Boosting phenazine-1-carboxylic acid (PCA) yield in Pseudomonas aeruginosa and assessing antifungal performance of PCA-loaded mesoporous carriers.

Phenazine-1-carboxylic acid (PCA) is a potent antifungal metabolite from Pseudomonas aeruginosa, but its application is limited by low production yields and stability issues. This study aimed to enhance PCA production and evaluate its efficacy using a nano-delivery system. We employed a two-stage statistical optimization strategy. First, a Plackett-Burman (PB) design identified pH, temperature, and glycerol concentration as critical factors. Subsequently, Response Surface Methodology (RSM) based on a Central Composite Design (CCD) was used to fine-tune these parameters. The optimal conditions of pH 7.2, 30 °C, 2% glycerol, and 200 rpm agitation resulted in a significant 2.5-fold increase in PCA yield. The antifungal activity of the optimized PCA was then evaluated against major plant pathogens, including Alternaria solani and Fusarium oxysporum. Both free PCA and a novel PCA-loaded mesoporous silica carrier exhibited potent antifungal effects. Mechanistic studies revealed this activity stems from disrupting fungal electron transport chains and compromising cell membrane integrity. These results demonstrate a robust, dual-pronged framework that improves both the production efficiency and functional performance of PCA. This integrated bioprocess-nanotechnology approach offers a promising and sustainable platform for developing PCA as an effective agricultural biocontrol agent and contributes toward broader efforts to combat plant diseases and antimicrobial resistance.