Blastocystis sp. is a widespread unicellular protozoan mainly parasitizing the intestines of humans and animals. This parasite has rich genetic diversity, with 42 subtypes (ST1–ST17, ST21, ST23–ST46) reported, of which ST1, ST2, and ST3 are prevalent. However, the pathogenicity levels and the pathogenicity differences among different subtypes have been controversial. [Objective] To determine the pathogenicity of ST1, ST2, and ST3 and explore whether there are differences in the pathogenicity between the three subtypes of Blastocystis sp. [Methods] Blastocystis sp. strains were isolated from fresh human and macaque faeces and identified by morphological observation, 18S rRNA gene amplification and sequencing, and cluster analysis. After BALB/c mice were infected with strains of ST1, ST2, and ST3, the distribution characteristics of the parasites in vivo were observed. In addition, the clinical signs, weight gain, feed conversion rate, and mortality of the infected mice were recorded to compare the pathogenicity of the three subtypes. Finally, the pathological changes in the intestines of mice were observed. [Results] Three subtypes of Blastocystis sp., ST1, ST2 and ST3, were successfully isolated and identified. Animal challenge results showed that the parasites predominantly colonized the intestine and negatively affected the health of mice. A high dose of ST3 resulted in death in mice, while ST1, ST2, and low doses of ST3 did not affect the survival of mice. Blastocystis sp. damaged the intestinal tissue of challenged mice. [Conclusion] Blastocystis sp. causes harm to the host by damaging the intestine. The pathogenicity varies among different subtypes and ST3 has stronger pathogenicity. This study lays a foundation for further studying the pathogenicity mechanism and provides data for assessing the threat of Blastocystis sp. to public health.

Porcine epidemic diarrhea virus (PEDV) is an enterovirus that can cause severe diarrhea and dehydration. The widespread epidemic of PEDV has caused huge economic losses to the pig breeding industry, which, however, lacks effective means for prevention and treatment. Nsp8 is an important non-structural protein involved in the replication of PEDV, while the host proteins interacting with Nsp8 remains unclear. [Objective] To screen the host proteins interacting with PEDV Nsp8 and explore the effects of the host proteins on the replication of PEDV, so as to provide a theoretical basis for discovering new key functional receptors or therapeutic targets of PEDV. [Methods] The eukaryotic expression plasmid of PEDV Nsp8 was successfully constructed with the eukaryotic expression vector pcDNA3.1(+). The host proteins interacting with PEDV Nsp8 were screened by co-immunoprecipitation, mass spectrometry, and laser confocal microscopy. The effects of the host proteins on PEDV replication were explored by overexpression and knockdown in LLC-PK cells. [Results] Thirty-six potential host proteins interacting with Nsp8 were screened by mass spectrometry, and the interaction between heat shock protein member 8 (HSPA8) and Nsp8 was verified. The overexpression of HSPA8 in LLC-PK cells inhibited the overexpression of Nsp8 in a dose-dependent manner. Meanwhile, it significantly inhibited the replication of PEDV in a dose-dependent manner at the protein and transcriptional levels. Interfering with endogenous HSPA8 expression significantly promoted the replication of PEDV. The 50% tissue culture infectious dose (TCID₅₀) and indirect immunofluorescence further proved that HSPA8 inhibited PEDV replication. [Conclusion] This study screened out the host protein HSPA8 interacting with PEDV Nsp8 and proved that HSPA8 could significantly inhibit PEDV replication, which provided a new idea for the design of HSPA8-targeted drugs for the prevention or treatment of PEDV.

[Objective] Soft rot is one of the major diseases affecting the yield and quality of konjac. This study screened a strain with antagonistic effect on Pectinobacterium aroidearum from the rhizosphere soil of konjac, aiming to provide germplasm resources for the biocontrol of soft rot in konjac. [Methods] An antagonistic strain was screened by the plate confrontation method, and its antagonistic effects on pathogenic fungi were measured. The control effect of GZA12 on soft rot in konjac was examined by the inoculation in konjac corm tissue, pot experiment, and root irrigation. The growth-promoting effect of this strain was tested indoors and preliminarily verified by tomato pot experiments. [Results] A strain GZA12 with antagonistic effect was screened out and identified as Bacillus velezensis. This strain showed the inhibition zone diameter of 21.33 mm against P. aroidearum and the inhibition rates of 58.16%, 47.30%, and 54.53% against Botryosphaeria dothidea, Fusarium oxysporum, and F. solani, respectively. Inoculation of GZA12 in konjac corm tissue decreased the disease index by 26.67%, 33.33%, and 40.00%, respectively, compared with the inoculation of B. dothidea alone. In the pot experiment, the treatment with GZA12 suspension decreased the disease index by 22.85% compared with the control group and reached the control effect of 53.31%. The results from the root irrigation experiment showed that compared with water irrigation, irrigation with GZA12 fermentation broth reduced the disease index by 4.89% and reached the control effect of 21.57%. Strain GZA12 had the ability to fix nitrogen, solubilize phosphorus, and produce siderophores and indole-3-acetic acid (IAA). Inoculation with GZA12 suspension promoted the growth of tomato seedlings in a concentration-dependent manner. [Conclusion] Strain GZA12 can inhibit the pathogen causing soft rot and promote the growth of konjac, demonstrating the potential for further development and utilization.

[Objective] To investigate the enzymatic properties and straw-degrading effect of a recombinant xylanase rRuXyn024. [Methods] We cloned RuXyn024 from the rumen of beef cattle and used bioinformatics tools for detailed sequence analysis. The expression vector pET-RuXyn024 was constructed and transformed into Escherichia coli BL21(DE3) for heterologous expression of RuXyn024. Furthermore, the enzymatic properties and straw-degrading effect of rRuXyn024 were examined. [Results] RuXyn024 was composed of 358 amino acid residues and had a molecular weight of approximately 40 kDa, belonging to the GH 10 family. The optimal pH and temperature of rRuXyn024 were pH 7.0 and 40 ℃, respectively. The relative activity of RuXyn024 at pH 6.0−9.0 and 30−70 ℃ remained above 60% and 70%, respectively. With xylan from wheat straw as the substrate, rRuXyn024 showcased the K_m and V_max of 18.8 g/L and 82.6 µg/min, respectively. The activity of rRuXyn024 was inhibited by Mg²⁺, Zn²⁺, Cu²⁺, Ni²⁺, EDTA, and SDS at 1 mmol/L and 5 mmol/L, as well as 5 mmol/L Ca²⁺ and β-mercaptoethanol. Cu²⁺ and β-mercaptoethanol at 5 mmol/L nearly inactivated the enzyme. Mn²⁺ at 1 mmol/L and 5 mmol/L increased the activity of rRuXyn024 by 46.9% and 35.8%, respectively. The degradation of xylan from wheat straw by rRuXyn024 produced oligosaccharides, including xylotriose and xylobiose. rRuXyn024 could degrade maize straw, rice straw, soybean straw, and rapeseed straw, with the strongest degrading effect on maize straw. [Conclusion] rRuXyn024 exhibits tolerance to broad scopes of pH and temperature and significant potential for improving the utilization of straw by ruminants.

[Objective] To explore the effects of different concentrations of chlortetracycline on the characteristics of microbial communities involved in inorganic phosphorus (Pi) dissolution and organic phosphorus (Po) mineralization in the soil applied with organic fertilizer, focusing on soil P transformation and availability. [Methods] The purple soil collected from Tongnan District of Chongqing was used for a pot experiment with the addition of chicken manure as the organic fertilizer. Three chlortetracycline treatments (No-CTC, Low-CTC, and High-CTC) were designed with the addition levels of 0.0, 0.1, and 4.0 mg/kg, respectively. The soil samples were collected on days 7 (D7) and 30 (D30) after pepper ('Xinxiang 8') was planted. Real-time qPCR and Illumina MiSeq high-throughput sequencing were employed to analyze the community characteristics of the bacteria carrying the key genes (pqqC and phoD) of Pi dissolution and Po mineralization, respectively. Furthermore, the sequencing results and biologically based P (BBP) fractionation were employed to examine the effects of CTC addition on soil P transformation. [Results] High-CTC increased the content of Citrate-P and Enzyme-P by 8.2% and 44.0%, respectively, compared with No-CTC on D7. Low-CTC and High-CTC increased the content of Enzyme-P by 44.0% and 65.6%, respectively, compared with No-CTC on D30. The addition of CTC suppressed alkaline phosphatase (ALP) activity and affected the community structures of pqqC and phoD-harboring bacteria in the soil. The Mantel test results showed that Citrate-P was significantly associated with the dominant pqqC-carrying taxa Pseudomonas, Geodermatophilus, and Saccharothrix on D7. The dominant phoD-carrying taxa Bradyrhizobium, Ensifer, and Skermanella exhibited notable correlations with Enzyme-P on D7, and such correlations weakened over time. The average degree of the community network of the bacteria carrying pqqC increased in the Low-CTC treatment and decreased in the High-CTC treatment on D7. The average degree of this network decreased in High-CTC and Low-CTC treatments on D30. The average degree of the community network of the bacteria carrying phoD decreased with the increase in CTC addition on D7, while this trend was opposite on D30. [Conclusion] The addition of CTC significantly affected soil Enzyme-P by regulating the community structure of pqqC- and phoD-carrying bacteria as well as acid phosphatase (ACP) and ALP activities, thereby affecting the P forms and availability in the soil. This study contributes to a deeper understanding of alterations in microbial communities associated with P cycling in the soil-plant system contaminated by CTC. Moreover, it lays a scientific foundation for enhancing nutrient utilization efficiency in the soil applied with antibiotics.

Sugarcane smut caused by Sporisorium scitamineum is one of the major diseases affecting the development of China's sugar industry, and biocontrol is currently the most efficient and safe means, which necessitates the screening of antagonists with strong environmental adaptability and inhibitory effects. [Objective] To isolate and identify the strains with good antagonistic effects against S. scitamineum from soil and provide high-quality biocontrol strain resources for the efficient prevention and control of sugarcane smut. [Methods] The antagonists were isolated by the plate confrontation assay, and their taxonomic status was determined by morphological observation, physiological and biochemical tests, and 16S rRNA gene sequencing. The pot and field experiments were conducted to study the inhibition effects of the antagonists on sugarcane smut. [Results] Three strains of bacteria with significant antagonistic effects were obtained. Strains GB-3 and GH16-3 were identified as Bacillus velezensis and GH16-8 as B. amyloliquefaciens, with the inhibition zone diameters of (30.00±1.07), (44.00±1.21), and (18.00±0.89) mm and the inhibition rates of 16.12%, 31.92%, and 5.91%, respectively. The inhibition effects of the three strains against sugarcane smut were 74.33%, 76.57%, and 69.07% in pots and 20.08%, 55.59%, and 50.08% in fields, respectively. All the three strains had phosphorus-solubilizing ability, tolerance to extreme salt-alkaline environments, and inhibitory effects on a variety of phytopathogenic bacteria and fungi, with the indole-3-acetic acid (IAA) yields of 2.12, 1.30, and 1.22 mg/L, respectively. The application of the three strains increased the sugarcane plant height by 28.25%, 17.09%, and 23.31%, respectively. [Conclusion] Strain GH16-3 has strong environmental adaptability, growth-promoting effect, and prevention effect against sugarcane smut, demonstrating a promising application prospect.

Depression is a prevalent affective disorder exerting negative impacts on an individual's emotional and cognitive functions and is commonly complicated with other diseases. As depression is affecting increasingly younger populations, it poses a serious challenge to the mental health initiatives in China. In recent years, the relationship between depressive symptoms and gut microbiota has garnered increasing attention, fueled by the deepening research on gut microbiota. Lactulose, a medication aimed at promoting gut health and known for its potential benefits on emotional and cognitive functions, has sparked interests regarding its clinical application in ameliorating depressive symptoms. This article reviews the clinical research findings on the efficacy of lactulose in alleviating depressive symptoms and outlines the potential mechanisms through which lactulose may mitigate these symptoms. Furthermore, this article offers a perspective on the mitigation of depressive symptoms through the gut-brain axis.

Type 2 diabetes mellitus (T2DM) stands as a chronic metabolic disorder posing a challenge to global public health, owing to its widespread prevalence. The intricate interplay between gut microbiota and the onset and progression of T2DM, along with the potential therapeutic benefits of modulating gut microbiota, has emerged as a focal point in contemporary research. Recent studies have underscored the capacity of traditional Chinese medicine to ameliorate T2DM by inducing alterations in gut microbiota. Nevertheless, the precise mechanisms underlying the pharmacological actions of traditional Chinese medicine via gut microbiota regulation remain elusive. The diverse bioactive compounds in traditional Chinese medicine play pivotal roles in eliciting its pharmacological effects. This article systematically reviews the advancements in the research concerning the modulation of gut microbiota for T2DM intervention by a spectrum of bioactive components in traditional Chinese medicine, encompassing polysaccharides, alkaloids, flavonoids, saponins, and other compounds. The objective of this review is to furnish a comprehensive theoretical framework supporting the preventive and therapeutic potential of traditional Chinese medicine in T2DM management, thereby significantly contributing to the modernization of traditional Chinese medicine.

[Objective] To investigate the effects of a metabolite cocktail composed of indole-3-propionic acid (IPA), sodium butyrate (SB), and valeric acid (VA) of gut microbiota on the proliferation of hepatocellular carcinoma cells. [Methods] The human hepatocellular carcinoma HepG2 cells were cultured in vitro and treated with the cocktail at different concentrations (1×, 2×, 3×, 4×, and 5×). The total cholesterol (TC) and triglyceride (TG) levels in the cells were determined by the total cholesterol and triglyceride assay kits. The Cell Counting Kit-8 (CCK-8) and colony formation assays were employed to examine the cell proliferation. Twelve BALB/c athymic nude mice were randomized into a control (Ctrl) group and a treatment (Treat) group and then subjected to subcutaneous injections of HepG2 cells. The tumor size was measured every three days, and the tumor volume and tumor inhibition rate were calculated. When the tumor volume reached 100 mm³, the mice in the Ctrl group were administered with sterile water by gavage daily, while those in the Treat group received the cocktail via gavage until euthanized under anesthesia. After 27 days of treatment, the body weights of mice in both groups were measured, and tumors were excised and weighed, with the tumor weight/body weight ratio calculated. The content of Ki-67 protein in the tumors was determined by immunohistochemical (IHC) staining, and the lipid accumulation within tumor cells was assessed by Oil Red O staining. [Results] The cocktail of IPA, SB, and VA lowered the levels of TC and TG in hepatocellular carcinoma HepG2 cells and exerted an inhibitory effect on the proliferation of HepG2 cells. Both CCK-8 and colony formation assays indicated that the cocktail inhibited the proliferation of HepG2 cells in a dose-dependent manner. The oral administration of the cocktail inhibited the growth of hepatocellular carcinoma cells, as evidenced by smaller and lighter tumors and lower tumor weight/body weight ratios in the Treat group than in the Ctrl group (Ctrl: 723 mm³, 0.47 g, 22.23%; Treat: 526 mm³, 0.32 g, 16.65%). IHC and Oil Red O staining further demonstrated reductions in Ki-67 expression and lipid accumulation in the mice administered with the cocktail via gavage. [Conclusion] The cocktail of IPA, SB, and VA can inhibit the proliferation and suppress the lipid synthesis of hepatocellular carcinoma cells.

[Objective] To improve the culture medium components of Parvimonas micra, increase the number of live cells, and develop a demonstration method for culturing fastidious bacteria. [Methods] Biochemical analysis was conducted on a strain of P. micra to screen the potential substrates that could promote bacterial growth. A single-factor experiment was carried out for each substrate with three concentrations. The substrate with a significant bacterial enrichment effect was further optimized for concentration, and thus a new culture medium was obtained. [Results] The single-factor experiment results showed that the substrates with significant bacterial enrichment effects included L-serine, L-threonine, and glycyl-L-glutamine. In the medium with the addition of 4.8 g/L L-serine, the live cell count of P. micra reached 3.6×10⁸ CFU/mL, representing a 4.2-fold increase compared with that in the basic medium with tryptone soya broth (TSB) and fetal bovine serum (FBS). Furthermore, the improved culture medium was applied to the culture of another P. micra strain, demonstrating a significant growth-promoting effect. [Conclusion] This study proves that using biochemical identification plates to screen medium supplements is a fast and efficient method, providing a reference for the enlargement culture of fastidious bacteria.