ABSTRACT
Pollution of soil and water along with the development of mining
and manufacturing has emerged as a social issue. Particularly in
the hydrosphere, heavy metal ion pollution has been caused by
effluent wastewater from factories, mines, and metal refineries.
This is a serious environmental issue to be addressed, but it is
difficult to remove heavy metal ions from the environment because
they cannot be chemically degraded, unlike organic pollutants. As
a means of addressing this issue, there are two main methods of
treating wastewater: physicochemical techniques and bioremedia-
tion usingmicroorganisms as a bioadsorbent. Conventionalmethods
of removing heavy metal ions by physicochemical techniques are
often ineffective and costly when applied to dilute effluents.1,2
Recently, interest in bioremediation has increased owing to its great
potential.3−5 The cleanup of polluted wastewater using biological functions inherent inmicroorganisms is a prospective solution to the
problem. In studies on bioremediation, how to recover and recycle
heavy metal ions from a bioadsorbent after metal adsorption as
well as removal of heavy metal ions are also problems to be solved.
Therefore, a novel approach using a protein display system on the
yeast cell surface (yeast cell surface engineering)6,7 was applied to
cell surface design for the molecular breeding of a bioadsorbent. In
this chapter, yeast bioadsorbents constructed by displaying metal-
binding molecules on their cell surface and their improvements are
introduced, and the potential of an environmental cleanup system
using the constructed yeast is discussed.
