Metabolomics’ Change Under β-Cypermethrin Stress and Detoxification Role of CYP5011A1 in Tetrahymena thermophila

Background: β-cypermethrin (β-CYP) exhibits high toxicity to aquatic organisms and poses significant risks to aquatic ecosystems. Tetrahymena thermophila, a protozoa widely distributed in aquatic environments, can tolerate high concentrations of β-cypermethrin. However, the comprehensive detoxification mechanisms remain poorly understood in Tetrahymena. Methods: Untargeted metabolomics was used to explore the detoxification mechanisms of T. thermophila under β-CYP stress. Results: Trehalose, maltose, glycerol, and D-myo-inositol were upregulated under β-CYP exposure in Tetrahymena. Furthermore, the expression level of CYP5011A1 was upregulated under β-CYP treatment. CYP5011A1 knockout mutants resulted in a decreasing proliferation rate of T. thermophila under β-CYP stress. The valine–leucine and isoleucine biosynthesis and glycine–serine and threonine metabolism were significantly affected, with significantly changed amino acids including serine, isoleucine, and valine. Conclusions: These findings confirmed that T. thermophila develops β-CYP tolerance by carbohydrate metabolism reprogramming and Cyp5011A1 improves cellular adaptations by influencing amino acid metabolisms. Understanding these mechanisms can inform practices aimed at reducing the adverse effects of agricultural chemicals on microbial and environmental health.