Abstract
M.Sc. (Biochemistry)
An Acinetobacter sp. was isolated which had the ability to
metabolise both organic nitriles and inorganic cyanide salts. The
enzyme responsible for the degradation of the nitrile groups, was
found to be an extra-cellular complex.
This complex was partially purified and was shown to consist
of not only a number of protein fractions, but also a definite
lipid fraction which was identified as being fatty acids. The
entire complex had a molecular weight of about 80 000 Da.
The enzyme complex exhibited a high degree of stability in
the crude form, but rapidly lost its activity on further
purification. The complex had a Km of 0.154 ug/ml and a Vmax of
0.534 ug/ml/min for KCN as substrate. This Km value indicates
that the complex has a high affinity for KCN and may be of use in
the removal of cyanide at low levels. The temperature optimum was
shown to be 20·C and the pH-optimum 6.5.
Fatty acids were produced both in the presence and absence of
a nitrile substrate, and it is unclear whether carbon from CN degradation
can be channeled into fatty acid synthesis by this
particular bacterium. This bacterium was found to be very
effective in the degradation of nitrile compounds.
The removal of cyanide from mine effluents is of particular
interest in South Africa today and no effective biological method
is currently in use.