11. TD/GC–MS analysis of volatile markers emitted from mono- and co-cultures of Enterobacter cloacae and Pseudomonas aeruginosa in artificial sputumIain R. White, Oluwasola Lawal, Hugo Knobel, Weda Hans, Tamara M E Nijsen, Royston Goodacre, Stephen J. Fowler, Waqar M Ahmed, Antonio Artigas, Jonathan Barnard-Smith, Lieuwe D Bos, Marta Camprubi, Luis Coelho, Paul Dark, Alan Davie, Emili Diaz, Gemma Goma, Timothy Felton, Jan H Leopold, Pouline M P van Oort, Pedro Póvoa, Craig Portsmouth, 2018, original scientific article Abstract: Introduction: Infections such as ventilator-associated pneumonia (VAP) can be caused by one or more pathogens. Current methods for identifying these pathogenic microbes often require invasive sampling, and can be time consuming, due to the requirement for prolonged cultural enrichment along with selective and differential plating steps. This results in delays in diagnosis which in such critically ill patients can have potentially life-threatening consequences. Therefore, a non-invasive and timely diagnostic method is required. Detection of microbial volatile organic compounds (VOCs) in exhaled breath is proposed as an alternative method for identifying these pathogens and may distinguish between mono- and poly-microbial infections. Objectives: To investigate volatile metabolites that discriminate between bacterial mono- and co-cultures. Methods: VAP-associated pathogens Enterobacter cloacae and Pseudomonas aeruginosa were cultured individually and together in artificial sputum medium for 24 h and their headspace was analysed for potential discriminatory VOCs by thermal desorption gas chromatography–mass spectrometry. Results: Of the 70 VOCs putatively identified, 23 were found to significantly increase during bacterial culture (i.e. likely to be released during metabolism) and 13 decreased (i.e. likely consumed during metabolism). The other VOCs showed no transformation (similar concentrations observed as in the medium). Bacteria-specific VOCs including 2-methyl-1-propanol, 2-phenylethanol, and 3-methyl-1-butanol were observed in the headspace of axenic cultures of E. cloacae, and methyl 2-ethylhexanoate in the headspace of P. aeruginosa cultures which is novel to this investigation. Previously reported VOCs 1-undecene and pyrrole were also detected. The metabolites 2-methylbutyl acetate and methyl 2-methylbutyrate, which are reported to exhibit antimicrobial activity, were elevated in co-culture only. Conclusion: The observed VOCs were able to differentiate axenic and co-cultures. Validation of these markers in exhaled breath specimens could prove useful for timely pathogen identification and infection type diagnosis. Keywords: Bacteria, Enterobacter cloacae, Gas Chromatography-Mass Spectrometry, Infection, Pseudomonas aeruginosa, Volatile organic compounds Published in RUNG: 18.07.2019; Views: 4527; Downloads: 114 Full text (1,29 MB) |
12. Vitis vinifera berry metabolic composition during fruit maturation: Implications of defoliationGerhard C. Rossouw, Katja Šuklje, Jason P. Smith, Celia Barril, Alain Deloire, Holzapfel Bruno, 2018, original scientific article Keywords: vinska trta, defoliacija, metabolomika, primarni metabolizem Published in RUNG: 03.04.2018; Views: 5239; Downloads: 0 This document has many files! More... |
13. Vitis vinifera root and leaf metabolic composition during fruit maturation: Implications of defoliationGerhard, C. Rossouw, Baverley, A, Orchard, Katja Šuklje, Jason, A Smith, Celia Barril, Alain Deloire, Bruno, P. Holzapfel, original scientific article Keywords: leaf removal, metabolomics, primary metabolsim, vitis vinifera Published in RUNG: 26.07.2017; Views: 4974; Downloads: 0 This document has many files! More... |
14. Electrical characteristics of the vertical GaN rectifiers fabricated on bulk GaN waferYaqi Wang, Hui Xu, Siddharth Alur, Yogesh Sharma, Fei Tong, Patrick Gartland, Tamara Issacs-Smith, Claude Ahyi, John Williams, Minseo Park, Ginger Wheeler, Mark Johnson, Andrew A. Allerman, Andrew Hanser, Tanya Paskova, Edward A. Preble, Keith R. Evans, 2011, original scientific article Keywords: GaN, rectifier Published in RUNG: 17.01.2017; Views: 4389; Downloads: 0 This document has many files! More... |
15. Growth of ZnO Nanorod Arrays on Flexible Substrates: Effect of Precursor Solution ConcentrationFei Tong, Kyusang Kim, Yaqi Wang, Resham Thapa, Yogesh Sharma, Aaron Modic, Ayayi Ahyi, Tamara Issacs-Smith, John Williams, Hosang Ahn, Hyejin Park, Dong-Joo Kim, Sungkoo Lee, Eunhee Lim, Kyeong K. Lee, Minseo Park, 2012, original scientific article Keywords: ZnO Nanorod Arrays, ITO-PET, solution growth Published in RUNG: 16.01.2017; Views: 4721; Downloads: 0 This document has many files! More... |
16. Ultra-low leakage and high breakdown Schottky diodes fabricated on free-standing GaN substrateYaqi Wang, Siddharth Alur, Yogesh Sharma, Fei Tong, Resham Thapa, Patrick Gartland, Tamara Issacs-Smith, Claude Ahyi, John Williams, Minseo Park, Mark Johnson, Tanya Paskova, Edward A Preble, Keith Evans, 2011, original scientific article Keywords: free-standing GaN substrate, Ultra-low leakage and high breakdown Schottky diodes Published in RUNG: 16.01.2017; Views: 4269; Downloads: 0 This document has many files! More... |