Institute of Light Industry and Food Engineering, Guangxi University, Nanning, 530005, China.
Institute of Light Industry and Food Engineering, Guangxi University, Nanning, 530005, China.
Anal Biochem. 2022 Sep 15;653:114771. doi: 10.1016/j.ab.2022.114771. Epub 2022 Jun 2.
Penicillium is universal in dark tea, and Penicillium citrinum can produce a kidney toxin called citrinin (CIT). Determining CIT is difficult because of the complexity of the dark tea substrate and the diversity of CIT-producing fungi. Therefore, this study established a real-time PCR (qPCR) detection method for CIT-related synthetic genes (ctnD, orf1, ctnA, pksCT, orf5, orf7, and ctnG) in Liupao tea and determined the content of CIT in samples at different production stages and the toxin-producing abilities of fungi (Aspergillus oryzae, etc.) in Liupao tea. CIT was found in all samples during the pile-fermentation process of Liupao tea, and CIT was detected in two samples during the aging process. The established method demonstrated good sensitivity and specificity in detecting CIT-related synthetic genes. The reaction efficiency was within the preferred range of 100 ± 10%. CIT was not detected or was below the detection limit when the Ct value of one or more related synthetic genes was greater than 33.5. Therefore, the established qPCR method can effectively predict the production of CIT in Liupao tea, and it is applicable to the judgment of whether fungi produce CIT.
黄曲霉菌普遍存在于黑茶中，而青霉属中的青霉可以产生一种名为桔青霉素（CIT）的肾毒素。由于黑茶基质的复杂性和产桔青霉素真菌的多样性，CIT 的检测具有一定难度。因此，本研究建立了一种实时 PCR（qPCR）检测方法，用于检测六堡茶中与 CIT 相关的合成基因（ctnD、orf1、ctnA、pksCT、orf5、orf7 和 ctnG），并测定了不同生产阶段样品中 CIT 的含量以及六堡茶中真菌（米曲霉等）的产毒能力。结果发现，在六堡茶渥堆发酵过程的所有样品中均检测到 CIT，在陈化过程的两个样品中检测到 CIT。所建立的方法在检测与 CIT 相关的合成基因方面具有良好的灵敏度和特异性。反应效率在 100 ± 10%的首选范围内。当一个或多个相关合成基因的 Ct 值大于 33.5 时，未检测到 CIT 或低于检测限。因此，该 qPCR 方法可有效预测六堡茶中 CIT 的产生，适用于判断真菌是否产生 CIT。
