Aquatic pathogens such as Vibrio parahaemolyticus cause a bacterial infection that reduces the economic benefits of aquaculture and affects the food quality and safety of human beings. Quorum quenching (QQ) is considered a novel strategy of microbial antagonism that inhibits pathogens and reduces the abuse of antibiotics. This study investigates a QQ bacterial strain, Bacillus velezensis DH82 from the deep sea Yap trench, in vitro to examine the effects of DH82 and its functional products against V. parahaemolyticus, focusing on the Quorum sensing (QS) regulation and the inhibition of pathogenicity and bacterial growth. The study also conducted in vivo investigation in the aquaculture of Litopenaeus vannamei challenged with V. parahaemolyticus by immersion and injection challenge. The results of the QS regulator transcription level demonstrated the multiple QQ enzymes in DH82 regulated the pathogenicity but could not fully control the biofilm formation; the effective antibacterial activity of extracellular peptides on microbial antagonism verified the inhibition on bacterial growth of V. parahaemolyticus. The in vivo experiment in aquaria demonstrated the effective enrichment of DH82 and inhibition of Vibrio in both the aquatic system and the shrimp intestine. The dietary DH82 relieved the negative effect of Vibrio on the activity of enzyme acid phosphatase (ACP), alkaline phosphatase (AKP), superoxide dismutase (SOD) under challenge of Vibrio pathogens, and was not harmful to host according to lysozyme (LZM) activity. DH82 also ameliorated the damage to the intestine and muscles induced by V. parahaemolyticus infection according to tissue imaging. Though DH82 did present some dose-dependent adverse effects to the host, the findings revealed the effective QQ and antibacterial activity of DH82 on emerging biocontrol against V. parahaemolyticus, therefore indicating the potential application of DH82 as a biological control reagent in the sustainable and green production of aquaculture.

The chemical profile of Myrica rubra (a native species in China) leaf extract was investigated by UPLC-PDA-HRMS, and the neuroprotective activity of two characteristic constituents, myricanol and myricetrin, was evaluated with N2a cells using H₂O₂-inducedoxidative challenge through a series of methods, e.g., MTT assay, ROS assay and [Ca²⁺]i assay. Among the 188 constituents detected in the extract of Myrica rubra leaf, 116 were identified definitely or tentatively by the comprehensive utilization of precise molecular weight and abundant multistage fragmentation information obtained by quadrupole orbitrap mass spectrometry. In addition, 14 potential new compounds were reported for the first time. This work established an example for the research of microconstituents in a complex analyte and revealed that suppression of H₂O₂-induced cytotoxicity in N2a cells was achieved by the pretreatment with myricanol. The evidence suggested myricanol may potentially serve as a remedy for prevention and therapy of neurodegenerative diseases induced by oxidative stress.

Wound infection caused by skin injury is the most common medical problem, and wound dressings can provide an appropriate healing environment for the injured skin and control wound inflammation during healing and treatment. Sodium alginate (SA) has been widely used in the biomedicine field as a natural biomass material. Due to excellent biocompatibility and hydrophilicity, hydrogels prepared from sodium alginate have become potential wound dressing materials. SA is natural biomass material, which has been widely applied to biomedicine field. Due to its excellent biocompatibility and hydrophilicity, hydrogels prepared from sodium alginate have become potential wound dressing materials. Hydrogels are extremely biocompatible and adaptable to biological tissues and have shown excellent practicability in biomedical applications. Herein, SA as the raw material was combined with polyhexamethylene biguanide (PHMB), which is an excellent antibacterial agent, and then combined via an autologous double network structure with macromolecular orientation to prepare a novel and high-strength antimicrobial hydrogel film. The hydrogel was subjected to mechanical strength tests, FTIR, SEM, TG, protein adsorption, and antibacterial test characterizations. Compared with traditional alginate hydrogels, the tensile strength of SA–PHMB/Ca100wt% increased by 1033.33%, and the maximum tensile strength and elongation at the break reached 3.82 MPa and 122.99%, respectively. The SA–PHMB/Ca100wt% hydrogel provides promising application prospects in the medical field.