Plant extracts as biocontrol agents against Aspergillus carbonarius growth and ochratoxin A production in grapes

A comprehensive review of mycotoxins, their toxicity, and innovative detoxification methods

A comprehensive overview of food mycotoxins, their toxicity, and contemporary detoxification techniques is given in this article. Mycotoxins, which are harmful secondary metabolites generated by a variety of fungi, including Fusarium, Aspergillus, and Penicillium, provide serious health concerns to humans and animals. These include hepatotoxicity, neurotoxicity, and carcinogenicity. Mycotoxins are commonly found in basic food products, as evidenced by recent studies, raising worries about public health and food safety. The article discusses detection techniques such as enzyme-linked immunosorbent assays (ELISA), and quick strip tests. Moreover, the use of various control systems associated with the detoxification of mycotoxinis highlighted. In addition, novel detoxification strategies such as nanotechnology, plant extracts, and omics studies were also discussed. When taken as a whole, this analysis helps to clarify the pressing need for efficient management and monitoring techniques to prevent mycotoxin contamination in the food chain.

An overview of the antifungal potential for aromatic plant extracts in agriculture and the food industry: A comprehensive analysis focusing on the Rubus, Cistus and Quercus genera against fungal infections of crops and food

This review article provides an overview of current research on aromatic plant extracts, particularly from the genera Rubus, Cistus and Quercus. These plants are characterized by their abundance in certain ecosystems such as dehesa, their robustness and adaptability to the environment, but despite their abundance in these regions, they remain relatively underutilized. In this review, the chemical profiles of plant extracts from these genera, the methodologies used for extraction of bioactive compounds and antifungal capabilities of are thoroughly investigated. Plants from Rubus, Cistus and Quercus genera are known for their richness in bioactive constituents, including terpenoids, flavonoids and phenols, which exhibit notable antifungal activities against various pathogenic fungi. Furthermore, the article explores future directions for the development and utilization of these extracts in agricultural and food sectors, underscoring their potential as natural and sustainable substitutes for synthetic fungicides. This comprehensive analysis explores the potential role of aromatic plant extracts in contributing to crop health, food safety, and environmentally sustainable agricultural practices, while recognizing the need for further research to fully substantiate their applications in these areas. The utilization of these plants not only aids in the preservation and promotion of biodiversity and environmental sustainability but also has the potential to create new products and markets, thereby providing economic benefits to the ecosystems where they are cultivated.

Anti-aflatoxin potential of phenolic compounds from common beans (Phaseolus vulgaris L.)

Common beans (Phaseolus vulgaris L.) are widely consumed legumes in Latin America and Africa, valued for their nutritional compounds and antioxidants. Their high polyphenol content contributes to the antioxidant properties, with bioactive compounds showing antifungal and antimycotoxin effects. Certain polyphenols, accumulated in the grain coat, exhibit antimicrobial activity. Mycotoxins, produced mainly by fungi of the genera Aspergillus, Fusarium, and Penicillium, pose health risks. This study explores polyphenols in tepary bean and in different common bean varieties, assessing their effect against aflatoxins. In vitro tests were done using grains inoculated with A. flavus to induce mycotoxin production, while polyphenols were extracted from non-inoculated grains. Polyphenol-rich extract reduced aflatoxin B1 produced by the fungus. In most bean varieties, especially red-grain types, the fungus exhibited decreased aflatoxin production, negatively correlating with flavonoids. Catechin was associated with reduced A. flavus toxigenicity. This study highlights beans' potential in mitigating aflatoxin contamination through their phenolic compounds.

The Global Secondary Metabolite Regulator AcLaeA Modulates Aspergillus carbonarius Virulence, Ochratoxin Biosynthesis, and the Mode of Action of Biopesticides and Essential Oils

Aspergillus carbonarius is considered one of the main fungi responsible for black and sour rot in grapes, as well as the production of the carcinogenic mycotoxin ochratoxin A. The global regulatory methyltransferase protein LaeA controls the production of various secondary metabolites in Aspergillus species, as well as influences sexual and asexual reproduction and morphology. The goal of this study was to investigate the role of the regulatory gene AclaeA in physiology, virulence, and ochratoxin A (OTA) production by deleting this gene from the genome of a wild-type A. carbonarius strain. The evaluation data on the morphological characteristics, virulence experiments in three different grape varieties, and OTA analysis of ΔAclaeA mutants showed that the growth and the OTA production by ΔAclaeA strains were significantly reduced. The mutant strains were also less virulent, producing 40-50% less conidia in three different cultivars of grape berries. Additionally, the gene AclaeA was considerably repressed after the application of three commercial biopesticides (Trianum-P®, Vacciplant®, and Serenade® Max) and the essential oils (EOs) cinnamon, geranium, and thyme, which were also shown to inhibit OTA biosynthesis in A. carbonarius. The study of the regulatory gene AclaeA can contribute to a broader understanding of the role of secondary metabolites during A. carbonarius-grape interactions, as well as the discovery of the mode of action of biological plant protection products and EOs against this mycotoxigenic fungus.

Application and antagonistic mechanisms of atoxigenic Aspergillus strains for the management of fungal plant diseases

This review covers, for the first time, all methods based on the use of Aspergillus strains as biocontrol agents for the management of plant diseases caused by fungi and oomycetes. Atoxigenic Aspergillus strains have been screened in a variety of hosts, such as peanuts, maize kernels, and legumes, during the preharvest and postharvest stages. These strains have been screened against a wide range of pathogens, such as Fusarium, Phytophthora, and Pythium species, suggesting a broad applicability spectrum. The highest efficacies were generally observed when using non-toxigenic Aspergillus strains for the management of mycotoxin-producing Aspergillus strains. The modes of action included the synthesis of antifungal metabolites, such as kojic acid and volatile organic compounds (VOCs), secretion of hydrolytic enzymes, competition for space and nutrients, and induction of disease resistance. Aspergillus strains degraded Sclerotinia sclerotiorum sclerotia, showing high control efficacy against this pathogen. Collectively, although two Aspergillus strains have been commercialized for aflatoxin degradation, a new application of Aspergillus strains is emerging and needs to be optimized.

Inhibitory Effects and Mechanisms of Perilla Essential Oil and Perillaldehyde against Chestnut Pathogen Botryosphaeria dothidea

Botryosphaeria dothidea, a notorious plant pathogen, is responsible for causing chestnut rot during postharvest storage. This research aimed to assess the antifungal properties of perilla essential oil (PEO) and perillaldehyde (PAE) against B. dothidea. PEO's and PAE's inhibitory effects on B. dothidea were investigated using an agar dilution method, a fumigation method, and an in vivo assay in chestnuts and shell buckets. Based on the results of gas chromatography-mass spectrometry, it was confirmed that the main component of PEO was elemicin. The antifungal mechanism of PEO and PAE against B. dothidea was investigated by conducting staining experiments of the fungal cell wall and cell membrane. PEO and PAE strongly inhibit the mycelial growth of B. dothidea in a dose-dependent manner. The inhibitory mechanism is mainly related to the destruction of the integrity of the fungal cell wall and plasma membrane. Notably, PEO retains its antifungal efficacy against B. dothidea in chestnuts, effectively prolonging their storage life. These findings indicate that PEO and PAE are nontoxic, eco-friendly botanical fungicides, holding promise for controlling postharvest chestnut rot.

Chitosan as an Antimicrobial, Anti-Insect, and Growth-Promoting Agent for Potato (Solanum tuberosum L.) Plants

A growing trend in plant protection is replacing chemical preparations with environmentally friendly biological compositions. Chitosan, due to its biocompatibility, biodegradability, and bioactivity, is an effective agent against plant diseases. The purpose of the study was to evaluate chitosan as a potential biopesticide for potato plants. Three variants of chitosan were tested: high (310-375 kDa, >75% deacetylated), medium (190-310 kDa, 75-85% deacetylated), and low (50-190 kDa, 75-85% deacetylated) molecular weight. The chitosan variants were dissolved in lactic and succinic acids and tested for antibacterial and antifungal properties against eight strains of mould and two strains of bacteria responsible for potato diseases. The possible cytotoxicity of chitosan was evaluated against different cell lines: insect Sf-9, human keratinocyte HaCaT, and human colon carcinoma Caco-2. The bioprotective activities of the chitosan were also evaluated in situ on potato tubers. Chitosan inhibited the growth of almost all the selected phytopathogens. The most active was medium molecular chitosan in lactic acid. This formula was characterized by low toxicity towards human cells and high toxicity towards Sf-9 cells. It was also found to have positive effects on the growth of stems and roots, gas exchange, and chlorophyll index in potato plants. Selected chitosan formulation was proposed as a functional biopesticide for potato protection against phytopathogens.

Enhanced sensitivity in electrochemical detection of ochratoxin A within food samples using ferrocene- and aptamer-tethered gold nanoparticles on disposable electrodes

Ensuring food security is crucial for public health, and the presence of mycotoxins, produced by fungi in improperly stored processed or unprocessed food, poses a significant threat. This research introduces a novel approach - a disposable aptasensing platform designed for the detection of ochratoxin A (OTA). The platform employs gold-nanostructured screen-printed carbon electrodes functionalized with a ferrocene derivative, serving as an integrated faradaic transducing system, and an anti-OTA aptamer as a bioreceptor site. Detection relies on the ferrocene electrochemical signal changes induced by the aptamer folding in the presence of the target molecule. Remarkably sensitive, the platform detects OTA within the range of 0.5 to 70 ng mL-1 and a detection limit of 11 pg mL-1. This limit is approximately 200 times below the levels stipulated by the European Commission for agricultural commodities. Notably, the sensing device exhibits efficacy in detecting OTA in complex media, such as roasted coffee beans and wine, without the need for sample pretreatment, yielding accurate recoveries. Furthermore, while label-free electrochemical aptasensors have proliferated, this study addresses a gap in understanding the binding mechanisms of some aptasensors. To enhance the experimental findings, a theoretical study was conducted to underscore the specificity of the anti-OTA aptamer as a donor for OTA detection. The molecular docking technique was employed to unveil the key binding region of the aptamer, providing valuable insights into the aptasensor specificity.