Synergistic Impact of Bioactive Byproduct Extract Leads to Anti-Fusarium and Anti-Mycotoxin Secretion

Fruit byproducts are considered a high source of bioactive molecules, which possess antioxidant activities. These antioxidants play principal functions in mycotoxin reduction. This study aimed to evaluate crude mandarin byproduct extract for its chemical interaction with fungal growth and suppression of mycotoxin production, and to illustrate whether the impact was regarding individual molecules or a synergistic antioxidation process. Extract contents were analyzed for their phenolic, flavonoids, and antioxidant activity. The fatty acid composition and volatile components were determined using the GC apparatus. The influence of the extract evaluated versus the standard phenolics of trans-ferulic and hesperidin were evaluated. The liposome technique was applied to prevent the antioxidant properties of the bioactive extract. The anti-mycotoxigenic effects of the liposomal and non-liposomal extract were determined in fungal media against the standard phenolics. The results manifested ferulic (235.54 ± 3.34 mg/100 g) and hesperidin (492.11 ± 1.15 mg/100 g) as high phenolics in the extract. Limonene was the main volatile (67.54 ± 1.74%), as well antioxidant activities determined in considerable values. The crude extract recorded efficiency as an anti-Fusarium agent, but less than the standard hesperidin applied in fungal media. The bioactive extract recorded possessed a reduction influence on mycotoxin production. The impact may be joining with its fungal inhibition or its component activity with the active groups on the mycotoxin molecule. The formation of liposomal extract enhanced its efficacy in mycotoxin reduction. This enhancement may illustrate its protective properties for antioxidant components of the bioactive extract.

Ecophysiology of Fusarium chaquense a Novel Type A Trichothecene Producer Species Isolated from Natural Grasses

Fusarium chaquense, a recently formally described novel species, has been identified as an T-2 toxin (T-2), HT-2 toxin (HT-2) and other toxins producer in natural grasses (Poaceae) from Argentina. The major objective of this study was to describe the effect of water activity (aW, 0.995, 0.98, 0.95, 0.93 and 0.91), temperature (15, 25 and 30 °C) and incubation time (5, 15 and 25 days) on growth and to evaluate the production of T-2, HT-2 toxins and beauvericin (BEA) by two F. chaquense strains in a grass-based media. The results showed a wide range of conditions for F. chaquense growth and mycotoxin production. Both strains had a maximum growth rate at the highest aW (0.995) and 25 °C. Regarding mycotoxin production, more T-2 than the other analysed mycotoxins were produced by the two strains. T-2 production was favoured at 0.995 aW and 30 °C, while HT-2 production at 0.98–0.95 aW and 15 °C. The maximum levels of BEA were produced at 0.995 aW and 25–30 °C. Two-dimensional profiles of aW by temperature interactions were obtained from these data in order to identify areas where conditions indicate a significant risk of mycotoxins accumulation on grass. For its versatility on growth and mycotoxin production in a wide range of aW and temperatures, F. chaquense would have an adaptive advantage over other Fusarium species, and this would explain its high frequency of isolation in natural grasses grown up in the Chaco wetlands.

Methods for suppressing Fusarium infection during malting and their effect on malt quality

The incidence of Fusarium head blight (FHB) in cereal grains such as barley and wheat is of growing concern due to climate change threatening food safety. Further processing of cereals by malting provides an ideal environment for the growth of Fusarium, leading to food safety concerns due to the production of mycotoxins, production challenges with the negative effects to malt and beer qualities, and economic loss owing to the field yield reduction. To improve food safety and product quality, different methods of fungal control have been investigated and reported in the literature. Traditional methods to control fungal growth and mycotoxin production have included chemical and physical methods, but these treatments led to worsened malt properties, limiting their applicability to the brewing industry. Biological control methods have, therefore, attracted wide interest as alternative treatments due to their ability to limit Fusarium growth and mycotoxin production in malting cereals without toxic by-products, thus exhibiting promise for improving food safety. Various biological agents have been investigated and applied in malting and have shown the potential to suppress Fusarium spp. growth and mycotoxin production. These agents include several lactic acid bacterial (LAB) species and Geotrichum candidum. Another promising biocontrol agent for malting control is Pythium oligandrum, which has successfully limited Fusarium infection in other agricultural crops. The review outlines the Fusarium-control methods reported referenced for the brewing industry and the present prospects in biological control applications on the promise of P. oligandrum as a novel agent for malting.

Fusarium verticillioides and Aspergillus flavus Co-Occurrence Influences Plant and Fungal Transcriptional Profiles in Maize Kernels and In Vitro

Climate change will increase the co-occurrence of Fusarium verticillioides and Aspergillus flavus, along with their mycotoxins, in European maize. In this study, the expression profiles of two pathogenesis-related (PR) genes and four mycotoxin biosynthetic genes, FUM1 and FUM13, fumonisin pathway, and aflR and aflD, aflatoxin pathway, as well as mycotoxin production, were examined in kernels and in artificial medium after a single inoculation with F. verticillioides or A. flavus or with the two fungi in combination. Different temperature regimes (20, 25 and 30 °C) over a time-course of 21 days were also considered. In maize kernels, PR genes showed the strongest induction at 25 °C in the earlier days post inoculation (dpi)with both fungi inoculated singularly. A similar behaviour was maintained with fungi co-occurrence, but with enhanced defence response at 9 dpi under 20 °C. Regarding FUM genes, in the kernels inoculated with F. verticillioides the maximal transcript levels occurred at 6 dpi at 25 °C. At this temperature regime, expression values decreased with the co-occurrence of A. flavus, where the highest gene induction was detected at 20 °C. Similar results were observed in fungi grown in vitro, whilst A. flavus presence determined lower levels of expression along the entire time-course. As concerns afl genes, considering both A. flavus alone and in combination, the most elevated transcript accumulation occurred at 30 °C during all time-course both in infected kernels and in fungi grown in vitro. Regarding mycotoxin production, no significant differences were found among temperatures for kernel contamination, whereas in vitro the highest production was registered at 25 °C for aflatoxin B1 and at 20 °C for fumonisins in the case of single inoculation. In fungal co-occurrence, both mycotoxins resulted reduced at all the temperatures considered compared to the amount produced with single inoculation.

In Vitro Biological Control of Aspergillus flavus by Hanseniaspora opuntiae L479 and Hanseniaspora uvarum L793, Producers of Antifungal Volatile Organic Compounds

Aspergillus flavus is a toxigenic fungal colonizer of fruits and cereals and may produce one of the most important mycotoxins from a food safety perspective, aflatoxins. Therefore, its growth and mycotoxin production should be effectively avoided to protect consumers’ health. Among the safe and green antifungal strategies that can be applied in the field, biocontrol is a recent and emerging strategy that needs to be explored. Yeasts are normally good biocontrol candidates to minimize mold-related hazards and their modes of action are numerous, one of them being the production of volatile organic compounds (VOCs). To this end, the influence of VOCs produced by Hanseniaspora opuntiae L479 and Hanseniaspora uvarum L793 on growth, expression of the regulatory gene of the aflatoxin pathway (aflR) and mycotoxin production by A. flavus for 21 days was assessed. The results showed that both yeasts, despite producing different kinds of VOCs, had a similar effect on inhibiting growth, mycotoxin biosynthetic gene expression and phenotypic toxin production overall at the mid-incubation period when their synthesis was the greatest. Based on the results, both yeast strains, H. opuntiae L479 and H. uvarum L793, are potentially suitable as a biopreservative agents for inhibiting the growth of A. flavus and reducing aflatoxin accumulation.

Influence of H2O2-Induced Oxidative Stress on In Vitro Growth and Moniliformin and Fumonisins Accumulation by Fusarium proliferatum and Fusarium subglutinans

Fusarium proliferatum and Fusarium subglutinans are common pathogens of maize which are known to produce mycotoxins, including moniliformin (MON) and fumonisins (FBs). Fungal secondary metabolism and response to oxidative stress are interlaced, where hydrogen peroxide (H2O2) plays a pivotal role in the modulation of mycotoxin production. The objective of this study is to examine the effect of H2O2-induced oxidative stress on fungal growth, as well as MON and FBs production, in different isolates of these fungi. When these isolates were cultured in the presence of 1, 2, 5, and 10 mM H2O2, the fungal biomass of F. subglutinans isolates showed a strong sensitivity to increasing oxidative conditions (27–58% reduction), whereas F. proliferatum isolates were not affected or even slightly improved (45% increase). H2O2 treatment at the lower concentration of 1 mM caused an almost total disappearance of MON and a strong reduction of FBs content in the two fungal species and isolates tested. The catalase activity, surveyed due to its crucial role as an H2O2 scavenger, showed no significant changes at 1 mM H2O2 treatment, thus indicating a lack of correlation with MON and FB changes. H2O2 treatment was also able to reduce MON and FB content in certified maize material, and the same behavior was observed in the presence and absence of these fungi, highlighting a direct effect of H2O2 on the stability of these mycotoxins. Taken together, these data provide insights into the role of H2O2 which, when increased under stress conditions, could affect the vegetative response and mycotoxin production (and degradation) of these fungi.