The Efficacy of Essential Oils on Growth and Morphogenesis of Soil-Borne Aflatoxigenic Aspergillus Species

Toxicology

Abstract

Mycotoxin contamination can occur at any point in the food chain from field to storage thereby lowering the quality of food and feed; and presenting risk to human health. Aspergillus spp. toxins specifically aflatoxins induce various adverse health effects like allergy, cancer and immunosuppression. Essential oils from different plant parts are known for their antimicrobial activity. The present study investigated the effects on morphology and efficacy of essential oils from Bidens pilosa, Eucalyptus cinerea, Rosmarinus officinalis and Leonitis nepetifolia on soil borne Aspergillus species. The mechanism of inhibitory action at the level of colony morphology with 1.0× 10^-3 µl/ml concentration treatment reduced conidial heads, poorly developed sterigmata with less or absence of flattened empty hyphae with the presence of undulations along the hyphal borders were observed. The potency of the essential oils was dose-dependent and complete cell wall disruption, squashed hyphae and total mycelial growth inhibition was observed on Aspergillus fumigatus, Aspergillus flavus, Aspergillus syndowii, Aspergillus niger Aspergillus parasiticus, A. tamarii, A. terreus, A. candidus, A. wentii, A. penicillioides and A. ochraceus species was seen with treatment of Eucalyptus cinerea. ANOVA analysis revealed that there was a significant effect of the essential oil on the mycelial growth at p value of 0.05. Post hoc comparison of mean mycelial growth inhibition were conducted and showed significant differences between the control and Leonitis nepetifolia (11.22 ± 3.67) and control and Eucalyptus cinerea (15.18 ± 3.67). The potent properties of these essential oils offer the possibility of using them as eco-friendly, safe and cost-effective natural alternatives for mitigating aflatoxin contamination in food and feed in the chain of production.