Isolation and characterization of motility-defective mutants of Haloferax volcanii.
Haloferax volcanii is a motile extreme halophile, and a detailed physical map of its genome exists. An effort is underway to locate more genes and to increase the detail of this map. Flagellated motile bacteria possess a number of filaments that function as cellular propellers. Motile bacteria swim outward in a low concentration agar medium (swarm medium) and form a swarm. I have isolated twenty-five independent motility-defective mutants and four independent super-motile mutants of Hf. volcanii WFD11. Some of these mutants were characterized by light and electron microscopy. The motility-defective mutants form three characteristic kinds of swarms on swarm medium: non-motile colonies, small fuzzy colonies and variable-size-colonies, Wild-type Hf. volcanii DS2 possesses 4-10 flagellar filaments which form a bundle. In stationary phase culture, some of these peritrichously flagellated cells become elongated and polarly flagellated. Light and electron microscopy of two mutants revealed that these cells that form non-motile colonies are non-motile, although they possess normal looking flagellar filaments. These mutants may have paralyzed filaments. Revertants of these mutants may produce dotted and/or scalloped-edge swarms. Mutants that form small fuzzy colonies were found to be cell cycle defective mutants which were not able to undergo normal cell division and thus continued growing until they formed very long spaghetti-like cells. These Hf. volcanii mutants have normal flagellar filaments and are motile when they are short but as they grow longer, they become less and less motile. The third group of mutants with variable size colonies, were normal looking motile cells under the light microscope. Super-motile mutants possess tens of flagellar filaments. Three independent Hf. volcanii DS2 genomic shot-gun libraries were constructed and amplified. These shot-gun libraries are presently being used to genetically complement Hf. volcanii mutants by a PEG-mediated transformation procedure. (Abstract shortened by UMI.)
Source: Masters Abstracts International, Volume: 33-02, page: 0470.
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