Physical properties and heavy metal uptake of encapsulated Escherichia coli expressing a metal binding gene (NCP).
A recombinant Escherichia coli expressing the Neurospora crassa metallothionein gene (NCP) has previously been shown to remove low levels of Cd and other metals from solution. For further development as a biosorbent, the encapsulation of the NCP is investigated by various matrices. The NCP was encapsulated in alginate, chitosan-alginate or kappa-carrageenan, and its physical properties characterized. Results indicated that encapsulation in alginate resulted in fragile beads, whereas encapsulation in kappa-carrageenan or chitosan-alginate provided more physical and chemical integrity to the beads. Maximal heavy metal removal by cells encapsulated in carrageenan occurred within 3 h, while a gradual increase in removal was observed up to 24 h for cells encapsulated in chitosan-alginate. Metal removal by cells encapsulated in alginate beads was lower than those encapsulated in carrageenan or chitosan-alginate.
Department of Chemistry and Chemical Engineering, South Dakota School of Mines and Technology, Rapid City 57701, USA.
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D000464:Alginates / Q000737:chemistry; D002104:Cadmium / Q000737:chemistry; D002351:Carrageenan / Q000737:chemistry; D002686:Chitin / Q000031:analogs & derivatives / Q000737:chemistry; D048271:Chitosan; D004339:Drug Compounding; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D005798:Genes, Bacterial; D008668:Metallothionein / Q000235:genetics* / Q000378:metabolism; D008854:Microscopy, Electron; D009492:Neurospora crassa / Q000235:genetics; D010316:Particle Size; D011108:Polymers / Q000737:chemistry
D000464:Alginates; D011108:Polymers; D002104:Cadmium; D002686:Chitin; D002351:Carrageenan; D048271:Chitosan; D008668:Metallothionein