Cellular, physiological and molecular approaches to investigate the antifungal and anti-aflatoxigenic effects of thyme essential oil on Aspergillus flavus

Several approaches, including the detection of apoptotic-like cell death, aflatoxin B-1 (AFB(1)) production and gene expression analysis, were carried out to provide insights into the antifungal and anti-aflatoxigenic effects of thyme essential oil (EO) on Aspergillus flavus. At 0.5 mu L mL(-1), thyme EO completely inhibited A. flavus growth. Furthermore, this antifungal activity triggered significant apoptosis, via nuclear condensation (87.5% of nuclei analyzed) and plasma membrane damage (in 100% of treated hyphae). Further analysis of AFB(1) production and gene expression related to secondary metabolism (laeA) and the mechanism of virulence (lipA and meT) of A. flavus in the presence of thyme EO indicated important physiological changes related to its anti-aflatoxigenic property. These results highlight the potent antifungal abilities of thyme EO in controlling A. flavus and AFB(1) production, especially the abilities that operate by exerting changes at the molecular level and inducing significant apoptotic-like cell death.