scholarly journals Temperature-Dependent Growth Modeling of Environmental and Clinical Legionella pneumophila Multilocus Variable-Number Tandem-Repeat Analysis (MLVA) Genotypes

2017 ◽  
Vol 83 (8) ◽  
Author(s):  
Yehonatan Sharaby ◽  
Sarah Rodríguez-Martínez ◽  
Olga Oks ◽  
Marina Pecellin ◽  
Hila Mizrahi ◽  
...  
Keyword(s):  
Drinking Water ◽  
Growth Kinetics ◽  
Legionella Pneumophila ◽  
Variable Number Tandem Repeat ◽  
Ecological Niches ◽  
Water Network ◽  
Temperature Dependent ◽  
Content Type ◽  
Dependent Growth ◽  
Kinetics Of

ABSTRACT Legionella pneumophila causes waterborne infections resulting in severe pneumonia. High-resolution genotyping of L. pneumophila isolates can be achieved by multiple-locus variable-number tandem-repeat analysis (MLVA). Recently, we found that different MLVA genotypes of L. pneumophila dominated different sites in a small drinking-water network, with a genotype-related temperature and abundance regime. The present study focuses on understanding the temperature-dependent growth kinetics of the genotypes that dominated the water network. Our aim was to model mathematically the influence of temperature on the growth kinetics of different environmental and clinical L. pneumophila genotypes and to compare it with the influence of their ecological niches. Environmental strains showed a distinct temperature preference, with significant differences among the growth kinetics of the three studied genotypes (Gt4, Gt6, and Gt15). Gt4 strains exhibited superior growth at lower temperatures (25 and 30°C), while Gt15 strains appeared to be best adapted to relatively higher temperatures (42 and 45°C). The temperature-dependent growth traits of the environmental genotypes were consistent with their distribution and temperature preferences in the water network. Clinical isolates exhibited significantly higher growth rates and reached higher maximal cell densities at 37°C and 42°C than the environmental strains. Further research on the growth preferences of L. pneumophila clinical and environmental genotypes will result in a better understanding of their ecological niches in drinking-water systems as well as in the human body. IMPORTANCE Legionella pneumophila is a waterborne pathogen that threatens humans in developed countries. The bacteria inhabit natural and man-made freshwater environments. Here we demonstrate that different environmental L. pneumophila genotypes have different temperature-dependent growth kinetics. Moreover, Legionella strains that belong to the same species but were isolated from environmental and clinical sources possess adaptations for growth at different temperatures. These growth preferences may influence the bacterial colonization at specific ecological niches within the drinking-water network. Adaptations for growth at human body temperatures may facilitate the abilities of some L. pneumophila strains to infect and cause illness in humans. Our findings may be used as a tool to improve Legionella monitoring in drinking-water networks. Risk assessment models for predicting the risk of legionellosis should take into account not only Legionella concentrations but also the temperature-dependent growth kinetics of the isolates.

scholarly journals Modelling of Temperature-Dependent Growth Kinetics of Oxide Scale on Hot-Rolled Steel Strip

2012 ◽  
Vol 13 (1) ◽  
pp. 219-223 ◽  
Author(s):  
Xianglong Yu ◽  
Zhengyi Jiang ◽  
Dongbin Wei ◽  
Xiaodong Wang ◽  
Quan Yang
Keyword(s):  
Oxide Scale ◽  
Growth Kinetics ◽  
Steel Strip ◽  
Rolled Steel ◽  
Temperature Dependent ◽  
Dependent Growth ◽  
Hot Rolled ◽  
Hot Rolled Steel ◽  
Kinetics Of

Temperature-dependent growth of protein crystals with temperature-independent solubility: case study of apoferritin

CrystEngComm ◽  
2020 ◽  
Vol 22 (26) ◽  
pp. 4478-4488
Author(s):  
Ivaylo L. Dimitrov
Keyword(s):  
Crystal Growth ◽  
Growth Kinetics ◽  
Growth Analysis ◽  
Small Variation ◽  
Protein Crystals ◽  
Temperature Dependent ◽  
Dependent Growth ◽  
Kinetics Of

Combined diffusion- and interface-controlled crystal growth analysis elucidates the temperature-dependent growth kinetics of protein crystals at a relatively small variation of supersaturation.

scholarly journals Occurrence, diversity and temperature-dependent growth kinetics of Aeromonas spp. in lettuce

2020 ◽  
Vol 335 ◽  
pp. 108852
Author(s):  
Noelle Umutoni ◽  
Anita N. Jakobsen ◽  
Kirill Mukhatov ◽  
Gunn Merethe Bjørge Thomassen ◽  
Hanne Karlsen ◽  
...  
Keyword(s):  
Growth Kinetics ◽  
Temperature Dependent ◽  
Dependent Growth ◽  
Kinetics Of

scholarly journals Virulence Traits of Environmental and ClinicalLegionella pneumophilaMultilocus Variable-Number Tandem-Repeat Analysis (MLVA) Genotypes

2018 ◽  
Vol 84 (10) ◽  
Author(s):  
Yehonatan Sharaby ◽  
Sarah Rodríguez-Martínez ◽  
Marina Pecellin ◽  
Rotem Sela ◽  
Avi Peretz ◽  
...  
Keyword(s):  
Drinking Water ◽  
Health Risks ◽  
Legionella Pneumophila ◽  
Variable Number Tandem Repeat ◽  
Variable Number ◽  
Content Type ◽  
Clinical Strains ◽  
Repeat Analysis ◽  
Public Health Risks ◽  
Virulence Traits

ABSTRACTLegionella pneumophilacauses water-based infections resulting in severe pneumonia. Recently, we showed that different MLVA-8 (multilocus variable-number tandem-repeat analysis using 8 loci) genotypes dominated different sites of a drinking-water distribution system. Each genotype displayed a unique temperature-dependent growth behavior. Here we compared the pathogenicity potentials of different MLVA-8 genotypes of environmental and clinical strains. The virulence traits studied were hemolytic activity and cytotoxicity toward amoebae and macrophages. Clinical strains were significantly more hemolytic than environmental strains, while their cytotoxicity toward amoebae was significantly lower at 30°C. No significant differences were detected between clinical and environmental strains in cytotoxicity toward macrophages. Significant differences in virulence were observed between the environmental genotypes (Gt). Gt15 strains showed a significantly higher hemolytic activity. In contrast, Gt4 and Gt6 strains were more infective towardAcanthamoeba castellanii. Moreover, Gt4 strains exhibited increased cytotoxicity toward macrophages and demonstrated a broader temperature range of amoebal lysis than Gt6 and Gt15 strains. Understanding the virulence traits ofLegionellagenotypes may improve the assessment of public health risks ofLegionellain drinking water.IMPORTANCELegionella pneumophilais the causative agent of a severe form of pneumonia. Here we demonstrated that clinical strains were significantly more cytotoxic toward red blood cells than environmental strains, while their cytotoxicity toward macrophages was similar. Genotype 4 (Gt4) strains were highly cytotoxic toward amoebae and macrophages and lysed amoebae in a broader temperature range than to the other studied genotypes. The results can explain the relatively high success of Gt4 in the environment and in clinical samples; thus, Gt4 strains should be considered a main factor for the assessment of public health risks ofLegionellain drinking water. Our findings shed light on the ecology, virulence, and pathogenicity potential of differentL. pneumophilagenotypes, which can be a valuable parameter for future modeling and quantitative microbial risk assessment ofLegionellain drinking-water systems.

Impact of pH on growth of Staphylococcus epidermidis and Staphylococcus aureus in vitro

2021 ◽  
Vol 70 (9) ◽  
Author(s):  
Vidula Iyer ◽  
Janhavi Raut ◽  
Anindya Dasgupta
Keyword(s):  
Staphylococcus Aureus ◽  
Growth Kinetics ◽  
Staphylococcus Epidermidis ◽  
Type Species ◽  
Ph Dependence ◽  
Skin Microbiome ◽  
Content Type ◽  
Link Type ◽  
Kinetics Of

The pH of skin is critical for skin health and resilience and plays a key role in controlling the skin microbiome. It has been well reported that under dysbiotic conditions such as atopic dermatitis (AD), eczema, etc. there are significant aberrations of skin pH, along with a higher level of Staphylococcus aureus compared to the commensal Staphylococcus epidermidis on skin. To understand the effect of pH on the relative growth of S. epidermidis and S. aureus , we carried out simple in vitro growth kinetic studies of the individual microbes under varying pH conditions. We demonstrated that the growth kinetics of S. epidermidis is relatively insensitive to pH within the range of 5–7, while S. aureus shows a stronger pH dependence in that range. Gompertz’s model was used to fit the pH dependence of the growth kinetics of the two bacteria and showed that the equilibrium bacterial count of S. aureus was the more sensitive parameter. The switch in growth rate happens at a pH of 6.5–7. Our studies are in line with the general hypothesis that keeping the skin pH within an acidic range is advantageous in terms of keeping the skin microbiome in balance and maintaining healthy skin.

scholarly journals Continuous Nucleation and Size Dependent Growth Kinetics of Indium Phosphide Nanocrystals

2020 ◽  
Vol 32 (10) ◽  
pp. 4358-4368 ◽  
Author(s):  
Brandon M. McMurtry ◽  
Kevin Qian ◽  
Joseph K. Teglasi ◽  
Anindya K. Swarnakar ◽  
Jonathan De Roo ◽  
...  
Keyword(s):  
Indium Phosphide ◽  
Growth Kinetics ◽  
Size Dependent ◽  
Dependent Growth ◽  
Kinetics Of ◽  
Continuous Nucleation

Chiral vector and metal catalyst-dependent growth kinetics of single-wall carbon nanotubes

Carbon ◽  
2018 ◽  
Vol 133 ◽  
pp. 283-292 ◽  
Author(s):  
Marianna V. Kharlamova ◽  
Christian Kramberger ◽  
Yuta Sato ◽  
Takeshi Saito ◽  
Kazu Suenaga ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Growth Kinetics ◽  
Single Wall Carbon Nanotubes ◽  
Metal Catalyst ◽  
Single Wall Carbon ◽  
Chiral Vector ◽  
Dependent Growth ◽  
Kinetics Of

scholarly journals The Legionella Lqs-LvbR regulatory network controls temperature-dependent growth onset and bacterial cell density

2021 ◽  
Author(s):  
Ramon Hochstrasser ◽  
Hubert Hilbi
Keyword(s):  
Cell Density ◽  
Legionella Pneumophila ◽  
Elevated Temperatures ◽  
Optimal Growth ◽  
Lag Phase ◽  
Temperature Dependent ◽  
Genes Encoding ◽  
Life Threatening ◽  
Cell Densities ◽  
Dependent Growth

Legionella species are facultative intracellular pathogens, which can cause a life-threatening pneumonia termed Legionnaires’ disease. Legionella pneumophila employs the Legionella quorum sensing (Lqs)-LvbR network to regulate virulence and motility, but its role for growth in media is ill-defined. Compared to the parental L. pneumophila strain JR32, a ΔlqsR mutant showed a reduced lag phase at 30°C and reached a higher cell density at 45°C, while the ΔlqsA, ΔlqsS and ΔlqsT mutants exhibited a longer lag phase and reached only a lower cell density. A ΔlvbR mutant resumed growth like the parental strain at 30°C, but exhibited a substantially reduced cell density at 45°C. Thus, LvbR is an important cell density regulator at elevated temperatures. A quantitative analysis of temperature-dependent growth characteristics of environmental and clinical strains revealed that L. pneumophila strains grew in AYE medium after distinct lag phases with similar rates at 30°C, reached different cell densities at the optimal growth temperature of 40°C, and no longer grew at 50°C. Legionella longbeachae reached a rather low cell density at 40°C and did not grow at and beyond 45°C. Genes encoding components of the Lqs-LvbR network were present in the genomes of the environmental and clinical L. pneumophila isolates, and the PlqsR, PlqsA, PlqsS and PlvbR promoters from strain JR32 were active in these strains. Taken together, our results indicate that the Lqs-LvbR network governs the temperature-dependent growth onset and cell density of the L. pneumophila reference strain JR32, and possibly also of environmental and clinical L. pneumophila isolates.

Microstructures evolution and growth kinetics of intermetallic compounds in Cu/Sn/Cu system during ultrasonic soldering process

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Xu Han ◽  
Xiaoyan Li ◽  
Peng Yao
Keyword(s):  
Grain Boundary ◽  
Microstructural Evolution ◽  
Growth Kinetics ◽  
Boundary Diffusion ◽  
Solder Joints ◽  
Content Type ◽  
Soldering Process ◽  
Different Temperatures ◽  
Ultrasonic Soldering ◽  
Kinetics Of

Purpose This study aims to investigate the effect of ultrasound on interfacial microstructures and growth kinetics of intermetallic compounds (IMCs) at different temperatures. Design/methodology/approach To investigate the effect of ultrasound on IMCs growth quantitatively, the cross-sectional area of IMCs layers over a confirmed length was obtained for calculating the thickness of the IMCs layer. Findings The generation of dimensional difference in normal direction between Cu6Sn5 and its adjacent Cu6Sn5, formation of bossed Cu6Sn5 and non-interfacial Cu6Sn5 in ultrasonic solder joints made the interfacial Cu6Sn5 layer present a non-scallop-like morphology different from that of traditional solder joints. At 260°C and 290°C, the Cu3Sn layer presented a wave-like shape. In contrast, at 320°C, the Cu3Sn in ultrasonic solder joints consisted of non-interfacial Cu3Sn and interfacial Cu3Sn with a branch-like shape. The Cu6Sn5/Cu3Sn boundary and Cu3Sn/Cu interface presented a sawtooth-like shape under the effect of ultrasound. The predominant mechanism of ultrasonic-assisted growth of Cu6Sn5 growth at 260°C, 290°C and 320°C involved the grain boundary diffusion accompanied by grain coarsening. The Cu3Sn growth was controlled by volume diffusion during the ultrasonic soldering process at 260°C and 290°C. The diffusion mechanism of Cu3Sn growth transformed to grain boundary diffusion accompanied by grain coarsening when the ultrasonic soldering temperature was increased to 320°C. Originality/value The microstructural evolution and growth kinetics of IMCs in ultrasonically prepared ultrasonic solder joints at different temperatures have rarely been reported in previous studies. In this study, the effect of ultrasound on microstructural evolution and growth kinetics of IMCs was systematically investigated.

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