Limitations to the Use of Solid-Phase Microextraction for Quantitation of Mixtures of Volatile Organic Sulfur Compounds

Murray, R. A.

doi:10.1021/ac001176m

Cited by 100 publications

(56 citation statements)

References 13 publications

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“…Peaks were detected by using the total ion current (TIC) and a selected ion trace with a mass range of m/z 59.85 to 60.15 for the determination of COS. Quantification was performed with comparison to a calibration curve based on a COS standard (Ն96%; Aldrich). As other volatiles (e.g., isothiocyanate) in the reaction mixture may interfere with adsorption of COS to the SPME fiber, which would not be the case for measurement of the calibration curve, this method should be regarded as semiquantitative and likely overestimates the amount of COS in the reaction mixture (28). The other expected reaction product was phenylethylamine.…”

Section: Methodsmentioning

confidence: 99%

SaxA-Mediated Isothiocyanate Metabolism in Phytopathogenic Pectobacteria

Welte

Rosengarten

Graaf

et al. 2016

Appl Environ Microbiol

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Pectobacteria are devastating plant pathogens that infect a large variety of crops, including members of the family Brassicaceae. To infect cabbage crops, these plant pathogens need to overcome the plant's antibacterial defense mechanisms, where isothiocyanates are liberated by hydrolysis of glucosinolates. Here, we found that a Pectobacterium isolate from the gut of cabbage root fly larvae was particularly resistant to isothiocyanate and even seemed to benefit from the abundant Brassica root metabolite 2-phenylethyl isothiocyanate as a nitrogen source in an ecosystem where nitrogen is scarce. The Pectobacterium isolate harbored a naturally occurring mobile plasmid that contained a sax operon. We hypothesized that SaxA was the enzyme responsible for the breakdown of 2-phenylethyl isothiocyanate. Subsequently, we heterologously produced and purified the SaxA protein and characterized the recombinant enzyme. It hydrolyzed 2-phenylethyl isothiocyanate to yield the products carbonyl sulfide and phenylethylamine. It was also active toward another aromatic isothiocyanate but hardly toward aliphatic isothiocyanates. It belongs to the class B metal-dependent beta-lactamase fold protein family but was not, however, able to hydrolyze beta-lactam antibiotics. We discovered that several copies of the saxA gene are widespread in full and draft Pectobacterium genomes and therefore hypothesize that SaxA might be a new pathogenicity factor of the genus Pectobacterium, possibly compromising food preservation strategies using isothiocyanates. P ectobacteria are phytopathogens that cause tuber soft rot and blackleg (stem rot) in many horticulturally and economically important crops during cultivation, transport, or storage. Most Pectobacterium spp., e.g., Pectobacterium carotovorum or P. wasabiae, can be detrimental to many different plants, such as potato, sugar beet, cabbage, wasabi, chicory, and Ornithogalum plants, whereas other Pectobacterium spp., e.g., P. atrosepticum and P. betavasulorum, have a more narrow host range of potato and sugar beet plants, respectively (1).Several pathogenicity factors of soft-rot-causing Pectobacterium spp. have been found during the last decades (2-4). Of these, plant cell wall-degrading enzymes produced by Pectobacterium spp. have a large impact on the progress of the disease, as their production leads to the degradation of invaded plant tissue (2, 3). The production of these enzymes is dependent on cell density and regulated by quorum sensing through N-acetylhomoserine lactone (5) and intracellular regulators (6, 7). Motility and nutrient uptake are also factors influencing phytopathogenicity (4,(8)(9)(10). Besides these general pathogenicity factors, phytopathogens have to overcome the toxicity of plant allelochemicals. Important allelochemicals of members of the family Brassicaceae (cabbages and mustards) are isothiocyanates that are liberated by the glucosinolate-myrosinase defense system (11-13). The antimicrobial effect of isothiocyanates has been mainly attributed to their reactivity w...

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Section: Methodsmentioning

confidence: 99%

SaxA-Mediated Isothiocyanate Metabolism in Phytopathogenic Pectobacteria

Welte

Rosengarten

Graaf

et al. 2016

Appl Environ Microbiol

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“…This type of coating is commonly recommended for pre-concentration of VSCs [21][22][23][24]26,32,33]. Prior to the use all fibers were preconditioned in GC injector at 290 • C for 2 h. SPME was performed in two types of vials: 21 ml in volume (PerkinElmer, USA) and 20 ml in volume (Gerstel, Germany).…”

Section: Spme Materials and Methodsmentioning

confidence: 99%

Improved pre-concentration and detection methods for volatile sulphur breath constituents

Mochalski

Wzorek

Śliwka

et al. 2009

Journal of Chromatography B

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“…7 Although solid-phase micro-extraction (SPME) was also applied to isolate BTEX from water samples either by direct adsorption from the liquid 8 or via headspace sampling, 9 the limitation of SPME for the quantitation of sulfurbased VOC has been reported. 12 The VOCs analyzed from air and water samples by open-tubular, wall-coated columns, 13 solvent trapping 14 and semi-VOC from air by atmosphericpressure chemical ionization mass spectrometry 15 were also described.…”

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confidence: 99%