Fusarium head blight (FHB) caused byFusarium graminearum is one of the major diseases limiting wheat production. Biocontrol has been considered an effective and sustainable method for the control of crop diseases. [Objective] To screen out endophytic strains with inhibitory effects onF.graminearum from wheat grains and evaluate their biocontrol potential, providing strain resources and theoretical support for the development and utilization of biocontrol agents against FHB in wheat. [Methods] Plate confrontation, spore germination, and cell-free supernatant (CFS) inhibition experiments were carried out to screen out the endophytic strains with antagonistic activity againstF.graminearum from wheat grains. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) were employed to observe the conidial morphology, membrane integrity, and mycelial reactive oxygen species ofF.graminearum treated with the CFS. Pot experiments were performed to verify the biocontrol effects of the endophytic bacteria on FHB. Illumina HiSeq was used for whole genome sequencing. [Results] A highly efficient endophytic strain JB7 inhibiting the growth ofF.graminearum was isolated from wheat grains. The CFS of strain JB7 in the decline stage showed the inhibition rate of 85.23% on the spore germination ofF.graminearum. Moreover, it led to concavity on spore surface, cell membrane damage, leakage of nucleic acids and proteins, and accumulation of reactive oxygen species in the mycelia ofF.graminearum. The CFS of strain JB7 significantly increased the content of soluble protein and malondialdehyde. Strain JB7 could produce protease, cellulase, glucanase, and siderophores. Pot experiments showed that strain JB7 decreased the disease index of FHB (P < 0.05) in wheat. The strain was identified asBacillus methylotrophic JB7 by whole genome sequencing, and it carried 12 gene clusters for the synthesis of secondary metabolites with antimicrobial functions. [Conclusion] Strain JB7 could inhibit the growth ofF.graminearum and demonstrated a strong control effect on FHB, serving as a candidate strain for the biocontrol of FHB in wheat.

[Objective] Over a prolonged period of growth, the old tea plant ecosystem ofCamellia sinensis 'Fujian Shuixian' in Gujing has acquired a distinctive fir flavor, with the mountainous environment playing a key role in shaping the tea quality. Microbial communities play a vital role in biogeochemical cycling within mountainous ecosystems. Nevertheless, the characteristics of the microbial community within the distinct old tea plant ecosystem remain incompletely understood. [Methods] Samples were collected from both the aboveground and belowground parts of the oldC.sinensis 'Fujian Shuixian' tea garden in Gujing, situated in the central region of the Wuyishan National Park. The samples encompassed the phyllosphere and leaf endosphere, along with soils from the rhizosphere, non-rhizosphere, and surrounding regions. High-throughput sequencing of the 16S rRNA gene and internal transcribed spacer (ITS) region were carried out to assess the bacterial and fungal diversity, respectively. [Results] The richness and diversity of bacterial and fungal communities in the aboveground part were markedly lower than those in the belowground part. Within co-occurrence networks, the modularity index for taxa networks in each niche exceeded 0.4, and the positive correlations in interactions among microbial taxa are greater than the competition. The prevailing phyla, with the relative abundance greater than 1%, wereProteobacteria,Acidobacteriota,Actinobacteriota,Ascomycota, andBasidiomycota, which were present in both above and belowground habitats. Notably, the relative abundance ofProteobacteria,Actinobacteria, andAscomycetes aboveground surpassed that belowground, whereas that ofAcidobacteria andBasidiomycetes displayed an opposite pattern (P＜0.05). The prominent genera (with the abundance exceeding 1%) identified wereMethylobacterium-Methylorubrum,Sphingomonas,Pseudomonas,Amnibacterium,Bacillus,Cladosporium, andFusarium. These genera potentially served as crucial biomarkers in the ecological niches ofC.sinensis 'Fujian Shuixian' within the old tea plant ecosystem in Gujing. [Conclusion] The present study unveiled the unique attributes of bacterial and fungal communities within the old tea plant ecosystem ofC.sinensis 'Fujian Shuixian' in Gujing, delivering valuable scientific insights for disease prevention and biocontrol in tea plant cultivation, tea quality improvement, and the exploration of functional microbial resources.

Pyrroloquinoline quinone (PQQ), the third oxidoreductase coenzyme discovered in the nature after nicotinamide and riboflavin, is ubiquitous in bacteria, fungi, plants, and animals. PQQ participates in a variety of life activities and has anti-inflammation, anti-oxidation, cell metabolism-enhancing, and cardioprotective activities, demonstrating broad application prospects in pharmaceuticals, agriculture, food and other fields. Therefore, the large-scale production of PQQ is the primary problem that needs to be solved at present. Microbial fermentation is a primary production method of PQQ. Deciphering the biosynthesis pathway and regulatory mechanism of PQQ is essential for the screening and breeding of strains with short production periods and high yields by metabolic engineering, which has been a hot topic in this field. This paper summarizes the synthesis pathways, strain screening and breeding, microbial production, and purification processes of PQQ, aiming to provide a reference for further research and application of PQQ.

[Objective] Microsporidia are obligate intracellular parasites capable of infecting a wide range of animal species, including both humans and animals of economic interests. We exploredNosemabombycis hexokinase (NbHK) in terms of the expression, subcellular localization, regulatory functions, and interacting proteins inBombyxmori embryo cells, aiming to provide insights into the function and mechanism of this protein during infection. [Methods] We prepared a polyclonal antibody against NbHK to analyze the expression and localization of NbHK inN.bombycis-infected BmE cells by using Western blotting and the indirect immunofluorescent assay. Overexpression and RNA interference experiments were performed to assess the impact of NbHK on pathogen proliferation. RNA-seq was employed to analyze the transcriptional responses of the NbHK-transgenic BmE cells. A biotin-streptavidin system and mass spectrometry were employed to identify the interacting proteins of NbHK from NbHK::APEX2-transgenic BmE cells. [Results] NbHK was predominantly localized in the nucleus of infected cells, with consistently upregulated expression during infection. The overexpression of NbHK significantly increased the pathogen load, while the knock-down of NbHK suppressed pathogen proliferation, which indicated the crucial roles of NbHK during infection. RNA-seq analysis identified 94 differentially expressed genes (DEGs) responsive to infection, comprising 58 up-regulated genes and 36 down-regulated genes. The enrichment analysis of DEGs revealed significant activation of pathways related to cell lifespan regulation and protein processing in the endoplasmic reticulum while significant inhibition of the mitophagy pathway. Additionally, we identified host proteins including nucleoprotein translocated promoter region (NTPR) in the nucleus that potentially interacted with NbHK. [Conclusion] NbHK is secreted into silkworm nucleus to modulate the expression of genes involved in multiple pathways for promoting pathogen proliferation. Our study offers novel insights into the roles of NbHK in the infection ofN.bombycis.

[Objective] To study the spatial and temporal distribution characteristics, community structure, and diversity of uncultured myxobacteria in the rhizosphere soil ofPhragmitesaustralis in the Ebinur Lake wetland, so as to enrich the knowledge of myxobacteria resources in saline-alkaline wetlands, lay a foundation for exploiting the myxobacteria resources in extreme environments, and provide data support for the restoration of saline desert ecosystems. [Methods] The rhizosphere soil samples ofP.australis were collected from 10 sites in Ebinur Lake wetland in 3 months, and high-throughput sequencing was conducted for the V4–V5 region of the 16S rRNA gene to reveal the diversity and spatial and temporal distribution of myxobacteria. [Results] The abundance of myxobacteria, as indicated by the presence of 16S rRNA gene tags, ranged from 0.22% to 3.54% of the total bacteria in the Ebinur Lake wetland. The highest diversity was observed in July and at the sampling site 4, suggesting the correlations of genus diversity with both seasons and sample sites. A total of 14 genera of myxobacteria belonging to 8 families of 3 suborders were identified. Among them,Haliangium was the dominant genus, with the relative abundance of 10.83%–71.01%. Network co-occurrence diagrams showed that most of the bacteria interacted with myxobacteria. Spearman correlation analyses showed that the Shannon, Chao1, and ACE indices of bacteria influenced the diversity and richness of myxobacteria. The redundancy analysis (RDA) showed that soil inorganic nitrogen (IN), organic matter (OM), and water-soluble magnesium ions (Mg²⁺) were the main abiotic factors influencing the diversity and community structure of myxobacteria. [Conclusion] The Ebinur Lake wetland is rich in myxobacteria, the diversity and community structure of which present spatial and temporal variations. Biotic factors (bacteria) and abiotic factors (soil physico-chemical properties) jointly affect the diversity of myxobacteria.

[Objective] To investigate the effects and mechanism ofLactobacillus plantarum postbiotics at different doses on amelioratingSalmonellaenterica Typhimurium (ST) infection in mice. [Methods] Sixty 5-week C57BL/6 mice were randomized into five groups: Control, ST, CFS-L+ST, CFS-M+ST, and CFS-H+ST.Lactobacillus plantarum postbiotics (cell-free supernatant, CFS) was administrated at low (L), medium (M), and high (H) doses (50, 100, and 200 μL, respectively) for 21 days. On day 22, mice were orally challenged with ST at 3×10⁸ CFU, and the samples were collected three days later. [Results] Compared with the control group, CFS-L+ST and CFS-M+ST groups showed no significant changes in body weight gain, while the CFS-H+ST group showed a significant decrease (P<0.05). The CFS-M+ST and CFS-H+ST groups alleviated ST-induced body weight loss (P<0.05). CFS pretreatment reduced ST-induced bacterial translocation in the colon, liver, spleen, and brain (P<0.05) and alleviated the pathological damages in the colon and spleen. ST reduced the levels of acetic acid and butyric acid in the cecum, which, however, increased in the CFS-M+ST group (P>0.05). Compared with the ST group, CFS-M+ST alleviated the inflammatory response by lowering the levels of pro-inflammatory cytokines including interleukin-1beta (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) (P<0.05) and elevating the levels of anti-inflammatory cytokines including interleukin-4 (IL-4) and interleukin-10 (IL-10) (P<0.05). Moreover, CFS-M+ST suppressed ST-induced inflammation by modulating the nucleotide-binding oligomerization domain-like receptor (NLR) family pyrin domain-containing protein 3 (NLRP3) inflammasome, as indicated by the down-regulated mRNA levels ofNLRP3, apoptosis-associated speck-like protein (ASC), cysteine-dependent aspartate-specific protease 1 (caspase-1), and gasdermin D (GSDMD) (P<0.05). Furthermore, CFS inhibited NLRP3 inflammasome by blocking the upstream key nuclear factor kappa beta (NF-κB) pathway, as indicated by the down-regulated expression levels of myeloid differentiation factor 88 (MyD88), tumor necrosis factor receptor-associated factor 6 (TRAF6), transforming growth factor beta-activated kinase 1 (TAK1), and NF-κB (P<0.05). [Conclusion] L.plantarum postbiotics CFS alleviated theS.enterica Typhimurium infection and inflammatory responses in mice by inhibiting the NF-κB-mediated NLRP3 inflammasome, and the pretreatment with medium-dose CFS showed the best effects.

[Objective] Fusarium proliferatum is one of the major pathogens causing root rot of alfalfa. This study aims to investigate the function of the aconitase family inF.proliferatum and give insights into the molecular mechanisms underlying the physiological metabolism of this pathogen. [Methods] We employed the hmmsearch tool to identify the proteins containing the aconitase domain inF.proliferatum and then carried out the phylogenetic analysis. real-time PCR and SWISS-MODEL were employed to analyze the expression profiles ofFpACO genes and the protein structures, respectively. The homologous recombination method was used to construct theFpACO-deleted mutants ofF.proliferatum. Furthermore, we explored the growth, sporulation, spore morphology, stress responses, and pathogenicity of ΔFpACO3, ΔFpACO4-1, and ΔFpACO4-2 and measured the mitochondrial metabolism indicators of the mutants. [Results] FpACO4-1 and FpACO4-2 were involved in sporulation and spore morphogenesis. FpACO3, FpACO4-1, and FpACO4-2 were responsible for regulating the sensitivity ofF.proliferatum to cell wall stress and metal ion stress. Moreover, FpACO3, FpACO4-1, and FpACO4-2 affected the mitochondrial metabolism indicators, including the total aconitase activity, the ATP level, the hydrogen peroxide level, and the expression of key genes in the tricarboxylic acid cycle. [Conclusion] The aconitase family members are involved in the regulation of the processes such as sporulation, spore morphogenesis, response to cell wall stress and metal ion stress, and mitochondrial metabolism inF.proliferatum.

2-phenylethanol (2-PE) is a rose-scented aromatic alcohol commonly used in the food, cosmetic, and pharmaceutical industries. The physical and chemical production methods of 2-PE are not suitable for industrial application due to the low yields. As a single-celled eukaryotic microorganism, yeast has the potential to efficiently synthesize natural 2-PE. Therefore, the strategy of using yeast as a chassis microorganism to synthesize 2-PE is favored by researchers. However, during the fermentation for 2-PE production, the yeast is inevitably affected by the toxic effects of 2-PE. Therefore, there is an urgent need to investigate the mechanisms of yeast tolerance to 2-PE, which will provide a theoretical basis for production practice and help to select yeast strains with high tolerance to 2-PE. In this paper, we review the research advances in 2-PE tolerance of yeast from the synthetic pathways of 2-PE and yeast tolerance mechanisms and introduce the methods for improving the 2-PE tolerance of yeast. Deciphering the mechanism of yeast tolerance to 2-PE for improving the yield and conversion efficiency of 2-PE in yeast is a top priority for the future research.

[Objective] The isolation and comparative genomic analysis ofAcidithiobacillus capable of oxidizing sulfur will enrich our knowledge about not only sulfur-oxidizing bacterial strains but also the molecular evolution and ecological adaptation mechanisms ofAcidithiobacillus. [Methods] The medium with sodium thiosulfate as the sole energy source was used to isolate the strain capable of oxidizing sulfur, which was followed by Illumina HiSeq X and Oxford Nanopore sequencing of strain M4-422-6. Bioinformatics tools were used for sequence assembly and gene annotation, and the comparative genomic analysis was performed withIgnacidithiobacilluscopahuensis VAN18-1. [Results] AnAcidithiobacillus strain M4-422-6 capable of oxidizing sulfur was isolated. The genome annotation results showed that the genome of strain M4-422-6 consisted of one chromosome and two plasmids, with a length of 2 917 823 bp and G+C content of 58.54%, encoding a total of 2 925 proteins. The 16S rRNA gene sequence and the phylogenetic tree built by the type (strain) genome server (TYGS) revealed that strain M4-422-6 represented a novel species ofAcidithiobacillus. Functional gene annotation showed that strain M4-422-6 carried numerous genes involved in sulfur oxidation, CO₂ fixation, and acid resistance. The comparative genomic analysis revealed that although strain M4-422-6 had the closest genetic relationship withIgnacidithiobacilluscopahuensis VAN18-1, and the two strains possessed numerous different genes, which were mainly involved in phage resistance and mobile element encoding. [Conclusion] Strain M4-422-6 represents a novel species ofAcidithiobacillus and has unique genes that are not present in strains of the same species. Therefore, we hypothesize that the intra-species differentiation ofAcidithiobacillus can be attributed to adaptation to specific niches.

People are exposed to environments containing various pathogens, which have multiple interactions with human cells or tissues. Pathogens can survive in the host environment by regulating pathogenic conditions such as virulence and invasiveness. At the same time, host cells resist the invasion of pathogens by mobilizing their own immune system. However, researchers mainly focus on the physiological functions of sRNAs in pathogens and have gained limited knowledge about the interactions between pathogens and hosts. How to use highly sensitive and high-resolution methods to study the interactions between pathogens and hosts have become a major challenge in the current research. By reviewing relevant studies, we summarize the commonly used techniques and experimental processes for studying the interactions between pathogens and hosts, aiming to improve the understanding about the mechanisms and principles of these experimental techniques and provide technical references for the research on interactions between pathogen sRNAs and host targets.