[Objective] A Talaromyces purpureogenus strain with solubilizing effects on tricalcium phosphate and calcium phytate was screened from the rhizosphere soil of maize and named XZY3PSF. To promote the application of this strain in serving agricultural production, we optimized the culture conditions for phosphorus solubilization of this strain and studied the effects of this strain on the growth and quality of red cluster pepper. [Methods] We evaluated the solubilizing effects of strain XZY3PSF on Ca₃(PO₄)₂, FePO₄, AlPO₄, phosphate rock powder, soybean lecithin, and egg yolk by measuring the available phosphorus content in the solution after liquid shaking culture. The effects of carbon source, nitrogen source, pH, and liquid loading volume on the phosphorus solubilization of this strain were studied. Pot experiments were carried out in a greenhouse to evaluate the effects of this strain on the growth and fruit quality of red cluster pepper. [Results] The carbon sources used by the strain were in an order of fructose>glucose>maltose>sucrose, and the nitrogen sources followed an order of ammonium chloride>ammonium nitrate>ammonium sulfate>potassium nitrate>urea. The phosphorus-solubilizing ability of the strain was higher under the condition of initial pH 6.0-7.0, and it was not affected by the liquid loading volume. The strain achieved higher phosphorus solubilization with tricalcium phosphate and phosphate rock powder as the phosphorus sources. With tricalcium phosphate as the phosphorus source, the strain showed the highest phosphorus solubilization on days 5, which was higher than that with other phosphorus sources (P<0.01). With phosphate rock powder as the phosphorus source, the strain showed the highest phosphorus solubilization on days 21 (P<0.01). Compared with the application of compound fertilizer, the inoculation of this strain increased the plant height, yield, vitamin C content, and total capsaicinoid content of red cluster pepper (P<0.05). The results of Pearson correlation analysis showed that the phosphorus solubilization of strain XZY3PSF in the culture medium with different nitrogen or carbon sources was negatively correlated with pH and the dry weight of mycelia. The capsaicinoid content was positively correlated with vitamin C and sugar content of pepper fruits. [Conclusion] Strain XZY3PSF has a strong ability to solubilize phosphorus, especially aluminum phosphate and iron phosphate, while improving the main nutritional indicators of crops. It is hypothesized that the strain will have a strong ability to solubilize phosphorus in the laterite soil in southern China. These findings lay a foundation for subsequent application of this strain in the fieled.

[Objective] To analyze the metabolic substrates required for the sclerotial formation of Rhizoctonia solani and understand the influence of nutritional elements and environmental factors on this process. [Methods] Biolog phenotypic microarray was used to study the effects of 663 nutritional substances, 96 osmotic environments, and 96 pH environments on the sclerotial formation of R. solani. [Results] Among the tested nutritional substances and environmental conditions, 19/95 carbon sources, 21/95 nitrogen sources, 16/94 phosphorus and sulfur sources, 69/94 nutritional supplements, 61/282 peptide nitrogen sources, 28/96 osmotic environments, and 40/96 pH environments induced the sclerotial formation of R. solani. Notably, N-acetyl-d-glucosamine, uridine 3′-monophosphate, phosphoryl choline, and five dipeptides (Arg-Trp, Met-Arg, Pro-Phe, Val-Tyr, and Val-Met), as well as three environmental conditions of 10 mmol/L and 20 mmol/L ammonium sulfate at pH 8.0, and pH 4.5+l-proline, significantly induced the sclerotial formation of R. solani. R. solani formed sclerotia in the environments with a broad range of pH 4.0-10.0. The KEGG analysis indicated that the substances inducing sclerotial formation were primarily involved in metabolic pathways, ABC transporters, secondary metabolite biosynthesis, and d-amino acid metabolism. [Conclusion] Nutrient limitation and environmental stress are key factors inducing the sclerotial formation of R. solani. Under nutrient-restricted conditions, the suitable substances for inducing sclerotial formation include five carbon sources (d-sorbitol, d-xylose, N-acetyl-d-galactosamine, d-arabinose, and d-melezitose), three nitrogen sources (N-acetyl-d-glucosamine, adenosine, and thymidine), two phosphorus sources (uridine 3′-monophosphate and phosphoryl choline), one nutritional supplement (Tween-80), and five peptide nitrogen sources (Arg-Trp, Met-Arg, Pro-Phe, Val-Tyr, and Val-Met). The suitable osmotic environments were 10 mmol/L and 20 mmol/L ammonium sulfate at pH 8.0, and the suitable pH environments were pH 4.0-4.5 and pH 9.5-10.0. These findings provide a foundation for understanding the sclerotial formation mechanism of R. solani.

[Objective] This study characterized a novel esterase EstE from Streptomyces griseus by heterologous expression in Escherichia coli and systematically evaluates its thermostability, alkaline stability, and the effects of various additives (metal ions, detergents, and organic solvents) on its enzymatic activity to explore its potential for industrial applications. [Methods] We synthesized the gene estE' encoding the same amino acid sequence as the native gene by optimizing the original sequence of estE from S. griseus. We then constructed the recombinant plasmid carrying the optimized gene by ligating the gene into the pET-28b(+) vector. The esterase EstE was then expressed under the induction of IPTG and purified via Co²⁺ affinity chromatography. Furthermore, the enzymatic properties of the purified EstE were determined by the p-nitrophenol method, and bioinformatics analysis was performed for this enzyme. [Results] EstE consisted of 289 amino acid residues, with a molecular weight of 31.6 kDa. It belonged to the GDS(L) family, with Ser¹⁶, Asp¹⁹⁴, and His²²⁴ forming its catalytic triad. The enzyme showed the optimal activity at 40 ℃ and pH 8.5, with the highest catalytic efficiency (specific activity of 61.03 U/mg) observed in the case of p-nitrophenyl acetate as a substrate. EstE demonstrated robust thermostability, with the relative activity of 50% after 156.11 h of incubation at 40 ℃ and 2.67 h of incubation at 100 ℃. Moreover, it showed excellent alkaline stability, with the relative activity exceeding 80% after incubation at pH 8.5 for 100 h. In addition, this enzyme exhibited excellent tolerance to organic solvents, maintaining stable activity in the presence of 30% DMSO. [Conclusion] A novel esterase EstE from S. griseus is successfully obtained through heterologous expression, demonstrating excellent catalytic properties, thermostability, alkaline stability, and organic solvent tolerance, positioning it as a promising candidate for industrial applications.

[Objective] Streptomyces rapamycinicus has large biosynthetic potential with 55 natural product biosynthetic gene clusters (BGCs), most of which have not yet been identified. This study aims to obtain a series of novel compounds by Bacterial Artificial Chromosome (BAC) library-based cloning of novel BGCs from S. rapamycinicus on a large scale and then heterologously expressing them in model Streptomyces strains. [Methods] The bioinformatics analysis of the novelty of BGCs screened out 11 unknown BGCs encoding non-ribosomal peptides, polyketides or terpenoids, from S. rapamycinicus SIPI RP202. Then, we cloned these BGCs by constructing a BAC library and screening via PCR, and then introduced them into three heterologous expression hosts by conjugative transfer. Finally, LC-MS was employed to detect whether these BGCs were successfully expressed after fermentation in three media and fermentation broth extraction with two approaches. Novel compounds were separated, purified, and structurally elucidated. [Results] An unknown terpenoid BGC was successfully expressed in Streptomyces albus Del14. Three novel aromatic meroterpenoids, rapamylic acids A-C, were identified. Then, the potential biosynthetic pathways of rapamylic acids A-C were proposed based on their structural features and BGC. [Conclusion] We successfully unlocked a silent BGC from S. rapamycinicus by large-scale BGC cloning and heterologous expression, providing an alternative strategy for the activation of silent BGCs from other Streptomyces strains. Meanwhile, the discovery of this kind of novel meroterpenoids expands the structural diversity of bacterial terpenoids.

Paranosema locustae, an environmentally friendly biocontrol agent, holds significant potential for managing locusts. However, its application is affected by various environmental factors. Understanding the resistance differences of P. locustae under different conditions is essential for its application in biocontrol. [Objective] To study the effects of different environmental conditions on the energy metabolism and stress responses of P. locustae, providing a theoretical foundation for its environmental adaptability. [Methods] Spores of P. locustae were exposed to three controlled experimental environments: a dry environment at 40 °C (40 °C GR), a wet environment at 20 °C (20 °C SR), and ultraviolet irradiation under dry conditions (≥100 µW/cm²) (ZW) for varying time periods. We employed a microplate reader, laser confocal microscopy, and differential interference contrast microscopy to assess the survival curves of infected locusts and the spore germination rate, ATP level, protein content, reactive oxygen species (ROS) level, and trehalose level of P. locustae. [Results] In the 20 °C SR group, P. locustae showed a decrease in the germination rate and notable rises in ATP and active oxygen (ROS) levels, and the median survival time of infected locusts increased. The 40 °C GR group showed no significant changes in the ATP level, ROS level, spore germination rate, or the survival curve of infected locusts compared with the control group. The ZW group showed increases in the ATP and ROS levels, but no significant change in the germination rate or the survival curve of infected locusts. Conclusions Dry spores of P. locustae exhibit greater resistance to environmental stress, while prolonged exposure to liquid conditions leads to a decrease or even loss of spore viability. These findings provide insights for the preservation and application of P. locustae formulations, establishing a theoretical basis for revealing its environmental adaptability.

[Objective] To explore the technical feasibility of using transgenic microalgae to control Aedes that transmit diseases such as dengue fever. [Methods] Taking the neurotransmitter transporter gamma-aminobutyric acid receptor gene (gat) of Aedes as a target, we constructed a shRNA-expressing vector and then transferred the vector into Chlamydomonas reinhardtiii CC124 and Chlorella vulgaris HOC5 through electroporation. The recombinant microalgae were used to feed the larvae and adults of Aedes albopictus. [Results] The transgenic algae delayed the larval development and had obvious lethal effects on the larvae and adults of A. albopictus, causing the mortality rates of 75.56% and 58.67%, respectively. The expression level of gat in the larvae was significantly down-regulated. [Conclusion] Deploying gat-shRNA transgenic microalgae in enclosed water environments to suppress mosquito populations in the vicinity is technically feasible. This strategy provides a new perspective on using biological methods to control mosquitoes and block the transmission of severe infectious diseases such as dengue fever and Zika virus disease.

[Objective] To explore the physiochemical response mechanism of a model algal strain Chlamydomonas reinhardtii that hyper-accumulates oils to exposure of naphthenic acids (NAs). [Methods] The impacts of a typical NA, cyclohexanecarboxylic acid (CHCA), on the physiochemical parameters, including growth, photosynthetic activity, pH value of the culture, uptake of nitrogen and phosphorus, and biochemical constituents (lipids, carbohydrates, proteins, and pigments), of C. reinhardtii with high initial cell density under high light-nitrogen repletion (HL+N) and high light-nitrogen deprivation (HL-N) conditions were studied. [Results] The exposure to CHCA prominently promoted the uptake of phosphorus by C. reinhardtii under HL+N, while significantly inceasing the relative abundance of saturated C16:0 and decreasing the relative abundance of polyunsaturated C18:3n3. In contrast, CHCA treatment significantly inhibited the photosynthetic activity and phosphorus uptake but did not affect the fatty acid profile of C. reinhardtii under HL-N stress. In addition, the growth, pH value of the culture, and content of lipids, carbohydrates, proteins, and pigments, in C. reinhardtii under both HL+N and HL-N conditions all remained relatively constant when subjected to CHCA exposure. [Conclusion] The tolerance of microalgae to environmental stress can be visualized by growth curves, photosythetic activity, uptake of nitrogen and phosphorus, and key biochemical constituents. HL+N improves the tolerance of C. reinhardtii to NAs by promoting the uptake of phosphorus and altering the fatty acid profile, while the case was contrary under HL-N. These findings are beneficial for establishing strategies on effective cultivation of microalgae that highly tolerate NAs.

[Objective] To express the recombinant nonstructural protein NSP1 of the porcine reproductive and respiratory syndrome virus (PRRSV) strain NADC 30, evaluate its immune effect in mice, and explore the potential value of the nonstructural proteins of PRRSV as vaccine antigens. [Methods] The prokaryotic expression system was used to express NSP1 of NADC30. After purification, the expression and antibody reactivity of NSP1 in vitro were identified by Western blotting. After mice were immunized with NSP1, the levels of cellular and humoral immunity induced by NSP1 were measured. The level of neutralizing antibody induced by NSP1 was evaluated by the virus neutralization assay. [Results] The target gene of NSP1 was connected to the Escherichia coli pET-28a vector for prokaryotic expression. Western blotting identified that the recombinant protein NSP1 was correctly expressed and had antibody reactivity. After mice were immunized with the confirmed recombinant protein NSP1, the levels of interferon (IFN)-γ and tumor necrosis factor (TNF)-α in the spleen lymphocytes of mice were elevated, and cellular immunity was stimulated. At the same time, the recombinant protein NSP1 significantly improved the proliferation of spleen lymphocytes in mice. ELISA results suggested that the level of specific antibodies in the serum rose after immunization. Further analysis of the specific antibody subtypes (IgG2a and IgG1) produced showed that the type of immunity stimulated by recombinant NSP1 was biased to Th2 humoral immunity. In addition, the virus neutralization assay showed that the recombinant protein NSP1 had a good virus neutralization ability, with the neutralization titer of 1:37 on day 28 and 1:31 on day 42, which were significantly higher than those of the PBS control group and had no difference from those of the commercial vaccine group. [Conclusion] The recombinant nonstructural protein NSP1 of PRRSV can stimulate cellular and humoral immunity in mice and has a good virus neutralization ability, which provides a new idea for the development of next-generation PRRSV vaccines.

[Objective] To study the composition, functional characteristics, and vertical distribution features of microbial communities of three different habitats in the Yellow River Delta wetland ecosystem, and provide theoretical support and potential microbial resources for targeted restoration and sustainable management of wetland ecology. [Methods] By using 16S rRNA gene amplicon sequencing and metabolomics analyses, we compared the composition and structures of soil bacterial communities in three habitats (vegetation-covered area, bare land, and biohabitat), and analyzed the characteristics of bacterial communities at varying soil depths as well as the potential interactions between habitat-specific bacteria and metabolites. [Results] The dominant phyla in the three habitats were Proteobacteria and Bacteroidota. The dominant phyla specific to the shallow and deep soil layers were Gemmatimonadota and Firmicutes, respectively. The unidentified MBNT15 in the vegetation-covered area, Halomonas in the bare land, and unidentified Rhodobacteraceae and Woeseia in the biohabitat showed significantly different abundance between different depths, and Bacillus was enriched in the deeper soil layer of all the three habitats. Metabolomic analysis revealed that the vegetation-covered area showed higher levels of sphinganine, 3-indoleacrylic acid, 2,4-dihydroxybenzoic acid, and perfluorooctanoic acid. Deoxycholic acid had the highest level in the bare land, while sulfamethoxazole was the highest in the biohabitat, which had lower level of l-tryptophan. Correlation analysis revealed that in the vegetation-covered area, Micrococcus luteus and Pseudomonas geniculata showed significantly positive correlations with sphinganine and perfluorooctanoic acid. Saccharospirillum salsuginis had significantly positive correlations with 3-indoleacrylic acid and 2,4-dihydroxybenzoic acid. In the bare land, Bacillus horikoshii showed a significantly positive correlation with deoxycholic acid. In the biohabitat, Halomonas ventosae had a significantly positive correlation with l-tryptophan, while Halomonas korlensis showed a significantly positive correlation with sulfamethoxazole. [Conclusion] Our study demonstrated that varying soil depths significantly impact the structure of microbial communities, and the structural and functional characteristics of soil microbial communities exhibit habitat specificity. The enriched bacteria such as M. luteus in the vegetation-covered area may promote plant growth and enhance stress resistance by regulating metabolites. The enriched Bacillus in the bare land plays a role in decomposing bird feces. The unique bacteria such as H. ventosae in the biohabitat demonstrate the potential for maintaining the ecological health of crab habitats through metabolite regulation. These findings offer new insights into the microbial regulation and management of wetland ecosystems.

Leaf photosynthesis forms the foundation of plant energy and material cycles. Mycorrhizal fungi, as a crucial component associated with roots, play a significant role in regulating the nutrient absorption, water utilization, and stress resistance of plants and are key ecological factors affecting the function and stability of forest ecosystems. However, at present, knowledge is limited regarding the effects of different mycorrhizal types on the photosynthetic capacity of woody plants and their responses to environmental changes. Objective To explore the differences in photosynthetic capacity among woody plants with different mycorrhizal types and their responses to changes in leaf characteristics and environmental factors. [Methods] According to the China Plant Trait Database and available articles, we identified three mycorrhizal types of woody plants, which included arbuscular mycorrhiza (AM), ectomycorrhiza (ECM), and AM+ECM. On this foundation, a database of woody plant traits for different mycorrhizal types in China was established, with the data of each sample encompassing photosynthetic capacity, photosynthetic physiology, leaf structure, nutrient characteristics, and environmental factors. [Results] The woody plants with ECM had higher photosynthetic capacity than those with AM. Mycorrhizal types significantly influenced the relationship between leaf traits and photosynthetic capacity. The photosynthetic capacity of woody plants was primarily affected by the stomatal conductance and transpiration rate of leaves. In addition, the photosynthetic capacity of plants with AM were influenced by leaf area, specific leaf area (SLA), and nitrogen and phosphorous content. The photosynthetic capacity of plants with AM+ECM were affected by SLA, specific leaf weight, and carbon and phosphorous content, while that of plants with ECM was influenced by the vapor pressure deficit. The maximum net photosynthetic rate and maximum electron transport rate of plants with ECM were more susceptible to temperature and precipitation than plants with AM and AM+ECM. [Conclusion] Mycorrhizal types significantly affect the maximum net photosynthetic rate of woody plants, and leaf characteristics primarily influence the maximum net photosynthetic rate by regulating the maximum electron transport rate. Moreover, the effects of environmental factors on the morphological and physiological traits of woody plant leaves depend on mycorrhizal types.