scholarly journals Changes in natural transformation after salt adaptation

2021 ◽  
Author(s):  
HA Kittredge ◽  
SE Evans
Keyword(s):  
Growth Rate ◽  
Driving Force ◽  
Transformation Efficiency ◽  
Natural Transformation ◽  
Pseudomonas Stutzeri ◽  
Serial Passage ◽  
Extracellular Dna ◽  
Salt Adaptation ◽  
Serial Transfer ◽  
Evolutionary Origins

AbstractThe exchange of genes between potentially unrelated bacteria is termed horizontal gene transfer (HGT) and is a driving force in bacterial evolution. Natural transformation is one mechanism of HGT where extracellular DNA (eDNA) from the environment is recombined into a host genome. The widespread conservation of transformation in bacterial lineages implies there is a fitness benefit. However, the nature of these benefits and the evolutionary origins of transformation are still unknown. Here, I examine how ∼330 generations or 100 days of serial passage in either constant or increasing salinities impacts the growth rate and transformation efficiency of Pseudomonas stutzeri. While the growth rate generally improved in response to serial transfer, the transformation efficiency of the evolved lineages varied extensively, with only 39-64% of populations undergoing transformation at the end of adaptive evolution. In comparison, 100% of the ancestral populations were able to undergo natural transformation. I also found that evolving P. stutzeri with different cell lysates (or populations of dead cells) minimally affected the growth rate and transformation efficiency, especially in comparison to the pervasiveness with which transformation capacity was lost across the evolved populations. Taken together, I show that the efficiency of eDNA uptake changes over relatively rapid timescales, suggesting that transformation is an adaptive and selectable trait that could be lost in environments where it is not beneficial.

Development of engineered genomic DNA to monitor the natural transformation ofPseudomonas stutzeriin soil-like microcosms

1997 ◽  
Vol 43 (1) ◽  
pp. 78-84 ◽  
Author(s):  
Eric Paget ◽  
Pascal Simonet
Keyword(s):  
Humic Acids ◽  
Genomic Dna ◽  
Natural Transformation ◽  
Pseudomonas Stutzeri ◽  
Viable Cell ◽  
Extracellular Dna ◽  
Sterile Soil ◽  
Soil Matrix ◽  
Soil Microcosms ◽  
Suicide Plasmid

The goal of this paper was to demonstrate whether natural transformation could occur in the environment to promote horizontal gene transfer between bacteria. Microcosms consisting of clay, clay and humic acids, or sterile soil were compared with respect to the natural transformation of Pseudomonas stutzeri by mineral-adsorbed DNA. Genes conferring resistance to tetracycline and ampicillin were first inserted in P. stutzeri pp100 chromosome via the pSUP202 suicide plasmid. Then, DNA extracted from the engineered P. stutzeri strain was used for transformation experiments, allowing the new transformed cells to be detected by hybridization with a tet probe. It turned out that DNA adsorbed on clay or soil particles and in presence of humic acids still transformed competent cells with frequencies up to 10−8transformants/viable cell. Finally, natural transformation assays involving two different DNAs were carried out in sterile soil microcosms. The use of nonisogenic DNA extracted from a rifampicin-resistant Pseudomonas fluorescens strain resulted in production of transformants, while isogenic DNA from our engineered strain failed to produce any. These observations confirmed that extracellular DNA adsorbed on a soil matrix composed of minerals and organic matter could still transform competent bacteria under environmental conditions.Key words: transformation, Pseudomonas stutzeri, soil microcosm, DNA, suicide plasmid.

scholarly journals The Extracellular Nuclease Dns and Its Role in Natural Transformation of Vibrio cholerae

2008 ◽  
Vol 190 (21) ◽  
pp. 7232-7240 ◽  
Author(s):  
Melanie Blokesch ◽  
Gary K. Schoolnik
Keyword(s):  
Vibrio Cholerae ◽  
Cell Density ◽  
Transformation Efficiency ◽  
Natural Transformation ◽  
Extracellular Dna ◽  
Aquatic Environments ◽  
Marine Habitats ◽  
Nucleotide Pools ◽  
Extracellular Nuclease ◽  
Low Cell Density

ABSTRACT Free extracellular DNA is abundant in many aquatic environments. While much of this DNA will be degraded by nucleases secreted by the surrounding microbial community, some is available as transforming material that can be taken up by naturally competent bacteria. One such species is Vibrio cholerae, an autochthonous member of estuarine, riverine, and marine habitats and the causative agent of cholera, whose competence program is induced after colonization of chitin surfaces. In this study, we investigate how Vibrio cholerae's two extracellular nucleases, Xds and Dns, influence its natural transformability. We show that in the absence of Dns, transformation frequencies are significantly higher than in its presence. During growth on a chitin surface, an increase in transformation efficiency was found to correspond in time with increasing cell density and the repression of dns expression by the quorum-sensing regulator HapR. In contrast, at low cell density, the absence of HapR relieves dns repression, leading to the degradation of free DNA and to the abrogation of the transformation phenotype. Thus, as cell density increases, Vibrio cholerae undergoes a switch from nuclease-mediated degradation of extracellular DNA to the uptake of DNA by bacteria induced to a state of competence by chitin. Taken together, these results suggest the following model: nuclease production by low-density populations of V. cholerae might foster rapid growth by providing a source of nucleotides for the repletion of nucleotide pools. In contrast, the termination of nuclease production by static, high-density populations allows the uptake of intact DNA and coincides with a phase of potential genome diversification.

scholarly journals Evolutionary economics: Crisis, transformation and metamorphosis

2021 ◽  
pp. 1-8
Author(s):  
Milan Zeleny
Keyword(s):  
Growth Rate ◽  
Productivity Growth ◽  
Driving Force ◽  
Evolutionary Economics ◽  
Regional Economies ◽  
Economic Evolution ◽  
Economic Sectors ◽  
Advanced Economies ◽  
First Time

Most world economies are undergoing fundamental transformations of economic sectors, shifting their employed workforce through the secular sequence of (1. Agriculture⟶2. Industry⟶3. Services⟶4. Government). The productivity growth rate is the driving force. Most advanced economies have reached the final stages of the sequence. Assorted recessions, crises and stagnations are simply cofluent, accompanying phenomena. Crises might be cyclical, but economic evolution is unidirectional. Traditional economics can hardly distinguish phenomena of crisis from those of the transformation. Because there is no “fifth sector”, some economies are entering the phase of metamorphosis, for the first time in history. Metamorphosis is manifested through deglobalization, relocalization and autonomization of local and regional economies. We are entering the Age of Entrepreneurship.

scholarly journals Effect of Cold Working on the Driving Force of the Crack Growth and Crack Growth Rate of Welded Joints under One Overload

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Hongliang Yang ◽  
He Xue ◽  
Fuqiang Yang ◽  
Shuai Wang
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Creep Rate ◽  
Crack Growth ◽  
Heat Affected Zone ◽  
Driving Force ◽  
Cold Working ◽  
Crack Tip ◽  
Simulation Method ◽  
Fusion Line

To understand the effect of cold working of welding heat-affected zone on the driving force of the crack growth and crack growth rate of stress corrosion cracking (SCC) near the welding fusion line, the finite element simulation method was used to analyze the effect of cold working on the tensile stress of the crack tip at different locations near the fusion line. On this basis, the strain rate of the crack tip in the Ford-Andresen model is replaced by the creep rate of the crack tip, and the creep rate of the crack tip is used as driving force for the crack growth of SCC. The effect of the cold working level at the heat-affected zone on the driving force of the crack growth and crack growth rate of SCC are analyzed, and driving force of the crack growth and crack growth rate of SCC after one overload was compared.

Research Progress on the Driving Force of Gas Hydrate Formation

2012 ◽  
Vol 616-618 ◽  
pp. 902-906 ◽  
Author(s):  
Chun Long Wang ◽  
Xue Min Zhang ◽  
Jin Ping Li ◽  
Lin Jun Wang ◽  
Liang Jiao
Keyword(s):  
Growth Rate ◽  
Gas Hydrate ◽  
Induction Time ◽  
Driving Force ◽  
Hydrate Formation ◽  
Research Direction ◽  
Research Progress ◽  
Force Model ◽  
Hydration Reaction ◽  
Gas Hydrate Formation

Predicting the driving force accurately is the key process to hydrate nucleating and growing of hydration reaction. The nucleating and growing process of hydrate is relevant to temperature, pressure and component of reactant, and the property of reaction tank and intermiscibility of reactant have notable effect on the formation process of hydrate with its nucleating position, the induction time, growth rate and hydration rate. However, the present driving force model of hydrate cannot predict nucleating area, induction time, growth rate and the reaction limit, and also can't explain the influence of some factors such as cooling rate, temperature disturbance and inlet way on the hydration reaction, it is uncertain of the process to gas hydrate nucleation. We introduced some driving force models, analyzed their merits and demerits, and looked into the distance of research direction to driving force in the future.

scholarly journals Biology of Pseudomonas stutzeri

2006 ◽  
Vol 70 (2) ◽  
pp. 510-547 ◽  
Author(s):  
Jorge Lalucat ◽  
Antoni Bennasar ◽  
Rafael Bosch ◽  
Elena García-Valdés ◽  
Norberto J. Palleroni
Keyword(s):  
Natural Transformation ◽  
Model Organism ◽  
Pseudomonas Stutzeri ◽  
Opportunistic Pathogen ◽  
Denitrifying Bacterium ◽  
The Past ◽  
History Of ◽  
Metabolic Properties ◽  
Degradation Of Pollutants ◽  
Made In

SUMMARY Pseudomonas stutzeri is a nonfluorescent denitrifying bacterium widely distributed in the environment, and it has also been isolated as an opportunistic pathogen from humans. Over the past 15 years, much progress has been made in elucidating the taxonomy of this diverse taxonomical group, demonstrating the clonality of its populations. The species has received much attention because of its particular metabolic properties: it has been proposed as a model organism for denitrification studies; many strains have natural transformation properties, making it relevant for study of the transfer of genes in the environment; several strains are able to fix dinitrogen; and others participate in the degradation of pollutants or interact with toxic metals. This review considers the history of the discovery, nomenclatural changes, and early studies, together with the relevant biological and ecological properties, of P. stutzeri.

scholarly journals Pseudomonas stutzeri and related species undergo natural transformation.

1983 ◽  
Vol 153 (1) ◽  
pp. 93-99 ◽  
Author(s):  
C A Carlson ◽  
L S Pierson ◽  
J J Rosen ◽  
J L Ingraham
Keyword(s):  
Related Species ◽  
Natural Transformation ◽  
Pseudomonas Stutzeri

scholarly journals Trusting the hand that feeds: microbes evolve to anticipate a serial transfer protocol as individuals or collectives

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Bram van Dijk ◽  
Jeroen Meijer ◽  
Thomas D. Cuypers ◽  
Paulien Hogeweg
Keyword(s):  
Growth Rate ◽  
In Silico ◽  
High Growth ◽  
Growth Cycle ◽  
High Growth Rate ◽  
Divergent Evolution ◽  
High Yield ◽  
Growth Strategies ◽  
Serial Transfer ◽  
Transfer Protocol

Abstract Background Experimental evolution of microbes often involves a serial transfer protocol, where microbes are repeatedly diluted by transfer to a fresh medium, starting a new growth cycle. This has revealed that evolution can be remarkably reproducible, where microbes show parallel adaptations both on the level of the phenotype as well as the genotype. However, these studies also reveal a strong potential for divergent evolution, leading to diversity both between and within replicate populations. We here study how in silico evolved Virtual Microbe “wild types” (WTs) adapt to a serial transfer protocol to investigate generic evolutionary adaptations, and how these adaptations can be manifested by a variety of different mechanisms. Results We show that all WTs evolve to anticipate the regularity of the serial transfer protocol by adopting a fine-tuned balance of growth and survival. This anticipation is done by evolving either a high yield mode, or a high growth rate mode. We find that both modes of anticipation can be achieved by individual lineages and by collectives of microbes. Moreover, these different outcomes can be achieved with or without regulation, although the individual-based anticipation without regulation is less well adapted in the high growth rate mode. Conclusions All our in silico WTs evolve to trust the hand that feeds by evolving to anticipate the periodicity of a serial transfer protocol, but can do so by evolving two distinct growth strategies. Furthermore, both these growth strategies can be accomplished by gene regulation, a variety of different polymorphisms, and combinations thereof. Our work reveals that, even under controlled conditions like those in the lab, it may not be possible to predict individual evolutionary trajectories, but repeated experiments may well result in only a limited number of possible outcomes.

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