Expression of a novel recombinant cyanate hydratase (rTl-Cyn) in Pichia pastoris, characteristics and applicability in the detoxification of cyanate.

A recombinant Pichia pastoris harbouring the cyanate hydratase gene (rTl-Cyn) from the thermophilic fungus Thermomyces lanuginosus SSBP yielded a high titre of extracellular cyanate hydratase (100±13UmL-1) which was ∼10-fold higher than the native fungal strain. The purified rTl-Cyn had a molecular mass of ∼20kDa on SDS-PAGE, with Km, Vmax, kcat and kcat/Km values of 0.34mM, 2857.14µmolesmg-1min-1, 2.14×104s-1 and 6.3 ×107M-1s-1, respectively. Its properties of thermostability, pH stability, and heavy metals insensitivity, make it a suitable candidate for bioremediation in extreme environments. The rTl-Cyn was able to degrade toxic cyanate completely with the liberation of ammonia, which was confirmed by FTIR analysis. This is the first report of any known cyanate hydratase that has been expressed in P. pastoris, characterized and effectively evaluated for cyanate detoxification.