Recombinant E. coli Metabolite Analysis

Recombinant E. coli cell growth was monitored by measuring optical density at 600 nm (OD₆₀₀) using microplate reader (SpectraMax iD3, Molecular Devices, USA). GABA and glutamate concentrations in the culture broth were determined using a high-performance liquid chromatograph system (1220 Infinity II LC, Agilent Technologies Inc., USA) equipped with a UV detector and ZORBAX SB-C18 column (250 × 4.6 mm) (Agilent Technologies Inc.) as previously reported [19 (link)]. Acetate and glucose concentrations were measured by HPLC equipped with an Aminex HPX-76H column (300 × 7.8 mm) (Bio-Rad, USA) and RI detector as previously reported [22 (link)].