Department of Microbiology and Ecology, University of Valencia, Burjassot, Spain.
Int J Food Microbiol. 2011 Sep 15;149(2):118-26. doi: 10.1016/j.ijfoodmicro.2011.06.006. Epub 2011 Jun 24.
Contamination of barley by moulds and mycotoxins results in quality and nutritional losses and represents a significant hazard to the food chain. The presence of aflatoxin B1 (AFB1), B2 (AFB2), G1 (AFG1) and G2 (AFG2) and ochratoxin A (OTA) in stored barley in Spain has been studied. Species-specific PCR assays were used for detection of Aspergillus flavus, A. parasiticus, A. ochraceus, A. steynii, A. westerdijkiae, A. carbonarius and A. niger aggregate in mycotoxin-positive barley samples at different incubation times (0, 1 and 2 days). Classical enumeration techniques (CFU/g) in different culture media for evaluation of Aspergillus in sections Flavi, Circumdati and Nigri were also used. One hundred and five barley kernel samples were collected in Spanish grain stores from 2008 to 2010, and analyzed using a previously optimized method involving accelerated solvent extraction, cleanup by immunoaffinity column, liquid chromatographic separation, post-column derivatization with iodine and fluorescence detection. Twenty-nine samples were contaminated with at least one of the studied mycotoxins. AFB1, AFB2, AFG1, AFG2, and OTA were detected in 12.4%, 2.9%, 4.8%, 2.9%, and 20% of the samples, respectively. Aflatoxins and OTA co-occurred in 4.8% of the samples. Maximum mycotoxin levels (ng/g) were 0.61 (AFB1), 0.06 (AFB2), 0.26 (AFG1), 0.05 (AFG2), and 2.0 (OTA). The results of PCR assays indicated the presence of all the studied species, except A. westerdijkiae. The PCR assays showed high levels of natural contamination of barley with the studied species of Aspergillus which do not correspond to the expected number of CFU/g in the cultures. These results suggest that a high number of non-viable spores or hyphae may exist in the samples. This is the first study carried out on the levels of aflatoxins and OTA in barley grain in Spain. Likewise, this is the first report on the presence of aflatoxigenic and ochratoxigenic Aspergillus spp. in barley grain naturally contaminated with those mycotoxins using a species-specific PCR approach.
霉菌和真菌毒素污染大麦会导致质量和营养损失，对食物链构成重大威胁。本研究对西班牙储存大麦中黄曲霉毒素 B1（AFB1）、B2（AFB2）、G1（AFG1）和 G2（AFG2）以及赭曲霉毒素 A（OTA）的存在情况进行了研究。在不同的培养时间（0、1 和 2 天）下，使用针对黄曲霉、寄生曲霉、赭曲霉、棒曲霉、威地曲霉、炭黑曲霉和黑曲霉属的种特异性 PCR 检测法对真菌毒素阳性大麦样品中的曲霉菌进行了检测。还使用不同培养基中的经典计数技术（CFU/g）对 Flavi、Circumdati 和 Nigri 节段的曲霉进行了评估。本研究于 2008 年至 2010 年期间在西班牙谷物仓库中采集了 105 个大麦样本，使用了一种先前优化的方法进行分析，该方法涉及加速溶剂提取、免疫亲和柱净化、液相色谱分离、碘柱后衍生化和荧光检测。29 个样本至少被一种研究真菌毒素污染。分别在 12.4%、2.9%、4.8%、2.9%和 20%的样本中检测到 AFB1、AFB2、AFG1、AFG2 和 OTA。4.8%的样本中同时检测到黄曲霉毒素和 OTA。最高真菌毒素含量（ng/g）分别为 0.61（AFB1）、0.06（AFB2）、0.26（AFG1）、0.05（AFG2）和 2.0（OTA）。PCR 检测结果表明，除威地曲霉外，所有研究的物种均存在。PCR 检测结果表明，大麦受到了研究曲霉属物种的高度自然污染，但与培养物中预期的 CFU/g 不相符。这些结果表明，样本中可能存在大量非存活孢子或菌丝。这是西班牙首次对大麦谷物中黄曲霉毒素和 OTA 水平进行的研究。同样，这也是首次使用种特异性 PCR 方法报告在受这些真菌毒素自然污染的大麦谷物中存在产黄曲霉毒素和产赭曲霉毒素的曲霉属物种。
