Cesium accumulation and plant growth promotion characteristics of <i>Paecilomyces lilacinus</i> A10 isolated from <i>Brassica juncea</i> L. rhizosphere soil

The combined microbial-plant remediation has increasingly been used to remediate heavy metal-contaminated soil. Some microorganisms could enhance phytoremediation efficiency by solubilizing heavy metal and improve plant growth by producing phytohormones in the heavy metal contaminated soils. In the present study, a strong cesium (Cs)-tolerant fungal strain <i>Paecilomyces lilacinus</i> was identified from soil microorganisms contaminated with Cs, and the enrichment conditions for Cs were optimized. Furthermore, the effects of the A10 fermentation solution on the growth of Indian mustard (<i>Brassica juncea</i> L.) seedlings were investigated. The results indicated that the optimal combination of factors consisted of a culture temperature of 28 °C, pH7.0, initial concentration of Cs at 5.91 g·L^-1. The maximum enrichment of Cs in the A10 was up to 75.36 mg·g^-1 DW. In addition, the enrichment of Cs in Indian mustard was significantly enhanced by the application of the A10 fermentation solution, and the growth of Indian mustard was promoted under Cs stress. The present study has expanded the repertoire of microbial resources available for facilitating the Cs contaminated soil, thereby enhancing its applicability in the phytoremediation strategies.