Effects of Light on the Ochratoxigenic Fungi Aspergillus ochraceus and A. carbonarius

Abstract

Ochratoxin A (OTA) usually contaminates agricultural products such as grapes, oatmeal, coffee and spices. Light was reported as an effective strategy to control spoilage fungi and mycotoxins. This research investigated the effects of light with different wavelengths on the growth and the production of OTA in Aspergillus ochraceus and Aspergillus carbonarius. The results showed that the growth of both fungi were extremely inhibited by UV-B. Short-wavelength (blue, violet) significantly inhibited the production of OTA in both fungi, while the inhibitory effect of white was only demonstrated on A. ochraceus. These results were supported by the expression profiles of OTA biosynthetic genes of A. ochraceus and A. carbonarius. To clarify, the decrease in OTA production is induced by inhibition or degradation; therefore, the degradation of OTA under different wavelengths of light was tested. Under UV-B, the degradation rate of 10 μg/mL OTA standard pure-solution samples could reach 96.50% in 15 days, and the degradation effect of blue light was relatively weak. Furthermore, infection experiments of pears showed that the pathogenicity of both fungi was significantly decreased under UV-B radiation. Thus, these results suggested that light could be used as a potential target for strategies in the prevention and control of ochratoxigenic fungi.

Biological Control of Aspergillus parasiticus and Aspergillus ochraceus and Reductions in the Amount of Ochratoxin A and Aflatoxins in Bread by Selected Non-Conventional Yeast

“…Greater capacity to grow than a pathogen and survival ability in harsh environments are important characteristics of biocontrol agents [43]. Many species of Aspergillus fungi can grow in environments poor in essential nutrients and thrive in a wide range of temperature (10-50 • C), pH (2)(3)(4)(5)(6)(7)(8)(9)(10)(11), and salinity (0-34%) conditions [44]. In the work presented here, effective antagonists against selected species of the genus Aspergillus were sought, so it was appropriate to study various aspects of the polyextremotolerance of the tested yeast strains, including their tolerance to different temperatures, pH, and salinity.…”

“…Of the two yeast species, only A. pullulans PP3 could grow actively under refrigerated conditions of 4 • C. This is a relevant feature of biocontrol because many fruits and vegetables are stored in such conditions. The yeast A. pullulans also showed a wider tolerance range to the medium's pH (4)(5)(6)(7)(8)(9)(10)(11) and salinity (0-12% NaCl). These properties vary depending on the strain tested.…”

“…include a range of filamentous fungi occurring in various ecological niches around the world and can cause healthand life-threatening diseases, especially in immunocompromised individuals [4]. The most dangerous species in this genus include A. flavus, A. parasiticus [5], A. ochraceus, and A. carbonarius [6]. These fungi produce highly harmful secondary metabolites, including aflatoxins (AFs) and ochratoxin A (OTA) [7].…”

Ochratoxin A: Overview of Prevention, Removal, and Detoxification Methods

“…The effects of UV light with different wavelengths on the growth, production, and degradation of OTA are significant. Zhang et al [ 26 ] found that UV-B inhibited the growth of Aspergillus ochraceus and Aspergillus carbonarius , two common OTA-producing strains, at different wavelengths. Shorter wavelengths (blue and purple) significantly inhibited both OTA-producing fungi, while white light only inhibited Aspergillus ochraceus .…”

Effects of AoOTAbZIP on OTA production and food infestation by Aspergillus ochraceus in response to water activity stress

“…Since OTA-producing fungi include Aspergillus and Penicillium fungi, OTA-producing fungi can contaminate both high water activity foods and low water activity foods. Water activity influences the growth and secondary metabolism of fungi, thereby regulating the production of mycotoxins [12][13][14] . There is a signalling pathway in fungi, the HOG-MAPK (high osmolarity glycerol mitogen-activated protein kinase) pathway, that can respond critically to various environmental stresses encountered by fungi, such as osmotic, oxidative, water activity, cold, heat, and light stresses [15][16][17] .…”