Qing Kong

To make high-value use of tropical fruits and by-products, in this study, polyphenols were extracted from four tropical fruits, and the molecular mechanism underlying the difference in activity was revealed by combining LC-ESI-MS/MS and molecular docking technology. UV-Vis and FT-IR verified the structural integrity of the polyphenols. The in vitro activity results indicate that the polyphenol extracts from different sources exhibit different antioxidant and antibacterial activities. The mango peel inhibited Staphylococcus aureus with an MIC of 0.1875 mg/mL. Metabolomics revealed higher polyphenol contents in peels than in flesh: chlorogenic acid was dominant in jackfruit peel, gallic acid was dominant in mango peel. Molecular docking further showed that catechin targeted the σA subunit of S. aureus RNA polymerase, while chlorogenic acid and neochlorogenic acid bound to Keap1, clarifying the differences in activity. This study provides a basis for the utilization of fruit by-products and the development of natural antibacterial agents.

This study aims to compare three encapsulated products of Litsea cubeba essential oil (emulsion, liposomes, and microcapsules) and apply them to the preservation of grouper, providing a theoretical basis for green preservation technologies for aquatic products. FT-IR spectroscopy results revealed that LCEO was successfully encapsulated in three products. The emulsion and liposomes had better pH and salt stability, whereas the microcapsules showed better stability during freeze-thaw cycles and the best flavor masking effect. The microbiological results indicated that the liposomes strongly inhibited Shewanella and that the microcapsules and emulsion had the greatest inhibitory effects on Carnobacterium and Psychrobacter, respectively. The addition of 0.1% microcapsules, 1% microcapsules, 0.1% emulsion, and 0.1% liposomes extended the shelf life of grouper by 2 days, whereas 1% emulsion and 1% liposomes prolonged the shelf life by 4 days. Considering their environmental stability, flavor masking effect, and preservation performance, the liposomes had the best overall effect.

Fusarium spp. cause devastating crop diseases and produce carcinogenic mycotoxins such as fumonisins, threatening global food safety and human health. In this study, Trichoderma longibrachiatum A25011, isolated from apples in Aksu, Xinjiang, exhibited significant antagonistic activity with mycelial growth inhibition rates of 54.52% against F. verticillioides 48.62% against F. proliferatum, and 58.22% against F. oxysporum in confrontation assays. Enzyme activity detection revealed high chitinase (583.21 U/mg protein) and moderate cellulase (43.92 U/mg protein) production, which may have the capacity to degrade fungal cell walls. High-Performance Liquid Chromatography–Mass Spectrometry (HPLC-MS/MS) analyses enabled the quantification of fungal hormones including gibberellin A3 (GA3, 2.44 mg/L), cytokinins (cis-zeatin riboside (CZR): 0.69 mg/L; trans-zeatin riboside (TZR): 0.004 mg/L; kinetin: 0.006 mg/L), and auxins (indole-3-acetic acid (IAA): 0.35 mg/L; abscisic acid: 0.06 mg/L). Application of a T. longibrachiatum A25011 spore suspension around the roots of peanut plants enhanced growth by 13.20% (height), 5.65% (stem and leaf biomass), and 39.13% (root biomass). Notably, A25011 reduced F. proliferatum-derived fumonisin accumulation in rice-based cultures by 93.58% (6 d) and 99.35% (10 d), suggesting biosynthetic suppression. The results demonstrated that T. longibrachiatum strain A25011 exhibited excellent biocontrol capability against Fusarium spp., proving its dual role in simultaneously suppressing fungal growth and fumonisin accumulation while promoting plant growth. T. longibrachiatum A25011 could be applied as a multifunctional biocontrol agent in sustainable agriculture in the future.