An efficient and green pretreatment of Astragalus membranaceus fermentation with magnetic cellulose-immobilized Bacillus natto using deep eutectic solvent assisted for improving thrombolytic activity and evaluation of its antioxidant activity

This study aimed to improve the thrombolytic activity of Astragalus membranaceus using magnetic cellulose-immobilized Bacillus natto fermentation. The fermentation parameters: time, temperature, pH, inoculum amount and solid-liquid ratio were screened by one-way experiments, and Plackett-Burman experiments were performed to determine the fermentation time, temperature, and inoculum amount as the key influencing factors, and the steepest-climbing experiments were performed to optimize the parameters, and then Box-Behnken design (BBD) experiments were conducted to determine the optimal conditions, which significantly increased the thrombolytic efficiency of Astragalus membranaceus immobilized natto fermentation to 311.156 IU/mg and exhibited superior antioxidant activity at 52.23 h of fermentation, an inoculum volume of 1.54 g/g, and a liquid-solid ratio of 30.61 mL/g. In addition, introducing deep eutectic solvent (DES) further enhanced the damage effect. The optimal type and concentration of DES were determined by screening. The magnetic cellulose system exhibited excellent thrombolytic activity and reusability compared to the calcium alginate immobilized system. This study provides a new strategy for immobilizing Bacillus natto provides a scientific basis for developing novel and efficient thrombolytic agents and highlights the potential of magnetic cellulose systems for biocatalysis and biomedical applications.