Abstract
To investigate the role of the buoyancy provided by gas vesicles in the facultative anaerobe Halobacterium salinarium PHH1, the growth of a gas-vacuolate (Gv+) strain in competition with two gas-vesicle-defective (Gvdef) mutants was examined. The Gv+
strain synthesized gas vesicles throughout its growth cycle, and
floated up to form a thick surface scum during the exponential growth
phase in static culture. Mutant Gvdef1 produced significantly fewer gas vesicles than the Gv+
strain in corresponding stages of growth, although in late stationary
phase a small proportion of cells floated up to the surface of static
cultures. Mutant Gvdef2 had a much lower gas
vesicle content in shaken culture and produced negligible amounts of
gas vesicles in static culture. The Gv+ and the two Gvdef
strains grew equally well in shaken cultures, but in static cultures,
where steep vertical gradients of oxygen concentration were established,
Gvdef1 was outgrown by the Gv+ strain. Gvdef2 outcompeted the Gv+ strain in shallow static cultures, perhaps because Gvdef2 carried a smaller protein burden, which offset the benefits of buoyancy. This selection for Gvdef2
was lost in deeper static cultures, although it could be restored by
aerating static cultures from below. The results support the hypothesis
that the role of buoyancy in halobacteria is to maintain cells at the
more aerated surface of brine pools.
Translated title of the contribution | Growth competition between Halobacterium salinarium strain PHH1 and mutants affected in gas vesicle synthesis |
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Original language | English |
Pages (from-to) | 467-473 |
Number of pages | 7 |
Journal | Microbiology |
Volume | 143 |
Publication status | Published - 1997 |