Essential Oils Modulate Gene Expression and Ochratoxin A Production in Aspergillus carbonarius

Abstract

Ochratoxin A (OTA) is a mycotoxin, mainly produced on grapes by Aspergillus carbonarius, that causes massive health problems for humans. This study aims to reduce the occurrence of OTA by using the ten following essential oils (E.Os): fennel, cardamom, anise, chamomile, celery, cinnamon, thyme, taramira, oregano and rosemary at 1 µL/mL and 5 µL/mL for each E.O.As a matter of fact, their effects on the OTA production and the growth of A. carbonarius S402 cultures were evaluated, after four days at 28 °C on a Synthetic Grape Medium (SGM). Results showed that A. carbonarius growth was reduced up to 100%, when cultured with the E.Os of cinnamon, taramira, and oregano at both concentrations and the thyme at 5 µL/mL. As for the other six E.Os, their effect on A. carbonarius growth was insignificant, but highly important on the OTA production. Interestingly, the fennel E.O at 5 µL/mL reduced the OTA production up to 88.9% compared to the control, with only 13.8% of fungal growth reduction. We further investigated the effect of these E.Os on the expression levels of the genes responsible for the OTA biosynthesis (acOTApks and acOTAnrps along with the acpks gene) as well as the two regulatory genes laeA and vea, using the quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR) method. The results revealed that these six E.Os reduced the expression of the five studied genes, where the ackps was downregulated by 99.2% (the highest downregulation in this study) with 5 µL/mL of fennel E.O.As for the acOTApks, acOTAnrps, veA and laeA, their reduction levels ranged between 10% and 96% depending on the nature of the E.O and its concentration in the medium.

Ability of Soil Isolated Actinobacterial Strains to Prevent, Bind and Biodegrade Ochratoxin A

“…This type of degradation mechanism can be adopted in detoxification techniques, since both of the resulting metabolites are virtually non-toxic. Other studies suggested that biodegradation can be achieved via the cleavage of the lactone ring, resulting in the formation of an opened lactone form of OTA that exhibits similar toxicity of OTA in rats [ 9 ].…”

“…Others have been focused on treating the contaminated food with living organisms such as lactic acid bacteria (LAB) and yeasts, to reduce the OTA concentration. This biological decontamination is either performed by OTA biodegradation using microorganisms and their enzymes [ 9 , 10 , 11 ], or by binding the toxin on the cell wall surface of these microorganisms [ 12 , 13 , 14 ]. Both approaches help reduce OTA without significant losses in nutritive values, since no harmful chemicals are used in this treatment of contaminated food [ 15 , 16 , 17 , 18 ].…”

Antifungal and Antiochratoxigenic Activities of Essential Oils and Total Phenolic Extracts: A Comparative Study

“…In our previous work, we studied the effect of several EOs, such as fennel, rosemary, celery, chamomile, oregano, cinnamon, and thyme on the growth of A. carbonarius and OTA production. In fact, the EOs of thyme, cinnamon, and oregano were found to be effective against A. carbonarius [ 17 ]. On the other hand, the EOs of the fennel, chamomile, and celery were only effective against OTA production by A. carbonarius , suggesting a different mode of action of the studied EOs.…”

Bioactivities of Anethole, Astragalin and Cryptochlorogenic Acid Extracted from Anise Oil and Moringa oleifera on the Keratinase Gene Expression of Trichophyton rubrum

“…Additionally, a qRT-PCR study was performed using essential oils to distinguish the extent of the gene expression, focusing on the production of ochratoxin A biosynthesis and two regulatory genes: laeA and vea. All six essential oils reduced the expression of the investigated genes, specifically the ackps that was down-regulated by 99.2%, which in this study is the maximum 39 .…”