Microbe-Assisted Phytoremediation (MAP) is an eco-friendly method for remediating soil contaminated with heavy metals such as cadmium (Cd) and chromium (Cr). This study demonstrates the potential of a king grass-Serratia marcescens strain S27 (KS) co-symbiotic system to enhance heavy metal remediation. The KS symbiosis increased the biomass of king grass by 48 % and enhanced the accumulation of Cd and Cr in the whole plant by 2.75-fold and 1.82-fold, respectively. Root exudates like γ-aminobutyric acid (GABA), glycine betaine (GB), and allantoin (Alla) were tested for enhancing the KS symbiotic, with 0.75 mM GB (GB