To address issues such as easy inactivation and short duration of microbial agents in the field,this study constructed a semi-interpenetrating network hydrogel microcapsule system based on sodium alginate (ALG),extracellular polysaccharides (EPS),and Bacillus velezensis CT32.After optimization,at a mass ratio of ALG∶EPS = 7∶1,the encapsulation efficiency reached 66.5%,with a live bacterial loading capacity of 2.13×108 CFU/g.Electron microscopy characterization revealed a dense surface of the microcapsules and an internal uniform porous structure with pore sizes ranging from 80 to 180 μm.Infrared spectroscopy confirmed that EPS enhanced the network stability through hydrogen bonding and Ca2+coordination.Based on this semi-interpenetrating network structure,the microcapsule system exhibited both long-term sustained release and moisture-responsive characteristics:it enabled sustained release of live bacteria in soil for over 70 days,while rapid release could be triggered within 4 days in a moist environment.Control trials on a strawberry Verticillium wilt model demonstrated its significant efficacy in promoting plant growth.This study provides effective support for enhancing the field stability and duration of microbial agents.
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