Degradation of cyanide by Trichoderma mutants constructed by restriction enzyme mediated integration (REMI).

REMI technique was used to construct mutants with improved cyanide-degradation ability from biocontrol fungus Trichoderma koningii strain T30. The plasmid pV2 transformation was confirmed by PCR and Southern blot analysis. Out of 21 transformants, 15 single-copied transformants (71.4%) were found. To compare enzyme activities of rhodanese and cyanide hydratase, T. atroviride T23, T. harzianum T21 and their transformants constructed by REMI previously were also included. Transformants TkB6 (0.173 micromols thiocyanate formed min(-1)mg protein(-1)) from T30 and TaK1 (0.174 micromols thiocyanate formed min(-1)mg protein(-1)) from T23 showed higher rhodanese activity than other transformants and their wild strains. TkA9 (5.53 micromols formamide formed h(-1)mg protein(-1)) from T30 and Th64 (5.35 micromols formamide formed h(-1)mg protein(-1)) from T21 had higher cyanide hydratase activity than other transformants and their wild strains.