Zearalanone(7) [HRP]

Ruminants are generally considered to be less susceptible to the effects of mycotoxins than monogastric animals as the rumen microbiota are capable of detoxifying some of these toxins. Despite this potential degradation, mycotoxin-associated subclinical health problems are seen in dairy cows. In this research, the disappearance of several mycotoxins was determined in an in vitro rumen model and the effect of realistic concentrations of those mycotoxins on fermentation was assessed by volatile fatty acid production. In addition, two hypotheses were tested: (1) a lower rumen pH leads to a decreased degradation of mycotoxins and (2) rumen fluid of lactating cows degrade mycotoxins better than rumen fluid of non-lactating cows. Maize silage was spiked with a mixture of deoxynivalenol (DON), nivalenol (NIV), enniatin B (ENN B), mycophenolic acid (MPA), roquefortine C (ROQ-C) and zearalenone (ZEN). Fresh rumen fluid of two lactating cows (L) and two non-lactating cows (N) was added to a buffer of normal pH (6.8) and low pH (5.8), leading to four combinations (L6.8, L5.8, N6.8, N5.8), which were added to the spiked maize substrate. In this study, mycotoxins had no effect on volatile fatty acid production. However, not all mycotoxins fully disappeared during incubation. ENN B and ROQ-C disappeared only partially, whereas MPA showed almost no disappearance. The disappearance of DON, NIV, and ENN B was hampered when pH was low, especially when the inoculum of non-lactating cows was used. For ZEN, a limited transformation of ZEN to alpha-ZEL and beta-ZEL was observed, but only at pH 6.8. In conclusion, based on the type of mycotoxin and the ruminal conditions, mycotoxins can stay intact in the rumen.

Ochratoxin A (OTA) is a type of mycotoxin mainly produced by fungus belonging to the genus Aspergillus and Penicillium and plays a critical role in food safety since it causes serious health problem. Biological control by using microorganisms is considered a promising approach for detoxification of this mycotoxin. In order to find bacteria with efficient OTA elimination capability, one bacteria strain JSW-B1 with OTA removal ability was isolated from soil samples and was identified as Bacillus megaterium based on morphological and 16S rRNA analysis. After incubation of isolate JSW-B1 in liquid culture medium containing 2.5 mu g/mL OTA for 72 h, the OTA removal percentage was 80.3%. No degradation products of OTA could be detected by liquid chromatography. About 62.6% OTA could be removed by the viable cell fraction after incubation for 72 h compared to 13.7% by cell-free supernatant. Meanwhile, heat treatment significantly enhanced OTA removing capability of the cells, suggesting that the OTA removal activity of the isolate JSW-B1 was mainly attributed to the adsorption by bacterial cells. In addition, the antifungal experiments revealed that isolate JSW-B1 was able to suppress the mycelial growth of Aspergillus ochraceus on solid medium with an inhibition ratio of 41.9% and reduce the fungal incidence on maize corns with a reduction ratio of 15%. Taken together, our results indicated that B. megaterium JSW-B1 could be considered as potential biological agent to control toxigenic fungal growth and mycotoxin contamination in agricultural products.