Bacillus subtilis 168 is unable to grow on xylose and galactose as sole carbon sources, owing to the lack of specific transporters. We show that they are imported into the cell by the activity of AraE, an arabinose transporter whose synthesis is induced by l-arabinose.
We have investigated the change in DNA supercoiling in Bacillus subtilis after exposure to different kinds of stress. No or only minor effects are induced by solvents. Anaerobiosis and heat shock result in plasmids which are less negatively supercoiled. Cold shock and salt stress result in an increase in negative supercoiling. The reduction of linking number starts immediately after addition of NaCl, and reached a maximal value after 2 min. Primer extension experiments revealed that the mRNA level of the gyrA gene is not specifically changed by stress. The response in B. subtilis is inverse to the response in vitro. We discuss the possible effects of these inverse in vivo and in vitro responses for B. subtilis.
Bacillus subtilis is unable to grow by consuming galactose because it is unable to transport it into the cell. The transcription of galE is not influenced by galactose but is repressed by glucose. Galactose is toxic for galE-negative bacteria because it results in elevated levels of metabolic intermediates. These negative effects are reduced in galKand galT mutants. Glucose is also toxic forgalE-negative strains.
We have investigated the change in DNA supercoiling in Bacillus subtilis after exposure to different kinds of stress. No or only minor effects are induced by solvents. Anaerobiosis and heat shock result in plasmids which are less negatively supercoiled. Cold shock and salt stress result in an increase in negative supercoiling. The reduction of linking number starts immediately after addition of NaCl, and reached a maximal value after 2 min. Primer extension experiments revealed that the mRNA level of the gyrA gene is not specifically changed by stress. The response in B. subtilis is inverse to the response in vitro. We discuss the possible effects of these inverse in vivo and in vitro responses for B. subtilis.
We isolated pepT from Bacillus subtilis, a gene with homology to various tripeptidases from different bacterial sources. pepT is preceded by genes encoding a two component regulatory system. Its expression is activated during stationary phase. In minimal medium this activation is boosted in the presence of phosphate. The response regulator is preceded by putative promoter consensus sequences recognized by the stationary phase specific sigma factors sigma H, sigma F, and sigma G. This is in accordance with the initiation of expression at the beginning of stationary phase. Inactivation of pepT causes no obvious phenotype.
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