scholarly journals The Stationary-Phase Sigma Factor σS Is Responsible for the Resistance of Escherichia coli Stationary-Phase Cells to mazEF-Mediated Cell Death

2009 ◽  
Vol 191 (9) ◽  
pp. 3177-3182 ◽  
Author(s):  
Ilana Kolodkin-Gal ◽  
Hanna Engelberg-Kulka
Keyword(s):  
Escherichia Coli ◽  
Cell Death ◽  
Stationary Phase ◽  
Growth Phase ◽  
Sigma Factor ◽  
Stationary Growth Phase ◽  
Cellular Growth ◽  
Oxygen Species ◽  
Stationary Growth ◽  
Gene Encoding

ABSTRACT Escherichia coli mazEF is a toxin-antitoxin gene module that mediates cell death during exponential-phase cellular growth through either reactive oxygen species (ROS)-dependent or ROS-independent pathways. Here, we found that the stationary-phase sigma factor σS was responsible for the resistance to mazEF-mediated cell death during stationary growth phase. Deletion of rpoS, the gene encoding σS from the bacterial chromosome, permitted mazEF-mediated cell death during stationary growth phase.

scholarly journals Aquaporin Z of Escherichia coli: Reassessment of Its Regulation and Physiological Role

2002 ◽  
Vol 184 (15) ◽  
pp. 4304-4307 ◽  
Author(s):  
Eric Soupene ◽  
Natalie King ◽  
Haidy Lee ◽  
Sydney Kustu
Keyword(s):  
Escherichia Coli ◽  
Adverse Effects ◽  
Growth Phase ◽  
Sigma Factor ◽  
Physiological Role ◽  
Single Copy ◽  
Stationary Growth Phase ◽  
Stationary Growth ◽  
Factor Expression ◽  
Aquaporin Z

ABSTRACT Transcription of an aqpZ-lac fusion in a single copy on the Escherichia coli chromosome increased as cells entered the stationary growth phase. This was true in a variety of media, and increased transcription in enriched medium required the RpoS sigma factor. Expression of the aqpZ-lac fusion was not affected by up- or downshifts in osmolality. Disruption of aqpZ had no detectable adverse effects.

scholarly journals Conversion of Daidzein and Genistein by an Anaerobic Bacterium Newly Isolated from the Mouse Intestine

2008 ◽  
Vol 74 (15) ◽  
pp. 4847-4852 ◽  
Author(s):  
Anastasia Matthies ◽  
Thomas Clavel ◽  
Michael Gütschow ◽  
Wolfram Engst ◽  
Dirk Haller ◽  
...  
Keyword(s):  
Stationary Phase ◽  
Enzyme Induction ◽  
Growth Phase ◽  
Anaerobic Bacterium ◽  
Stationary Growth Phase ◽  
Gut Bacteria ◽  
Soy Isoflavones ◽  
Strictly Anaerobic ◽  
Stationary Growth ◽  
Mouse Intestine

ABSTRACT The metabolism of isoflavones by gut bacteria plays a key role in the availability and bioactivation of these compounds in the intestine. Daidzein and genistein are the most common dietary soy isoflavones. While daidzein conversion yielding equol has been known for some time, the corresponding formation of 5-hydroxy-equol from genistein has not been reported previously. We isolated a strictly anaerobic bacterium (Mt1B8) from the mouse intestine which converted daidzein via dihydrodaidzein to equol as well as genistein via dihydrogenistein to 5-hydroxy-equol. Strain Mt1B8 was a gram-positive, rod-shaped bacterium identified as a member of the Coriobacteriaceae. Strain Mt1B8 also transformed dihydrodaidzein and dihydrogenistein to equol and 5-hydroxy-equol, respectively. The conversion of daidzein, genistein, dihydrodaidzein, and dihydrogenistein in the stationary growth phase depended on preincubation with the corresponding isoflavonoid, indicating enzyme induction. Moreover, dihydrogenistein was transformed even more rapidly in the stationary phase when strain Mt1B8 was grown on either genistein or daidzein. Growing the cells on daidzein also enabled conversion of genistein. This suggests that the same enzymes are involved in the conversion of the two isoflavones.

scholarly journals Borrelia burgdorferi Proteins Whose Expression Is Similarly Affected by Culture Temperature and pH

2001 ◽  
Vol 69 (4) ◽  
pp. 2739-2742 ◽  
Author(s):  
Ramesh Ramamoorthy ◽  
Dorothy Scholl-Meeker
Keyword(s):  
Borrelia Burgdorferi ◽  
Stationary Phase ◽  
Growth Phase ◽  
Environmental Conditions ◽  
Stationary Growth Phase ◽  
Culture Temperature ◽  
Stationary Growth ◽  
Encoding Genes ◽  
Midgut Ph ◽  
Tick Midgut

ABSTRACT Previously, we had demonstrated the upregulation in the expression of several proteins, including the lipoproteins OspC and P35, ofBorrelia burgdorferi in the stationary growth phase. Since the expression of OspC is also known to be affected by culture temperature and pH, we examined the effects of both variables on the expression of the remaining stationary-phase-upregulated proteins. Our study revealed that the expression of each of the remaining stationary-phase-upregulated proteins, P35 included, was also influenced by culture temperature; these proteins were selectively expressed at 34°C but not at 24°C. Significantly, the expression of a majority of these proteins was also affected by culture pH, since they were abundantly expressed at pH 7.0 (resembling the tick midgut pH of 6.8 during feeding) but only sparsely at pH 8.0 (a condition closer to that of the unfed tick midgut pH of 7.4). We propose that this group of B. burgdorferi proteins, which in culture is selectively expressed under conditions of 34°C and pH 7.0, may be induced in the tick midgut during the feeding event. Furthermore, the differential and coordinate expression of these proteins under different environmental conditions suggests that the encoding genes may be coregulated.

Effects of Additional Mg2+ on the Growth and Lipid Accumulation of Monoraphidium Sp. FXY-10 under Mixotrophic Conditions

2013 ◽  
Vol 860-863 ◽  
pp. 920-927
Author(s):  
Rao Qiong Che ◽  
Qiu Mei Wang ◽  
Li Huang ◽  
Peng Zhao ◽  
Xu Ya Yu
Keyword(s):  
Stationary Phase ◽  
Lipid Content ◽  
Growth Phase ◽  
Lipid Accumulation ◽  
Biomass Productivity ◽  
Stationary Growth Phase ◽  
Growth Media ◽  
Stationary Growth ◽  
The Media ◽  
Mixotrophic Conditions

The effects of additional Mg2+ on the growth and lipid accumulation of the microalgae Monoraphidium sp. FXY-10 under mixotrophic conditions were investigated. 100 μmol Mg2+ were added to the growth media during the stationary growth phase. Compared with the control (35.25%), the highest lipid content reached up to 37.13% biomass after Mg2+ was added to the media. Moreover, the higher lipid productivity of 79.83 mg L1 d1 and the biomass productivity of 214.65 mg L1 d1 were attained in the Mg2+-supplemented cultures, as compared with cultures without supplemented (72.95 mg L1 d1 and 179.28 mg L1 d1, respectively). The use of Mg2+ supplements were proven to stimulate cell regrowth, prolong the stationary phase, and promote lipid accumulation in Monoraphidium sp. FXY-10.

scholarly journals Role of the Stationary Growth Phase Sigma Factor RpoS of Burkholderia pseudomallei in Response to Physiological Stress Conditions

2003 ◽  
Vol 185 (23) ◽  
pp. 7008-7014 ◽  
Author(s):  
Benchamas Subsin ◽  
Mark S. Thomas ◽  
Gerd Katzenmeier ◽  
Jonathan G. Shaw ◽  
Sumalee Tungpradabkul ◽  
...  
Keyword(s):  
Growth Phase ◽  
Sigma Factor ◽  
Burkholderia Pseudomallei ◽  
Physiological Stress ◽  
Stationary Growth Phase ◽  
Null Mutant ◽  
Stationary Growth ◽  
Increased Sensitivity ◽  
And Oxidative Stress

ABSTRACT The Burkholderia pseudomallei rpoS gene was identified, and an rpoS null mutant was constructed. The mutant was shown to have an increased sensitivity to carbon starvation and oxidative stress. By using rpoS-lacZ fusions, transcription of rpoS was shown to be growth phase regulated, reaching a peak upon entry into stationary phase.

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