascorbic acid (45.1%). These findings highlight Streptomyces sp. WSN-2 as a promising biogenic source for the synthesis of stable AgNPs with significant antibacterial, antifungal, and antioxidant potential.