Isothermal microcalorimetry accurately detects bacteria, tumorous microtissues, and parasitic worms in a label‐free well‐plate assay

Braissant, Olivier; Keiser, Jennifer; Meister, Isabel; Bachmann, Alexander; Wirz, Dieter; Göpfert, Beat; Bonkat, Gernot; Wadsö, Ingemar

doi:10.1002/biot.201400494

Cited by 59 publications

(60 citation statements)

References 57 publications

(66 reference statements)

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“…The derivative of the OD curve, OD=(t), is a measure of dN/dt ϭ N ϫ k, where N is the number of cells, and exhibited two peaks of cell division, which were scaled to the corresponding heat flow maxima. This shows that the two thermogram peaks are indeed related to two growth events, which is not always the case (35). In both growth phases, the heat flow showed the same proportionality with cell division.…”

Section: Fig 5 Comparison Of Growth Rates During First and Second Phamentioning

confidence: 81%

Mechanism of Attenuation of Uranyl Toxicity by Glutathione in Lactococcus lactis

Obeid

Oertel

Solioz

et al. 2016

Appl Environ Microbiol

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b ABSTRACTBoth prokaryotic and eukaryotic organisms possess mechanisms for the detoxification of heavy metals, and these mechanisms are found among distantly related species. We investigated the role of intracellular glutathione (GSH), which, in a large number of taxa, plays a role in protection against the toxicity of common heavy metals. Anaerobically grown Lactococcus lactis containing an inducible GSH synthesis pathway was used as a model organism. Its physiological condition allowed study of putative GSH-dependent uranyl detoxification mechanisms without interference from additional reactive oxygen species. By microcalorimetric measurements of metabolic heat during cultivation, it was shown that intracellular GSH attenuates the toxicity of uranium at a concentration in the range of 10 to 150 M. In this concentration range, no effect was observed with copper, which was used as a reference for redox metal toxicity. At higher copper concentrations, GSH aggravated metal toxicity. Isothermal titration calorimetry revealed the endothermic binding of U(VI) to the carboxyl group(s) of GSH rather than to the reducing thiol group involved in copper interactions. The data indicate that the primary detoxifying mechanism is the intracellular sequestration of carboxyl-coordinated U(VI) into an insoluble complex with GSH. The opposite effects on uranyl and on copper toxicity can be related to the difference in coordination chemistry of the respective metal-GSH complexes, which cause distinct growth phase-specific effects on enzyme-metal interactions. IMPORTANCEUnderstanding microbial metal resistance is of particular importance for bioremediation, where microorganisms are employed for the removal of heavy metals from the environment. This strategy is increasingly being considered for uranium. However, little is known about the molecular mechanisms of uranyl detoxification. Existing studies of different taxa show little systematics but hint at a role of glutathione (GSH). Previous work could not unequivocally demonstrate a GSH function in decreasing the presumed uranyl-induced oxidative stress, nor could a redox-independent detoxifying action of GSH be identified. Combining metabolic calorimetry with cell number-based assays and genetics analysis enables a novel and general approach to quantify toxicity and relate it to molecular mechanisms. The results show that GSH-expressing microorganisms appear advantageous for uranyl bioremediation.T he natural abundance of uranium and the increasing health risks that originate from its anthropogenic release to the environment have generated a high demand for understanding the molecular mechanisms of uranium toxicity. Its radiotoxicity is of minor ecological relevance compared to its toxicity due to chemical interference with metabolism (1, 2). The latter is caused mostly by the displacement of Ca 2ϩ and Mg 2ϩ from functionally important binding sites in enzymes (3). The water-soluble uranyl cation UO 2 2ϩ is the most commonly found contaminant, which contains uranium in its highest ...

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Section: Fig 5 Comparison Of Growth Rates During First and Second Phamentioning

confidence: 81%

Mechanism of Attenuation of Uranyl Toxicity by Glutathione in Lactococcus lactis

Obeid

Oertel

Solioz

et al. 2016

Appl Environ Microbiol

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“…For each antibiotic, a two-fold dilution series was prepared following the concentration ranges on Table 1 In each plate there were control wells: one negative control that had only MHB, two positive control wells that had MHB and the bacterial inoculum but not the antibiotics. From this master plate, 120 mL of each sample (5 Â 10 5 CFU/mL bacterial suspension with or without antibiotic) were transferred to sterile plastic inserts designed to fit in titanium measurement vials (calWell; Symcel) as a part of the calScreener sample handling system [6,7]. The inserts were placed in the calWells, sealed and loaded in the calScreener.…”

Section: Inoculum and Antibiotic Preparation For Calscreenermentioning

confidence: 99%

Isothermal microcalorimetry minimal inhibitory concentration testing in extensively drug resistant Gram-negative bacilli: a multicentre study

Tellapragada

Hasan

Antonelli

et al. 2020

Clinical Microbiology and Infection

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Objectives: To evaluate the performance of an isothermal microcalorimetry (IMC) method for determining the MICs among extensively drug-resistant Gram-negative bacilli. Methods: A collection of 320 clinical isolates (n ¼ 80 of each) of Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii from Sweden, Spain, Italy and the Netherlands were tested. The MICs were determined using the IMC device calScreener (Symcel, Stockholm, Sweden) and ISO-broth microdilution as the reference method. Essential agreement, categorical agreement, very major errors (VME), major errors (ME) and minor (mE) errors for each antibiotic were determined. Results: Data from 316 isolates were evaluated. Four errors (two ME, one VME, one mE) among 80 K. pneumoniae, six errors (four ME, one VME, one mE) among 79 E. coli, 15 errors (seven VME, three ME, five mE) among 77 P. aeruginosa and 18 errors (12 VME, two ME, four mE) among 80 A. baumannii were observed. Average essential agreement and categorical agreement of the IMC method were 96.6% (95% confidence interval, 94.2e99) and 97.1% (95% confidence interval, 95.4e98.5) respectively when the MICs were determined at the end of 18 hours. Categorical agreement of the IMC method for prediction of MIC by the end of 8 hours for colistin, meropenem, amikacin, ciprofloxacin and piperacillin/tazobactam were 95%, 91.4%, 94%, 95.2% and 93.7% respectively. Conclusions: The IMC method could accurately determine the MICs among extensively drug-resistant clinical isolates of E. coli, K. pneumoniae, P. aeruginosa and A. baumannii isolates. C. Tellapragada, Clin Microbiol Infect 2020;▪:1

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“…The heat released by microbial metabolism can be used as a measure of the biodegradation rate and is easily quantified by direct calorimetry. High sensitivity calorimeters permit continuous measurements of heat rate without disturbing the living system at a detection level of nanowatts [10]. Biocalorimetry has been widely applied in microbiology and has also been used to monitor SOM biodegradation [11,12].…”

Section: Introductionmentioning

confidence: 99%

Calorimetry measures the response of soil organic matter biodegradation to increasing temperature

Barros

Hansen

Piñeiro

et al. 2015

J Therm Anal Calorim

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The temperature sensitivity of soil organic matter (SOM) is receiving an increasing interest due to its importance in the global carbon cycle and potential feedbacks to climate change. It constitutes a controversial topic in soil science due to different constrains involving the models employed, together with methodological limitations. It is welcome the introduction of new methods and indicators that can assess the sensitivity to temperature of the SOM macromolecule continuum on a more global basis. Calorimetry can be an attractive alternative if the SOM degradation is studied based on the heat rate under a gradient of temperature. The design of new calorimeters permits to do those measurements in real time through a temperature scan mode. We have applied and designed a preliminary protocol with this new type of calorimeters to calculate the activation energies and Q 10 values of soil samples with different recalcitrance. The calculation was run on short-term basis and continuously through a temperature gradient from 18 to 35°C for 1 week. Results showed fast adaptation of microbial decomposition rates to increasing temperature and enough sensitivity of the method to detect changes in the heat rate involving SOM thermal properties. Labile substrates as carbohydrates showed up as potential rulers explaining E a and Q 10 changes which fitted the rule of thumb connecting both.

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Isothermal microcalorimetry accurately detects bacteria, tumorous microtissues, and parasitic worms in a label‐free well‐plate assay

Cited by 59 publications

References 57 publications

Mechanism of Attenuation of Uranyl Toxicity by Glutathione in Lactococcus lactis

Mechanism of Attenuation of Uranyl Toxicity by Glutathione in Lactococcus lactis

Isothermal microcalorimetry minimal inhibitory concentration testing in extensively drug resistant Gram-negative bacilli: a multicentre study

Calorimetry measures the response of soil organic matter biodegradation to increasing temperature

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