Polymeric hydrogel improves biocontrol effect of Pseudomonas chlororaphis subsp. aureofaciens DA3 ‐5 against Fusarium wilt of cabbage

BACKGROUND Biological control using rhizobacteria for plant disease management presents a sustainable alternative to conventional chemical fungicides. However, these bacteria demonstrate vulnerability to harsh environmental conditions, resulting in unstable colonization efficiency. RESULTS This study identified Pseudomonas chlororaphis subsp. aureofaciens DA3‐5 exhibiting broad‐spectrum antimicrobial activity. The DA3‐5 fermentation extract (RFE) demonstrated inhibition of mycelial growth in Fusarium oxysporum f. sp. conglutinans (FOC) through disruption of cell wall and membrane function. Analysis revealed that RFE contains phenazine‐1‐carboxylic acid (PCA) at a concentration of 3.52 μg mL −1 , which effectively inhibits FOC mycelial growth. This study proposes a polymeric hydrogel (PMH) composed of carboxymethyl chitosan, sodium alginate, and calcium chloride for DA3‐5 encapsulation. CONCLUSION This hydrogel system enhances both biological control efficiency and rhizosphere colonization effectiveness in cabbage. The developed microbial encapsulation strategy shows promise in protecting sensitive microorganisms under controlled conditions, offering a potential approach for sustainable agriculture that requires further field validation.