Objective To develop a fluorescence method for Vibrio parahaemolyticus detection by the combination of CRISPR system and the hybridization chain reaction (HCR), thus achieving rapid, sensitive, and accurate detection of the pathogen. Methods Cascade probe (RP/I) and HCR hairpin structures were first designed according to a specific conserved sequences screened from V. parahaemolyticus. Subsequently, the feasibility, specificity, and sensitivity of the method were evaluated after the optimization of reaction conditions. Furthermore, V. parahaemolyticus-contaminated aquatic products were used to validate the interference resistance of the method. Results The cleavage of CRISPR/Cas13a was activated upon binding to the target RNA (T-RNA), leading to the trans-cleavage of the RP/I cascade probe and the release of I strand. Then, the released I strand subsequently triggered HCR, generating a significant fluorescence signal for target detection. The established method successfully distinguished target sequences with single-base, double-base, and triple-base mismatches and enabled the specific identification of V. parahaemolyticus against other non-target bacteria, including V. alginolyticus, V. vulnificus, V. harveyi, V. cholerae, and Escherichia coli, demonstrating excellent specificity. The assay showed a good linear correlation over a T-RNA concentration range of 25 pmol/L to 10 nmol/L. The corresponding linear regression equation was y=7 236.75×lg C_T-RNA-8 590.11 (R²=0.99, C represents the T-RNA concentration and y represents the fluorescence intensity), with the LOD of 1.01 pmol/L. The proposed method enabled rapid detection of RNA extracted from V. parahaemolyticus in various aquatic products, yielding results consistent with those obtained by RT-qPCR. Conclusion The fluorescence method based on CRISPR/Cas13a-HCR established in this study realizes rapid detection of V. parahaemolyticus, demonstrating good sensitivity, specificity, and accuracy.

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.

Sulfate-reducing bacteria (SRB) with unique reductive capabilities enable simultaneous sulfate reduction and heavy metal removal, demonstrating potential in heavy metal pollution remediation. Objective To isolate efficient SRB strains from marine sediments and investigate their reductive characteristics and application prospects in Cr(VI) contamination remediation. Methods We enriched and screened out an efficient SRB strain and systematically analyzed its sulfate reduction efficiency, Cr(VI) removal efficiency, and metabolic responses under environmental stressors (such as pH, sulfate concentration, and heavy metal concentration). This strain was then used to synthesize biological iron sulfide composite, the physicochemical characteristics of which were then investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). Furthermore, the feasibility of applying the biological iron sulfide composite in the remediation of Cr(VI)-contaminated environments was explored. Results Strain S5 was identified as Desulfovibrio sp. with GenBank accession number OR140726. Its protein concentration and sulfate reduction followed an S-shaped curve. This strain exhibited a certain degree of acid tolerance, with the OD₆₀₀ and sulfate reduction rate reaching 0.16±0.01 and (83.71±1.49)% at pH 5.0, respectively. The strain exhibited sulfate reduction capability in the presence of 0.5-1.3 g/L sulfate, achieving a maximum reduction rate of (92.27±1.20)%. In the presence of 10-30 mg/L Cr(VI), strain S5 demonstrated efficient Cr(VI) removal. However, when the Cr(VI) concentration was higher than 30 mg/L, the Cr(VI) removal rate of this strain decreased significantly. The biological iron sulfide composite prepared based on strain S5 was porous, amorphous, and rich in functional groups such as C=O, N-H, and Fe-S, and its Cr(VI) removal rates were above 85% and did not differ significantly when exposed to Cr(VI) at high concentrations. Conclusion Desulfovibrio sp. S5 is a strain with high efficiency of sulfate reduction and Cr(VI) removal, and the biological iron sulfide composite prepared with it can overcome the limitation of higher Cr(VI) concentration and maintain high Cr(VI) removal rate, which has obvious advantages in the remediation of Cr(VI) pollution. The results of this study can provide a scientific basis for the application of SRB in the bioremediation of Cr(VI)-polluted environments.

Plant endophytes are non-pathogenic microbial groups residing inside or in the interstices of plant tissue. They constitute a pivotal component of the plant microecological environment. These organisms are distinguished by their remarkable biodiversity and wide distribution across diverse regions of the host plant. Plant endophytes exhibit high species diversity, host plant diversity, habitat diversity, and functional diversity. They can secrete hormones that regulate plant growth and enhance the nutrient absorption capacity of their hosts to promote plant growth. Additionally, endophytes can promote plant growth indirectly by enhancing the host plant resistance to abiotic and biotic stresses. Notably, these endophytes are capable of producing substantial secondary metabolites, which exhibit antimicrobial, antiviral, antioxidant, and other biological activities. This capacity offers considerable potential for the development of novel pharmaceuticals, the extraction of natural products, and the creation of biopesticides. Endophytes have a wide range of applications in agriculture, industry, and medicine. They can be used as biocontrol agents to enhance crop yields or used for the production of natural pigments and perfumes and the development of novel pharmaceuticals. However, the research on plant endophytes still faces many challenges in species identification and function verification, molecular mechanism analysis of endophyte-host interactions, practical application technology, and safety evaluation.

Siderophores are low-molecular-weight, high-affinity iron-chelating molecules produced by bacteria in response to iron deficiency. Pseudomonas secrete siderophores to efficiently chelate insoluble Fe³⁺ in the environment, which is a crucial mechanism for their adaptation to iron-limited conditions. This article systematically reviews the types, structural characteristics, biosynthetic pathways (the non-ribosomal peptide synthetase,NRPS), and regulatory mechanisms of siderophores in Pseudomonas. Several regulatory factors at multiple levels were vitally elucidated, including Fur protein, σ factors, quorum sensing, and two-component system. Moreover, siderophores not only promote iron absorption in plants and bioremediation to remove pollutants but also are virulence factors in pathogen infection and factors in microbial spoilage. The siderophore-iron complex can be specifically recognized and actively taken up by bacteria, which is known as the “Trojan horse” mechanism, enabling covalently conjugated antibiotics to enter the cell and thus significantly boosting antibiotic efficacy. Future research should delve into the molecular regulatory networks and microbial interaction mechanisms to promote the application and development of siderophores in agriculture, medicine, and environmental protection.

[Objective] We explored the nuclear translocation dynamics and pathways of the structural protein VP1 of Junonia coenia densovirus (JcDV) in the epidermal cell line HaEpi derived from the larvae of Helicoverpa armigera, aiming to provide theoretical support for clarifying the assembly and proliferation processes of JcDV. [Methods] The wild-type and mutant plasmids of VP1 protein fused with green fluorescent protein (GFP) were constructed and transfected into HaEpi cells. Subsequently, the subcellular localization dynamics of the VP1 protein were analyzed, and the nuclear localization signal (NLS) and key amino acid residues of the protein were identified. The importin genes expressed by HaEpi cells were cloned. Subsequently, the plasmids of importins fused with DsRed2 were constructed to analyze their subcellular localization. The co-localization and co-immunoprecipitation (Co-IP) assays were employed to analyze the interactions between VP1 protein and importins. [Results] The VP1 protein was located in the cytoplasm at 6 h post transfection, and then gradually translocated to the nucleus until 48 h. The NLS of VP1 protein was located at 325-EGTKRKADTPVEEGPSKKGAH-345, among which K328, R329, K341 were the key amino acid residues affecting the nuclear localization. The importins Haimpα1, Haimpα4, and Haimpα7 were located in the nucleus, while Haimpβ1 was mainly located around the nuclear membrane. The co-localization and Co-IP results indicated that the VP1 protein interacted with Haimpα1, Haimpα4, and Haimpβ1 but not with Haimpα7. [Conclusion] The structural protein VP1 of JcDV can be translocated into the nucleus through the dual pathways of importin α/β and importin β.

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.

Streptococcus pneumoniae is a common opportunistic pathogen that can cause various infectious diseases, including acute otitis media, bronchitis, sinusitis, community-acquired pneumonia, septicemia, and purulent meningitis. Autophagy, a lysosome-dependent intracellular degradation pathway, plays a dual regulatory role in both bacterial infection and host defense against pathogens. During S. pneumoniae infection, host cells can activate xenophagy to eliminate invading bacteria. However, this pathogen has evolved multiple evasion strategies, such as interfering with autophagosome maturation, escaping autophagic encapsulation, and even hijacking the autophagy pathway to promote intracellular survival and dissemination. Recent years have witnessed significant progress in understanding the molecular mechanisms underlying the dynamic interplay between S. pneumoniae and host autophagy systems during bacterial infection, yet a systematic review synthesizing these findings remains unavailable. This review focuses on the interaction network and key mechanisms of S. pneumoniae with host cell autophagy, aiming to provide theoretical foundations and research perspectives for developing novel targeted therapeutic strategies against S. pneumoniae infections.

Objective To identify the species and investigate the diversity of 120 Burkholderia cepacia complex (Bcc) strains isolated from industrial products and their production environments between 2022 and 2023. Additionally, the whole genome of a novel sequence type (ST) strain, Burkholderia aenigmatica ST2120, was analyzed to assess its virulence and pathogenicity. Methods Multilocus sequence typing (MLST) was employed to assign sequence types (STs) of Bcc strains. Multilocus sequence analysis (MLSA) was conducted for phylogenetic analysis and species identification of novel ST Bcc strains. Whole genome sequencing of ST2120 was performed on the Nanopore platform, followed by genome assembly, gene prediction, functional annotation, and prediction of biosynthetic gene clusters (BGCs) for secondary metabolites. Results Among the 120 Bcc strains, seven species (B. aenigmatica, B. cenocepacia, B. cepacia, B. contaminans, B. vietnamiensis, B. stabilis, and B. multivorans) and 38 STs were identified. Twenty-two novel alleles and 20 new STs were discovered. The novel ST strains were predominantly identified as B. aenigmatica and B. vietnamiensis. B. aenigmatica accounted for 55% of Bcc strains associated with industrial contamination, representing the most prevalent species within the industrial contamination-related Bcc. The genome (8 909 914 bp, G+C content: 65.73%) of B. aenigmatica ST2120 comprised 8 192 protein-coding genes, and the genome data were deposited in NCBI under the accession number CP184468-CP184476. Genomic analysis predicted siderophore-related BGCs for secondary metabolites (e.g., ornibactin C8 and chromobactin), five efflux pump-associated antibiotic resistance genes, and virulence genes linked to secretion systems, host adhesion/invasion, immune modulation, and quorum sensing. Conclusion B. aenigmatica has emerged as a predominant Bcc species in industrial contamination. The genome of B. aenigmatica ST2120 contains comprehensive virulence genes, indicating significant pathogenicity.

Objective To investigate the effects of the antidepressant mirtazapine on the microbial resistome in complex intestinal environments. Methods We employed read mapping and metagenomic assembly to analyze the antibiotic resistance genes (ARGs) and their bacterial hosts based on metagenomic sequencing data of fecal and cecal content samples. Results A total of 29 classes of ARGs, comprising 610 subtypes, were identified. Bacitracin-, tetracycline-, and vancomycin-class ARGs were the predominant types. Chronic restrain stress (CRS) increased the total abundance of ARGs, significantly elevating the abundance of high-risk ARGs belonging to aminoglycoside, MLS (macrolide-lincosamide-streptogramin), and tetracycline classes (e.g., tetM, tetO, and tet40). Oral administration of mirtazapine exhibited initial microbiota-dependent effects on the resistome. It increased the total abundance of ARGs in healthy rats but decreased that in depressed rats. In addition, mirtazapine significantly enhanced the abundance of vancomycin-, aminoglycoside-, and mupirocin-class ARGs in healthy rats, as well as the tetracycline resistance gene tetP and multidrug resistance gene ompR in depressed rats. Bacillota, Bacteroidota, and Pseudomonadota were the dominant phyla of gut microbiota and served as the primary bacterial hosts of ARGs. Bacillota, as the main host phylum for aminoglycoside and MLS-class ARGs, showed increased abundance after CRS treatment, which was a key factor driving the significant enrichment of these two ARG classes. Furthermore, CRS increased the proportion of pathogenic bacteria such as vancomycin-resistant enterococci. Lactobacillus and Blautia were identified as potential hosts of tetP and ompR, respectively. The significant increases in the abundance of Lactobacillus and Blautia in the intestines of depressed rats after oral mirtazapine administration were critical factors for the marked enrichment of tetP and ompR. Conclusion CRS increases gut microbiota resistance risks by elevating the abundance of high-risk ARGs and pathogenic bacteria carrying ARGs. The effects of oral mirtazapine on the gut resistome are dependent on the initial microbiota composition. This study provides insights into the relationship between non-antibiotic drugs and gut microbiota resistance, offering important implications for the prevention and control of antibiotic resistance transmission.