Abstract
This paper reports the first results on obtaining an enzyme preparation that might be promising for the simultaneous decontamination of plant feeds contaminated with a polyketide fusariotoxin, zearalenone (ZEN), and enhancing the availability of their nutritional components. A novel ZEN-specific lactonohydrolase (ZHD) was expressed in a Penicillium canescens strain PCA-10 that was developed previously as a producer of different hydrolytic enzymes for feed biorefinery. The recombinant ZHD secreted by transformed fungal clones into culture liquid was shown to remove the toxin from model solutions, and was able to decontaminate wheat grain artificially infected with a zearalenone-producing Fusarium culmorum. The dynamics of ZEN degradation depending on the temperature and pH of the incubation media was investigated, and the optimal values of these parameters (pH 8.5, 30 °C) for the ZHD-containing enzyme preparation (PR-ZHD) were determined. Under these conditions, the 3 h co-incubation of ZEN and PR-ZHD resulted in a complete removal of the toxin from the model solutions, while the PR-ZHD addition (8 mg/g of dried grain) to flour samples prepared from the infected ZEN-polluted grain (about 16 µg/g) completely decontaminated the samples after an overnight exposure.
Highlights
For current high-productive agriculture, the provision of the safety of feedstuffs and the improvement of their nutritional value are important and interrelated challenges, which requireToxins 2020, 12, 475; doi:10.3390/toxins12080475 www.mdpi.com/journal/toxinsToxins 2020, 12, 475 an integrated approach
A comparison of PR-ZEN-specific lactonohydrolase (ZHD) and a preparation of ZEN-catabolizing extracellular metabolites from the strain GRZ7 (p-GRZ7) used in our research as a source of a zearalenone-specific lactonohydrolase obtained from the strain GRZ7 (p-GRZ7) used in our research as a source of a zearalenone-specific gene showed that the target activity of PR-ZHD was significantly more effective (Figure 7)
After a 3 day lactonohydrolase gene showed that the target activity of PR-ZHD was significantly more effective incubation under optimal conditions, the average reduction of ZEN content exposed to p-GRZ7 used at a (Figure 7)
Summary
For current high-productive agriculture, the provision of the safety of feedstuffs and the improvement of their nutritional value are important and interrelated challenges, which requireToxins 2020, 12, 475; doi:10.3390/toxins12080475 www.mdpi.com/journal/toxinsToxins 2020, 12, 475 an integrated approach. One of the most common fusariotoxins, zearalenone (ZEN) [4,5], is synthesized through a polyketide pathway as a secondary metabolite in several common Fusarium species (e.g., F. culmorum, F. graminearum, and F. avenaceum, F. poae, F. equiseti), which damage grain cereals, forage grasses, legumes, vegetables, and other economically significant crops in regions of temperate or warm climate including Russia [6,7,8]. These fungi keep growing on forage grasses and grain during storage, causing post-harvest contamination with ZEN [9]. In contrast to steroid hormones, ZEN is a nonsteroidal compound (a macrocyclic lactone of β-resorcylic acid [13]), but possesses a high estrogenic activity, disrupts the functioning of reproductive and endocrine systems in humans and animals [10,11], as well as suppresses the immunity [14,15]
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