A stress-tolerant strain Rhodococcus sp. WH103 was isolated and co-immobilized to more efficiently degrade phenazine-1-carboxylic acid

Phenazine-1-carboxylic acid (PCA), the main active ingredient of the bio-fungicide shenqinmycin, has been widely used in agriculture due to its excellent antimicrobial properties. However, it poses risks to non-target microorganisms and causes phytotoxicity, necessitating efficient degradation strategies. In this study, six PCA-degrading bacterial strains were isolated from the rice rhizosphere by enrichment culture. Subsequently, Rhodococcus sp. WH103, which showed the highest efficiency in degrading PCA as well as tolerance to high temperature (42 °C) and osmotic stress (addition of 0.7 M NaCl) was subjected to further study. Additionally, the co-immobilization of strain WH103 cells with sodium alginate (SA) and biochar was explored. The SA-biochar-bacterial beads successfully degraded PCA to below 0.001 mM under optimized conditions within 21 h and exhibited reusability for up to 12 cycles. Notably, the SA-biochar-bacterial beads significantly alleviated the phytotoxicity of PCA during seed germination. This study provides an excellent strain resource and method reference for PCA degradation, lays the foundation for the practical application of pollutant-degrading microorganisms in environmental remediation.