Journal of Bacteriology, March 2000, p. 1264-1271, Vol. 182, No. 5
0021-9193/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Center for Marine Biotechnology and Biomedicine, Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093-0202
Received 28 September 1999/Accepted 1 December 1999
To more fully explore the role of unsaturated fatty acids in
high-pressure, low-temperature growth, the fabF gene from
the psychrotolerant, piezophilic deep-sea bacterium
Photobacterium profundum strain SS9 was characterized and
its role and regulation were examined. An SS9 strain harboring a
disruption in the fabF gene (strain EA40) displayed growth
impairment at elevated hydrostatic pressure concomitant with diminished
cis-vaccenic acid (18:1) production. However, growth
ability at elevated pressure could be restored to wild-type levels by
the addition of exogenous 18:1 to the growth medium. Transcript
analysis did not indicate that the SS9 fabF gene is
transcriptionally regulated, suggesting that the elevated 18:1 levels
produced in response to pressure increase result from
posttranscriptional changes. Unlike many pressure-adapted bacterial
species such as SS9, the mesophile Escherichia coli did not
regulate its fatty acid composition in an adaptive manner in response
to changes in hydrostatic pressure. Moreover, an E. coli
fabF strain was as susceptible to elevated pressure as wild-type cells. It is proposed that the SS9 fabF product,
-ketoacyl-acyl carrier protein synthase II has evolved novel
pressure-responsive characteristics which facilitate SS9 growth at high pressure.
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