| Title: | A chromatographic approach to distinguish Gram-positive from Gram-negative bacteria using exogenous volatile organic compound metabolites |
| Author(s): | Ramirez-Guizar S; Sykes H; Perry JD; Schwalbe EC; Stanforth SP; Perez-Perez MCI; Dean JR; |
| Address: | "Department of Applied Sciences, Northumbria University, Newcastle upon Tyne NE1 8ST, UK; Tecnologico Nacional de Mexico, Instituto Tecnologico de Celaya, Departamento de Ingenieria Bioquimica, Av. Tecnologico y Garcia Cubas S/N, Celaya, Gto. C.P. 38010, Mexico. Department of Applied Sciences, Northumbria University, Newcastle upon Tyne NE1 8ST, UK. Department of Microbiology, Freeman Hospital, Newcastle upon Tyne, NE7 7DN, UK. Tecnologico Nacional de Mexico, Instituto Tecnologico de Celaya, Departamento de Ingenieria Bioquimica, Av. Tecnologico y Garcia Cubas S/N, Celaya, Gto. C.P. 38010, Mexico. Department of Applied Sciences, Northumbria University, Newcastle upon Tyne NE1 8ST, UK. Electronic address: John.Dean@northumbria.ac.uk" |
| DOI: | 10.1016/j.chroma.2017.04.015 |
| ISSN/ISBN: | 1873-3778 (Electronic) 0021-9673 (Linking) |
| Abstract: | "This paper utilized L-alanine aminopeptidase activity as a useful approach to distinguish between Gram-negative and Gram-positive bacteria. This was done using two enzyme substrates, specifically 2-amino-N-phenylpropanamide and 2-amino-N-(4-methylphenyl)propanamide which liberated the volatile compounds aniline and p-toluidine, respectively. Two complementary analytical techniques have been used to identify and quantify the VOCs, specifically static headspace multicapillary column gas chromatography ion mobility spectrometry (SHS-MCC-GC-IMS) and headspace solid phase microextraction gas chromatography mass spectrometry (HS-SPME-GC-MS). Superior limits of detection were obtained using HS-SPME-GC-MS, typically by a factor of x6 such that the LOD for aniline was 0.02mug/mL and 0.01mug/mL for p-toluidine. In addition, it was also possible to determine indole interference-free by HS-SPME-GC-MS at an LOD of 0.01mug/mL. The approach was applied to a range of selected bacteria: 15 Gram-negative and 7 Gram-positive bacteria. Use of pattern recognition, in the form of Principal Component Analysis, confirmed that it is possible to differentiate between Gram-positive and Gram-negative bacteria using the enzyme generated VOCs, aniline and p-toluidine. The exception was Stenotrophomonas maltophilia which showed negligible VOC concentrations for both aniline and p-toluidine, irrespective of the analytical techniques used and hence was not characteristic of the other Gram-negative bacteria investigated. The developed methodology has the potential to be applied for clinical and food applications" |
| Keywords: | Discriminant Analysis Gas Chromatography-Mass Spectrometry/*methods Gram-Negative Bacteria/*chemistry/metabolism Gram-Positive Bacteria/*chemistry/metabolism Solid Phase Microextraction/*methods Volatile Organic Compounds/*chemistry/isolation & purificati; |
| Notes: | "MedlineRamirez-Guizar, Susana Sykes, Hannah Perry, John D Schwalbe, Edward C Stanforth, Stephen P Perez-Perez, Ma Cristina I Dean, John R eng Evaluation Study Netherlands 2017/04/26 J Chromatogr A. 2017 Jun 9; 1501:79-88. doi: 10.1016/j.chroma.2017.04.015. Epub 2017 Apr 12" |
