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.