Immobilisation of the D-2-haloacid dehalogenase fromPseudomonas putida strain AJ1/23

A variety of procedures were used to immobilise D-2-haloacid dehalogenase. Natural polymer supports were insufficiently robust to withstand degradation by high concentrations of 2-chloropropionate. The best results were obtained with enzyme covalently attached to controlled-pore glass via a diazo linkage. The immobilisation procedure was optimised with respect to enzyme loading, pH, temperature and the presence of substrate during attachment. Immobilisation significantly modified the kinetics of the enzyme, in particular improving its temperature stability and ability to withstand mildly alkaline conditions where it is most active. The performance of the immobilised preparation in batch and plug-flow bioreactors was assessed. Biocatalyst half-life in plug-flow reactors was better than in batch bioreactors whereas effectiveness factors, although concentration dependent in the batch reactor, were similar at least with 200 mM D,L-2-CPA as substrate.