Reding C L, Harrison M A
Department of Food Science and Technology, University of Georgia, Athens.
Mycopathologia. 1994 Sep;127(3):175-81. doi: 10.1007/BF01102918.
Fatty acid synthetase (FAS) activity measured over time corresponded to aflatoxin B1 biosynthesis by Aspergillus parasiticus grown in minimal salts sucrose medium. Succinate dehydrogenase (SDH) activity, our primary metabolism indicator, decreased as FAS activity increased demonstrating that as primary metabolism slows, secondary metabolism and subsequently aflatoxin production begins. Fungal biomass, as measured by chitin, increased up to day 13 then stabilized. Calcium, potassium, magnesium, manganese, zinc, and a combination of these minerals were tested to determine their effect in culture on FAS and SDH activities. Cultures grown in broth supplemented with zinc had greater FAS activity and produced more aflatoxin B1 when compared to the unsupplemented control. To determine if enzyme activity in a complex substrate is altered due to mineral composition, peanuts were cultivated with gypsum (calcium sulfate) supplementation. The peanuts grown had higher calcium content but less zinc. All peanuts grown in gypsum treated fields had less aflatoxin produced on them when compared to unsupplemented peanuts. Also, FAS activity was lower and chitin content was less when compared to the unsupplemented control peanuts. The FAS activity observed in these experiments indirectly suggests that the FAS complex may be responsible for producing the precursor for aflatoxin synthesis. However, additional information is needed to validate this hypothesis.
随着时间的推移所测得的脂肪酸合成酶（FAS）活性与寄生曲霉在最低盐蔗糖培养基中生长时黄曲霉毒素B1的生物合成情况相对应。琥珀酸脱氢酶（SDH）活性作为我们的主要代谢指标，随着FAS活性的增加而降低，这表明随着初级代谢减缓，次级代谢以及随后的黄曲霉毒素产生开始。以几丁质衡量的真菌生物量在第13天前增加，然后趋于稳定。对钙、钾、镁、锰、锌以及这些矿物质的组合进行了测试，以确定它们在培养中对FAS和SDH活性的影响。与未添加矿物质的对照相比，在添加了锌的肉汤中生长的培养物具有更高的FAS活性，并且产生了更多的黄曲霉毒素B1。为了确定复杂底物中的酶活性是否因矿物质组成而改变，用添加石膏（硫酸钙）的方法种植花生。所种植的花生钙含量较高但锌含量较低。与未添加石膏的花生相比，在经过石膏处理的田地中种植的所有花生上产生的黄曲霉毒素都较少。此外，与未添加石膏的对照花生相比，其FAS活性较低且几丁质含量较少。在这些实验中观察到的FAS活性间接表明，FAS复合物可能负责产生黄曲霉毒素合成的前体。然而，需要更多信息来验证这一假设。
