scholarly journals The Growth Advantage in Stationary-Phase PhenotypeConferred by rpoS Mutations Is Dependent on the pH andNutrientEnvironment

2003 ◽  
Vol 185 (24) ◽  
pp. 7044-7052 ◽  
Author(s):  
Michael J. Farrell ◽  
Steven E. Finkel
Keyword(s):  
Stationary Phase ◽  
Batch Culture ◽  
Environmental Conditions ◽  
Sole Source ◽  
Culture Conditions ◽  
Luria Bertani ◽  
Relative Fitness ◽  
Wild Type ◽  
Fitness Advantage ◽  
Casamino Acids

ABSTRACT Escherichia coli cells that are aged in batch culture display an increased fitness referred to as the growth advantage in stationary phase, or GASP, phenotype. A common early adaptation to this culture environment is a mutant rpoS allele, such as rpoS819, that results in attenuated RpoS activity. However, it is important to note that during long-term batch culture, environmental conditions are in flux. To date, most studies of the GASP phenotype have focused on identifying alleles that render an advantage in a specific environment, Luria-Bertani broth (LB) batch culture. To determine what role environmental conditions play in rendering relative fitness advantages to E. coli cells carrying either the wild-type or rpoS819 alleles, we performed competitions under a variety of culture conditions in which either the available nutrients, the pH, or both were manipulated. In LB medium, we found that while the rpoS819 allele confers a strong competitive fitness advantage at basic pH, it confers a reduced advantage under neutral conditions, and it is disadvantageous under acidic conditions. Similar results were found using other media. rpoS819 conferred its greatest advantage in basic minimal medium in which either glucose or Casamino Acids were the sole source of carbon and energy. In acidic medium supplemented with either Casamino Acids or glucose, the wild-type allele conferred a slight advantage. In addition, populations were dynamic under all pH conditions tested, with neither the wild-type nor mutant rpoS alleles sweeping a culture. We also found that the strength of the fitness advantage gained during a 10-day incubation is pH dependent.

scholarly journals Effect of the Bacillus atrophaeus subsp. globigii Spo0F H101R Mutation on Strain Fitness

2012 ◽  
Vol 78 (24) ◽  
pp. 8601-8610 ◽  
Author(s):  
Doncho V. Zhelev ◽  
Mia Hunt ◽  
Anna Le ◽  
Christopher Dupuis ◽  
Suelynn Ren ◽  
...  
Keyword(s):  
Developmental Process ◽  
Point Mutations ◽  
Relative Fitness ◽  
Evolutionary Constraint ◽  
Wild Type ◽  
Low Oxygen ◽  
Bacillus Atrophaeus ◽  
Experimental Conditions ◽  
Content Type ◽  
Fitness Advantage

ABSTRACTSporulation is a critical developmental process inBacillusspp. that, once initiated, removes the possibility of further growth until germination. Therefore, the threshold conditions triggering sporulation are likely to be subject to evolutionary constraint. Our previous studies revealed two spontaneous hypersporulating mutants ofBacillus atrophaeussubsp.globigii, both containing point mutations in thespo0Fgene. One of these strains (Detrick-2; contains thespo0F101allele with a C:T [His101Arg] substitution) had been deliberately selected in the early 1940s as an anthrax surrogate. To determine whether the experimental conditions used during the selection of the “military” strains could have supported the emergence of hypersporulating variants, the relative fitness of strain Detrick-2 was measured in several experimental settings modeled on experimental conditions employed during its development in the 1940s as a simulant. The congenic strain Detrick-1 contained a wild-typespo0Fgene and sporulated like the wild-type strain. The relative fitness of Detrick-1 and Detrick-2 was evaluated in competition experiments using quantitative single nucleotide polymorphism (SNP)-specific real-time PCR assays directed at the C:T substitution. The ancestral strain Detrick-1 had a fitness advantage under all conditions tested except when competing cultures were subjected to frequent heat shocks. The hypersporulating strain gained the maximum fitness advantage when cultures were grown at low oxygen tension and when heat shock was applied soon after the formation of the first heat-resistant spores. This is interpreted as gain of fitness by the hypersporulating strain in fast-changing fluctuating environments as a result of the increased rate of switching to the sporulating phenotype.

scholarly journals Physiology of Methylotrophs Living in the Phyllosphere

2021 ◽  
Vol 9 (4) ◽  
pp. 809
Author(s):  
Hiroya Yurimoto ◽  
Kosuke Shiraishi ◽  
Yasuyoshi Sakai
Keyword(s):  
Plant Growth ◽  
Crop Yield ◽  
Environmental Conditions ◽  
Sole Source ◽  
Current Understanding ◽  
Methylotrophic Bacteria ◽  
Cellular Mechanisms ◽  
Diurnal Cycles ◽  
Promote Plant Growth ◽  
Increase Crop Yield

Methanol is abundant in the phyllosphere, the surface of the above-ground parts of plants, and its concentration oscillates diurnally. The phyllosphere is one of the major habitats for a group of microorganisms, the so-called methylotrophs, that utilize one-carbon (C1) compounds, such as methanol and methane, as their sole source of carbon and energy. Among phyllospheric microorganisms, methanol-utilizing methylotrophic bacteria, known as pink-pigmented facultative methylotrophs (PPFMs), are the dominant colonizers of the phyllosphere, and some of them have recently been shown to have the ability to promote plant growth and increase crop yield. In addition to PPFMs, methanol-utilizing yeasts can proliferate and survive in the phyllosphere by using unique molecular and cellular mechanisms to adapt to the stressful phyllosphere environment. This review describes our current understanding of the physiology of methylotrophic bacteria and yeasts living in the phyllosphere where they are exposed to diurnal cycles of environmental conditions.

scholarly journals Effects of Environmental Conditions on Nephron Number: Modeling Maternal Disease and Epigenetic Regulation in Renal Development

2021 ◽  
Vol 22 (8) ◽  
pp. 4157
Author(s):  
Lars Fuhrmann ◽  
Saskia Lindner ◽  
Alexander-Thomas Hauser ◽  
Clemens Höse ◽  
Oliver Kretz ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
High Glucose ◽  
Culture Conditions ◽  
Renal Development ◽  
Organ Cultures ◽  
Renal Growth ◽  
Epigenetic Modifiers ◽  
Metabolic Conditions ◽  
Renal Size ◽  
Maternal Disease

A growing body of evidence suggests that low nephron numbers at birth can increase the risk of chronic kidney disease or hypertension later in life. Environmental stressors, such as maternal malnutrition, medication and smoking, can influence renal size at birth. Using metanephric organ cultures to model single-variable environmental conditions, models of maternal disease were evaluated for patterns of developmental impairment. While hyperthermia had limited effects on renal development, fetal iron deficiency was associated with severe impairment of renal growth and nephrogenesis with an all-proximal phenotype. Culturing kidney explants under high glucose conditions led to cellular and transcriptomic changes resembling human diabetic nephropathy. Short-term high glucose culture conditions were sufficient for long-term alterations in DNA methylation-associated epigenetic memory. Finally, the role of epigenetic modifiers in renal development was tested using a small compound library. Among the selected epigenetic inhibitors, various compounds elicited an effect on renal growth, such as HDAC (entinostat, TH39), histone demethylase (deferasirox, deferoxamine) and histone methyltransferase (cyproheptadine) inhibitors. Thus, metanephric organ cultures provide a valuable system for studying metabolic conditions and a tool for screening for epigenetic modifiers in renal development.

scholarly journals Effects of Combination of Different −10 Hexamers and Downstream Sequences on Stationary-Phase-Specific Sigma Factor ςS-Dependent Transcription in Pseudomonas putida

2000 ◽  
Vol 182 (23) ◽  
pp. 6707-6713 ◽  
Author(s):  
Eve-Ly Ojangu ◽  
Andres Tover ◽  
Riho Teras ◽  
Maia Kivisaar
Keyword(s):  
Stationary Phase ◽  
Pseudomonas Putida ◽  
Sigma Factor ◽  
Sigma Factors ◽  
Deficient Mutant ◽  
Wild Type ◽  
In Vivo Experiments ◽  
Silent Genes ◽  
Rna Polymerase Holoenzyme

ABSTRACT The main sigma factor activating gene expression, necessary in stationary phase and under stress conditions, is ςS. In contrast to other minor sigma factors, RNA polymerase holoenzyme containing ςS (EςS) recognizes a number of promoters which are also recognized by that containing ς70 (Eς70). We have previously shown that transposon Tn4652 can activate silent genes in starvingPseudomonas putida cells by creating fusion promoters during transposition. The sequence of the fusion promoters is similar to the ς70-specific promoter consensus. The −10 hexameric sequence and the sequence downstream from the −10 element differ among these promoters. We found that transcription from the fusion promoters is stationary phase specific. Based on in vivo experiments carried out with wild-type and rpoS-deficient mutant P. putida, the effect of ςS on transcription from the fusion promoters was established only in some of these promoters. The importance of the sequence of the −10 hexamer has been pointed out in several published papers, but there is no information about whether the sequences downstream from the −10 element can affect ςS-dependent transcription. Combination of the −10 hexameric sequences and downstream sequences of different fusion promoters revealed that ςS-specific transcription from these promoters is not determined by the −10 hexameric sequence only. The results obtained in this study indicate that the sequence of the −10 element influences ςS-specific transcription in concert with the sequence downstream from the −10 box.

scholarly journals Acinetobacter baylyi Starvation-Induced Genes Identified through Incubation in Long-Term Stationary Phase

2010 ◽  
Vol 76 (14) ◽  
pp. 4905-4908 ◽  
Author(s):  
C. Phoebe Lostroh ◽  
Bruce A. Voyles
Keyword(s):  
Gene Expression ◽  
Stationary Phase ◽  
Batch Culture ◽  
Exponential Growth ◽  
Hypothetical Proteins ◽  
Acinetobacter Baylyi ◽  
Metabolic Gene Expression ◽  
Induced Genes ◽  
Dna Maintenance

ABSTRACT Acinetobacter species encounter cycles of feast and famine in nature. We show that populations of A cinetobacter baylyi strain ADP1 remain dynamic for 6 weeks in batch culture. We created a library of lacZ reporters inserted into SalI sites in the genome and then isolated 30 genes with lacZ insertions whose expression was induced by starvation during long-term stationary phase compared with their expression during exponential growth. The genes encode metabolic, gene expression, DNA maintenance, envelope, and conserved hypothetical proteins.

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.

scholarly journals Effects of Growth Phase and Extracellular Slime on Photodynamic Inactivation of Gram-Positive Pathogenic Bacteria

2004 ◽  
Vol 48 (6) ◽  
pp. 2173-2178 ◽  
Author(s):  
Faten Gad ◽  
Touqir Zahra ◽  
Tayyaba Hasan ◽  
Michael R. Hamblin
Keyword(s):  
Stationary Phase ◽  
Pathogenic Bacteria ◽  
Capsular Polysaccharide ◽  
Photodynamic Inactivation ◽  
Wild Type ◽  
Gram Positive ◽  
Slime Production ◽  
Subsequent Exposure ◽  
Cationic Compounds ◽  
Extracellular Slime

ABSTRACT The emergence of antibiotic resistance among pathogenic bacteria has led to efforts to find alternative antimicrobial therapeutics to which bacteria will not be easily able to develop resistance. One of these may be the combination of nontoxic dyes (photosensitizers [PS]) and visible light, known as photodynamic therapy, and we have reported its use to treat localized infections in animal models. While it is known that gram-positive species are generally susceptible to photodynamic inactivation (PDI), the factors that govern variation in degrees of killing are unknown. We used isogenic pairs of wild-type and transposon mutants deficient in capsular polysaccharide and slime production generated from Staphylococcus epidermidis and Staphylococcus aureus to examine the effects of extracellular slime on susceptibility to PDI mediated by two cationic PS (a polylysine-chlorin e6 conjugate, pL-c e6 , and methylene blue [MB]) and an anionic molecule, free c e6 , and subsequent exposure to 665-nm light at 0 to 40 J/cm2. Free c e6 gave more killing of mutant strains than wild type, despite the latter taking up more PS. Log-phase cultures were killed more than stationary-phase cultures, and this correlated with increased uptake. The cationic pL-c e6 and MB gave similar uptakes and killing despite a 50-fold difference in incubation concentration. Differences in susceptibility between strains and between growth phases observed with free c e6 largely disappeared with the cationic compounds despite significant differences in uptake. These data suggest that slime production and stationary phase can be obstacles against PDI for gram-positive bacteria but that these obstacles can be overcome by using cationic PS.

scholarly journals Increase in Zucchini yellow mosaic virus Symptom Severity in Tolerant Zucchini Cultivars Is Related to a Point Mutation in P3 Protein and Is Associated with a Loss of Relative Fitness on Susceptible Plants

2003 ◽  
Vol 93 (12) ◽  
pp. 1478-1484 ◽  
Author(s):  
C. Desbiez ◽  
A. Gal-On ◽  
M. Girard ◽  
C. Wipf-Scheibel ◽  
H. Lecoq
Keyword(s):  
Mosaic Virus ◽  
Point Mutation ◽  
Zucchini Yellow Mosaic Virus ◽  
Genetic Load ◽  
Yellow Mosaic Virus ◽  
Relative Fitness ◽  
Interspecific Crosses ◽  
Mixed Infections ◽  
Wild Type ◽  
Sequence Comparisons

Zucchini yellow mosaic virus (ZYMV, Potyvirus) is a very damaging cucurbit virus worldwide. Interspecific crosses with resistant Cucurbita moschata have led to the release of “resistant” zucchini squash (C. pepo) F1 hybrids. However, although the resistance is almost complete in C. moschata, the commercial C. pepo hybrids are only tolerant. ZYMV evolution toward increased aggressiveness on tolerant hybrids was observed in the field and was obtained experimentally. Sequence comparisons and recombination experiments revealed that a point mutation in the P3 protein of ZYMV was enough to induce tolerance breaking. Competition experiments were performed between quasi-isogenic wild-type, and aggressive variants of ZYMV distinguished by monoclonal antibodies. The aggressive mutants were more fit than wild-type strains in mixed infections of tolerant zucchini, but they presented a drastic fitness loss in mixed infections of susceptible zucchini or melon. Thus, the ability to induce severe symptoms in tolerant zucchini is related to a genetic load in susceptible zucchini, but also on other susceptible hosts. This represents the first quantitative study of the fitness cost associated with tolerance breaking for a plant virus. Thus, although easily broken, the tolerance might prove durable in some conditions if the aggressive variants are counterselected in susceptible crops.

scholarly journals Plasmid DNA Supercoiling and Gyrase Activity in Escherichia coli Wild-Type and rpoS Stationary-Phase Cells

2003 ◽  
Vol 185 (3) ◽  
pp. 1097-1100 ◽  
Author(s):  
Yazmid Reyes-Domínguez ◽  
Gabriel Contreras-Ferrat ◽  
Jesús Ramírez-Santos ◽  
Jorge Membrillo-Hernández ◽  
M. Carmen Gómez-Eichelmann
Keyword(s):  
Escherichia Coli ◽  
Stationary Phase ◽  
Plasmid Dna ◽  
Bimodal Distribution ◽  
Dna Supercoiling ◽  
Wild Type

ABSTRACT Stationary-phase cells displayed a distribution of relaxed plasmids and had the ability to recover plasmid supercoiling as soon as nutrients became available. Preexisting gyrase molecules in these cells were responsible for this recovery. Stationary-phase rpoS cells showed a bimodal distribution of plasmids and failed to supercoil plasmids after the addition of nutrients, suggesting that rpoS plays a role in the regulation of plasmid topology during the stationary phase.

scholarly journals Multiple Promoters Contribute to Swarming and the Coordination of Transcription with Flagellar Assembly in Salmonella

2010 ◽  
Vol 192 (18) ◽  
pp. 4752-4762 ◽  
Author(s):  
Christopher E. Wozniak ◽  
Fabienne F. V. Chevance ◽  
Kelly T. Hughes
Keyword(s):  
Transcriptional Regulation ◽  
Stationary Phase ◽  
Basal Body ◽  
Environmental Conditions ◽  
Swarming Motility ◽  
Multiple Promoters ◽  
Associated Proteins ◽  
Flagellar Assembly

ABSTRACT In Salmonella, there are three classes of promoters in the flagellar transcriptional hierarchy. This organization allows genes needed earlier in the construction of flagella to be transcribed before genes needed later. Four operons (fliAZY, flgMN, fliDST, and flgKL) are expressed from both class 2 and class 3 promoters. To investigate the purpose for expressing genes from multiple flagellar promoters, mutants were constructed for each operon that were defective in either class 2 transcription or class 3 transcription. The mutants were checked for defects in swimming through liquids, swarming over surfaces, and transcriptional regulation. The expression of the hook-associated proteins (FlgK, FlgL, and FliD) from class 3 promoters was found to be important for swarming motility. Both flgMN promoters were involved in coordinating class 3 transcription with the stage of assembly of the hook-basal body. Finally, the fliAZY class 3 promoter lowered class 3 transcription in stationary phase. These results indicate that the multiple flagellar promoters respond to specific environmental conditions and help coordinate transcription with flagellar assembly.

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