Detection and validation of volatile metabolic patterns over different strains of two human pathogenic bacteria during their growth in a complex medium using multi-capillary column-ion mobility spectrometry (MCC-IMS)

Abstract

Headspace analyses over microbial cultures using multi-capillary column-ion mobility spectrometry (MCC-IMS) could lead to a faster, safe and cost-effective method for the identification of pathogens. Recent studies have shown that MCC-IMS allows identification of bacteria and fungi, but no information is available from when on during their growth a differentiation between bacteria is possible. Therefore, we analysed the headspace over human pathogenic reference strains of Escherichia coli and Pseudomonas aeruginosa at four time points during their growth in a complex fluid medium. In order to validate our findings and to answer the question if the results of one bacterial strain can be transferred to other strains of the same species, we also analysed the headspace over cultures from isolates of random clinical origin. We detected 19 different volatile organic compounds (VOCs) that appeared or changed their signal intensity during bacterial growth. These included six VOCs exclusively changing over E. coli cultures and seven exclusively changing over P. aeruginosa cultures. Most changes occurred in the late logarithmic or static growth phases. We did not find differences in timing or trends in signal intensity between VOC patterns of different strains of one species. Our results show that differentiation of human pathogenic bacteria by headspace analyses using MCC-IMS technology is best possible during the late phases of bacterial growth. Our findings also show that VOC patterns of a bacterial strain can be transferred to other strains of the same species.

The in vitro identification and quantification of volatile biomarkers released by cystic fibrosis pathogens

“…These include but are not limited to selected ion ow tube mass spectrometry (SIFT-MS), 6 gas chromatography mass spectrometry (GCMS), 14 proton transfer reaction mass spectrometry (PTR-MS), 15 ion mobility spectrometry (IMS). 16 A detailed review of each of these techniques is beyond the scope of this review but each has relative pro and cons. 17 The technique most frequently used by our team is SIFT-MS and this will therefore be discussed in more detail.…”

Non-invasive monitoring of bacterial growth and auto-induced protein production in a bioreactor with a closed-loop GC-IMS

“…Ion mobility spectrometry (IMS) in combination with a pre-separation via multi capillary chromatography (MCC) has been used to detect specific MVOCs, e.g., emitted from Escherichia coli (E. coli) [8], or to differentiate between E. coli and Pseudomonas aeruginosa [9], each grown in shake flasks. Furthermore, in recent work Halbfeld et al [10] used a commercially available MCC-IMS with lower mobility resolution as exhaust gas sensor to monitor the yeast fermentation in a small bioreactor.…”

Analysis of Volatile Metabolites Released by Staphylococcus Aureus using Gas Chromatography-Mass Spectrometry and Determination of its Antifungal Activity

“…Thirty five bioactive compounds were identified in the methanolic extract of Staphylococcus aureus. GC-MS analysis of Staphylococcus aureus revealed the existence of the: Hexanoic acid , 2-methyl, 12,15-Octadecadiynoic acid , methyl ester, 1-Aminononadecane , 2,3,4,5,6,7, Cystine,3,butylamine, 3-methoxy-2-(1-methylethyl)-5-(2-methylpropyl)pyrazine, Uric acid, Thiocyanic acid 4-methoxy-2,6-dimethyl-3-pyridyl ester, 12-Dimethylamino-10-oxododecanoic acid, Glycyl-D-asparagine, Actinomycin C2, 12-Octadecenoic acid , methyl ester, 6-Octadecenoic acid , methyl ester ,(z)-, 2,5-Piperazinedione , 3,6-bis(2-methylpropyl)-, l-Leucyl-d-leucine and Methyl 12-hydroxy-9-octadecenoate. Gramineae poaceae was very highly active (6.71±0.13) mm.…”

“…It has been estimated that approx. 20-30% of the general population are S. aureus carriers 6 . Staphylococcus aureus can be found in the anterior nares of a great proportion of a healthy human population.…”