Objective To investigate the differences and associations in endophytic microbial communities across four ecological niches of pepper varieties with varying pulp thickness and to delve into the microbial community disparities associated with different pepper pulp thickness. Methods We extracted DNA from the roots, stems, leaves, and fruits of pepper varieties with varying pulp thickness. The bacterial 16S rRNA gene and fungal ITS region of the endophytic microbial communities within these four niches were sequenced on the Illumina platform. Microbial taxa potentially associated with pulp thickness were identified and screened, followed by validation through pot experiments. Results Endophytic bacterial and fungal communities in the four ecological niches of pepper varieties with different pulp thicknesses all exhibited differences. Particularly, the bacterial community structure in the fruit displayed the most significant variations. Bar plots at the genus level and analyses of species disparities revealed that the genus Sphingomonas was significantly enriched in the pepper varieties with thick pulp and showed a positive correlation with pulp thickness. A total of 28 endophytic strains were isolated from pepper fruits. Among them, two strains belonged to the genus Sphingomonas, identified as S. aquatilis and S. yabuuchiae. Each of the two bacterial strains exhibited capabilities of both indole-3-acetic acid production and nitrogen fixation. Pot experiments demonstrated that inoculation with the two endophytic strains significantly promoted the fruit growth of pepper plants, increasing the pulp thickness by 75.44%. Conclusion The relative abundance of Sphingomonas in pepper fruits showed a significantly positive correlation with pulp thickness and Sphingomonas promoted fruit growth. This study is of great significance for revealing the role of endophytic microbial communities in the regulation of pepper fruit development and lays a theoretical foundation for improving pepper fruit quality.

Objective To perform biological characterization and genomic analysis for a multidrug-resistant Streptococcus strain isolated from the tonsils of a dead piglet, thus elucidating its phenotypic and genotypic characteristics. Methods The tonsillar tissue homogenate from the dead piglet was inoculated into the Streptococcus enrichment medium for enrichment culture. The enriched culture was then streaked onto Columbia blood agar medium for Streptococcus isolation. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), a biochemical identification system, and 16S rRNA gene sequencing were employed for strain identification. The minimum inhibitory concentrations (MICs) were determined by the broth microdilution method. Whole-genome sequencing was conducted via the Illumina platform. The ResFinder database was used to analyze the resistance genes, and mutations in the genes encoding penicillin-binding proteins (PBPs) were investigated through multiple sequence alignment. Results The phylogenetic analysis based on 16S rRNA gene sequences identified the isolate as Streptococcus orisratti. Antimicrobial susceptibility testing revealed that the strain was resistant to penicillin G, erythromycin, clindamycin, and compound sulfamethoxazole, and it exhibited reduced susceptibility to linezolid. Whole-genome analysis identified the presence of the macrolide and lincoamide resistance gene ermB and the oxazolidinone resistance gene optrA. Furthermore, multiple mutations were detected in the genes encoding PBPs. Conclusion This study reports the first isolate of S. orisratti harboring both ermB and optrA and exhibiting resistance to penicillin. It highlights the capacity of porcine-derived streptococcal strains to acquire multidrug resistance genes, underscoring the need for increased vigilance regarding the resistance traits and transmission risks of animal-derived streptococci.

Objective To systematically isolate and purify the polysaccharide from the mycelium of Streptomyces rochei D74 (SRP), elucidate its fine structure, and evaluate the effect of the purified polysaccharide fraction on the growth of Salvia miltiorrhiza hairy roots and the biosynthesis of tanshinones, along with the underlying mechanism. Methods The crude polysaccharide was extracted using hot water, which was followed by ethanol precipitation and deproteinization via the Sevag method. Further purification was performed using DEAE-52 anion-exchange chromatography and Sephadex G-100 gel filtration chromatography. The physicochemical properties and structural features of the main active fraction, SRP-W-2, were systematically characterized by Fourier transform infrared spectroscopy (FTIR), high performance liquid chromatography-mass spectrometry (HPLC-MS), and nuclear magnetic resonance (NMR). The effects of SRP-W-2 on hairy root growth and the biosynthesis of tanshinones were assessed by measuring biomass, tanshinone content, and the expression levels of key biosynthetic genes. Results SRP-W-2 was obtained with a yield of 2.41%. It was primarily composed of glucose and galactose at a molar ratio of 12.53:1. Structural analysis revealed that the backbone of SRP-W-2 consisted of →4)-α-d-Glcp-(1→ and →4)-α-d-Galp-(1→ residues, with branching points at →4,6)-α-d-Glcp-(1→ and →4,6)-α-d-Galp-(1→. The side chain was identified as α-d-Glcp-(1→4)-α-d-Glcp-(1→. Bioactivity assays demonstrated that SRP-W-2 significantly enhanced both the biomass of S. miltiorrhiza hairy roots and the accumulation of tanshinones. After 15 d of treatment with 50 mg/L SRP-W-2, the dry weight of the hairy roots increased by 37.52%. Meanwhile, the content of cryptotanshinone (CT), dihydrotanshinone I (DT-I), tanshinone I (T-I), and tanshinone IIA (T-IIA) was increased by 19.0-fold, 6.4-fold, 2.8-fold, and 4.8-fold, respectively. Gene expression analysis further indicated that SRP-W-2 up-regulated key genes involved in the tanshinone biosynthetic pathway, including HMGR, DXS, DXR, and GGPPS. Conclusion The polysaccharide fraction SRP-W-2 from S. rochei D74 simultaneously promoted the growth of S. miltiorrhiza hairy roots and the biosynthesis of tanshinones, demonstrating its potential as an effective elicitor. This study provided a new strategy for the utilization and development of S. miltiorrhiza resources.

Heat shock protein family A member 8 (HSPA8) is a widely distributed molecular chaperone in cells. HSPA8 is involved in multiple cellular physiological processes, mainly including the correct folding and transport of proteins, stress responses, presentation of antigenic proteins, mediation of autophagy, and immune regulation. It is also crucial for maintaining the homeostasis of the intracellular environment. In addition, HSPA8 plays a key role in multiple processes of virus infections. This paper reviewed the important roles and molecular mechanisms of HSPA8 in processes such as virus adhesion, formation of virus glycoprotein-receptor complexes, internalization, uncoating, genome replication, assembly, and regulation of host metabolism and immune responses, with the hope of laying a foundation for the subsequent development of drugs targeting HSPA8 for the treatment of virus infections.

Staphylococcus aureus, a common foodborne pathogen causing hospital-acquired infection, poses a grave threat to public health and safety, resulting in a substantial economic burden on the society. As a conditionally essential amino acid, arginine exhibits a dual role in the infection of S. aureus and the immune response of the host. On the one hand, arginine synthesis and catabolism are involved in pathogenic processes such as the biofilm formation and antibiotic resistance of S. aureus. On the other hand, arginine metabolites play an important role in anti-infective immunity, tissue repair, and wound healing through the modulation of macrophage polarization, immune modulation, metabolic reprogramming, and signaling. Recent studies suggest that arginine metabolism constitutes a regulatory hub for S. aureus-macrophage interactions, and its metabolic balance affects the progression and regression of infection and anti-infection. Consequently, targeting the arginine metabolic pathway to impede S. aureus infection by regulating host-pathogen metabolic interactions has emerged as a novel anti-S. aureus therapeutic strategy with significant translational medical relevance. In this review, we focus on the metabolic utilization of arginine to describe how S. aureus and macrophages exert their respective biological functions by competing for the utilization of arginine. In addition, we summarize the changes of arginine levels in macrophages during S. aureus infection to explore the feasible research directions and challenges of regulating arginine metabolism as a potential antimicrobial strategy in the future.

As a globally prevalent malignancy with poor prognosis, liver cancer exhibits a well-established pathological association with the gut microbiota (GM). In recent years, increasing attention has been paid to the role of the GM in the initiation and pathological progression of liver cancer, which often evolves through stages of hepatitis, liver fibrosis, cirrhosis, and ultimately liver cancer. The GM influences the development of liver cancer through multiple mechanisms, including the regulation of the hepatic immune microenvironment by the GM and its metabolites, the mediation of epigenetic modifications and exosomal signaling pathways, and the synergy with other risk factors. Notably, patients with liver cancer commonly demonstrate reduced GM diversity and enriched pathogenic bacteria. These findings offer a new theoretical foundation and suggest potential therapeutic strategies such as probiotic supplementation, rational antibiotic use, fecal microbiota transplantation, combination therapies integrating GM modulation with conventional treatments, and integrated treatment regimens based on the above methods. This article reviews the pathogenesis of liver cancer mediated by GM dysbiosis and the research advances in GM-targeted interventions in recent years, providing reference for future studies on the pathogenesis and treatment of liver cancer.

Objective To evaluate the in vitro antifungal activity of quercetin against Trichosporon asahii and investigate its molecular mechanism of inducing fungal apoptosis. Methods According to the CLSI M27-A3 protocol, the inhibitory effects of quercetin on planktonic cells and biofilm formation of nine T. asahii strains were determined. On this basis, changes in intracellular reactive oxygen species (ROS) level, mitochondrial membrane potential (MMP), and cysteinyl aspartate-specific proteinase 3 (Caspase-3) activity were measured following quercetin intervention. Subsequently, transcriptome sequencing was utilized to verify and analyze the differentially expressed genes. Results The minimum inhibitory concentrations (MICs) of quercetin against T. asahii ranged from 8 to 32 μg/mL, and quercetin effectively inhibited biofilm formation. Cellular experiments indicated that quercetin triggered apoptosis by inducing ROS accumulation, reducing MMP, and activating Caspase-3. Transcriptomic data further confirmed the aforementioned mechanisms at the gene expression level. Conclusion Quercetin exerts antifungal activity against T. asahii primarily by inducing oxidative stress-mediated apoptosis.

Actinobacteria are Gram-positive bacteria of major ecological and biotechnological importance, responsible for organic matter turnover in nature and serving as a primary source of antibiotics and other bioactive natural products. Their complex physiological adaptation and life cycles are regulated by sophisticated signal transduction networks. This review examines the metabolism, signaling, and regulatory networks of nucleotide second messengers including cyclic diadenosine monophosphate (c-di-AMP), cyclic di-guanosine monophosphate (c-di-GMP), adenosine monophosphate (cAMP), and (p)ppGpp in the morphologically complex Streptomyces with rich secondary metabolites and pathogenic Mycobacterium with host adaptation. We discuss how these second messengers interact with other signaling systems, such as two-component systems, quorum sensing, and protein acylation, to integrate environmental and developmental cues. This coordination regulates the growth, development, secondary metabolite biosynthesis, and environmental adaptation of actinobacteria. By synthesizing current knowledge, this review provides reference for understanding the integrity and dynamics of the signal transduction system of actinobacteria, as well as their potential applications in the basic research of life sciences and in the fields of biotechnology and medicine.

Objective To investigate the effect of Kelch-like ECH-associated protein 1 (KEAP1) on the replication of herpes simplex virus type 1 (HSV-1) and thus provide theoretical support for anti-herpes simplex virus research. Methods The mRNA and protein levels of molecules in the KEAP1-NRF2 signaling pathway and viral molecules in ARPE-19 cells infected with HSV-1 were determined by qPCR and Western blotting, respectively. KEAP1-silenced and overexpressing ARPE-19 cell lines were constructed, and Western blotting was employed to assess the effects of KEAP1 silencing and overexpression on the nuclear factor erythroid 2-related factor 2 (NRF2) signaling pathway. The KEAP1-silenced and overexpressing cell lines were subsequently infected with HSV-1. Changes in viral mRNA expression were detected via qPCR, while immunofluorescence and Western blotting were used to evaluate alterations in viral protein expression. Additionally, a plaque formation assay was conducted to measure variations in viral titer. Western blotting was performed on KEAP1-silenced cell lines infected with HSV-1 to assess the expression levels of NRF2 signaling pathway and viral proteins at different time points. Results Silencing of KEAP1 activated the NRF2 signaling pathway and promoted HSV-1 replication, whereas KEAP1 overexpression downregulated the NRF2 signaling pathway and inhibited HSV-1 replication. These findings contradict previous studies suggesting that upregulation and activation of the NRF2 signaling pathway can suppress HSV-1 replication. Further investigation revealed that KEAP1 silencing-induced NRF2 upregulation was significantly inhibited following HSV-1 infection. Conclusion KEAP1 plays a crucial role in the host cell resistance to HSV-1 infection, and its interaction with NRF2 exerts complex biological functions in antiviral immune responses.

Objective To evaluate the effects of medium concentration, soil suspension dilution, and soil type on bacterial high-throughput cultivation outcomes, providing a reference for the exploration of bacterial resources in soda saline-alkali soils. Methods High-throughput cultivation and identification of bacteria from soda saline-alkali wildland and maize field soils were conducted. Three medium concentrations (1×TSB, 1/5×TSB, and 1/10×TSB), two soil suspension dilutions (optimal dilution and 2× optimal dilution), and two soil types (wildland and maize field) were set as experimental factors to analyze bacterial cultivation preferences under different treatments. Results The dominant bacterial phyla in both soils were Pseudomonadota, Actinomycetota, Acidobacteriota, Bacillota, and Chloroflexota. Among the top 10 dominant genera, only Bacillus and Rubrobacter were cultivable. A total of 2 256 positive cultures were obtained through high-throughput cultivation, with pure cultures accounting for 79.3%. A total of 153 amplicon sequence variants (ASVs) were identified, belonging to 52 genera of 4 phyla. On average, every 100 pure cultures yielded 6.8 ASVs or 2.3 genera. The 1/10×TSB medium resulted in the highest proportion of pure culture wells, while the 1×TSB medium showed the highest ASVs isolation efficiency. Cultivation with 2× optimal soil suspension dilution achieved higher pure culture ratios and isolation efficiency than the optimal dilution. The proportion of pure cultures, ASVs isolation efficiency, and genus isolation efficiency were all higher in wildland soil than in maize field soil, with more unique ASVs detected in wildland. The most frequently isolated genera via high-throughput cultivation were Pseudomonas, Hydrogenophaga, Bacillus, Paenibacillus, Acidovorax, and Arthrobacter, among which only Bacillus was a dominant genus in the soda saline-alkali soils. Conclusion High-throughput cultivation is an efficient method for obtaining numerous pure bacterial strains from soda saline-alkali soils within a short period. Natural wildland soil yielded more diverse cultivable bacteria than dryland soil. Moderately reducing medium concentration and soil suspension dilution improved pure culture isolation efficiency and diversity. However, most dominant soil taxa could not be cultivated via a single medium type, underscoring the need to diversify cultivation conditions to enhance the cultivability of dominant soil bacteria.