Identification of Volatile Organic Compounds Produced by Bacteria Using HS-SPME-GC–MS

Abstract

The analysis of volatile organic compounds (VOCs) as a tool for bacterial identification is reported. Headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography-mass spectrometry (GC-MS) was applied to the analysis of bacterial VOCs with the aim of determining the impact of experimental parameters on the generated VOC profiles. The effect of culture medium, SPME fiber type and GC column were fully evaluated with the Gram-negative bacteria Escherichia coli and Klebsiella pneumoniae and the Gram-positive species Staphylococcus aureus. Multivariate analysis, including cluster analysis and principal component analysis, was applied to VOC data to determine whether the parameters under investigation significantly affected bacterial VOC profiles. Culture medium, and to a lesser extent, SPME fiber type, were found to significantly alter detected bacterial VOC profiles. The detected VOCs varied little with the polarity of the GC column. The results indicate that the generated bacterial VOC profiles need careful evaluation if they are to be used for clinical diagnostics. The whole process is limited by the need to grow the bacteria in broth (18 h) before extraction and analysis (63 min).

Coupling dye-integrated polymeric membranes with smartphone detection to classify bacteria

“…During their growth process, these bacteria produce volatile organic compounds (VOCs) 6,7 that are unique to each genus or species. The VOCs produced can therefore be viewed as a chemical ngerprint for these organisms and can subsequently be used to help to detect the pathogens in, for example, spiked blood culture.…”

Detection of exogenous VOCs as a novel in vitro diagnostic technique for the detection of pathogenic bacteria

“…Many cultures produce a number of VOCs naturally (endogenous VOCs) as a result of metabolism of substrates available in the growth media provided, thus the methodology can be broadly applied to culture methods currently in use assuming the bacteria of interest produces VOCs. A number of studies have described the ability to identify bacteria based on the VOCs detected in the atmosphere surrounding a culture [2][3][4][5]. The potential methods for VOC detection are shown in Figure 1.…”

“…In reality the odour experienced by the human olfactory system is caused by a complex mixture of VOCs. There has been a significant volume of research conducted into the elucidation of the odour causing compounds in a search for species specific profiles of volatile metabolites, which could act as biomarkers and serve as a means of diagnosis [3,5,[7][8][9][10][11].…”

“…In initial evaluation of this approach it is important to consider and optimize various sampling parameters, such as the fibre coating type, extraction time, temperature equilibration time, extraction temperature and desorption temperature [5]. There is a large body of published data regarding the identification of in vitro volatile microbial metabolites by HS-SPME-GC-MS and other techniques such as ion mobility spectrometry (IMS), which have been extensively reviewed in the literature by various authors [12][13][14][15], much of which has been compiled in the online database mVOC [16].…”

Mining into interspecific bacterial interactions

“…This discrepancy between numbers of detected and identified compounds shows that the identification of bacterial volatiles is yet a challenging and time demanding task, even with the use of sophisticated programs and software for metabolomics data analysis. Hence, the produced volatile blends are very complex and consist of a mixture of many unknown and difficult to identify compounds (Tait et al, 2014). Most of the volatile organic compounds that were tentatively identified within this study (~58 %) contained sulfur (e.g.…”