Facile and fast detection of bacteria via the detection of exogenous volatile metabolites released by enzymatic hydrolysis

Abstract

A low-cost, innovative and non-invasive colorimetric test, which can be universally used, is proposed to detect pathogenic bacteria via the simple and fast detection of volatile metabolites released by enzymatic hydrolysis. The proof of concept is shown via three sets of experiments studying the release of the p-nitrophenol metabolite in solution in the E. coli cultures containing 4-nitrophenyl-β-d-glucuronide, the trapping efficiency of the gaseous metabolite by various tailored and functionalized xerogels, and the trapping and detection of gaseous p-nitrophenol released by E. coli bacteria.

Analysis of pathogenic bacteria using exogenous volatile organic compound metabolites and optical sensor detection

“…However, using a xerogel, p-nitrophenol was detected aer 16 h incubation with an initial E. coli inoculum of 10 5 CFU mL À1 . 8 The initial inoculum required to produce a detectable amount of colour could be reduced by decreasing the headspace volume. Following the implementation of a new experimental set-up with a smaller sample headspace volume, a study investigating the minimum time required for sufficient exogenous VOC liberation and detection would be useful.…”

“…7 E. coli was detected via the generation of the exogenous 2-nitrophenol using the enzyme substrate 2-nitrophenyl-b-D-galactoside; ion mobility spectrometry was used for VOC detection. Subsequently xerogels have been used to trap and colorimetrically detect VOCs, specically 4-nitrophenol released by enzymatic hydrolysis of 4nitrophenyl-b-D-glucuronide 8 and p-dimethylaminocinnamaldehyde for the detection of E. coli (a known indole producer). 9 In the case of the latter example, p-dimethylaminocinnamaldehyde reacted with indole to generate a green colour within the xerogel.…”

Functionalized nanoporous materials for volatile metabolites monitoring with direct optical transduction

“…Here we propose to replace GC-IMS by a low-cost, disposable sensor, using optical transduction. It is based on a silica xerogel where the volatile metabolites are trapped and concentrated [6]. This nanoporous matrix shows a high surface area with a pore size adjusted to the metabolite.…”

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

“…Using this sensor and a modified petri dish with a suspended compartment to house the sensor, as few as 100 cells of E. coli could be detected when cultured on LB agar or DEV tryptophan agar within 17 hours of incubation by observing the gel colour change from orange to green. A similar APTES functionalized silica xerogel was also produced by the same group [37] for the detection of 4-nitrophenol produced by the enzymatic hydrolysis of 4-nitrophenyl-β-D-glucuronide by E. coli. In this system [37], the xerogel is cast into the recess of a cuvette, above which an E. coli culture containing the substrate (i.e.…”

“…A similar APTES functionalized silica xerogel was also produced by the same group [37] for the detection of 4-nitrophenol produced by the enzymatic hydrolysis of 4-nitrophenyl-β-D-glucuronide by E. coli. In this system [37], the xerogel is cast into the recess of a cuvette, above which an E. coli culture containing the substrate (i.e. 4-nitrophenyl-β-D-glucuronide) was placed in a microcentrifuge tube.…”