Development of a metallothionein based heavy metal biosorbent.

The potential utility of a recombinant E. coli expressing the Neurospora crassa metallothionein gene (NCP) as a heavy metal biosorbent was investigated. It was shown that the NCP was capable of efficiently removing low levels of several metals (including cadmium, lead, and mercury) from solutions. The reusability of the NCP was demonstrated through 5 cycles of metal binding, stripping with dilute acid, and regeneration of the binding sites with out any adverse effect on the metal binding activity. The NCP was successfully encapsulated in alginate and acrylamide without any inhibitory effect on its metal uptake activity. Furthermore, the metal uptake activity of the NCP was shown to be metabolism independent and resistant to solvents and other compounds (eg. polyaromatic hydrocarbons) which are often present along with heavy metals in waste waters thereby creating the potential for non-viable, encapsulated cells to be used.