ABSTRACT
Microbial formation of elemental selenium (Se) or tellurium (Te) has
already been reported by 1960s.1−4 Depositions of Se or Te granule have been observed in many species of microorganisms. The
intra-and extracellular formations of Se or Te fine nano-particles
had been attributed to the reduction of Se or Te oxyanions due to
detoxification mechanism5−7 or retention of the electron poise8−11
in microbes. Furthermore, recent report disclosed that those nano-
particles generate it as results that Se oxyanions were reduced to
elemental Se as an electron acceptor for growth in the anaerobic
respiration.7,12,13 Similar possibility is also suggested about Te
oxyanion and its anaerobic respiratory metabolism.14 Many mi-
croorganisms are involved in the geobiochemical cycles of Se and
Te due to their abilities in enzymatic reduction.15−22 Cosmopolitan distribution of microbes capable of reducing Se or Te oxyanions in
various environments suggests that elemental Se and Te crystals can
be formed in diverse natural sediments and soils.23,24 So far, many
chemical methods for neutralizing or cohesive precipitation have
been used to remove poisonous substances such as heavymetals and
metalloid elements frommining, refining,manufacturing, and power
generation drains. However, these chemical treating methods have
to administer a large amount of reagents to drain. In addition, it is
necessary to remove the administered chemical treatment reagents.
Although heavy metals and metalloid elements can be essential to
industrial material production as rare element, the effective recov-
ery method of these released or contaminated elements have not
been developed. Further research should explore the biological func-
tion which can apply to develop the recovery and recycling technol-
ogy. Nowadays, metal and metalloid removals by bacterial reduction
represent a bioremediation process.8−11,19,24−27
