Gas Chromatography–Differential Mobility Spectrometry and Gas Chromatography–Mass Spectrometry for the detection of coliform bacteria

Abstract

The use of miniaturized Gas Chromatography -Differential Mobility Spectrometry (GC-DMS) is shown for the detection and identification of coliform bacteria (including Escherichia coli) grown in five different media: Colilert ® -18, glucose broth, M9-medium, tryptophan broth, and tryptic soy broth. After incubation in the different media, headspace containing the volatile compounds were analyzed by the GC-DMS and the results were validated by Gas Chromatography -Mass Spectrometry (GC-MS). Results showed that the GC-DMS and GC-MS were able to detect onitrophenol released by coliform bacteria incubated in Colilert ® -18. In addition to that, GC-MS was able to detect indole compound released by coliform bacteria grown in all media. Neither GC-DMS nor GC-MS could detect 4methylumbelliferone from the headspace of E. coli grown in media containing 4-methylumbelliferyl-β-D-glucoronide (MUG) substrate, which was available in Colilert ® -18. With the miniaturized GC-DMS being portable and can be operated using ambient pressure, this method offers a potential on-site detection of coliform bacteria.

Approaches for the Detection of Escherichia coli in Wastewater: A Short Review

“… The Scheme for the identification of E. coli in water using GC‐DMS. Reprinted from 2015 Elsevier [38] …”

“…The -D-galactosidase enzyme in coliform bacteria hydrolyzes ONPG in the existence of ONPG substrate, creating o-nitrophenol. [38] The visible or absence of coliform (especially E. coli) can be established in a conventional way employing Colilert®-18 after 18 h of culture by the visible or absence of yellowish colour of o-nitrophenol. The existence or lack of brilliant blue fluorescence results can be exploited to validate the occurrence of E. coli.…”

“…An o‐nitrophenyl‐D‐galactopyranoside (ONPG) substrate is included in a Colilert®‐18 condition. The ‐D‐galactosidase enzyme in coliform bacteria hydrolyzes ONPG in the existence of ONPG substrate, creating o‐nitrophenol [38] . The visible or absence of coliform (especially E. coli ) can be established in a conventional way employing Colilert®‐18 after 18 h of culture by the visible or absence of yellowish colour of o‐nitrophenol.…”

Modern Analytical Techniques for Detection of Bacteria in Surface and Wastewaters

“…These methods exhibit high specificity and require low volumes of samples; however, complex pre-steps for sample preparation are involved, and highly qualified and skilled individuals must operate the equipment. The strategies for bacterial detection applied in the case of PCR require the extraction of bacterial DNA and the use of a thermocycler, which is unsuitable for on-field testing [34,35].…”

Paper-based sensors for bacteria detection

“…In addition to the enzyme-linked immunosorbent assay (ELISA), polymerase chain reaction (PCR) and conventional culture-based assays [8][9][10] , common pathogen detection methods include biochemical techniques 11 , instrumental-based approaches, such as flow cytometry and gas chromatography 12,13 , as well as spectroscopy-based techniques, such as Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy 14,15 . Despite being accurate, robust and sensitive down to the single-cell level 16 , these techniques are costly and time-consuming (hours to days), requiring centralized laboratories, trained personnel, sample pre-treatment and multi-step processing.…”