フ-ト-ル分光法によるリジン分解性プロバイオティクスの迅速な表現型スクリーニング：高リジン血症の精密治療に向けて

Hyperlysinemia is a life-threatening metabolic disorder that requires the continuous clearance of lysine. Engineered probiotics capable of degrading lysine in the gut represent a promising therapeutic strategy. However, the introduction of heterologous metabolic pathways can impose a substantial fitness burden on the bacterial host, potentially compromising the therapeutic efficacy. Current screening methods fail to adequately assess this pathway-induced stress. Therefore, optimizing methods to evaluate bacterial fitness after pathway modification is essential for developing effective bacterial therapies. Here, we present a label-free phenotypic screening approach using Fourier transform infrared (FTIR) spectroscopy to evaluate the physiological burden imposed by two distinct lysine catabolism pathways engineered Escherichia coli Nissle 1917 (EcN): the plant-derived bifunctional enzyme LKR-SDR and the yeast-derived two-enzyme cascade Lys2-Lys5. Employing FTIR under lysine stress mimicking pathological concentrations, decoded pathway-specific stress signatures, and molecular resilience. Probiotics expressing LKR-SDR exhibited severe multisystem damage, including proteotoxicity, lipid peroxidation, and significant nucleic acid stress. In contrast, the Lys2-Lys5 strain demonstrated superior resilience, maintained structural integrity, and exhibited adaptive metabolic changes, primarily through lipid membrane remodeling. This study establishes FTIR spectroscopy as a rapid screening platform that identifies the Lys2-Lys5 pathway as optimal for probiotic therapies. By directly linking spectroscopic signatures to cellular fitness, FTIR spectroscopy accelerates the rational development of durable microbial therapeutics for inborn metabolic disorders.