Molecular design of yeast cell surface for adsorption and recovery of molybdenum, one of rare metals

Abstract

In modern industrial society, molybdenum is one of the important metals for development of the industry of rare metals. It is important to recycle the rare metals from wastes because they are technically and economically difficult to be dug and be purified, and they exist in only a few regions in the world. In this study, ModE protein derived from Escherichia coli, which is a molybdate-dependent transcriptional regulator with the ability to bind molybdate as a form of soluble molybdenum, was displayed on the yeast cell surface by alpha-agglutinin-based cell surface display system for the adsorption and recovery of molybdate. Displayed ModE, confirmed by immunofluorescence labeling, caught molybdate more preferably at pH 3.0 than at basic pH. Yeast cells displaying C-terminal domain of ModE, which lacks N-terminal DNA binding domain, more effectively adsorbed molybdate than those displaying full-length ModE, suggesting that the deletion of the domain unrelated to metal binding enhanced the binding ability. Our results indicated that the adsorption system on cell surface of yeast cells displaying ModE is effective not only for adsorption of molybdate as a rare metal bioadsorbent but also for the easy recovery of molybdate located on the cell surface.

Engineering Bacteria for Bioremediation

“…al., 2002;Rutherford & Moures, 2006;Wang et. al., 2007;Nishitani et. al., 2010;Kuroda & Ueda, 2011).…”

“…Therefore, as the pH increases, an increasing number of sites (acetamide chitin, structural polysaccharides of fungi, phosphate and amino groups of nucleic acids, amino and carboxyl groups of proteins and hydroxyl groups of polysaccharides) are replaced by negative charges, increasing the attraction of metallic cations and adsorption on the cell surface. Accordingly, the solubility of metallic ions decreases and, consequently, their bioavailability is reduced, and precipitation occurs Chen & Wang, 2008;Nishitani et. al., 2010;Kuroda & Ueda, 2011).…”

“…Adsorption: Physical adsorption is a process where the metal ion in solutions binds onto polyelectrolytes present in microbial cell wall through electrostatic interactions, Van der Waals forces, covalent bonding, redox interaction and biomineralization to achieve electroneutrality. This process is independent of metabolism, and it is reversible and very promising, as it presents many advantages, especially for treating large volumes of wastewater with low concentrations of contaminants (Ahluwalia & Goyal, 2007;Nishitani et. al., 2010).…”

“…al., 2003;Kim et. al., 2005;Nishitani et al, 2010), MTS, PCs and ECs were also explored so that these proteins remain anchored to the outer surface cell ("cell-surface display"). The aim was to increase the capacity these special microorganisms in adsorption processes involving heavy metal ions in comparison with non-recombinant microorganisms (Bae et.…”

Bioremediation of industrial effluents containing heavy metals using brewing cells of Saccharomyces cerevisiae as a green technology: a review

“…To overcome the problem of cell separation from the treated effluent, a transformed strain with dual features was obtained, and it enhanced the removal of copper and improved the ability to self-aggregate in response to binding to and accumulation of copper ion (Kuroda et al 2002). Besides the selective removal of toxic metals described above, genetically modified yeast cells have also been designed to selectively remove rare metal ions, such as molybdenum (Nishitani et al 2010).…”