Modified mycotoxins

Food or feed are not necessarily safe due to the absence or low concentrations of well-known mycotoxins, as these toxic compounds can be present in disguise as a result of plant, mammal or fungal metabolism or even food processing (Berthiller, Schuhmacher, Adam, Krska, 2009 Berthiller et al., 2013). Modified mycotoxins... 

Several Fusarium toxins such as DON, fumonisins, fusarenon-x, fusaric acid, nivalenol, T-2, HT-2 and ZEA are prone to masking biofransformations or binding by plants (Berthiller et al., 2013). In addition, other mycotoxins such as OTA and patulin have been found in conjugated forms. The major form of modified DON is deoxynivalenol-3-p-D-glucopyranoside (D3G), which is perhaps the most widely studied cereal-associated modified mycotoxin so far. 

Food and beverage processing can alter mycotoxins chanically. For example, microbes used in fermentations may transform mycotoxins to less toxic compounds. So far, only a few studies have been carried out concerning the modified mycotoxins in the barley-to-beer chain. The studies have indicated that bound DON appears to be fairly common in barley (Lancova et al., 2008 Zhou, He, Schwarz, 2008). Zhou et al. (2008) reported that bound DON in naturally infected barley was detected in almost 40% of samples and represented an additional 6-21% of DON determined by the standard gas chromatography method. 

The extractable conjugated or bound mycotoxins are not currently regulated by legislation (Berthiller et al., 2013). Further studies are required on determination of modified mycotoxins and on their stability, transformation, toxic properties and bioavailability. With respect to regulation, a possible approach in the future could be the definition of the sum of all relevant forms of each mycotoxin, including its relevant derivatives. 

The stages in commodity handling at which aflatoxin and other mycotoxins can be detected and their amounts modified are shown in Figure 9.4. Aspergillus spp. thrive in hot, humid, subtropical and tropical climates. When environmental conditions favor aflatoxin production, accumulation is rapid, both in the field and in storage. 

Some cultivars that have shown resistance to FHB are ten times more resistant to mycotoxin contamination (Wang and Miller, 1988). This was due to the presence of a modified peptidyl transferase (at protein synthesis). Early studies had suggested that wheat appeared able to metabolize deoxynivalenol in the field (Miller and Young, 1985 Scott et al., 1984). This was shown later to... 

SPR systems also showed encouraging results with their ability to detect mycotoxins. The BIACORE was used to detect a mycotoxin, DON, produced by Fusarium species, from spiked wheat sample in a competitive inhibition assay (Schnerr et ah, 2002). Biotinylated DON was immobilized on the sensor chip which was previously coated with strep-tavidin. Mycotoxin extracts from wheat samples were first allowed to react with the antibody and then injected into the BIACORE. The detection range was established to be 0.13-10 pg/ml. In a slightly modified format, DON was also detected by SPR at a range of 2.5-30 ng/ml (Tudos et ah, 2003). 

Yeasts have also been used to detoxify the diet of mycotoxins. Modified yeast cell wall mannanoligosaccharide (MOS) has been reported to effectively bind aflatoxin and to bind ochratoxin and the fusariotoxins to a lesser degree. This product has advantages over other binding agents in that it does not bind vitamins or minerals (Devegowda et al., 1998). 

Ochratoxin-A (OTA), a mycotoxin produced in unstored food and beverages has recently been detected using CH-Fe304 nanobiocomposite modified indium-tin oxide (ITO) electrode [73], This immunosensor shows a specific response to OTA detection in the range of 0.5 - 6 ng/dL with a detection limit of 0.5 ng dL 1. The sensitivity of the bioelectrode has been found to be 36 pA/ng dL"1 cm 2 with response time of 18s [101],... 

Natural products represent a diversity of chemical compounds with varied biological activities. Natural products are an important source of novel pharmaceuticals as well as agricultural pesticides (1,2). Natural products are derived from a number of pathways that create basic scaffolds that are further modified by various tailoring enzymes to create the wide diversity of structures that exist in nature. Polyketide synthases are responsible for the synthesis of an array of natural products including antibiotics such as erythromycin in bacteria (3) and mycotoxins such as aflatoxin in fungi (4). Furthermore, in plants they are part of the biosynthetic machinery of flavonoids, phytoalexins, and phenolic lipi (5,6). 

Maragos, CM, M AppeU, V Lippolis and AL Visconti (2008). Use of cyclodextrins as modifiers of fluorescence in the detection of mycotoxins. Food Additives Contaminants Part A, 25(2), 164-171. 

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