4.1.2.5 biotechnology development of a growth-dependent selection system for identification of L-threonine aldolases in Pseudomonas putida KT2440. The functionality is demonstrated with different growth studies by introducing recombinant, nonnative The functionality was demonstrated with different growth studies by introducing recombinant, nonnative threonine aldolases into the selection strain, restoring its deficiency in growth in minimal medium supplemented with DL-threo-beta-phenylserine as sole carbon source 746894 4.1.2.5 synthesis threonine aldolase is a very promising enzyme that can be used to prepare biologically active compounds or building blocks for pharmaceutical industry. Rational design is applied to thermophilic threonine aldolase from Thermotoga maritima to improve thermal stability by the incorporation of salt and disulfide bridges between subunits in the functional tetramer 748265