Engineering cyanobacteria for the production of isoprene and other terpenoids has gained increasing attention in the field of biotechnology. Several studies have addressed optimization of isoprene synthesis in cyanobacteria via enzyme and pathway engineering. However, only little attention has been paid to the optimization of cultivation conditions. In this study, an isoprene-producing strain of Synechocystis sp. PCC 6803 and two control strains were grown under a variety of cultivation conditions. Isoprene production, as quantified by modified membrane inlet mass spectrometer (MIMS) and interpreted using Flux Balance Analysis (FBA), increased under violet light and at elevated temperature. Increase of thermotolerance in the isoprene producer was attributed to the physical presence of isoprene, similar to plants. The results demonstrate a beneficial effect of isoprene on cell survival at higher temperatures. This increased thermotolerance opens new possibilities for sustainable bio-production of isoprene and other products.

• Klíčová slova
• Biofuels, Cultivation conditions, Flux Balance Analysis, Optimization, Thermotolerance,
• MeSH
• butadieny metabolismus   MeSH
• hemiterpeny metabolismus   MeSH
• Synechocystis * metabolismus   MeSH
• teplota MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• butadieny MeSH
• hemiterpeny MeSH
• isoprene MeSH Prohlížeč

We have used our selected ion flow tube mass spectrometric method (SIFT-MS) to study isoprene levels in the alveolar breath of 29 healthy volunteers during normal working hours at the varying states of nutrition occurring during this period. Quantification of the breath isoprene was achieved using O(2)(+) precursor ions to avoid complications which can arise when using H(3)O(+) precursor ions for isoprene analysis. The present data indicate that the spread of the alveolar isoprene levels in this sample of healthy individuals is 22 to 234 ppb and that the mean value is 83 ppb with a standard deviation of 45 ppb. These levels are compared with those previously determined using other techniques and are seen to be at the low end of the values previously reported. The present studies are a prelude to an investigation of the proposed correlation of breath isoprene levels with psychological, physical and biochemical stress.

• MeSH
• butadieny analýza   MeSH
• časové faktory MeSH
• dechové testy metody   MeSH
• dieta MeSH
• dospělí MeSH
• hemiterpeny * MeSH
• hmotnostní spektrometrie přístrojové vybavení   metody   MeSH
• lidé středního věku MeSH
• lidé MeSH
• pentany * MeSH
• senioři MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• butadieny MeSH
• hemiterpeny * MeSH
• isoprene MeSH Prohlížeč
• pentany * MeSH

The prediction of vegetation responses to climate requires a knowledge of how climate-sensitive plant traits mediate not only the responses of individual plants, but also shifts in the species and functional compositions of whole communities. The emission of isoprene gas - a trait shared by one-third of tree species - is known to protect leaf biochemistry under climatic stress. Here, we test the hypothesis that isoprene emission shapes tree species compositions in tropical forests by enhancing the tolerance of emitting trees to heat and drought. Using forest inventory data, we estimated the proportional abundance of isoprene-emitting trees (pIE) at 103 lowland tropical sites. We also quantified the temporal composition shifts in three tropical forests - two natural and one artificial - subjected to either anomalous warming or drought. Across the landscape, pIE increased with site mean annual temperature, but decreased with dry season length. Through time, pIE strongly increased under high temperatures, and moderately increased following drought. Our analysis shows that isoprene emission is a key plant trait determining species responses to climate. For species adapted to seasonal dry periods, isoprene emission may tradeoff with alternative strategies, such as leaf deciduousness. Community selection for isoprene-emitting species is a potential mechanism for enhanced forest resilience to climatic change.

• Klíčová slova
• climate feedback, drought, plant functional traits, plant secondary metabolism, thermotolerance, tree physiology, tropical forest, volatile organic compounds,
• MeSH
• butadieny analýza   MeSH
• časové faktory MeSH
• fylogeneze * MeSH
• hemiterpeny analýza   MeSH
• klimatické změny * MeSH
• lesy MeSH
• stromy fyziologie   MeSH
• tropické klima * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH
• Názvy látek
• butadieny MeSH
• hemiterpeny MeSH
• isoprene MeSH Prohlížeč

An analytical method for determination of isoprene in expired breath as a marker of body cholesterol synthesis was developed with a special emphasis on breath sampling. Patients were breathing controlled air using respiratory masks for 2 min (washout period) and then their expired breath was collected in 8-1 Tedlar bags. The bags were heated to 40 degrees C and the solid-phase microextraction fiber Carboxen-polydimethylsiloxane 75 microm was inserted through the septum. Extraction time was 10 min. Analytes were desorbed in the GC injector for 2 min at 270 degrees C. Analyses were performed on a Q-PLOT column and fragment ions 68, 67 and 53 were quantified. The concentration range was 1-40 nmol/l, limit of detection was 0.25 nmol/l, the calibration curve was linear. Precision, expressed as RSD, was 5.5-12.5%. These tests are non-invasive, feasible and relatively inexpensive.

• MeSH
• butadieny analýza   MeSH
• časové faktory MeSH
• dechové testy metody   MeSH
• hemiterpeny * MeSH
• kalibrace MeSH
• lidé MeSH
• oxid uhličitý chemie   MeSH
• pentany * MeSH
• plynová chromatografie s hmotnostně spektrometrickou detekcí metody   MeSH
• reprodukovatelnost výsledků MeSH
• řízení kvality MeSH
• stabilita léku MeSH
• teplota MeSH
• vlhkost MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• butadieny MeSH
• hemiterpeny * MeSH
• isoprene MeSH Prohlížeč
• oxid uhličitý MeSH
• pentany * MeSH

Atmospheric concentrations of isoprene (2-methylbutadiene) in environmental research and in exhaled breath for medical research are usually measured by soft chemical ionization mass spectrometry that relies on a knowledge of the kinetics of the gas phase reactions of H3O+, NO+ or O2+• ions with isoprene molecules. Thus, we have carried out an experimental study of the rate coefficients, k, and product ions distributions for such reactions over a range of ion-molecule interaction energy, Er, (0.05-0.8 eV) in a helium-buffered selected ion flow-drift tube, SIFDT. It is found that contrary to the ion-induced dipole capture model, k for the NO+ and O2+• charge transfer reactions almost doubled over the E r range, while k for the H3O+ proton transfer reaction did not significantly change with E r, as predicted. These results reveal that the reaction mechanism involving ion-molecule capture forming an intermediate complex does not properly describe charge transfer to isoprene molecules. It is important to account for this increase in k with E r in these isoprene charge transfer reactions, and probably for other such reactions, when using drift tube reactors for trace gas analysis.

• Publikační typ
• časopisecké články MeSH

Fluxes of CO2 and isoprenoids were measured for the first time in Stipa tenacissima L (alfa grass), a perennial tussock grass dominant in the driest areas of Europe. In addition, we studied how those fluxes were influenced by environmental conditions, leaf ontogeny and UV radiation and compared emission rates in two contrasting seasons: summer when plants are mostly inactive and autumn, the growing season in this region. Leaf ontogeny significantly affected both photosynthesis and isoprenoids emission. Isoprene emission was positively correlated with photosynthesis, although a low isoprene emission was detected in brown leaves with a net carbon loss. Moreover, leaves with a significant lower photosynthesis emitted only monoterpenes, while at higher photosynthetic rates also isoprene was produced. Ambient UV radiation uncoupled photosynthesis and isoprene emission. It is speculated that alfa grass represent an exception from the general rules governing plant isoprenoid emitters.

• Klíčová slova
• Alfa grass, Isoprene, Monoterpene, Semiarid ecosystems, UV radiation,
• MeSH
• butadieny MeSH
• fotosyntéza fyziologie   MeSH
• hemiterpeny MeSH
• látky znečišťující vzduch analýza   MeSH
• lipnicovité metabolismus   MeSH
• listy rostlin MeSH
• monitorování životního prostředí MeSH
• monoterpeny MeSH
• oxid uhličitý MeSH
• pentany MeSH
• rostliny MeSH
• terpeny analýza   MeSH
• uhlík MeSH
• ultrafialové záření * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Evropa MeSH
• Názvy látek
• butadieny MeSH
• hemiterpeny MeSH
• isoprene MeSH Prohlížeč
• látky znečišťující vzduch MeSH
• monoterpeny MeSH
• oxid uhličitý MeSH
• pentany MeSH
• terpeny MeSH
• uhlík MeSH

The amphiphilic polystyrene- block-poly((sulfamate-carboxylate)isoprene) (PS-PISC) diblock copolymer was synthesized from the precursor diblock copolymer polystyrene- block-isoprene by reaction with chlorosulfonyl isocyanate. The structure and behavior of self-assembled PS-PISC nanoparticles was studied in alkaline and acidic aqueous solutions by a combination of static and dynamic light scattering, analytical ultracentrifugation, atomic force and cryogenic transmission electron microscopies, NMR spectroscopy, potentiometric titration, and fluorometry using pyrene as a polarity-sensitive fluorescent probe. It was found that PS-PISC exists in aqueous solutions in the form of micellar aggregates. The aggregation tendency increases with decreasing effective charge density in the shell, that is, with decreasing pH of the solution, and aggregates found in alkaline aqueous media have much smaller molar masses than those formed in acidic media. The latter are dense, collapsed structures with immobile PISC domains in which most of the COOH and NH 2 (+)SO 3 (-) groups are buried inside of the nanoparticles. The swelling of PISC domains and disentanglement of PISC chains after addition of a base are slow processes occurring on the time scale of days.

• Publikační typ
• časopisecké články MeSH

Thermophilic bacteria of four genera in contrast to the commonly used production strains such as Bacillus subtilis, produce homologs other than menaquinone (MK) with seven isoprene units. The number of isoprene units and the configuration of double bonds are essential factors for their biological activity. The goal was to obtain a strain of bacteria that produces a wide range of MK homologs and only all-trans geometrical isomers, which was the strain G. kaustophilus. Using off-line two-dimensional LC-tandem MS in columns with the RP18 phase and the COSMOSIL cholester phase (separation according to the geometric configuration of double bonds) it was shown that thermophilic bacteria grown at different temperatures produce only all-trans isomers of menaquinones from MK-5 (menaquinone with five isoprenyl units) to MK-15 (fifteen isoprenyl units). Therefore, G. kaustophilus appears to be a biotechnologically important strain produces only trans isomers and additionally homologs from 5 to 15 isoprene units.

• Klíčová slova
• Cis/trans isomers, LC/ESI–tandem MS, Menaquinones, Shotgun mass spectrometry, Thermophilic bacteria,
• MeSH
• Bacteria * MeSH
• butadieny * MeSH
• hmotnostní spektrometrie MeSH
• vitamin K 2 chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• butadieny * MeSH
• isoprene MeSH Prohlížeč
• vitamin K 2 MeSH

Throughout the development of breath analysis research, there has been interest in how the concentrations of trace compounds in exhaled breath are related to their concentrations in the ambient inhaled air. In considering this, Phillips introduced the concept of 'alveolar gradient' and judged that the measured exhaled concentrations of volatile organic compounds should be diminished by an amount equal to their concentrations in the inhaled ambient air. The objective of the work described in this paper was to investigate this relationship quantitatively. Thus, experiments have been carried out in which inhaled air was polluted by seven compounds of interest in breath research, as given below, and exhaled breath has been analysed by SIFT-MS as the concentrations of these compounds in the inhaled air were reduced. The interesting result obtained is that all the exogenous compounds are partially retained in the exhaled breath and there are close linear relationships between the exhaled and inhaled air concentrations for all seven compounds. Thus, retention coefficients, a, have been derived for the following compounds: pentane, 0.76 ± 0.09; isoprene, 0.66 ± 0.04; acetone, 0.17 ± 0.03; ammonia, 0.70 ± 0.13, methanol, 0.29 ± 0.02; formaldehyde, 0.06 ± 0.03; deuterated water (HDO), 0.09 ± 0.02. From these data, correction to breath analyses for inhaled concentration can be described by coefficients specific to each compound, which can be close to 1 for hydrocarbons, as applied by Phillips, or around 0.1, meaning that inhaled concentrations of such compounds can essentially be neglected. A further deduction from the experimental data is that under conditions of the inhalation of clean air, the measured exhaled breath concentrations of those compounds should be increased by a factor of 1/(1 - a) to correspond to gaseous equilibrium with the compounds dissolved in the mixed venous blood entering the alveoli. Thus, for isoprene, this is a factor of 3, which we have confirmed experimentally by re-breathing experiments.

• MeSH
• aceton farmakokinetika   MeSH
• amoniak farmakokinetika   MeSH
• butadieny farmakokinetika   MeSH
• dechové testy * MeSH
• formaldehyd farmakokinetika   MeSH
• hemiterpeny farmakokinetika   MeSH
• hmotnostní spektrometrie metody   MeSH
• látky znečišťující vzduch farmakokinetika   MeSH
• lidé MeSH
• methanol farmakokinetika   MeSH
• nadechnutí * MeSH
• oxid deuteria farmakokinetika   MeSH
• pentany farmakokinetika   MeSH
• vydechnutí * MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• aceton MeSH
• amoniak MeSH
• butadieny MeSH
• formaldehyd MeSH
• hemiterpeny MeSH
• isoprene MeSH Prohlížeč
• látky znečišťující vzduch MeSH
• methanol MeSH
• oxid deuteria MeSH
• pentany MeSH

Volatile breath metabolites serve as potential disease biomarkers. Online mass spectrometry (MS) presents real-time quantification of breath volatile organic compounds (VOCs). The study aims to assess the relationship between two online analytical mass spectrometry techniques in the quantification of target breath metabolites: selected ion flow tube mass spectrometry (SIFT-MS) and proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF-MS). The two following techniques were employed: (i) direct injection with bag sampling using SIFT-MS and PTR-ToF-MS and (ii) direct injection and thermal desorption (TD) tube comparison using PTR-ToF-MS. The concentration of abundant breath metabolites, acetone and isoprene, demonstrated a strong positive linear correlation between both mass spectrometry techniques (r = 0.97, r = 0.89, respectively; p < 0.001) and between direct injection and TD tube (r = 0.97, r = 0.92, respectively; p < 0.001) breath sampling techniques. This was reflected for the majority of short chain fatty acids and alcohols tested (r > 0.80, p < 0.001). Analyte concentrations were notably higher with the direct injection of a sampling bag compared to the TD method. All metabolites produced a high degree of agreement in the detection range of VOCs between SIFT-MS and PTR-ToF-MS, with the majority of compounds falling within 95% of the limits of agreement with Bland-Altman analysis. The cross platform analysis of exhaled breath demonstrates strong positive correlation coefficients, linear regression, and agreement in target metabolite detection rates between both breath sampling techniques. The study demonstrates the transferability of using data outputs between SIFT-MS and PTR-ToF-MS. It supports the implementation of a TD platform in multi-site studies for breath biomarker research in order to facilitate sample transport between clinics and the laboratory.

• Klíčová slova
• SIFT-MS, breath analysis, direct injection, thermal desorption: PTR-ToF-MS, volatile organic compound,
• MeSH
• aceton analýza   MeSH
• butadieny analýza   MeSH
• dechové testy přístrojové vybavení   metody   MeSH
• dospělí MeSH
• hemiterpeny analýza   MeSH
• hmotnostní spektrometrie přístrojové vybavení   metody   MeSH
• lidé MeSH
• těkavé organické sloučeniny analýza   MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• aceton MeSH
• butadieny MeSH
• hemiterpeny MeSH
• isoprene MeSH Prohlížeč
• těkavé organické sloučeniny MeSH