Confirmation of the Biomethylation of Antimony Compounds
Hakan Gürleyük, Verena Van Fleet-Stalder, and Thomas. G. Chasteen*
Department of Chemistry, Sam Houston State University, Huntsville, Texas,
77341-2117
Applied Organometallic Chemistry, 1997, 11, 471-483.
Abstract
We have evidence that an organic and an inorganic salt of antimony were
reduced and methylated biologically by microorganisms in laboratory experiments.
The organoantimony compound produced was trimethylstibine (CH3)3Sb
and was detected in culture headspace. This was confirmed by matching the
compound's retention time in capillary gas chromatography, as detected
by fluorine-induced chemiluminescence, with a commercial standard and by
its mass spectrum determined with gas chromatography/mass spectrometry.
Trimethylstibine was detected in the headspace of soil samples amended
with either potassium antimonyl tartrate or potassium hexahydroxy antimonate
and augmented with any one of three different nitrate containing growth
media. The identity of the microorganisms in soil that accomplished this
are as yet unknown. Of 48 soil samples amended with these two compounds,
24 produced trimethylstibine. Bioreduction of trimethyldibromoantimony
was also detected in a liquid monoculture of Pseudomonas fluorescens
K27 which also produced trimethylstibine. This headspace production of
(CH3)3Sb was determined to be linked to the culture's
cell population as measured by optical density. This microbe, however,
did not biomethylate either potassium antimonyl tartrate or potassium hexahydroxy
antimonate in any experiments we performed.
As the abstract above notes, a strain of Pseudomonas fluorescens
isolated by Dr. Ray Fall at the University of Colorado, produces trimethylstibine in the
headspace above bacterial cultures grown on minimal medium amended with
an antimony compound, trimethyldibromoantimony. The organism is grown anaerobically
with nitrate as its terminal electron acceptor in sealed culture tubes
with septa (caps) for gas phase sampling using a gas syringe.
The chromatographic determination of trimethylstibine over time (a
time course experiment) is seen here,
with the headspace concentration of (CH3)3Sb versus
time plotted along with the bacterial cell population in replicate tubes
of live bacterial cultures. The concentration of trimethyldibromoantimony
added to these replicate culture tubes was 0.01 millimolar.
The calibration curve for trimethylstibine-also called trimethyl antimony-generated
by our capillary gas chromatograph coupled to a fluorine-induced chemiluminescence
detector can be seen here.
Trimethylstibine detection by this instrument broadens the suite of
organometalloidal compounds detectable via this chemiluminescence detector.
Initially applied to
this systems has also been used for gas phase detection of
Earlier work also determined the viability of this system to determine
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