Influence of prior growth conditions on low nutrient response of Escherichia coli in seawater

1989 ◽  
Vol 35 (3) ◽  
pp. 379-383 ◽  
Author(s):  
Michel J. Gauthier ◽  
Patrick M. Munro ◽  
Violette A. Breittmayer
Keyword(s):  
Escherichia Coli ◽  
High Temperature ◽  
Nutrient Content ◽  
Growth Conditions ◽  
Exponential Phase ◽  
Alkaline Ph ◽  
Complex Media ◽  
Early Exponential Phase ◽  
Nutrient Response ◽  
Physicochemical Conditions

By use of experimental microcosms, it was demonstrated that the survival of Escherichia coli in nutrient-free seawater depended on the age of cells and on some physicochemical conditions during their prior growth. Cells grown in a bacteriological medium, with an acid or an alkaline pH, at high temperature (44 °C), or in the absence of oxygen were more sensitive to exposure to seawater of low nutrient content. In contrast, some complex media allowed production of cells adapting more rapidly to seawater. Cells grown in urine were far more sensitive than those grown in all bacteriological media tested. The sensitivity of all cells was highest when they were harvested during the early exponential phase of growth.Key words: Escherichia coli, seawater, growth, survival.

Antecedent Oxygen Growth Conditions and Recovery of Heat-Stressed Escherichia coli1

1991 ◽  
Vol 54 (2) ◽  
pp. 90-93 ◽  
Author(s):  
CAROLINE E. O'NEILL ◽  
GARY K. BISSONNETTE
Keyword(s):  
Escherichia Coli ◽  
Heat Stress ◽  
Thermal Stress ◽  
Stationary Phase ◽  
Physiological State ◽  
Growth Conditions ◽  
Exponential Phase ◽  
Physiological Age ◽  
E Coli

Four strains of Escherichia coli were examined for response to heat stress (60°C) as a function of physiological age and antecedent oxygen growth conditions. Exponential phase cells were more susceptible to heat than cells grown to the stationary phase. Anaerobically grown, exponential phase cells were more susceptible to thermal stress than were cells grown to a similar physiological state but under aerobic conditions. In the case of stationary phase cells, differences in response to heat stress as related to prior oxygen growth conditions were equivocal. Repair characteristics of thermally injured cells were also examined. Cells grown anaerobically prior to heat stress required 1.5 h longer than their aerobically grown counterparts to complete repair. These findings suggest that antecedent oxygen growth conditions influence the response of E. coli to thermal stress and perhaps, more generally, that persistence of environmentally stressed enteric microorganisms must be considered in relation to prior oxygen growth conditions in vivo.

scholarly journals Regulation of the expression of the Acidithiobacillus ferrooxidans rus operon encoding two cytochromes c, a cytochrome oxidase and rusticyanin

Microbiology ◽  
2004 ◽  
Vol 150 (7) ◽  
pp. 2113-2123 ◽  
Author(s):  
Andrés Yarzábal ◽  
Corinne Appia-Ayme ◽  
Jeanine Ratouchniak ◽  
Violaine Bonnefoy
Keyword(s):  
Acidithiobacillus Ferrooxidans ◽  
Ferrous Iron ◽  
Growth Conditions ◽  
Exponential Phase ◽  
Northern Hybridization ◽  
Early Exponential Phase ◽  
Protein Levels ◽  
Cytochromes C ◽  
Operon Expression ◽  
Transfer Chain

The regulation of the expression of the rus operon, proposed to encode an electron transfer chain from the outer to the inner membrane in the obligate acidophilic chemolithoautroph Acidithiobacillus ferrooxidans, has been studied at the RNA and protein levels. As observed by Northern hybridization, real-time PCR and reverse transcription analyses, this operon was more highly expressed in ferrous iron- than in sulfur-grown cells. Furthermore, it was shown by immunodetection that components of this respiratory chain are synthesized in ferrous iron- rather than in sulfur-growth conditions. Nonetheless, weak transcription and translation products of the rus operon were detected in sulfur-grown cells at the early exponential phase. The results strongly support the notion that rus-operon expression is induced by ferrous iron, in agreement with the involvement of the rus-operon-encoded products in the oxidation of ferrous iron, and that ferrous iron is used in preference to sulfur.

scholarly journals Ref2, a regulatory subunit of the yeast protein phosphatase 1, is a novel component of cation homoeostasis

2010 ◽  
Vol 426 (3) ◽  
pp. 355-364 ◽  
Author(s):  
Jofre Ferrer-Dalmau ◽  
Asier González ◽  
Maria Platara ◽  
Clara Navarrete ◽  
José L. Martínez ◽  
...  
Keyword(s):  
Protein Phosphatase ◽  
Living Organism ◽  
Calcium Sensitivity ◽  
Growth Conditions ◽  
Protein Phosphatase 1 ◽  
Regulatory Subunit ◽  
Alkaline Ph ◽  
Yeast Protein ◽  
Increased Sensitivity

Maintenance of cation homoeostasis is a key process for any living organism. Specific mutations in Glc7, the essential catalytic subunit of yeast protein phosphatase 1, result in salt and alkaline pH sensitivity, suggesting a role for this protein in cation homoeostasis. We screened a collection of Glc7 regulatory subunit mutants for altered tolerance to diverse cations (sodium, lithium and calcium) and alkaline pH. Among 18 candidates, only deletion of REF2 (RNA end formation 2) yielded increased sensitivity to these conditions, as well as to diverse organic toxic cations. The Ref2F374A mutation, which renders it unable to bind Glc7, did not rescue the salt-related phenotypes of the ref2 strain, suggesting that Ref2 function in cation homoeostasis is mediated by Glc7. The ref2 deletion mutant displays a marked decrease in lithium efflux, which can be explained by the inability of these cells to fully induce the Na+-ATPase ENA1 gene. The effect of lack of Ref2 is additive to that of blockage of the calcineurin pathway and might disrupt multiple mechanisms controlling ENA1 expression. ref2 cells display a striking defect in vacuolar morphogenesis, which probably accounts for the increased calcium levels observed under standard growth conditions and the strong calcium sensitivity of this mutant. Remarkably, the evidence collected indicates that the role of Ref2 in cation homoeostasis may be unrelated to its previously identified function in the formation of mRNA via the APT (for associated with Pta1) complex.

scholarly journals A Rhodobacter sphaeroides Protein Mechanistically Similar to Escherichia coli DksA Regulates Photosynthetic Growth

mBio ◽  
2014 ◽  
Vol 5 (3) ◽  
Author(s):  
Christopher W. Lennon ◽  
Kimberly C. Lemmer ◽  
Jessica L. Irons ◽  
Max I. Sellman ◽  
Timothy J. Donohue ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Structure Function ◽  
Rhodobacter Sphaeroides ◽  
Fatty Acid Content ◽  
Regulatory Protein ◽  
Growth Conditions ◽  
Globular Domain ◽  
Content Type ◽  
E Coli

ABSTRACTDksA is a global regulatory protein that, together with the alarmone ppGpp, is required for the “stringent response” to nutrient starvation in the gammaproteobacteriumEscherichia coliand for more moderate shifts between growth conditions. DksA modulates the expression of hundreds of genes, directly or indirectly. Mutants lacking a DksA homolog exhibit pleiotropic phenotypes in other gammaproteobacteria as well. Here we analyzed the DksA homolog RSP2654 in the more distantly relatedRhodobacter sphaeroides, an alphaproteobacterium. RSP2654 is 42% identical and similar in length toE. coliDksA but lacks the Zn finger motif of theE. coliDksA globular domain. Deletion of the RSP2654 gene results in defects in photosynthetic growth, impaired utilization of amino acids, and an increase in fatty acid content. RSP2654 complements the growth and regulatory defects of anE. colistrain lacking thedksAgene and modulates transcriptionin vitrowithE. coliRNA polymerase (RNAP) similarly toE. coliDksA. RSP2654 reduces RNAP-promoter complex stabilityin vitrowith RNAPs fromE. coliorR. sphaeroides, alone and synergistically with ppGpp, suggesting that even though it has limited sequence identity toE. coliDksA (DksAEc), it functions in a mechanistically similar manner. We therefore designate the RSP2654 protein DksARsp. Our work suggests that DksARsphas distinct and important physiological roles in alphaproteobacteria and will be useful for understanding structure-function relationships in DksA and the mechanism of synergy between DksA and ppGpp.IMPORTANCEThe role of DksA has been analyzed primarily in the gammaproteobacteria, in which it is best understood for its role in control of the synthesis of the translation apparatus and amino acid biosynthesis. Our work suggests that DksA plays distinct and important physiological roles in alphaproteobacteria, including the control of photosynthesis inRhodobacter sphaeroides. The study of DksARsp, should be useful for understanding structure-function relationships in the protein, including those that play a role in the little-understood synergy between DksA and ppGpp.

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