Microcalorimetric Studies of the
Action of Na
2
SeO
3
on the Growth
of Halobacterium halobium R1
Y
I
L
IU
,*
,
1
,
3
H
UA
-G
UANG
Y
U
,
1
Y
U
-P
ING
H
UANG
,
2
P
IN
S
HEN
,
2
AND
S
ONG
-S
HENG
Q
U
1
1
Department of Chemistry, College of Chemistry and Molecular
Sciences,
2
Department of Biotechnology, School of Life Sciences,
and
3
Research Center of Chemical Biology, Wuhan University,
Wuhan 430072, People’s Republic of China
Received January 9, 2002; Revised April 7, 2002;
Accepted September 18, 2002
ABSTRACT
The effect of Na
2
SeO
3
on the growth of Halobacterium halobium R1 was
investigated by means of microcalorimetry at 37°C. The biological response
to toxicants is observed as the inhibition of the rate constant of growth of
living cells. A low concentration of Na
2
SeO
3
stimulated the growth of H.
halobium R1, and a high concentration of Na
2
SeO
3
inhibited the growth of
H. halobium R1. Toxicity may be expressed as the half-inhibition concentra-
tion (IC
50
). The rate constants of growth (k) and the concentrations of
Na
2
SeO
3
(c) shows a linear relationship: k = 1.790 × 10
–6
– 2.27 × 10
–3
c. The
value of IC
50
obtained from the accompanying figure of I-c is 679 µg/mL.
Index Entries: Selenium; metabolism; microcalorimetry; toxicity;
Halobacterium halobium R1.
INTRODUCTION
Selenium (Se) is one of the essential trace elements of life (1), and
selenium deficiency has caused cardiomyopathy, Keshan disease and the
Kaschin–Beck disease in some areas with a low soil content of selenium in
China. People have widely studied the protective effects of selenium on
cell membranes (2), and its antivirus and anticancer activity (3). In our
Biological Trace Element Research
83
Vol. 92, 2003
© Copyright 2003 by Humana Press Inc.
All rights of any nature, whatsoever, reserved.
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*Author to whom all correspondence and reprint requests should be addressed.