Enzymology and Fungal Biotechnology Lab, Botany and Microbiology Department, Faculty of Science, Zagazig University, Zagazig, 44519, Egypt.
Botany Department, Faculty of Science, Mansoura University, Mansoura, Egypt.
BMC Plant Biol. 2024 May 13;24(1):394. doi: 10.1186/s12870-024-05065-w.
Wheat is one of the essential crops for the human and animal nutrition, however, contamination with aflatoxigenic fungi, due to the improper storage conditions and high humidity, was the main global threats. So, preventing the growth of aflatoxigenic fungi in stored wheat grains, by using different essential oils was the main objective of this work. Aspergillus flavus EFBL-MU12 PP087400, EFBL-MU23 PP087401 and EFBL-MU36 PP087403 isolates were the most potent aflatoxins producers inhabiting wheat grains. The effect of storage conditions of wheat grains "humidity, temperature, incubation period, and pH" on growth of A. flavus, was assessed by the response surface methodology using Plackett-Burman design and FCCD. The highest yield of aflatoxins EFBL-MU12 B and B by A. flavus grown on wheat grains were 145.3 and 7.6 μg/kg, respectively, at incubation temperature 35°C, 16% moisture contents, initial pH 5.0, and incubated for 14 days. The tested oils had a powerful antifungal activity for the growth and aflatoxins production by A. flavus in a concentration-dependent manner. Among these oils, cinnamon oil had the highest fungicidal activity for A. flavus at 0.125%, with about 85-90 % reduction to the aflatoxins B and B, conidial pigmentation and chitin contents on wheat grains. From the SEM analysis, cinnamon oils had the most deleterious effect on A. flavus with morphological aberrations to the conidial heads, vegetative mycelia, alteration in conidiophores identity, hyphae shrank, and winding. To emphasize the effect of the essential oils on the aflatoxins producing potency of A. flavus, the molecular expression of the aflatoxins biosynthetic genes was estimated by RT-qPCR. The molecular expression of nor-1, afLR, pKsA and afLJ genes was suppressed by 94-96%, due to cinnamon oil at 0.062% compared to the control. Conclusively, from the results, cinnamon oils followed by the peppermint oils displayed the most fungicidal activity for the growth and aflatoxins production by A. flavus grown on wheat grains.
小麦是人类和动物营养的重要作物之一，然而，由于储存条件不当和高湿度，真菌产生黄曲霉毒素是全球主要威胁之一。因此，使用不同的精油来防止储存小麦中的黄曲霉生长是这项工作的主要目标。栖息在麦粒中的最具产毒能力的黄曲霉分离株为 A. flavus EFBL-MU12 PP087400、EFBL-MU23 PP087401 和 EFBL-MU36 PP087403。使用 Plackett-Burman 设计和 FCCD 通过响应面方法评估了储存条件（湿度、温度、培养期和 pH）对黄曲霉生长的影响。在 35°C 的培养温度、16%的水分含量、初始 pH 值为 5.0 且培养 14 天时，A. flavus 在麦粒上生长产生的黄曲霉毒素 EFBL-MU12 B 和 B 的最高产量分别为 145.3 和 7.6μg/kg。测试油在浓度依赖性方式下对黄曲霉的生长和产毒具有强大的抑菌活性。在这些油中，肉桂油对 A. flavus 的杀菌活性最高，在 0.125%时，对黄曲霉毒素 B 和 B、分生孢子色素沉着和几丁质含量的抑制率约为 85-90%。从 SEM 分析来看，肉桂油对 A. flavus 的影响最大，导致分生孢子头部、营养菌丝、分生孢子梗形态发生变化，菌丝收缩和缠绕。为了强调精油对黄曲霉产毒能力的影响，通过 RT-qPCR 估计了黄曲霉生物合成基因的分子表达。与对照相比，肉桂油在 0.062%时，nor-1、afLR、pKsA 和 afLJ 基因的分子表达分别抑制了 94-96%。综上所述，从结果来看，肉桂油和薄荷油对在麦粒上生长的黄曲霉的生长和产毒具有最强的杀菌活性。
