Respiratory CO2 combined with a blend of volatiles emitted by endophytic Serendipita strains strongly stimulate growth of Arabidopsis implicating auxin and cytokinin signaling

Rhizospheric microorganisms can alter plant physiology and morphology in many different ways including through the emission of volatile organic compounds (VOCs). Here we demonstrate that VOCs from beneficial root endophytic Serendipita spp. are able to improve the performance of in vitro grown Arabidopsis seedlings, with an up to 9.3-fold increase in plant biomass. Additional changes in VOC-exposed plants comprised petiole elongation, epidermal cell and leaf area expansion, extension of the lateral root system, enhanced maximum quantum efficiency of photosystem II (Fv/Fm), and accumulation of high levels of anthocyanin. Notwithstanding that the magnitude of the effects was highly dependent on the test system and cultivation medium, the volatile blends of each of the examined strains, including the references S. indica and S. williamsii, exhibited comparable plant growth-promoting activities. By combining different approaches, we provide strong evidence that not only fungal respiratory CO2 accumulating in the headspace, but also other volatile compounds contribute to the observed plant responses. Volatile profiling identified methyl benzoate as the most abundant fungal VOC, released especially by Serendipita cultures that elicit plant growth promotion. However, under our experimental conditions, application of methyl benzoate as a sole volatile did not affect plant performance, suggesting that other compounds are involved or that the mixture of VOCs, rather than single molecules, accounts for the strong plant responses. Using Arabidopsis mutant and reporter lines in some of the major plant hormone signal transduction pathways further revealed the involvement of auxin and cytokinin signaling in Serendipita VOC-induced plant growth modulation. Although we are still far from translating the current knowledge into the implementation of Serendipita VOCs as biofertilizers and phytostimulants, volatile production is a novel mechanism by which sebacinoid fungi can trigger and control biological processes in plants, which might offer opportunities to address agricultural and environmental problems in the future

Breath analysis by gas chromatography-mass spectrometry and electronic nose to screen for pleural mesothelioma : a cross-sectional case-control study

Rationale: Malignant pleural mesothelioma (MPM) is mainly caused by previous exposure to asbestos fibers and has a poor prognosis. Due to a long latency period between exposure and diagnosis, MPM incidence is expected to peak between 2020-2025. Screening of asbestos-exposed individuals is believed to improve early detection and hence, MPM management. Recent developments focus on breath analysis for screening since breath contains volatile organic compounds (VOCs) which reflect the cell’s metabolism. Objectives: The goal of this cross-sectional, case-control study is to identify VOCs in exhaled breath of MPM patients with gas chromatography-mass spectrometry (GC-MS) and to assess breath analysis to screen for MPM using an electronic nose (eNose). Methods: Breath and background samples were taken from 64 subjects: 16 healthy controls (HC), 19 asymptomatic former asbestos-exposed (AEx) individuals, 15 patients with benign asbestos-related diseases (ARD) and 14 MPM patients. Samples were analyzed with both GC-MS and eNose. Results: Using GC-MS, AEx individuals were discriminated from MPM patients with 97% accuracy, with diethyl ether, limonene, nonanal, methylcyclopentane and cyclohexane as important VOCs. This was validated by eNose analysis. MPM patients were discriminated from AEx+ARD participants by GC-MS and eNose with 94% and 74% accuracy, respectively. The sensitivity, specificity, positive and negative predictive values were 100%, 91%, 82%, 100% for GC-MS and 82%, 55%, 82%, 55% for eNose, respectively. Conclusion: This study shows accurate discrimination of patients with MPM from asymptomatic asbestos-exposed persons at risk by GC-MS and eNose analysis of exhaled VOCs and provides proof-of-principle of breath analysis for MPM screening

Indoor and outdoor air quality assessment in daycare centres in Ghent (Belgium) in view of outdoor sleeping in an urban environment

Within Flanders, there is an increasing trend to let children sleep outdoors while in daycare. However, within an urban environment, the densely spread emission sources might affect the air quality and possibly limit the areas where outdoor sleeping is favourable. Nevertheless, there is a lack of data regarding the atmospheric pollution levels in and around daycare centres (DCC). Therefore, the focus of this study is to chemically characterize the air quality indoors, outdoors, and in specifically designed cubicles for outdoor sleeping at 12 DCCs spread over the city of Ghent (Belgium). The measuring of a very broad range of different pollutants, provides unique data for indoor and outdoor air quality at daycare centres in Ghent. The use of axial tube (for volatile organic compounds, VOCs) and Radiello (for NO2, SO2, O3) passive samplers enables multi-component sampling, resulting in time -weighted average concentrations for one week. Forty-seven VOCs are identified and, for the majority (40), in-door to outdoor concentration (I/O) ratios higher than one are found. For the remaining seven compounds (e.g. benzene) outdoor concentrations are a factor 1.3-17.9 (median) higher than indoors. Median indoor TVOC concentrations are 152 mu g/m3 and 142 mu g/m3 for the September and January campaign, respectively. Outdoors, these median TVOC concentrations are much lower (24.5 mu g/m3 and 30.6 mu g/m3). For NO2, no noticeable dif-ferences are observed between average indoor and outdoor concentrations (indoors 12 +/- 3 mu g/m3 and 13 +/- 2 mu g/m3 for the September and January campaign, respectively, and outdoors 11 +/- 3 mu g/m3 and 14 +/- 4 mu g/m3). The highest (outdoor) measured concentration is 21 +/- 1 mu g/m3. SO2 concentrations are below 2.62 mu g/m3 (LOQ). Average indoor O3 concentrations are 4 +/- 3 mu g/m3 and 2 +/- 2 mu g/m3 for the September and January campaign, respectively. Much higher values are measured outdoors (46 +/- 3 mu g/m3 and 40 +/- 11 mu g/m3), but the concentrations stayed well below legal standards

Residential VOCs concentration levels in Nsukka, Nigeria

The concentrations of 26 VOCs were measured in ten rural and ten urban households for two 7-day sampling campaigns in the Nsukka area, Southeast Nigeria, between 2017 and 2019. Samples were passively collected in the kitchen, living room, and outdoor using Tenax TA axial sorbent tubes. Analysis was done by thermal desorption gas chromatography coupled with mass spectrometry using ethylbenzene-d10 as an internal standard. The wet season kitchen and outdoor TVOCs are 265 and 45 mu g/m3 in urban, and 199 and 21 mu g/m3 in rural households. The dry season median TVOCs concentrations in the kitchens, living rooms, and outdoors are 254, 115, and 71 mu g/m3 in urban and 324, 145, and 41 mu g/m3 in rural areas, indicating a rank order of kitchen > living room > outdoor. This indicates spatial and seasonal variability of the VOCs concentration among the locations in the homes and between urban and rural areas. However, the difference between the urban and rural TVOCs levels is only significant (p < 0.05) for the outdoor levels. The TVOCs indoor to outdoor concentration ratios for the kitchen during the dry season are 1.3-18, implying indoor sources. The median (range) benzene concentrations in the kitchens are 80 mu g/m3 (10-306 mu g/m3), 47 mu g/m3 (18-90 mu g/m3), 26 mu g/m3 (4-122 mu g/m3), and 15 mu g/m3 (8-104 mu g/m3) for kitchens using firewood, charcoal, kerosene, and LPG which indicates that exposure to benzene could be five times more in firewood kitchens than in LPG ones. Furthermore, the estimated lifetime cancer risk and hazard quotient from the present study exceed the respective thresholds of 6.00E-06 and 1.0, indicating that people are at risk in the studied homes and underscores the urgency for effective air quality management in the area

Headspace volatile organic compound profiling of pleural mesothelioma and lung cancer cell lines as translational bridge for breath research

IntroductionMalignant pleural mesothelioma (MPM) is a lethal cancer for which early-stage diagnosis remains a major challenge. Volatile organic compounds (VOCs) in breath proved to be potential biomarkers for MPM diagnosis, but translational studies are needed to elucidate which VOCs originate from the tumor itself and thus are specifically related to MPM cell metabolism. MethodsAn in vitro model was set-up to characterize the headspace VOC profiles of six MPM and two lung cancer cell lines using thermal desorption-gas chromatography-mass spectrometry. A comparative analysis was carried out to identify VOCs that could discriminate between MPM and lung cancer, as well as between the histological subtypes within MPM (epithelioid, sarcomatoid and biphasic). ResultsVOC profiles were identified capable of distinguishing MPM (subtypes) and lung cancer cells with high accuracy. Alkanes, aldehydes, ketones and alcohols represented many of the discriminating VOCs. Discrepancies with clinical findings were observed, supporting the need for studies examining breath and tumor cells of the same patients and studying metabolization and kinetics of in vitro discovered VOCs in a clinical setting. ConclusionWhile the relationship between in vitro and in vivo VOCs is yet to be established, both could complement each other in generating a clinically useful breath model for MPM