[Objective] To clarify the diversity characteristics of gut microbiota in the important wild pollinator, Xylocopa appendiculata, and provide theoretical basis for the conservation and utilization of wild pollinator resources. [Methods] Utilizing employed 16S rRNA gene high-throughput sequencing, we conducted comparative analyses of gut microbiota diversity in adults X. appendiculata from different habitats and sexes. Functional prediction of gut microbial communities was performed using PICRUSt2. [Results] The gut microbiota in adults X. appendiculata was predominantly composed of Bacillota (relative abundance of 50.17%), Pseudomonadota (relative abundance of 32.04%), Actinomycetota (relative abundance of 12.84%), and Bacteroidota (relative abundance of 3.77%). The genus Lactobacillus was identified as a core microbiota present in all sampled individuals. Significant differences in the relative abundance of gut microbiota were observed across habitats and sexes. The samples from the Sui and Tang Dynasties City Ruins Botanical Garden habitat (HXST) exhibited the highest richness, diversity, and evenness of gut microbiota. In the Sui and Tang Dynasties City Ruins Botanical Garden habitat (ST) and the Caoyao Village habitat (CY), female adults showed higher microbial richness, diversity, and evenness compared to males. In the Shuiquan Village habitat (SQ), male adults showed higher microbial richness, diversity, and evenness compared to females. The genus Gilliamella, as the dominant genus of male samples from Caoyao Village (HXCYM), accounts for a very small proportion in other samples. Functional prediction PICRUSt2 showed that the metabolic gene functions of the gut microbiota of adults X. appendiculata are the most enriched, with an abundance ratio of 74.00%. [Conclusion] The gut microbiota of adults X. appendiculata exhibits ecological adaptive features with social bees (e.g., Apis mellifera and Bombus spp.), characterized by low diversity, highly conservation, and specialized core microbial community structure. Environmental heterogeneity and host sex were identified as key drivers of gut microbiota divergence. These findings suggest that the gut microbiota of X. appendiculata may play a central role in maintaining host energy homeostasis and population adaptability.

[Objective] To explore the autophagy induced by the African swine fever virus (ASFV) protein E423R. [Methods] The RFP-LC3 fluorescent spots following the transfection of HeLa-Difluo^TM hLC3 cells with pCMV-Myc-E423R was quantified by the High-Content Analysis System, and the autophagic flux was assessed. The expression levels of key autophagy proteins, LC3-Ⅱ and SQSTM1/p62, in HeLa cells were analyzed via Western blotting. Co-localization of autophagosomes and lysosomes was examined by laser confocal microscopy. Additionally, Western blotting was employed to investigate the dose-dependent effect of E423R on LC3-Ⅱ expression and the regulatory effect of E423R on the AKT/mTOR/ULK1 signaling pathway. [Results] The High-Content Analysis System demonstrated a significant increase in RFP-LC3 fluorescence spots in the reporter cells expressing E423R, suggesting that E423R induced the activation of autophagy. Western blotting further confirmed that the expression of E423R significantly elevated the LC3-Ⅱ/β-actin ratio while decreasing the expression level of p62. Confocal microscopy results indicated that E423R enhanced the expression of GFP-LC3, promoted the co-localization of GFP-LC3 with Lyso-Tracker Red, and facilitated the fusion of autophagosomes and lysosomes. Additionally, the expression level of E423R exhibited a positive correlation with the expression level of LC3-Ⅱ in HeLa cells. Furthermore, E423R down-regulated the expression of p-AKT, p-mTOR, and p-ULK1 (Ser757) in the mTOR signaling pathway. [Conclusion] This study demonstrates that the ASFV E423R protein induces complete autophagy via the AKT/mTOR/ULK1 signaling pathway, exhibiting a dose-dependent effect on LC3-Ⅱ expression to a certain degree. These findings provide a foundation for further investigation into the infection and pathogenic mechanisms of ASFV.

[Objective] Stenotrophomonas can promote the growth of plants and aquatic algae. However, limited studies have focused on the bacteriophages infecting Stenotrophomonas. In this study, we isolated bacteriophages infecting Stenotrophomonas from water and studied their biological and genomic characteristics, aiming to improve our understanding of the ecological functions of Stenotrophomonas and its bacteriophages. [Methods] The double-layer plate method was employed to isolate bacteriophages infecting S. indicatrix EB12 from lake water. The biological characteristics, whole genome sequence characteristics, gene functions, phylogenetic relationship, and protein structures of the isolates were analyzed. [Results] Transmission electron microscopy showed that two isolates Ste-X and Ste-D were short-tailed bacteriophages. The incubation period of both strains was 20 min. Ste-X and Ste-D showed the optimal multiplicities of infection being 1 000 and 10, burst sizes of 28.8 PFU/cell and 131.1 PFU/cell, temperature tolerance ranges of 20-60 °C and 20-70 °C, and pH tolerance ranges of pH 4.0-13.0 and pH 3.0-12.0, respectively. Ste-X and Ste-D were deactivated by UV irradiation for 60 min and 120 min, respectively. Their host ranges were narrow. The genomes of both strains showed the lengths of 39 429 bp, with the G+C content of 57.80% and 57.85%, respectively, and both of them contained 65 open reading frames (ORFs). The genomes of the two strains contained only three different bases. However, their homology with other bacteriophages was low, which suggested that the two strains were novel short-tailed bacteriophages. The structures of the proteins encoded by ORF34 and ORF52 were predicted. Result showed thant the proteins encoded by ORF34 were acidic, stable, and hydrophilic, containing two conserved domains, ChtBD3 and PHA00661, with the three-dimensional structures dominated by random coils. The proteins encoded by ORF52 were alkaline, unstable, hydrophilic, with no conserved domain and the three-dimensional structures dominated by α-helixes. [Conclusion] Two novel strains of short-tailed bacteriophages with high genome similarity but distinct biological characteristics were isolated from water.

Allergic asthma is a prevalent chronic inflammatory disease characterized by airway hyperresponsiveness and airway inflammation, often triggered by inhalant allergens such as pet dander and pollen. [Objective] Studies have revealed that helper T cells (Th cells) play a crucial role in the immune regulation of allergic asthma. Particularly, Th2 cells exacerbate airway inflammation by secreting cytokines such as interleukin (IL)-4 and IL-5, which promote the proliferation of eosinophils and mast cells. Additionally, the activation of Th17 cells is closely related to the inflammatory response in allergic asthma. Therefore, modulating the balance of Th1/Th2 and Th17/Treg cells has become an effective strategy for treating allergic asthma. This study explores the pathogenesis of allergic asthma and novel therapeutic approaches. [Methods] We constructed an engineered bacterium EcN ^canf-1 specifically expressing the dog allergen Canf-1. Using the pBAD promoter, we controlled the expression of Canf-1 in the lungs of mice. [Results] EcN ^canf-1 exerted immunomodulatory effects by regulating pulmonary cytokine expression profiles, specifically downregulating the expression of pro-inflammatory cytokines including IL-6, IL-5, and IL-13, while upregulating the expression of anti-inflammatory mediators such as interferon-γ (IFN-γ), transforming growth factor-β (TGF-β), and IL-10, thus alleviating allergic symptoms in the lungs. EcN ^canf-1 demonstrated remarkable efficacy in suppressing the pathological overexpression of Th2 and Th17 lymphocyte subsets under allergic conditions, while enhancing the functions of Th1 and regulatory T cells. Furthermore, EcN ^canf-1 significantly reduced pulmonary mast cell infiltration, attenuated vascular permeability, and mitigated allergen-induced hypothermia and airway constriction. These findings demonstrated that EcN ^canf-1 played a pivotal role in immune homeostasis regulation and represented a promising therapeutic candidate for allergic pulmonary inflammation through its multifaceted modulation of immunological pathways. [Conclusion] EcN ^canf-1 provides a new therapeutic avenue for allergic asthma by modulating the expression of immune cells and cytokines. This not only offers new insights into the immune mechanisms of allergic asthma but also provides a scientific basis for the development of new targeted biological treatment strategies.

[Objective] To isolate and identify a strain of foot-and-mouth disease virus (FMDV) from bovine oropharyngeal fluid (OPF) and subsequently analyze the amino acid mutations in antigenic proteins and the proliferative properties of the isolated virus. [Methods] RT-PCR and sequencing were performed to identify the FMDV-positive OPF samples. The FMDV strain was isolated from bovine OPF samples by cell inoculation and identified by indirect immunofluorescence assay. The whole genome sequence of the strain was obtained by fragment amplification and sequencing. The amino acid sequences were compared to reveal the amino acid mutations in the antigenic proteins of the strain. The proliferative properties of the isolated FMDV strain were analyzed by the plaque forming assay and one-step growth curve. [Results] A FMDV strain O/FMDV/OP/2022/B was successfully isolated from bovine OPF, belonging to serotype O and Ind-2001 lineage. Amino acid mutations were identified in the antigenic proteins VP1, VP2, and VP3 of O/FMDV/OP/2022/B. In addition, the plaque of O/FMDV/OP/2022/B in BHK-21 cells was smaller than that of the vaccine strain O/FMDV/HN/93. The one-step growth curves showed that O/FMDV/OP/2022/B had significantly lower replication titer than O/FMDV/HN/93 in BHK-21 cells. [Conclusion] A strain of FMDV was isolated from bovine OPF, and it displayed amino acid mutations in antigenic proteins and had lower proliferative capacity than the vaccine strain O/FMDV/HN/93. This study contributes to a better understanding of the mechanism of persistent FMDV infection in the bovine oropharynx and provides a reference for the prevention and control of FMD.

[Objective] To isolate and screen the salt-tolerant strains with good plant growth-promoting effect from the saline-alkali soil of the Yellow River Delta, thus providing strain resources for the efficient cultivation of crops in saline-alkali soil. [Methods] Bacillus strains were isolated by the dilution coating method, and the strains with good plant growth-promoting effects were further selected by the seed soaking test. The growth-promoting characteristics of the selected strains were measured, and the growth-promoting effects of the strains on Sesbania cannabina under salt stress was evaluated by pot experiments. The strain with the strongest plant growth-promoting effect was identified based on morphological characteristics, physiological and biochemical characteristics, and molecular biological evidence. Through the whole genome sequence analysis, the genes related to the plant growth-promoting function were discovered. [Results] A total of 60 Bacillus strains were isolated, from which strains M4, M5, B5, L3, and Q17 were screened out by the seed soaking test. These strains showed robust plant growth-promoting properties, being capable of solubilizing inorganic phosphorus, solubilizing potassium, and producing inole-3-acetic acid. The pot experiment results showed that under normal culture conditions and under low salt stress (NaCl concentration of 100 mmol/L), inoculation with Bacillus increased the plant height, maximum leaf area, stem dry weight, and root dry weight of S. cannabina seedlings (P<0.05). Under high salt stress (NaCl concentration of 200 mmol/L), the fresh and dry weights of stem and leaves of S. cannabina seedlings were increased by inoculation with five strains of Bacillus (P<0.05). In addition, inoculation with Bacillus enhanced the activities of catalase, superoxide dismutase, and peroxidase while reducing the content of malondialdehyde in the leaves of S. cannabina seedlings (P<0.05). Strain M4 with the strongest plant growth-promoting effect was identified as Bacillus thuringiensis. [Conclusion] All the five isolates have various plant growth-promoting properties, being capable of promoting the growth of S. cannabina seedlings under salt stress and alleviating the inhibitory effect of salt on the seedlings. Strain M4 with the robust plant growth-promoting effect is identified as B. thuringiensis, and it has the potential to be developed as plant growth-promoting bacterial fertilizer for saline-alkali soil.

The aggravating soil-borne diseases threaten the production of a variety of crops and undermine the sustainable development of agriculture. Streptomyces-based bio-agents have been widely explored as an environmentally safe and economically durable biocontrol resource. However, the biocontrol efficacy and influencing factors require further optimization. [Objective] Here we conducted a meta-analysis to evaluate the efficacy of Streptomyces-based bio-agents in controlling the two common soil-borne diseases and identify the key influencing factors. [Methods] The relevant articles were retrieved from Web of Science and CNKI with the keywords “Streptomyces” and “Fusarium wilt”, “Streptomyces” and “bacterial wilt”, “Streptomyces” and “Fusarium oxysporum”, and “Streptomyces” and “Ralstonia solanacearum (or Pseudomonas solanacearum)”. The articles containing comparable treatment groups (with Streptomyces application) and control groups (without Streptomyces application), disease incidence, sample sizes, and mean values were systematically selected. Finally, 76 articles (113 groups) on Streptomyces-based bio-agents for Fusarium wilt control and 19 articles (28 groups) on those for bacterial wilt control were obtained. [Results] After the application of Streptomyces-based bio-agents, the disease incidence of Fusarium wilt decreased from 75.58% to 24.49% (average control efficacy of 67.60%), and that of bacterial wilt decreased from 73.75% to 19.83% (average control efficacy of 73.11%). The soil density of Streptomyces, the final concentration ratio of Streptomyces to pathogen in soil, and climate types were vital for the biocontrol performance of Streptomyces-based bio-agents. Moreover, Streptomyces at the final concentration of 10⁷ CFU/g demonstrated the best biocontrol performance on both diseases. The biocontrol effect of Streptomyces on Fusarium wilt was better when the final concentration ratio of Streptomyces to pathogen was 1:1, whereas the biocontrol effect on bacterial wilt disease was better when the ratio was 10:1 or 100:1. Notably, Streptomyces demonstrated enhanced biocontrol effects on the both diseases in tropical monsoon climate regions. [Conclusion] The application dose of Streptomyces-based bio-agents in soil-borne disease management should be adjusted according to the species and concentration of the pathogen. In addition, it may be better to apply Streptomyces-based bio-agents in tropical monsoon climate regions.

[Objective] To extract and purify extracellular polysaccharides (EPS) from Sphingomonas echinoides 1K04342 and investigate the ameliorating effects and mechanisms of the purified EPS on glucose and lipid metabolism disorders induced by oleic acid (OA) in human hepatoma cells (HepG2). [Methods] A response surface methodology was employed to optimize the ultrasound power, ultrasound time, and incubation time for maximizing the EPS yield of S. echinoides 1K04342 from ultrasound-assisted extraction. The crude EPS underwent deproteinization and was further purified through a DEAE-Sepharose Fast Flow anion exchange column. The effects of the purified EPS on the proliferation, glucose uptake, and α-glucosidase inhibition and pancreatic lipase inhibition rates in HepG2 cells were evaluated. The most effective EPS component for mitigating OA-induced glucose and lipid metabolism disorders in IR-HepG2 cells was selected for in-depth physicochemical and bioactivity analyses. [Results] The optimal EPS extraction parameters were as follows: ultrasound power at 59.39 W, extraction for 42.08 s, and incubation for 9.24 h, under which the estimated yield of EPS reached 2.13 g/L. Under the adjusted parameters (60 W, 42 s, and 9.2 h), the EPS yield was 2.10 g/L, which was statistically consistent with the theoretical value (2.13 g/L). The optimal component for ameliorating glucose and lipid metabolism disorders in IR-HepG2 cells was EPS-2, which showed the total sugar content of 74.3%, with a monosaccharide profile comprising fucose, rhamnose, arabinose, galactose, glucose, and mannose. EPS-2 alleviated OA-induced glucose and lipid metabolic disorders in IR-HepG2 cells. EPS-2 reversed OA-induced decreases in cell viability. EPS-2 may activate the IRS-1/PI3K/AKT pathway, up-regulating the protein levels of GSK3β and FoxO1 and down-regulating the mRNA and protein levels of PEPCK and G6Pase, thereby mitigating glucose metabolism disorders. EPS-2 may regulate OA-induced lipid metabolism disorders by activating the AMPK/ACC1/SREBP-1C pathway, lowering the triacylglycerol (TG), total cholesterol (TC), and low-density lipoprotein (LDL) levels, and increasing the high-density lipoprotein (HDL) level. [Conclusion] EPS-2 derived from S. echinoides 1K04342 could effectively ameliorate glucose and lipid metabolism disorders in IR-HepG2 cells.

Lactic acid bacteria (LAB) are the predominant probiotics with significant health-promoting potential. Xizang pigs, an invaluable indigenous breed in China, harbor a unique and largely unexplored reservoir of intestinal LAB. [Objective] To screen high-quality LAB isolated from Xizang pigs. [Methods] LAB were isolated by the streak plate method and identified by 16S rRNA gene sequencing. Two Limosilactobacillus reuteri strains with significantly different lactic acid production capacities were selected from Xizang pigs. The two strains, together with one L. reuteri strain previously preserved in our laboratory, which originated from duroc×landrace×yorkshire pigs, were assessed in terms of acid and bile salt tolerance, antioxidant activity, antibacterial properties, and antibiotic resistance. [Results] A total of 21 LAB strains were isolated and identified from the intestinal microbiota of Xizang pigs, including ten Streptococcus alactolyticus strains, six L. reuteri strains, three Lactobacillus amylovorus strains, one Leuconostoc mesenteroides strain, and one Limosilactobacillus vaginalis strain. Among the three strains screened out, L. reuteri T-B5L2 exhibited the highest lactic acid production. Moreover, this strain demonstrated strong survival under pH 3.0 and 0.1% bile salts. L. reuteri T-B5L2 exhibited the strongest inhibitory activity against enteropathogenic Escherichia coli and Salmonella Choleraesuis. There were no significant differences in antioxidant activity among the three strains. All the three strains exhibited high sensitivity to penicillins and cephalosporins but displayed resistance to tetracyclines, aminoglycosides, and glycopeptides. [Conclusion] In this study, 21 LAB strains were isolated from the feces of Xizang pigs, among which L. reuteri T-B5L2 exhibited the highest acid production capacity. Further in vitro biochemical characterization demonstrated that this strain exhibited good growth performance, acid and bile salt tolerance, antioxidant activity, and the ability to inhibit pathogenic bacteria. These findings suggest that L. reuteri T-B5L2 is a promising probiotic candidate with potential applications in improving intestinal health and mitigating pathogenic infections.

[Objective] To investigate the antibiotic resistance and virulence of pet-derived Klebsiella pneumoniae in some areas of Guangdong Province. [Methods] Fecal swabs were collected from dogs and cats for strain isolation, and 16S rRNA and khe genes were amplified by PCR to identify the strains. The sensitivity of K. pneumoniae isolates to 17 antibiotics was determined by the agar diffusion method. PCR was employed to detect resistance genes to β-lactams (bla_SHV, bla_CTX, and bla_TEM), carbapenems (bla_KPC and bla_NDM), aminoglycosides (rmtB), quinolones (qnrS and oqxAB), sulfonamides (Sul1 and Sul2), amphenicols (floR), tetracyclines (tet(A)), and fosfomycin (fosA3) and some virulence genes (rmpA, maga, fimH, mrkD, uge, WabG, kfu, Aerobactin, and ureA). [Results] A total of 126 strains of K. pneumoniae were isolated from 428 fecal samples, with an isolation rate of 29.4%. The 126 isolates had high resistance rates to amoxicillin (75.40%), ampicillin (73.81%), and cotrimoxazole (61.90%). They were moderately sensitive to ceftazidime, amikacin, apramycin, and enrofloxacin, and they were sensitive to tigecycline, colistin, and meropenem. The detection rate of the resistance gene oqxAB was the highest, which was 86.51%, followed by those of the β-lactam resistance gene bla_SHV (73.81%) and the tetracycline resistance gene tet(A) (52.68%). Other resistance genes were detected to varying degrees (0.79%-46.03%) and the carbapenem resistance gene bla_KPC, colistin resistance gene mcr-1, and aminoglycoside resistance gene rmtB were not detected. Among the virulence genes, the urease gene urea, lipopolysaccharide-related gene uge, and fimbria-related gene fimH showed the detection rates of 100.00%, 95.54%, and 91.07%, respectively. Other virulence genes were detected to varying degrees (2.70%-8.90%), while the capsule-related gene magA and the fimbria-related gene mrkD were not detected. [Conclusion] In some areas of Guangdong Province, the antibiotic resistance of pet-derived K. pneumoniae is serious, but its pathogenicity is relatively weak. Monitoring of its drug resistance and pathogenicity should be strengthened. In addition, antibiotics should be strictly managed and rationally used in the clinical practice, so as to avoid the generation and dissemination of multidrug resistant strains of K. pneumoniae.