Abstract
Trichothecenes are the most common mycotoxins contaminating small grain cereals worldwide. The C12,13 epoxide group in the trichothecenes was identified as a toxic group posing harm to humans, farm animals, and plants. Aerobic biological de-epoxidation is considered the ideal method of controlling these types of mycotoxins. In this study, we isolated a novel trichothecene mycotoxin-de-epoxidating bacterium, Desulfitobacterium sp. PGC-3-9, from a consortium obtained from the soil of a wheat field known for the occurrence of frequent Fusarium head blight epidemics under aerobic conditions. Along with MMYPF media, a combination of two antibiotics (sulfadiazine and trimethoprim) substantially increased the relative abundance of Desulfitobacterium species from 1.55% (aerobic) to 29.11% (aerobic) and 28.63% (anaerobic). A single colony purified strain, PGC-3-9, was isolated and a 16S rRNA sequencing analysis determined that it was Desulfitobacterium. The PGC-3-9 strain completely de-epoxidated HT-2, deoxynivalenol (DON), nivalenol and 15-acetyl deoxynivalenol, and efficiently eliminated DON in wheat grains under aerobic and anaerobic conditions. The strain PGC-3-9 exhibited high DON de-epoxidation activity at a wide range of pH (6–10) and temperature (15–50 °C) values under both conditions. This strain may be used for the development of detoxification agents in the agriculture and feed industries and the isolation of de-epoxidation enzymes.
Highlights
Trichothecenes are a particular group of sesquiterpenes
To further enrich this Desulfitobacterium species, an MMYPF medium commonly used for culture of species belonging to Desulfitobacterium [34] was selected to culture the PGC-3 consortium
These results indicate that the DON-degrading rate was faster in MMYPF media (144 h under aerobic conditions in Figure 1) than in MSB media (168 h under aerobic conditions) [26] and was associated with the increased abundance of Desulfitobacterium species observed in the PGC-3 consortium (Figure 2A,B)
Summary
Trichothecenes are a particular group of sesquiterpenes. Produced by various fungi (including insect and plant pathogens), their family encompasses over 200 mycotoxins [1,2]. Type A trichothecenes, including T2, HT2, and neosolaniol (NEO) have no ketone at the C8 location; type B trichothecenes, which include deoxynivalenol (DON), nivalenol (NIV), Fusarenone X (FUS), 3-Acetyl DON (3ADON), and 15-Acetyl DON (15ADON) do have a ketone at the C8 location. These kinds of trichothecenes are produced on several cereal grains (maize, rye, oats, barley, or wheat) in the field by Fusarium head blight (FHB) pathogens such as Fusarium culmorum or Fusarium graminearum, after which they end up in the feed/food chains [3,5]
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