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Enhanced bioaccumulation of heavy metals by bacterial cells displaying synthetic phytochelatins
Author(s) -
Bae Weon,
Chen Wilfred,
Mulchandani Ashok,
Mehra Rajesh K.
Publication year - 2000
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/1097-0290(20001205)70:5<518::aid-bit6>3.0.co;2-5
Subject(s) - bioaccumulation , peptide , phytochelatin , chemistry , chelation , metal , biochemistry , fusion protein , gene , recombinant dna , enzyme , environmental chemistry , glutathione , organic chemistry
A novel strategy using synthetic phytochelatins is described for the purpose of developing microbial agents for enhanced bioaccumulation of toxic metals. Synthetic genes encoding for several metal‐chelating phytochelatin analogs (Glu‐Cys) n Gly (EC8 (n = 8), EC11 (n = 11), and EC20 (n = 20)) were synthesized, linked to a lpp‐ompA fusion gene, and displayed on the surface of E. coli . For comparison, EC20 was also expressed periplasmically as a fusion with the maltose‐binding protein (MBP‐EC20). Purified MBP‐EC20 was shown to accumulate more Cd 2+ per peptide than typical mammalian metallothioneins with a stoichiometry of 10 Cd 2+ /peptide. Cells displaying synthetic phytochelatins exhibited chain‐length dependent increase in metal accumulation. For example, 18 nmoles of Cd 2+ /mg dry cells were accumulated by cells displaying EC8, whereas cells exhibiting EC20 accumulated a maximum of 60 nmoles of Cd 2+ /mg dry cells. Moreover, cells with surface‐expressed EC20 accumulated twice the amount of Cd 2+ as cells expressing EC20 periplasmically. The ability to genetically engineer ECs with precisely defined chain length could provide an attractive strategy for developing high‐affinity bioadsorbents suitable for heavy metal removal. © 2000 John Wiley & Sons, Inc. Biotechnol Bioeng 70: 518–524, 2000.