Objective To investigate the growth-promoting properties and mechanisms of Bacillus amyloliquefaciens DGL1 isolated from arid sandy soils of the Qinghai-Xizang Plateau on oat plants under drought stress, thus providing a high-quality microbial resource and a theoretical basis for developing microbial fertilizers suitable for arid regions. Methods The growth-promoting effects of strain DGL1 on oat root length, plant height, and fresh weight under drought stress were determined. The degree of cell membrane lipid peroxidation and the activities of antioxidant enzymes in oat plants under drought stress were measured. The genome and transcriptome of strain DGL1 were sequenced via high-throughput technology. Results Strain DGL1 significantly increased the root length, plant height, and fresh weight of oat plants under drought stress. It markedly elevated the activities of antioxidant enzymes [(superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT)] while reducing the content of malondialdehyde and H₂O₂. Genomic analysis revealed that DGL1 carried the genes related to oxidative stress (gpx encoding glutathione peroxidase, opuD encoding glycine-betaine transporter, and ahpF encoding alkyl hydroperoxide reductase), synthesis of the IAA precursor l-tryptophan (trpA, trpB, and trpC), and flagellar biosynthesis (FliP, FliQ, and FliR). Transcriptome sequencing further revealed that genes associated with biofilm formation, nitrogen and phosphorus uptake, material and energy metabolism, and auxin precursor synthesis—all crucial for root colonization—presented upregulated expression under drought stress. The strain might enhance plant drought tolerance via these pathways. Conclusion Strain DGL1 can enhance the drought tolerance of oat plants and has great potential for application in developing bio-inoculants for arid land agriculture.

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.

The enzootic nasal tumor of sheep and goats is a progressive and contagious disease caused by enzootic nasal tumor virus. It is mainly characterized by tumor growth in the mucosal epithelial tissue of the ethmoid bone and nasal turbinates within the nasal cavity of sheep and goats. In the later stage of the disease, the significant enlargement of tumor volume can lead to upper respiratory tract obstruction, which subsequently causes the affected animals to die of asphyxiation. This disease markedly reduces the production performance of infected animals, causing economic losses to the livestock industry. Moreover, it poses a threat to precious local breeds and core breeding flocks, resulting in the loss of high-quality breeding sheep. Consequently, it has become one of the major diseases threatening the sheep and goat industry. Currently, there are no vaccines or specific treatments for this disease. This article reviews enzootic nasal tumor virus in terms of the etiology, epidemiology, clinical symptoms, main pathological changes, diagnosis, and prevention and control, providing references and ideas for the prevention and control of this disease.

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 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.

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 Tad pili are widely distributed in Gram-negative bacteria and are associated with the virulence of various pathogens. However, the studies about the Tad pili in Vibrio parahaemolyticus remain limited. This study aimed to elucidate the role of the Tad pilus secretin CpaC (VP2419) in the biological functions of V. parahaemolyticus. Methods The cpaC-deleted mutant (ΔcpaC) and complemented strain (CΔcpaC) were constructed from the wild-type (WT) strain (SH112) of V. parahaemolyticus. The strains were compared in terms of biofilm formation, competitiveness, swarming and swimming motility, cell adhesion, cytotoxicity, as well as virulence, tissue colonization, and pathology in mice. Results Regarding environmental adaptation, compared with the WT strain, ΔcpaC exhibited significantly decreased competitiveness, motility, and biofilm formation. In terms of pathogenicity, ΔcpaC demonstrated significantly reduced cell adhesion, cytotoxicity, as well as attenuated virulence, tissue colonization, and pathological damage in mice, compared with the WT strain. Conclusion As the Tad pilus secretin in V. parahaemolyticus, CpaC participates in multiple functions related to environmental adaptation and pathogenicity, including competitiveness, biofilm formation, motility, cell adhesion, cytotoxicity, and tissue colonization. These findings provide important insights for a deeper understanding of the biological functions of Tad pili.

Objective To determine the efficacy of Cucurbita pepo cv Dayangua (CPD) in alleviating hypoxia and explore the potential mechanisms involving the modulation of the gut microbiota and its metabolites. Methods Male Kunming mice were randomly assigned into two groups: a control group (normoxia ddH₂O, ND) and a CPD intervention group (normoxia CPD, CPD). The CPD group received a dose of 800 mg/(kg·d) of CPD, while the ND group received an equal volume of ddH₂O for 15 consecutive days. One hour after the final administration, mice from each group were placed in wide-mouth bottles, and the survival time was observed and recorded. Fecal samples collected prior to the last administration were subjected to 16S rRNA gene amplicon sequencing and targeted metabolomics analysis. Correlation analysis between gut microbiota and metabolites was subsequently performed. Results CPD intervention significantly prolonged the survival time of mice under hypoxic conditions compared to the ND group. CPD altered the structural composition of the gut microbiota in mice. Linear discriminant analysis effect size (LEfSe) revealed significantly different bacterial taxa between the ND group and the CPD group, with higher relative abundance of Bacillota, Lactobacillus, and Alistipes in the CPD group. Microbial genera, including Paraprevotella and Lactobacillus, showed a positive correlation with survival time. Targeted metabolomics identified 9 upregulated and 31 downregulated metabolites in the CPD group. Notably, metabolites such as palmitoleic acid, glyoxylic acid, hendecanoic acid, l-aspartic acid, O-succinylhomoserine, and allantoic acid were significantly enriched and positively correlated with the survival time of mice after CPD intervention. Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis of differential metabolites showed the highest enrichment in the tryptophan metabolism and glycine, serine, and threonine metabolism pathways. Conclusion CPD intervention significantly prolonged the survival time of hypoxic mice. CPD intervention enriched beneficial microorganisms, including Lactobacillus, and elevated the levels of beneficial metabolites such as choline and allantoic acid. These findings suggest that modulating the “gut microbiota-metabolite” axis may be one mechanism through which CPD enhances host hypoxia tolerance, providing a theoretical basis and potential targets for developing microecological intervention strategies against hypoxia-related diseases.

Objective To investigate the effects of mannanoligosaccharides (MOS) on the in vitro fermentation characteristics and composition of intestinal microbiota in weaned piglets by using an in vitro microbial fermentation technique, with fructooligosaccharides (FOS) taken as the control. Methods Using microbial inocula derived from the jejunal and colonic chyme of piglets, with FOS and MOS as respective substrates, this study measured microbial gas production and fermentation broth pH at five time points (0, 6, 12, 24, and 48 h), and collected fermentation broth samples at each time point for subsequent microbial analysis. Results In the in vitro jejunal microbial fermentation system, both the fermentation broth pH and gas production in the MOS group were significantly higher than those in the FOS group (P<0.05). At 24 h of fermentation, compared with FOS, MOS significantly increased the concentrations of acetate, propionate, and total short-chain fatty acids (SCFAs) (P<0.01). The formate production in the MOS group was significantly lower than that in the FOS group (P<0.01). At 48 h of fermentation, the lactate concentration in the MOS group was significantly lower than that in the FOS group (P<0.01). In the in vitro colonic microbial fermentation system, gas production in the MOS group was significantly higher than that in the FOS group (P<0.05). At 48 h of fermentation, the production of formate, acetate, butyrate, SCFAs, and lactate in the MOS group was significantly higher than that in the FOS group (P<0.01). The 16S rRNA gene sequencing results of the jejunal fermentation broth revealed that at 48 h of fermentation, both the Shannon and Simpson indices in the MOS group were significantly higher than those in the FOS group (P<0.01). Furthermore, the microbiota composition exhibited disparity between the MOS and FOS groups. Moreover, the relative abundances of Bifidobacterium, Limosilactobacillus, and Megasphaera were significantly higher in the MOS group than in the FOS group (P<0.05). Conclusion Compared to FOS, MOS enabled the microbiota in the small intestine of piglets to significantly improve the microbial community structure, increase the abundance of beneficial bacteria such as Bifidobacterium, enhance gas production, and promote the generation of acetate and other SCFAs. These findings suggested that MOS held potential for modulating microecology in the small intestine of weaned piglets.

Objective To compare the regulatory effects and underlying physiological mechanisms of Pseudomonas huaxiensis M11 and Bacillus megaterium M28 on the photosynthetic characteristics of maize subjected to low soil fertility stress. Methods A pot experiment was implemented with four treatments: normal soil control (CK), low nutrient treatment (LNT), and bacterial inoculation under LNT conditions (M11+LNT, M28+LNT). At the tasseling stage, measurements were taken for soil nutrients, plant growth indices, gas exchange parameters, chlorophyll fluorescence characteristics, and the fast chlorophyll a fluorescence induction kinetics (O-J-I-P chlorophyll a fluorescence transient, OJIP curve). Yield components were assessed at physiological maturity. Results Inoculation with M11 significantly increased the content of available phosphorus, available potassium, and organic matter, while reducing the electrical conductivity in soil. M28 significantly enhanced the total nitrogen content. Both bacterial treatments significantly promoted maize growth, increasing the plant height, leaf area, SPAD value, and biomass. Moreover, they highly significantly enhanced the net photosynthetic rate (P_n), stomatal conductance (G_s), transpiration rate (T_r), and water use efficiency (WUE), while reducing the intercellular CO₂ concentration (C_i). Chlorophyll fluorescence analysis revealed a decrease in minimal fluorescence (F_o) and increases in the maximum photochemical efficiency (F_v/F_m), actual photochemical quantum yield of PSII (Φ_PSII), apparent photosynthetic electron transport rate (ETR), photochemical quenching (qP), and the fraction of open PSII centers based on excitation energy (qL), with no significant change in non-photochemical quenching (NPQ). The OJIP curves indicated the absence of a K-step in inoculated plants, a decrease in fluorescence at the J-step, and increases at the I-step and P-step. The differential kinetic curves of relative variable fluorescence (ΔV_t analysis) confirmed that both strains synchronized the optimization of electron transport on both the donor and acceptor sides of photosystem II (PSII). The increased amplitude of the I-P phase suggested enhanced photosystem I (PSI) activity. Junction-intermediate-peak test (JIP-test) parameters demonstrated that inoculation significantly enhanced the performance index based on absorbed light energy (PI_ABS), the performance index on a cross-section basis (PI_CS), the probability that a trapped exciton moves an electron into the electron transport chain beyond Q_A (Ψ_o), the quantum yield for electron transport (φ_Eo), and the electron transport flux per reaction center (ET_o/RC). Conversely, dissipated energy flux per cross-sectional area (DI_o/RC) and quantum ratio for dissipated energy (φ_Do) decreased. Consequently, compared with the LNT group, the M11 and M28 treatments resulted in significant increases of 30.61% and 22.64% in maize fresh weight and 26.68% and 23.41% in dry weight, respectively. Conclusion P. huaxiensis M11 primarily enhances photosynthetic performance by increasing soil available phosphorus and potassium content, directly optimizing energy metabolism and stomatal movement, whereas B. megaterium M28 mainly acts by elevating soil total nitrogen content, focusing on stabilizing the structure of the photosynthetic apparatus. Together, they protect the integrity of photosynthetic apparatus and optimize the electron transport efficiency of photosystems, significantly improving the photosynthetic performance and yield of maize under low fertility stress. These findings provide a theoretical basis for the targeted application of microbial inoculants in sustainable agricultural production.