Electronic Nose-Based Fusarium Detection and Deoxynivalenol Aptamer Development

Abstract

Fungal infestation on wheat is an increasingly grave nutritional problem in many countries worldwide. Fusarium species are especially harmful pathogens due to their toxic metabolites. Deoxynivalenol (DON) in particular, is a secondary metabolite that contaminates frequently cereal grain, cereal-based food or feed and is thus a serious health risk to humans. To comply with governmental regulations, new tools for fast and accurate DON and Fusaria estimation have to be developed. The discrimination properties of electronic noses have already been shown and are promising with respect to food control. Aptamers for ligand binding are already known and are suitable as recognition elements for biosensors. In this work the volatile compounds released by Fusarium cerealis, Fusarium graminearum, Fusarium culmorum and Fusarium redolens were studied. Using an electronic nose, it was possible to differentiate between infected and non-infected dry, whole wheat grain. The electronic nose was capable of distinguishing between four Fusaria species with an accuracy higher than 80%. Furthermore, DNA aptamers have been selected, reacting to DON with different affinities. The used SELEX is based on the formation of aptamer beacons upon DON binding. A single-stranded DNA library, covering 40 random positions, was bound to an affinity column. The library consisted of an estimated diversity of 6.6e14 molecules. Sequences which underwent a conformational change consequently to the addition of DON were collected and amplified. Eventually, 39 DNA structures of the amplifed pool were chosen for binding analysis among which 14 reacted to the application of DON.