Kollarczik B, Gareis M, Hanelt M
Institute for Medical Microbiology, Veterinary Faculty, Ludwig-Maximilians-University, Munich, Germany.
Nat Toxins. 1994;2(3):105-10. doi: 10.1002/nt.2620020303.
The biotransformation of the Fusarium mycotoxins deoxynivalenol and zearalenone by the normal bacterial gut flora of pigs was examined in this in vitro study. For that purpose, suspensions of intestinal contents (duodenum, jejunum, caecum, colon, rectum) of porcine origin were incubated anaerobically with deoxynivalenol (DON) or zearalenone (ZEA). DON and ZEA were degraded by the flora of the caudal segments (caecum, colon, rectum) of the gut--particularly the colon content--whereas the microorganisms of the cranial segments (duodenum, jejunum) exhibited no transforming activity. DON was showed to be deepoxidated, ZEA was hydrolyzed to alpha-zearalenol and an unknown metabolite. The transformation of DON was correlated with a loss of cytotoxicity, which could be demonstrated in the MTT(3-[4,5-dimethylthiazol-2yl]-2,5-diphenyltetrazolium++ + bromide)-cell-culture assay using swine kidney cells as target cells. The results of the study presented here correspond with the data found in in vivo studies. On the basis of these findings one could conclude that this in vitro method seems to be well suited to the study of the transformation of mycotoxins by the microflora of the gut. The in vitro study is cheaper than a feeding trial, and the preliminary information on the metabolism of mycotoxins obtained in such studies is helpful in designing feeding trials more clearly. Besides the simple and fast handling, reproducibility and the protection of the animals studied are further advantages of this in vitro method. In connection with the MTT-cell-culture assay, additional information about the cytotoxic potential of the bacterial transformation products can be obtained.
本体外研究检测了猪正常肠道菌群对镰刀菌属霉菌毒素脱氧雪腐镰刀菌烯醇和玉米赤霉烯酮的生物转化作用。为此，将猪源十二指肠、空肠、盲肠、结肠、直肠的肠内容物悬浮液与脱氧雪腐镰刀菌烯醇（DON）或玉米赤霉烯酮（ZEA）进行厌氧培养。DON和ZEA在肠道尾段（盲肠、结肠、直肠）的菌群中被降解，尤其是结肠内容物中的菌群，而头段（十二指肠、空肠）的微生物则无转化活性。结果显示DON发生了脱环氧化反应，ZEA被水解为α-玉米赤霉烯醇和一种未知代谢产物。DON的转化与细胞毒性的丧失相关，这在以猪肾细胞为靶细胞的MTT（3-[4,5-二甲基噻唑-2-基]-2,5-二苯基四氮唑溴盐）细胞培养试验中得到了证实。本研究结果与体内研究数据相符。基于这些发现可以得出结论，这种体外方法似乎非常适合研究肠道微生物群对霉菌毒素的转化作用。体外研究比饲养试验成本更低，在此类研究中获得的关于霉菌毒素代谢的初步信息有助于更清晰地设计饲养试验。除了操作简单快速外，这种体外方法的其他优点还包括可重复性以及对受试动物的保护。结合MTT细胞培养试验，可以获得关于细菌转化产物细胞毒性潜力的更多信息。
