Survival of Escherichia coli from freeze–thaw damage: influence of nutritional status and growth rate

1974 ◽  
Vol 20 (5) ◽  
pp. 683-689 ◽  
Author(s):  
Peter H. Calcott ◽  
Robert A. MacLeod
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Nutritional Status ◽  
Cooling Rate ◽  
Growth Rates ◽  
Upward Trend ◽  
Rate Range ◽  
Carbon And Nitrogen ◽  
Freeze Thaw

The influence of nutritional status and growth rate on the cryosurvival of Escherichia coli was investigated. Organisms grown at rates between 0.1 and 0.6 h−1, under carbon- or nitrogen-limiting conditions all showed a basically similar cooling rate – survival profile; a peak of survival was noted in the lower cooling rate range (less than 100 C/min), a trough of minimum survival at 100 C/min, and increased survival as the cooling rate was increased to ultrarapid rates. Carbon-limited organisms showed a shift of the peak from 6 C/min for slowly grown organisms (D = 0.11) to 40 C/min at higher growth rates (D = 0.60 h−1); their survival at these peaks also showed a slightly upward trend. Nitrogen-limited organisms showed a similar trend of a shifting of the peak of survival. However, as the growth rate was increased, survival at this peak, and at other regions, decreased. For carbon-limited organisms, above 100 C/min, survival was growth rate independent, unlike nitrogen-limited organisms, which exhibited lower survivals as the cooling rate was increased in the ultrarapid range. The survival of both carbon-and nitrogen-limited organisms at the peak of survival showed a correlation with their carbohydrate and protein contents. The relevance of these findings is discussed.

scholarly journals Escherichia colipopulations adapt to complex, unpredictable fluctuations without any trade-offs across environments

2016 ◽  
Author(s):  
Shraddha Karve ◽  
Devika Bhave ◽  
Dhanashri Nevgi ◽  
Sutirth Dey
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Growth Rates ◽  
Complex Environments ◽  
Multiple Stresses ◽  
Trade Off ◽  
Trade Offs ◽  
Fluctuating Environments ◽  
Laboratory Populations ◽  
Lower Variation

AbstractIn nature, organisms are simultaneously exposed to multiple stresses (i.e. complex environments) that often fluctuate unpredictably. While both these factors have been studied in isolation, the interaction of the two remains poorly explored. To address this issue, we selected laboratory populations ofEscherichia coliunder complex (i.e. stressful combinations of pH, H2O2and NaCl) unpredictably fluctuating environments for ~900 generations. We compared the growth rates and the corresponding trade-off patterns of these populations to those that were selected under constant values of the component stresses (i.e. pH, H2O2and NaCl) for the same duration. The fluctuation-selected populations had greater mean growth rate and lower variation for growth rate over all the selection environments experienced. However, while the populations selected under constant stresses experienced severe tradeoffs in many of the environments other than those in which they were selected, the fluctuation-selected populations could by-pass the across-environment trade-offs completely. Interestingly, trade-offs were found between growth rates and carrying capacities. The results suggest that complexity and fluctuations can strongly affect the underlying trade-off structure in evolving populations.

Relationships Between RNA–DNA Ratio, Prey Density, and Growth Rate in Atlantic Cod (Gadus morhua) Larvae

1979 ◽  
Vol 36 (12) ◽  
pp. 1497-1502 ◽  
Author(s):  
L. J. Buckley
Keyword(s):  
Growth Rate ◽  
Nutritional Status ◽  
Growth Rates ◽  
Prey Density ◽  
Gadus Morhua ◽  
Slow Growth ◽  
Atlantic Cod ◽  
Larval Fish ◽  
Dry Weight ◽  
Dna And Rna

The protein, DNA, and RNA content of larvae maintained at 1.0 plankter/mL increased at the rates of 9.3, 9.9, and 9.8% per day, respectively, for the 5 wk after hatching. Protein reserves of larvae held at 0 or 0.2 plankters/mL were depleted by 45 and 35%, respectively, prior to death 12–13 d after hatching. Starved larvae had similar protein concentrations (percent of dry weight), lower RNA concentrations, and higher DNA concentrations than fed larvae. Larvae held at higher plankton densities had higher RNA–DNA ratios and faster growth rates than larvae held at lower plankton densities. The RNA–DNA ratio was significantly correlated (P < 0.01) with the protein growth rate. The RNA–DNA ratio appears to be a useful index of nutritional status in larval Atlantic cod (Gadus morhua) and may be useful for determining if cod larvae were in a period of rapid or slow growth at the time of capture. Key words: RNA–DNA ratio, starvation, protein, nucleic acids, growth, larval fish, Atlantic cod

scholarly journals Rapid Growth of UropathogenicEscherichia coliduring Human Urinary Tract Infection

mBio ◽  
2018 ◽  
Vol 9 (2) ◽  
Author(s):  
Valerie S. Forsyth ◽  
Chelsie E. Armbruster ◽  
Sara N. Smith ◽  
Ali Pirani ◽  
A. Cody Springman ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Urinary Tract ◽  
Growth Rates ◽  
High Growth ◽  
Replication Forks ◽  
Chromosomal Replication ◽  
E Coli ◽  
Tract Infections

ABSTRACTUropathogenicEscherichia coli(UPEC) strains cause most uncomplicated urinary tract infections (UTIs). These strains are a subgroup of extraintestinal pathogenicE. coli(ExPEC) strains that infect extraintestinal sites, including urinary tract, meninges, bloodstream, lungs, and surgical sites. Here, we hypothesize that UPEC isolates adapt to and grow more rapidly within the urinary tract than otherE. coliisolates and survive in that niche. To date, there has not been a reliable method available to measure their growth ratein vivo. Here we used two methods: segregation of nonreplicating plasmid pGTR902, and peak-to-trough ratio (PTR), a sequencing-based method that enumerates bacterial chromosomal replication forks present during cell division. In the murine model of UTI, UPEC strain growth was robustin vivo, matching or exceedingin vitrogrowth rates and only slowing after reaching high CFU counts at 24 and 30 h postinoculation (hpi). In contrast, asymptomatic bacteriuria (ABU) strains tended to maintain high growth ratesin vivoat 6, 24, and 30 hpi, and population densities did not increase, suggesting that host responses or elimination limited population growth. Fecal strains displayed moderate growth rates at 6 hpi but did not survive to later times. By PTR,E. coliin urine of human patients with UTIs displayed extraordinarily rapid growth during active infection, with a mean doubling time of 22.4 min. Thus, in addition to traditional virulence determinants, including adhesins, toxins, iron acquisition, and motility, very high growth ratesin vivoand resistance to the innate immune response appear to be critical phenotypes of UPEC strains.IMPORTANCEUropathogenicEscherichia coli(UPEC) strains cause most urinary tract infections in otherwise healthy women. While we understand numerous virulence factors are utilized byE. colito colonize and persist within the urinary tract, these properties are inconsequential unless bacteria can divide rapidly and survive the host immune response. To determine the contribution of growth rate to successful colonization and persistence, we employed two methods: one involving the segregation of a nonreplicating plasmid in bacteria as they divide and the peak-to-trough ratio, a sequencing-based method that enumerates chromosomal replication forks present during cell division. We found that UPEC strains divide extraordinarily rapidly during human UTIs. These techniques will be broadly applicable to measurein vivogrowth rates of other bacterial pathogens during host colonization.

scholarly journals Growth Rate-Dependent Accumulation of RNA from Plasmid-Borne rRNA Operons in Escherichia coli

1998 ◽  
Vol 180 (7) ◽  
pp. 1970-1972 ◽  
Author(s):  
Bradley S. Stevenson ◽  
Thomas M. Schmidt
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Growth Rates ◽  
Doubling Time ◽  
Slow Growth ◽  
Metabolic Burden ◽  
Rate Dependent ◽  
Rna Concentration

ABSTRACT Inadequate regulation of the expression of additional plasmid-borne rRNA operons in Escherichia coli was exaggerated at slow growth rates, resulting in increases of approximately 100% for RNA concentration and 33% for doubling time. These observations are consistent with the hypothesis that multiple rRNA operons constitute a metabolic burden at slow growth rates.

scholarly journals Determination of the in situ growth rate of Microcystis based on carbon and nitrogen stable isotope fractionation

2017 ◽  
Vol 18 (3) ◽  
pp. 984-993 ◽  
Author(s):  
Shucong Zhen ◽  
Wei Zhu
Keyword(s):  
Growth Rate ◽  
Stable Isotope ◽  
Growth Rates ◽  
Isotope Fractionation ◽  
Taihu Lake ◽  
Nitrogen Stable Isotope ◽  
Average Growth ◽  
Carbon And Nitrogen ◽  
Stable Isotope Fractionation

Abstract Stable isotope fractionation of carbon and nitrogen in algal cells can be affected by photosynthesis, temperature, nutrient and CO2 concentrations, and cell size. As a consequence, carbon and nitrogen stable isotope techniques are not popular for determining algal growth rates. To counter these issues, this study used BG11 medium to cultivate Microcystis in the laboratory. First, the carbon and nitrogen stable isotope values of the culture medium and the algae are determined. Then, based on changes in isotope fractionation before and after cell division, a function μ = 1.32(1 + x)−0.52 relating growth rate and stable isotope fractionation is established. By substituting stable isotope values from Taihu Lake water and Microcystis into this function, the growth rate of the Microcystis in Taihu Lake is calculated to be 0.64 d−1 in May and 0.12 d−1 in September, with an average growth rate of 0.42 d−1. By incorporating most of the above-mentioned factors influencing isotope fractionation, this method can determine the growth rate of algae based directly on the stable isotope fractionation relationship, enabling simple and practical determination of algae growth rates.

scholarly journals Positive Growth Rate-Dependent Regulation of the pdxA, ksgA, and pdxB Genes of Escherichia coli K-12

2002 ◽  
Vol 184 (5) ◽  
pp. 1359-1369 ◽  
Author(s):  
Andrew J. Pease ◽  
Benjamin R. Roa ◽  
Wen Luo ◽  
Malcolm E. Winkler
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Growth Rates ◽  
Protein Accumulation ◽  
Rate Regulation ◽  
Specific Transcript ◽  
Positive Growth ◽  
Positive Growth Rate ◽  
K 12 ◽  
Per Gene

ABSTRACT We found that transcription of the pdxA and pdxB genes, which mediate steps in the biosynthesis of the essential coenzyme pyridoxal 5"-phosphate, and the ksgA gene, which encodes an rRNA modification enzyme and is partly cotranscribed with pdxA, is subject to positive growth rate regulation in Escherichia coli K-12. The amounts of the pdxA-ksgA cotranscript and pdxB- and ksgA-specific transcripts and expression from pdxA- and pdxB-lacZ fusions increased as the growth rate increased. The half-lives of ksgA- and pdxB-specific transcripts were not affected by the growth rate, whereas the half-life of the pdxA-ksgA cotranscript was too short to be measured accurately. A method of normalization was applied to determine the amount of mRNA synthesized per gene and the rate of protein accumulation per gene. Normalization removed an apparent anomaly at fast growth rates and demonstrated that positive regulation of pdxB occurs at the level of transcription initiation over the whole range of growth rates tested. RNA polymerase limitation and autoregulation could not account for the positive growth rate regulation of pdxA, pdxB, and ksgA transcription. On the other hand, growth rate regulation of the amount of the pdxA-ksgA cotranscript was abolished by a fis mutation, suggesting a role for the Fis protein. In contrast, the fis mutation had no effect on pdxB- or ksgA-specific transcript amounts. The amounts of the pdxA-ksgA cotranscript and ksgA-specific transcript were repressed in the presence of high intracellular concentrations of guanosine tetraphosphate; however, this effect was independent of relA function for the pdxA-ksgA cotranscript. Amounts of the pdxB-specific transcript remained unchanged during amino acid starvation in wild-type and relA mutant strains.

Quantitative relationships for specific growth rates and macromolecular compositions of Mycobacterium tuberculosis, Streptomyces coelicolor A3(2) and Escherichia coli B/r: an integrative theoretical approach

Microbiology ◽  
2004 ◽  
Vol 150 (5) ◽  
pp. 1413-1426 ◽  
Author(s):  
Robert A. Cox
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Mycobacterium Tuberculosis ◽  
Growth Rates ◽  
Specific Growth ◽  
Streptomyces Coelicolor ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
E Coli ◽  
Specific Growth Rates

Further understanding of the physiological states of Mycobacterium tuberculosis and other mycobacteria was sought through comparisons with the genomic properties and macromolecular compositions of Streptomyces coelicolor A3(2), grown at 30 °C, and Escherichia coli B/r, grown at 37 °C. A frame of reference was established based on quantitative relationships observed between specific growth rates (μ) of cells and their macromolecular compositions. The concept of a schematic cell based on transcription/translation coupling, average genes and average proteins was developed to provide an instantaneous view of macromolecular synthesis carried out by cells growing at their maximum rate. It was inferred that the ultra-fast growth of E. coli results from its ability to increase the average number of rRNA (rrn) operons per cell through polyploidy, thereby increasing its capacity for ribosome synthesis. The maximum growth rate of E. coli was deduced to be limited by the rate of uptake and consumption of nutrients providing energy. Three characteristic properties of S. coelicolor A3(2) growing optimally (μ=0·30 h−1) were identified. First, the rate of DNA replication was found to approach the rate reported for E. coli (μ=1·73 h−1); secondly, all rrn operons were calculated to be fully engaged in precursor-rRNA synthesis; thirdly, compared with E. coli, protein synthesis was found to depend on higher concentrations of ribosomes and lower concentrations of aminoacyl-tRNA and EF-Tu. An equation was derived for E. coli B/r relating μ to the number of rrn operons per genome. Values of μ=0·69 h−1 and μ=1·00 h−1 were obtained respectively for cells with one or two rrn operons per genome. Using the author's equation relating the number of rrn operons per genome to maximum growth rate, it is expected that M. tuberculosis with one rrn operon should be capable of growing much faster than it actually does. Therefore, it is suggested that the high number of insertion sequences in this species attenuates growth rate to still lower values.

scholarly journals Threshold effect of growth rate on population variability of Escherichia coli cell lengths

2017 ◽  
Vol 4 (2) ◽  
pp. 160417 ◽  
Author(s):  
Manasi S. Gangan ◽  
Chaitanya A. Athale
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Cell Size ◽  
Growth Rates ◽  
Threshold Effect ◽  
Cell Length ◽  
Replication Forks ◽  
E Coli ◽  
Cell Size Distributions ◽  
Rate Threshold

A long-standing question in biology is the effect of growth on cell size. Here, we estimate the effect of Escherichia coli growth rate ( r ) on population cell size distributions by estimating the coefficient of variation of cell lengths (CV L ) from image analysis of fixed cells in DIC microscopy. We find that the CV L is constant at growth rates less than one division per hour, whereas above this threshold, CV L increases with an increase in the growth rate. We hypothesize that stochastic inhibition of cell division owing to replication stalling by a RecA-dependent mechanism, combined with the growth rate threshold of multi-fork replication (according to Cooper and Helmstetter), could form the basis of such a threshold effect. We proceed to test our hypothesis by increasing the frequency of stochastic stalling of replication forks with hydroxyurea (HU) treatment and find that cell length variability increases only when the growth rate exceeds this threshold. The population effect is also reproduced in single-cell studies using agar-pad cultures and ‘mother machine’-based experiments to achieve synchrony. To test the role of RecA, critical for the repair of stalled replication forks, we examine the CV L of E. coli ΔrecA cells. We find cell length variability in the mutant to be greater than wild-type, a phenotype that is rescued by plasmid-based RecA expression. Additionally, we find that RecA-GFP protein recruitment to nucleoids is more frequent at growth rates exceeding the growth rate threshold and is further enhanced on HU treatment. Thus, we find growth rates greater than a threshold result in increased E. coli cell lengths in the population, and this effect is, at least in part, mediated by RecA recruitment to the nucleoid and stochastic inhibition of division.

scholarly journals Initiation and Velocity of Chromosome Replication in Escherichia coli B/r and K-12

1998 ◽  
Vol 180 (2) ◽  
pp. 265-273 ◽  
Author(s):  
Meeshel Bipatnath ◽  
Patrick P. Dennis ◽  
Hans Bremer
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Growth Rates ◽  
Cell Mass ◽  
Chromosome Replication ◽  
Chromosomal Replication ◽  
Copy Numbers ◽  
Identical Manner ◽  
Time Required ◽  
K 12

ABSTRACT The macromolecular composition and a number of parameters affecting chromosome replication were examined over a range of exponential growth rates in two common Escherichia coli strains, B/r and K-12 AB1157. Based on improved measurements of DNA after treatment of exponential cultures with rifampin, the cell mass per chromosomal replication origin (initiation mass) and the time required to replicate the chromosome from origin to terminus (C period) were determined. For these two strains, the initiation mass approached values of 8 × 10−10 and 10 × 10−10 units of optical density (at 460 nm) of culture mass per oriC, respectively, at growth rates above 1 doubling/h (at 37°C). The amount of protein per oriC decreased with increasing growth rate for AB1157 and remained nearly constant for the B/r strain. The C period decreased for both strains in an essentially identical manner from about 70 min at 0.6 doublings/h to about 33 min at 3 doublings/h. From the initiation mass andC period, relative or absolute copy numbers for genes with known map locations can be accurately determined at different growth rates. At growth rates above 2 doublings/h, when chromosomes are highly branched, genes near the origin are about threefold more prevalent than genes near the terminus. At a growth rate of 0.6 doubling/h, this ratio is only about 1.7, which reflects the lower degree of chromosome branching.

Age estimation by measurement of pouch young of the Quokka (Setonix brachyurus).

1961 ◽  
Vol 9 (1) ◽  
pp. 14 ◽  
Author(s):  
JW Shield ◽  
P Woolley
Keyword(s):  
Growth Rate ◽  
Body Weight ◽  
Nutritional Status ◽  
Growth Rates ◽  
Age Estimation ◽  
Tail Length ◽  
Estimation Procedure ◽  
Full Term ◽  
Male And Female ◽  
Young Growth

Removal of pouch young of Setonix can lead to the resumption of development of quiescent blastocysts. Thirty-six pouch young obtained in this way have been used in this study. As the time in days from resumption of development to parturition is known, accurate ages may be calculated without actual birth or copulation being observed. These 36 animals have been repeatedly measured during their pouch life, and body weight, pes length, and tail length over the full term of pouch occupancy are given as regressions of these measures versus age. Larger-scale regressions are given for the first 80 days of pouch life. A tabulation based on the three regressions and giving average measures at stated ages is also given. During pouch life there is no difference in growth rate between male and female pouch young. Growth proportions of field-reared and compound-reared animals of comparable nutritional status are also similar. It is therefore considered that growth rates are equal, and that the age-estimation procedure established on compound-reared animals is applicable to field animals.

Sign in / Sign up

Export Citation Format

Share Document