Adaptive evolution-derived Klebsiella variicola for heavy metal and herbicide detoxification

The combined contamination of heavy metals and pesticides in soil has become a critical environmental issue threatening ecological safety and food security. Developing efficient microbial strains with multi-detoxification capabilities is of great significance for pollution remediation. In this study, Klebsiella variicola was used as the parental strain, and an Adaptive Laboratory Evolution (ALE) strategy was employed to obtain an evolved strain with significant multiple resistance and detoxification functions through long-term serial passaging under selective pressures of heavy metals and herbicides. The results demonstrated that after adaptive domestication, the evolved strain exhibited significantly enhanced tolerance to heavy metals and markedly improved degradation efficiency for herbicides compared to the original strain. Additionally, the evolved strain displayed effective extracellular adsorption and intracellular accumulation capabilities for heavy metals, as well as biodegradation and mineralization of herbicides. Genome resequencing analysis revealed adaptive mutations in genes related to heavy metal efflux pumps, oxidative stress response, and herbicide-degrading enzymes during the evolutionary process. This study provides theoretical basis and technical reference for constructing efficient remediation strains for combined pollution using evolutionary engineering approaches.