Antimicrobial metabolite of Cordyceps tenuipes targeting MurE ligase and histidine kinase via in silico study.

Cordyceps spp. are widely healthy foods around the world with several traditional uses and bio-functionalities. The chemical characterization of ethyl acetate-soluble extract of the entomopathogenic fungus Cordyceps tenuipes NBRC 111,630 afforded two new metabolites with 1,6-dioxaspiro[4.4]nonane motif, tenuipesone A (1) and tenuipesone B (2), along with four well-known metabolites (3-6). The elucidation of the chemical structures was carried out via extensive spectroscopic experiments including FTIR, HRMS, 1D-NMR, and 2D-NMR. The probable biosynthetic pathway of 1 and 2 was hypothesized. From the six isolates, beauvericin (6) exhibited antimicrobial activity against Bacillus subtilis and Staphylococcus aureus with respective MIC of 6.25 and 12.5 µM. Docking results exhibited that beauvericin (6) has significant binding affinities against MurE and HK proteins with ΔG = - 8.021 and - 8.585 kcal/mol, respectively. KEY POINTS: • Six compounds, including two new, were isolated from the entomopathogenic fungus Cordyceps tenuipes. • Plausible biosynthetic pathway of compounds 1, 2, 4, and 5 was hypothesized. • Beauvericin (6) exhibited significant antimicrobial activity against Bacillus subtilis and Staphylococcus aureus alongside binding affinities against MurE and HK proteins in MOE study.

Improving nitrogen uptake efficiency by chitin nanofiber promotes growth in tomato.

Chitin, an N-acetyl-D-glucosamine polymer, has been known to enhance plant growth. However, this polysaccharide has not been used extensively in experimental work or agriculture practices because its hydrophobic nature makes it difficult to handle. Chitin nanofiber (CNF), which disperses well in water, can feasibly be used to evaluate the effect of chitin on the promotion of plant growth. In this study, we analysed the contents of inorganic elements and global gene expression to obtain an overview of the growth-promoting action of chitins in plants. Significant increases in the biomass of aerial parts and concentration of chlorophyll following treatment with CNF or short-chain chitin oligomers were observed in tomatoes that were hydroponically cultivated under ultralow nutrient concentrations. The results of the quantification of inorganic elements demonstrated that concentrations of nitrogen and carbon significantly increased in whole tomato plant under chitin treatment. Transcriptome analysis of CNF-treated tomatoes by RNA sequencing showed that the expression levels of genes related to nitrogen acquisition and assimilation, nutrient allocation and photosynthesis were altered. These results indicate that the growth-promoting action of chitin treatment is caused by an improvement in nitrogen uptake efficiency and that CNF could be a useful material for nutrient management in tomato production.