[Objective] This study investigated the optimal proportion of green manure replacing chemical fertilizer and its effect on soil fungal community in the paddy field of Ultisol, aiming to achieve soil fertilization and sustainable utilization of Ultisol in southern China. [Methods] This study set seven treatments: no fertilizer (Control), application of Chinese milk vetch without chemical fertilizer in early season rice (G), conventional application of chemical fertilizer in early season rice (NPK100), application of Chinese milk vetch and conventional chemical fertilizer in early season rice (NPK100+G), application of Chinese milk vetch and 80% conventional chemical fertilizer in early season rice (NPK80+G), application of Chinese milk vetch and 60% conventional chemical fertilizer in early season rice (NPK60+G), and application of Chinese milk vetch and 40% conventional chemical fertilizer in early season rice (NPK40+G). The conventional chemical fertilizer was applied in late season rice for other treatments except the Control. The root surface soil samples of different treatments were collected at the maturity stage of late rice for the measurement of soil properties. At the same time, high-throughput sequencing (Illumina MiSeq) was employed to analyze the features of soil fungal community. [Results] Compared with NPK100, the treatments of green manure replacing chemical fertilizer increased the yields of rice and straw. Different treatments significantly altered the soil fungal community composition (P=0.001). Replacing medium and low amounts of chemical fertilizer with green manure increased the relative abundance of saprophytic fungi in soil, which increased the conversion rate of soil organic matter and nutrient turnover rate. Compared with NPK100, replacing 0, 20%, and 40% chemical fertilizer with green manure increased the relative abundance of saprophytic fungi in soil by 33.55%, 167.27%, and 55.28%, respectively. In addition, replacing medium and low amounts of chemical fertilizer with green manure decreased the relative abundance and diversity of potential plant pathogens in soil. [Conclusion] Replacing medium and low amounts (20%–40%) of chemical fertilizer with green manure not only increased rice yield but also reduced environmental pollution, improved soil nutrients, and optimized the fungal community in soil. This study systematically evaluated the effect of replacing different proportions of chemical fertilizer with green manure on the Ultisol paddy ecosystems. The results provided a theoretical basis for the sustainable development of agriculture in the Ultisol region of southern China.

Acinetobacter spp. are the common opportunistic pathogens worldwide and pose a threat to the health of humans and animals. As the resistance rate to carbapenems aggravates, tigecycline has become one of the last lines for the treatment of multidrug-resistant Acinetobacter spp. infection. The rapid dissemination of tigecycline resistance genes tet(X3), tet(X4), tet(X5), tet(X6), and other variants in recent years has seriously affected the clinical application of new tetracycline antibiotics such as tigecycline, eravacycline, and omadacycline, whereas there is a lack of review on the tet(X) genes in Acinetobacter spp. This article comprehensively expounds the mechanisms of action, epidemiological characteristics, transmission risks, and inhibitors of tet(X) genes in Acinetobacter spp. and evaluates the diversity of their variants, bacterial hosts, geographical distribution, and sampling sources, aiming to provide a theoretical basis for the prevention and control of tet(X)-positive Acinetobacter spp.

Ferroptosis is a novel form of programmed cell death that is iron-dependent and primarily characterized by lipid peroxidation. Studies have indicated that ferroptosis is closely related to the occurrence and development of various diseases. A variety of pathogens have been confirmed to induce ferroptosis of host cells, which facilitates pathogen proliferation and counteracting host immunity. Therefore, ferroptosis extensively participates in the pathophysiological processes caused by pathogen infection. In addition, ferroptosis is involved in the pathological process of many metabolic and poisoning diseases. This paper reviews the research progress in the occurrence and mechanism of ferroptosis in livestock and poultry diseases, aiming to provide reference for further exploring the effect and mechanism of ferroptosis in livestock and poultry diseases.

[Objective] To elucidate the structural and functional characteristics of the gut microbiota of Trypoxylus dichotomus larvae and isolate cellulose-degrading bacteria. [Methods] Metagenomic sequencing was employed to analyze the structure and functions of the gut microbiota. Cellulose-degrading bacteria were isolated and screened from the larval gut with carboxymethyl cellulose (CMC) as the sole carbon source. The strains were identified based on morphological characteristics and molecular evidence. [Results] The gut microbiota was dominated by bacteria, which accounted for 81.3%. At the phylum level, Firmicutes (45.8%) and Bacteroidota (20.3%) were the dominant phyla. The top three abundant genera were Clostridium (3.90%), Bacteroidia (3.52%), and Dysgonomonas (2.41%). The functional analysis of metagenome data revealed that the genes of the gut microbiota were mainly associated with carbohydrate, amino acid, and energy metabolism. The annotation in the Kyoto Encyclopedia of Genes and Genomes (KEGG) revealed that the genes related to carbohydrate metabolism were predominant. The annotation in the carbohydrate-active enzyme database (CAZy) indicated that 48 856 (7.43%) genes were successfully annotated to 344 carbohydrate metabolism enzyme families, with glycoside hydrolase (GH, 48.67%) being the most dominant enzyme family in the gut bacteria. Among the top ten functionally abundant enzymes, six belonged to the GH family. Additionally, three strains of cellulose-degrading bacteria, TRC-3 (Bacillus subtilis), TRC-5 (B. subtilis), and TRC-6 (B. safensis), were isolated from the gut. TRC-3 exhibited stronger activities of filter paper enzyme, endoglucanase, exoglucanase, and β-glucosidase. [Conclusion] The gut microbiota of Trypoxylus dichotomus larvae exhibits high diversity and complexity, carrying a large number of genes encoding carbohydrate-active enzymes and harboring rich cellulose-degrading bacteria.

[Objective] To study the mechanism of plant growth-promoting rhizobacterium (PGPR) in the rhizosphere of sea rice and the effects of PGPR on the growth of terrestrial crops under salt stress. [Methods] The salt tolerance, alkali-reducing ability, and plant growth-promoting effect were determined for 15 bacterial strains isolated from the rhizosphere soil of sea rice. Highly active strains were selected for species identification and construction of a consortium. The effect of the consortium on the seed germination of mung bean was verified. [Results] The 15 strains of PGPR were moderately halophilic and strain SL-1 was an extreme halophile among them. Four halophilic strains had alkali tolerance and alkali-degrading effect, among which strain SH-3 had the highest alkali-degrading effect (16.83%). These four strains demonstrated different plant growth-promoting effects. All the strains could produce extracellular polymers (EPS), and strain SH-3 had the highest EPS production (0.47 g/g). The strains were capable of producing indole-3-acetic acid (IAA), with the yields between 0.70 mg/L and 1.48 mg/L. Three highly active strains SL-1, SM-1 and SH-3 belonging to Bacillus and Enterobacter were used to construct a consortium. Seed germination experiments showed that PGPR and the consortium promoted the seed germination of mung bean under salt stress. Moreover, the consortium showcased stronger promoting effect on seed germination than single PGPR. Compared with the control group, the consortium was more effective at the salt concentration of 15 g/L. Specifically, it improved the root length, germination rate, and simplified vitality index, while decreasing the relative salt injure rate from 80.53% to 18.95% and increasing the salt tolerance threshold of mung bean seeds from 10 g/L to 15 g/L. The data indicated that strains of the consortium coordinated to promote the seed germination of mung bean. The correlation analysis showed a strong positive correlation between EPS and IAA, both of which promoted the seed germination, growth, and development of mung bean under salt stress. [Conclusion] Strains SL-1, SM-1 and SH-3 had strong halophilicity, alkali tolerance, and abilities of degrading alkali, producing EPS and IAA, and promoting plant growth. The findings provide a scientific basis for the rational development and utilization of soil microbial resources and the improvement of saline-alkali soil environment.

[Objective] Streptococcus suis is a prevalent pathogen attacking pigs and a zoonotic agent. In 1998, an outbreak of S. suis infection in Jiangsu caused numerous pig deaths and 14 human deaths. Therefore, investigating S. suis infections in healthy pigs from slaughterhouses in Jiangsu is crucial for public health. [Methods] Tonsils were collected from healthy pigs in slaughterhouses of Jiangsu in 2023, and S. suis was isolated, identified, and serotyped. The pathogenicity of S. suis isolates to zebrafish and mouse models was examined. Furthermore, the antibiotic resistance characteristics and genes and the antimicrobial susceptibility of the isolates were identified and evaluated. [Results] The positive rate of S. suis in the samples collected from Kunshan in July 2023 was 50.85% (30/59). A total of 62 strains were isolated from the samples collected from Kunshan, and serotype 31 (12.90%, 8/62) had the highest isolation rate, followed by serotype 19 (11.29%, 7/62) and serotype NCL2 (8.06%, 5/62). In the samples collected from Danyang in July and November 2023, the positive rate of S. suis was 60.71% (34/56), and 77 strains were isolated. Serotype 16 had the highest isolation rate of 11.69% (9/77), followed by serotype 9 (10.39%, 8/77), serotype 21 (10.39%, 8/77), and serotype 31 (10.39%, 8/77). The isolates from both regions exhibited high resistance to lincosamides (98.56%, 137/139), macrolides (95.68%, 133/139), and tetracyclines (96.40%, 134/139). Furthermore, 97.84% (136/139) of strains were multi-drug resistant. All the strains were sensitive to cefotaxime and vancomycin. According to the sources and serotypes, we selected 42 representative strains (18 from Kunshan and 24 from Danyang) to perform zebrafish infection experiments. At a dose of 3×10⁶ CFU/fish, seven strains exhibited high pathogenicity to zebrafish, causing the mortality rates ≥80.00%. Three strains (serotypes 1, 3, and 23) causing mortality rates ≥80.00% in zebrafish and comparable to the virulent strain SC070731 were selected for mouse infection experiments. All the three strains led to the mortality rates ≥80.00% in mice. [Conclusion] The healthy pigs in Jiangsu have a high carrying rate of S. suis (55.65%, 64/115), and 97.84% (136/139) of the isolates are multi-drug resistant. Strains of serotypes 1, 3, and 23 exhibited strong pathogenicity.

[Objective] Epoxide hydrolases (EHs) play a key role in the synthesis of chiral pharmaceuticals. We explored new EHs by engineering or gene retrieval, aiming to enrich and discover more high-performance EHs. [Methods] A novel epoxide hydrolase (Aspergillus carlsbadensis epoxide hydrolase, AcEH) from Aspergillus carlsbadensis was identified by gene retrieval technology. We then used AutoDock2 to predict the key hydrolysis sites of AcEH and employed computational design to clarify the influences of important sites on the structure and catalytic mechanism of AcEH. [Results] The primary structure of the novel EH had three characteristic α/β EH motifs: HGWP, GYTFS, and GGDIGS. AcEH exhibited high activity and could completely hydrolyze styrene oxide (SO) within 15 min, with a specific activity of 13 951 U/g. The K_m, V_max, and k_cat/K_m of AcEH were (107.07±57.98) mmol/L, (37.22±17.85) μmol/(min·mg), and 1.17 mmol/(L·s), respectively. The key hydrolysis sites of AcEH were Asp192-His372-Glu346, which catalyzed the triad, and two conserved tyrosine residues, Tyr251/314. The mutations R49L and R49Y caused enzyme inactivation, while the mutation Y45L resulted in the formation of inactive inclusion bodies. The interaction network revealed that changes in the 49th amino acid residue disrupted the interactions between key active site residues, leading to enzyme inactivation. On the other hand, the alteration of the 45th amino acid residue destabilized the enzyme structure, leading to the formation of inclusion bodies. [Conclusion] This study discovered a novel EH and analyzed its hydrolysis mechanism. The findings provide valuable insights for further research and engineering on this enzyme.

[Objective] We investigated the occurrence of ginger bacterial wilt, identified the pathogens, and screened the antagonistic bacteria, aiming to provide a scientific basis for the control of the disease. [Methods] We systematically investigated the occurrence of bacterial wilt in the main ginger production areas in Chenzhou City, Hunan Province. The ginger tubers with typical symptoms of bacterial wilt and the rhizosphere soil were collected. Major pathogens were isolated and identified based on morphological characteristics and molecular evidence. The pathogenicity of the isolates was determined by inoculation of the isolates to ginger seedlings. Moreover, the sequevars of Ralstonia solanacearum isolates were identified based on the endogenous glucanase gene egl. Finally, the Bacillus strains for biocontrol of the pathogens were screened, and their biocontrol effects were measured. [Results] The average incidence of ginger bacterial wilt in the field was 8.52%. Two bacterial strains FJAT-15492 and FJAT-15494 were isolated from diseased ginger tubers, and three bacterial strains FJAT-15495, FJAT-15496, and FJAT-15497 were isolated from the rhizosphere soil of diseased ginger. The strain FJAT-15492 was identified as Enterobacter mori and the other four isolates were R. solanacearum. Both the isolates of E. mori and R. solanacearum could infect ginger seedlings and cause bacterial wilt. R. solanacearum strains existed in both diseased ginger tubers and rhizosphere soil, while E. mori only existed in diseased ginger tubers, with the count (1.33×10³ CFU/g) lower than that (5.67×10³ CFU/g) of R. solanacearum.Furthermore, the R. Solanacearum isolates were identified as phylotype Ⅰ and sequevar 14. Brevibacillus brevis FJAT-JK-2 demonstrated inhibitory effect on R. solanacearum, and Bacillus velezensis FJAT-54560 on E. mori, with inhibition zone diameters of 19.41 mm and 16.11 mm and indoor control effects of 69.45% and 61.11%, respectively. Moreover, the fermentation mixture of the two biocontrol strains had the field control effect of 52.57%. [Conclusion] This work identified the pathogens of ginger bacterial wilt and provided two new biocontrol strains against the disease.

[Objective] Based on the critical role of type Ⅰ signal peptidase in the secretion system, this study explores the interaction between signal peptidase and signal peptides to guide the optimization of aminopeptidase secretion expression in Bacillus amyloliquefaciens. [Methods] The endogenous signal peptidase and signal peptide of Bacillus amyloliquefaciens TCCC 19030 were examined using relative fluorescence intensity and enzyme activity for analysis, and molecular docking to study their interaction. [Results] The signal peptide YolC fused with aminopeptidase exhibited the highest extracellular enzyme activity, reaching 11 847.67 U/mL. Overexpression of the signal peptidase SipW increased aminopeptidase activity to 16 261 U/mL. Molecular docking results also showed that YolC had the lowest binding free energy with SipW, at −4.4 kcal/mol. [Conclusion] Optimization of signal peptides and overexpression of signal peptidase can effectively enhance the secretion of aminopeptidase. The binding energy between signal peptidase and signal peptide is a key factor influencing the secretion levels of the target protein.

Type 2 diabetes mellitus (T2DM) is a prevalent metabolic disease, yet its pathogenesis remains inconclusive. Recent studies have revealed a close relationship between the gut microbiota and T2DM, and specific gut microbiota structures and metabolic characteristics are associated with the onset and progression of T2DM. Exercise is an effective intervention for the prevention and management of T2DM, capable of reversing the dysbiosis induced by T2DM and regulating gut metabolites. However, the effects of exercise on the gut microbiota in T2DM patients still present many unresolved issues. Furthermore, the regulation of gut microbiota by exercise in T2DM patients is closely linked to multiple organs and can exert alleviation effects on T2DM via various gut-organ axis pathways. This paper reviews the characteristics of gut microbiota in T2DM and the effects of exercise on the gut microbiota in T2DM, with a particular focus on the mechanisms by which exercise regulates the gut microbiota to ameliorate T2DM via the gut-organ axis. This review aims to provide a reference for elucidating the relationship between exercise, gut microbiota, and T2DM.