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

Choque

et al. 2018

Toxins

Self Cite

Ochratoxin A (OTA) is a mycotoxin produced by several species of Aspergillus and Penicillium that contaminate food and feed raw materials. To reduce OTA contamination, we first tested in vitro, actinobacterial strains as potential biocontrol agents and afterward, through a physical decontamination method using activated carbon fibers (ACFs). Actinobacterial strains were screened for their ability to reduce OTA in solid co-culture with A. carbonarius, which is the major OTA-producing species in European vineyards. Four strains showed a high affinity for removing OTA (67%–83%) with no significant effect on fungal growth (<20%). The mechanism of action was first studied by analyzing the expression of OTA cluster genes (acOTApks, acOTAnrps, acOTAhal) by RT-qPCR showing a drastic reduction in all genes (7–15 times). Second, the ability of these strains to degrade OTA was assessed in vitro on ISP2 solid medium supplemented with OTA (100 µg/L). Two strains reduced OTA to undetectable levels. As for the physical method, high adsorption rates were obtained for ACFs at 0.8 g/L with a 50% adsorption of OTA in red wine by AC15 and 52% in grape juice by AC20 within 24 h. These promising methods could be complementarily applied toward reducing OTA contamination in food chains, which promotes food safety and quality.

Section: Resultsmentioning

confidence: 99%

“…Also, a Bacillus licheniformis strain was able to inhibit the growth of A. westerdijkiae (34%) and to remove 92.5% of the initial OTA concentration [ 13 ]. Actinobacterial strains have as well demonstrated an ability to reduce mycotoxin concentration without affecting fungal growth [ 14 , 15 , 16 ].…”

Section: Introductionmentioning

confidence: 99%

OTA Prevention and Detoxification by Actinobacterial Strains and Activated Carbon Fibers: Preliminary Results

Choque

et al. 2018

Toxins

Self Cite

“…This observation led researchers to develop alternative strategies such as the use of biocontrol agents. In fact, certain microorganisms have demonstrated the ability to reduce mycotoxin concentrations while maintaining an ecological niche balance [ 11 , 12 ]. Concerning AFB 1 biocontrol, one of the best-known strategies is the use of non-aflatoxigenic A. flavus strains, like Afla-guard ® (Circle One Global, Inc., Shellman, GA, USA) or Aflasafe ® (IITA, Ibandan, Nigeria).…”

Section: Introductionmentioning

confidence: 99%

Streptomyces roseolus, A Promising Biocontrol Agent Against Aspergillus flavus, the Main Aflatoxin B1 Producer

Caceres

Snini

Puel

et al. 2018

Toxins

Self Cite

Crop contamination by aflatoxin B1 is a current problem in tropical and subtropical regions. In the future, this contamination risk may be expanded to European countries due to climate change. The development of alternative strategies to prevent mycotoxin contamination that further contribute to the substitution of phytopharmaceutical products are thus needed. For this, a promising method resides in the use of biocontrol agents. Several actinobacteria strains have demonstrated to effectively reduce the aflatoxin B1 concentration. Nevertheless, the molecular mechanism of action by which these biological agents reduce the mycotoxin concentration has not been determined. The aim of the present study was to test the potential use of Streptomyces roseolus as a biocontrol agent against aflatoxin B1 contamination. Co-cultures with Aspergillus flavus were conducted, and the molecular fungal response was investigated through analyzing the q-PCR expression of 65 genes encoding relevant fungal functions. Moreover, kojic and cyclopiazonic acid concentrations, as well as morphological fungal changes were also analyzed. The results demonstrated that reduced concentrations of aflatoxin B1 and kojic acid were respectively correlated with the down-regulation of the aflatoxin B1 gene cluster and kojR gene expression. Moreover, a fungal hypersporulated phenotype and a general over-expression of genes involved in fungal development were observed in the co-culture condition.

“…Microbes can affect OTA concentration by degradation or absorption and at gene regulation level. OTA biosynthesis genes (acpks, acOTApks, and acOTAnrps) and the general SM regulator veA of A. carbonarius were downregulated upon co-culturing with Streptomyces isolates, with a concomitant decrease in OTA production (El Khoury et al, 2017). While acOTAnrps and acOTApks, along with laeA, a general regulator of fungal secondary metabolism, were found to be downregulated by Lactobacillus plantarum (Lappa et al, 2018).…”

Section: Aspergilli and Their Mycotoxins Versus Soil Microbiomementioning

confidence: 98%

The Aspergilli and Their Mycotoxins: Metabolic Interactions With Plants and the Soil Biota

et al. 2020

Species of the highly diverse fungal genus Aspergillus are well-known agricultural pests, and, most importantly, producers of various mycotoxins threatening food safety worldwide. Mycotoxins are studied predominantly from the perspectives of human and livestock health. Meanwhile, their roles are far less known in nature. However, to understand the factors behind mycotoxin production, the roles of the toxins of Aspergilli must be understood from a complex ecological perspective, taking mold-plant, mold-microbe, and mold-animal interactions into account. The Aspergilli may switch between saprophytic and pathogenic lifestyles, and the production of secondary metabolites, such as mycotoxins, may vary according to these fungal ways of life. Recent studies highlighted the complex ecological network of soil microbiotas determining the niches that Aspergilli can fill in. Interactions with the soil microbiota and soil macro-organisms determine the role of secondary metabolite production to a great extent. While, upon infection of plants, metabolic communication including fungal secondary metabolites like aflatoxins, gliotoxin, patulin, cyclopiazonic acid, and ochratoxin, influences the fate of both the invader and the host. In this review, the role of mycotoxin producing Aspergillus species and their interactions in the ecosystem are discussed. We intend to highlight the complexity of the roles of the main toxic secondary metabolites as well as their fate in natural environments and agriculture, a field that still has important knowledge gaps.