Technetium-99（99Tc）
is a long-lived β-emitting radionuclide (half-life, 2.1 X 105 years) released
into the environment from the past nuclear power weapon tests, and is also contained
in effluents from nuclear reprocessing plants. Pertechnetate anion (Tc(VII)O4-),
which is its most stable form in seawater, is highly soluble and shows very poor
capability of ligand-complexing, so that 99Tc discharged into marine
environment was dispersed throughout the world. For these characteristics of 99Tc,
a technique for the removal of 99Tc from the environment has been intensely
needed.
The objects of the present study were to isolate aerobic bacteria accumulating
99Tc aerobically and to characterize their removal of 99Tc
from solution. Here we show the presence of the bacteria and describe its ability
of accumulation. Marine bacterium (Tc-202 strain), which had the capability to
remove 99Tc(VII) from solid and aqueous phase in aerobic condition,
was isolated from a drifting seaweed. Tc-202 strain was identified as Halomonas
sp. by sequencing analysis of 16S rDNA. This strain was able to remove 53.5 ±
3.2% of total amount of 99Tc in solutions at 15℃. |
