ISSN:
1432-0991
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Abstract. In Bacillus subtilis, osmotolerance is a stationary phase-dependent, adaptive response inhibiting sporulation and sharing common regulators with this process. The extent of this inhibition was determined by measuring transcription activity of promoter lacZ fusions to early sigma genes (spoIIG and spoIIA coding for precursors of σE and σF) and to reporters of them (spoIID, spoIIQ and spoIIIG), in the absence and presence of 0.6 M or 1 M NaCl. The transcription activity of these sigma precursors, normally occurring at the onset of the stationary phase, was reduced to 30–50% of their maximal expression in hyperosmotic conditions; expression of genes under their control was, however, more inhibited (〈10%). Therefore, sporulation was blocked at the sigma σE and σF activation steps. This assumption was confirmed by electron microscopic examinations of hyperosmotic cultures, which presented asymmetric septa characteristic of stage II mutants. Discussion was focused on the particular composition and/or structure of membranes during hyperosmotic growth and their involvement in the arrest of sporulation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s002849900282
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