Analysis of the expression and function of the sigmaB-dependent general stress regulon of Bacillus subtilis during slow growth.
Glucose-limited continuous cultures were used to analyze sigmaB activity at decreasing growth rates. Expression of the sigmaB-dependent genes gsiB and ctc started to increase at a growth rate of 0.2 h-1, and both genes were induced approximately fivefold at a growth rate of 0.1 h-1 as compared to expression at the maximal growth rate. However, maximal sigmaB activity was only reached when the growth stopped as a result of the exhaustion of the carbon and energy source glucose. During glucose-limited growth, increased expression of the general stress regulon at growth rates below 0.2 h-1 did not provide wild-type cells with a growth advantage over sigB mutants. Instead, expression of the stress regulon seems to constitute a significant burden during glucose-limited growth, resulting in a selective growth advantage of the sigB mutant as compared to the wild-type at a growth rate of 0.08 h-1.
Schweder
T
T
Institut für Mikrobiologie und Molekularbiologie, Friedrich-Ludwig-Jahn-Strasse 15, Ernst-Moritz-Arndt-Universität, D-17487 Greifswald, Germany. schweder@microbio1.biologie.uni-greifswald.de
Kolyschkow
A
A
Völker
U
U
Hecker
M
M
D001412:Bacillus subtilis / Q000235:genetics* / Q000254:growth & development; D005947:Glucose / Q000502:physiology; D009154:Mutation; D018085:Regulon / Q000502:physiology*; D012808:Sigma Factor / Q000502:physiology*
D012808:Sigma Factor; D005947:Glucose