scholarly journals rpoS Gene Function Is a Disadvantage forEscherichia coli BJ4 during Competitive Colonization of the Mouse Large Intestine

2000 ◽  
Vol 68 (5) ◽  
pp. 2518-2524 ◽  
Author(s):  
Karen A. Krogfelt ◽  
Marianne Hjulgaard ◽  
Kristine Sørensen ◽  
Paul S. Cohen ◽  
Michael Givskov
Keyword(s):  
Escherichia Coli ◽  
Large Intestine ◽  
Gene Function ◽  
Nutrient Starvation ◽  
Treated Mouse ◽  
Wild Type ◽  
E Coli ◽  
Rpos Gene

ABSTRACT The ability of Escherichia coli to survive stress during growth in different environments is, in large part, dependent onrpoS and the genes that comprise the rpoSregulon. E. coli BJ4 and an isogenic BJ4 rpoSmutant were used to examine the influence of the rpoS gene on E. coli colonization of the streptomycin-treated mouse large intestine. Colonization experiments in which the wild-typeE. coli BJ4 and its rpoS mutant were fed individually as well as simultaneously to mice suggested that E. coli BJ4 does not face prolonged periods of nutrient starvation in the mouse large intestine and that the rpoS regulon is not expressed during long-term colonization after adaptation of the bacteria to the gut environment.

scholarly journals A Role for Single-Stranded Exonucleases in the Use of DNA as a Nutrient

2009 ◽  
Vol 191 (11) ◽  
pp. 3712-3716 ◽  
Author(s):  
Vyacheslav Palchevskiy ◽  
Steven E. Finkel
Keyword(s):  
Escherichia Coli ◽  
Bacterial Cells ◽  
Wild Type ◽  
Nutrient Source ◽  
Term Survival ◽  
Natural Competence ◽  
E Coli ◽  
Double Stranded Dna ◽  
Better Than

ABSTRACT Nutritional competence is the ability of bacterial cells to utilize exogenous double-stranded DNA molecules as a nutrient source. We previously identified several genes in Escherichia coli that are important for this process and proposed a model, based on models of natural competence and transformation in bacteria, where it is assumed that single-stranded DNA (ssDNA) is degraded following entry into the cytoplasm. Since E. coli has several exonucleases, we determined whether they play a role in the long-term survival and the catabolism of DNA as a nutrient. We show here that mutants lacking either ExoI, ExoVII, ExoX, or RecJ are viable during all phases of the bacterial life cycle yet cannot compete with wild-type cells during long-term stationary-phase incubation. We also show that nuclease mutants, alone or in combination, are defective in DNA catabolism, with the exception of the ExoX− single mutant. The ExoX− mutant consumes double-stranded DNA better than wild-type cells, possibly implying the presence of two pathways in E. coli for the processing of ssDNA as it enters the cytoplasm.

scholarly journals The adaptive response to long-term nitrogen starvation in Escherichia coli requires the breakdown of allantoin

2020 ◽  
Author(s):  
Amy Switzer ◽  
Lynn Burchell ◽  
Josh McQuail ◽  
Sivaramesh Wigneshweraraj
Keyword(s):  
Escherichia Coli ◽  
Cell Function ◽  
Nitrogen Starvation ◽  
Nutrient Starvation ◽  
Continuous Growth ◽  
E Coli ◽  
Transcriptional Changes ◽  
N Starvation ◽  
Over Time

ABSTRACTBacteria initially respond to nutrient starvation by eliciting large-scale transcriptional changes. The accompanying changes in gene expression and metabolism allow the bacterial cells to effectively adapt to the nutrient starved state. How the transcriptome subsequently changes as nutrient starvation ensues is not well understood. We used nitrogen (N) starvation as a model nutrient starvation condition to study the transcriptional changes in Escherichia coli experiencing long-term N starvation. The results reveal that the transcriptome of N starved E. coli undergoes changes that are required to maximise chances of viability and to effectively recover growth when N starvation conditions become alleviated. We further reveal that, over time, N starved E. coli cells rely on the degradation of allantoin for optimal growth recovery when N becomes replenished. This study provides insights into the temporally coordinated adaptive responses that occur in E. coli experiencing sustained N starvation.IMPORTANCEBacteria in their natural environments seldom encounter conditions that support continuous growth. Hence, many bacteria spend the majority of their time in states of little or no growth due to starvation of essential nutrients. To cope with prolonged periods of nutrient starvation, bacteria have evolved several strategies, primarily manifesting themselves through changes in how the information in their genes is accessed. How these coping strategies change over time under nutrient starvation is not well understood and this knowledge is not only important to broaden our understanding of bacterial cell function, but also to potentially find ways to manage harmful bacteria. This study provides insights into how nitrogen starved Escherichia coli bacteria rely on different genes during long term nitrogen starvation.

scholarly journals Escherichia coli robustly expresses ATP synthase at growth rate maximizing concentrations

2021 ◽  
Author(s):  
Iraes Rabbers ◽  
Frank J Bruggeman
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Protein Expression ◽  
Genetic Variants ◽  
Evolutionary Adaptation ◽  
Wild Type ◽  
Short Term ◽  
E Coli ◽  
Fitness Maximization

AbstractImproved protein expression is an important evolutionary adaptation of bacteria. A key question is whether evolution has led to optimal protein expression that maximizes immediate growth rate (short-term fitness) across conditions. Alternatively, fitter genetic variants could display suboptimal short-term fitness, because they cannot do better or because they strive for long-term fitness maximization by, for instance, anticipating future conditions. To answer this question, we focus on the ATP-producing enzyme F1F0 H+-ATPase, which is an abundant enzyme and ubiquitously expressed across conditions. We tested the optimality of H+-ATPase expression in Escherichia coli across 27 different nutrient conditions. In all tested conditions, wild-type E. coli expresses its H+- ATPase remarkably close to optimal concentrations that maximize immediate growth rate. This work indicates that bacteria can achieve robust optimal protein expression for immediate growth- rate.

Colonization of 8-week-old conventionally reared goats by Escherichia coli O157 : H7 after oral inoculation

2005 ◽  
Vol 54 (5) ◽  
pp. 485-492 ◽  
Author(s):  
R M La Ragione ◽  
N MY Ahmed ◽  
A Best ◽  
D Clifford ◽  
U Weyer ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Large Intestine ◽  
Direct Contact ◽  
Distal Colon ◽  
Escherichia Coli O157 ◽  
Wild Type ◽  
E Coli ◽  
Goat’S Milk ◽  
Oral Inoculation ◽  
Strain Nctc

Enterohaemorrhagic Escherichia coli O157 : H7 infections of man have been associated with consumption of unpasteurized goat's milk and direct contact with kid goats on petting farms, yet little is known about colonization of goats with this organism. To assess the contribution of flagella and intimin of E. coli O157 : H7 in colonization of the goat, 8-week-old conventionally reared goats were inoculated orally in separate experiments with 1×1010 c.f.u. of a non-verotoxigenic strain of E. coli O157 : H7 (strain NCTC 12900 Nalr), an aflagellate derivative (DMB1) and an intimin-deficient derivative (DMB2). At 24 h after inoculation, the three E. coli O157 : H7 strains were shed at approximately 5×104 c.f.u. (g faeces)−1 from all animals. Significantly fewer intimin-deficient bacteria were shed only on days 2 (P = 0.003) and 4 (P = 0.014), whereas from day 7 to 29 there were no differences. Tissues from three animals inoculated with wild-type E. coli O157 : H7 strain NCTC 12900 Nalr were sampled at 24, 48 and 96 h after inoculation and the organism was cultured from the large intestine of all three animals and from the duodenum and ileum of the animal examined at 96 h. Tissues were examined histologically but attaching-effacing (AE) lesions were not observed at any intestinal site of the animals examined at 24 or 48 h. However, the animal examined at 96 h, which had uniquely shed approximately 1×107 E. coli O157 : H7 (g faeces)−1 for the preceding 3 days, showed a heavy, diffuse infection with cryptosporidia and abundant, multifocal AE lesions in the distal colon, rectum and at the recto-anal junction. These AE lesions were confirmed by immunohistochemistry to be associated with E. coli O157 : H7.

scholarly journals The Adaptive Response to Long-Term Nitrogen Starvation in Escherichia coli Requires the Breakdown of Allantoin

2020 ◽  
Vol 202 (17) ◽  
Author(s):  
Amy Switzer ◽  
Lynn Burchell ◽  
Josh McQuail ◽  
Sivaramesh Wigneshweraraj
Keyword(s):  
Escherichia Coli ◽  
Nitrogen Starvation ◽  
Nutrient Starvation ◽  
Continuous Growth ◽  
Content Type ◽  
E Coli ◽  
Transcriptional Changes ◽  
N Starvation ◽  
Over Time

ABSTRACT Bacteria initially respond to nutrient starvation by eliciting large-scale transcriptional changes. The accompanying changes in gene expression and metabolism allow the bacterial cells to effectively adapt to the nutrient-starved state. How the transcriptome subsequently changes as nutrient starvation ensues is not well understood. We used nitrogen (N) starvation as a model nutrient starvation condition to study the transcriptional changes in Escherichia coli experiencing long-term N starvation. The results reveal that the transcriptome of N-starved E. coli undergoes changes that are required to maximize chances of viability and to effectively recover growth when N starvation conditions become alleviated. We further reveal that, over time, N-starved E. coli cells rely on the degradation of allantoin for optimal growth recovery when N becomes replenished. This study provides insights into the temporally coordinated adaptive responses that occur in E. coli experiencing sustained N starvation. IMPORTANCE Bacteria in their natural environments seldom encounter conditions that support continuous growth. Hence, many bacteria spend the majority of their time in states of little or no growth due to starvation of essential nutrients. To cope with prolonged periods of nutrient starvation, bacteria have evolved several strategies, primarily manifesting themselves through changes in how the information in their genes is accessed. How these coping strategies change over time under nutrient starvation is not well understood, and this knowledge is important not only to broaden our understanding of bacterial cell function but also to potentially find ways to manage harmful bacteria. This study provides insights into how nitrogen-starved Escherichia coli bacteria rely on different genes during long-term nitrogen starvation.

scholarly journals The Escherichia coli K-12 gntP gene allows E. coli F-18 to occupy a distinct nutritional niche in the streptomycin-treated mouse large intestine.

1996 ◽  
Vol 64 (9) ◽  
pp. 3497-3503 ◽  
Author(s):  
N J Sweeney ◽  
P Klemm ◽  
B A McCormick ◽  
E Moller-Nielsen ◽  
M Utley ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Large Intestine ◽  
Treated Mouse ◽  
E Coli ◽  
K 12

scholarly journals degS Is Necessary for Virulence and Is among Extraintestinal Escherichia coli Genes Induced in Murine Peritonitis

2003 ◽  
Vol 71 (6) ◽  
pp. 3088-3096 ◽  
Author(s):  
Peter Redford ◽  
Paula L. Roesch ◽  
Rodney A. Welch
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract Infection ◽  
Urinary Tract ◽  
Tract Infection ◽  
Luria Bertani ◽  
Broth Culture ◽  
Wild Type ◽  
E Coli ◽  
Virulence Attenuation

ABSTRACT Extraintestinal Escherichia coli strains cause meningitis, sepsis, urinary tract infection, and other infections outside the bowel. We examined here extraintestinal E. coli strain CFT073 by differential fluorescence induction. Pools of CFT073 clones carrying a CFT073 genomic fragment library in a promoterless gfp vector were inoculated intraperitoneally into mice; bacteria were recovered by lavage 6 h later and then subjected to fluorescence-activated cell sorting. Eleven promoters were found to be active in the mouse but not in Luria-Bertani (LB) broth culture. Three are linked to genes for enterobactin, aerobactin, and yersiniabactin. Three others are linked to the metabolic genes metA, gltB, and sucA, and another was linked to iha, a possible adhesin. Three lie before open reading frames of unknown function. One promoter is associated with degS, an inner membrane protease. Mutants of the in vivo-induced loci were tested in competition with the wild type in mouse peritonitis. Of the mutants tested, only CFT073 degS was found to be attenuated in peritoneal and in urinary tract infection, with virulence restored by complementation. CFT073 degS shows growth similar to that of the wild type at 37°C but is impaired at 43°C or in 3% ethanol LB broth at 37°C. Compared to the wild type, the mutant shows similar serum survival, motility, hemolysis, erythrocyte agglutination, and tolerance to oxidative stress. It also has the same lipopolysaccharide appearance on a silver-stained gel. The basis for the virulence attenuation is unclear, but because DegS is needed for σE activity, our findings implicate σE and its regulon in E. coli extraintestinal pathogenesis.

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