A semi-quantitative high-throughput screening method for microbial l-tyrosine production in microtiter plates

In this study, we developed a fluorescence-based assay for quantifying the aromatic amino acid l-tyrosine in small sample volumes employing 96-well microtiter plates. The method was based on the specific derivatisation of l-tyrosine with 1-nitroso-2-naphthol and the formation of a stable complex for the fluorescent determination of l-tyrosine concentrations. The original procedure for l-tyrosine measurements in blood or tissue samples (Waalkes and Udenfriend in J Lab Clin Med 50:733–736, 1957) was modified to a simple assay suitable for high-throughput screening of l-tyrosine producing microorganisms such as engineered Escherichia coli.