Mycotoxins are produced by fungi under certain conditions of temperature and humidity and pose a risk to the health of consumers [1]. World Health Organization (WHO) in collaboration with Food and Agriculture Organization of the United Nations (FAO), is monitoring this major issue globally [2] [3]. Mycotoxins are secondary metabolites of Aspergillus, Fusarium and Penicillium, fungi present in the soil, that grow and multiply rapidly on various agricultural raw materials showing a risk to both animals and humans [1] [4] [5] [6]. Fungi and their metabolites, including Fusarium sp., have been a stringent problem for decades [7] [8] [9] [10]. Fungi can pose a risk to agricultural products cereals, nuts, fruits, and products derived from these raw materials [11] - [16].

Temperature and humidity favor the rapid growth of fungi. As an example, Fusarium oxysporum is often reported in works related to plant pathology [17] [18] [19] [20] [21]. Fusarium species have been isolated from food: Fusarium oxysporum (beans, beverages, chocolate, cereals, fruit, nuts, seeds, and vegetables) [22]; Fusarium verticillioides (maize/corn, rice, and wheat) and other Fusarium sp. (beans, barley, millet etc.) [19] [22] [23] [24] [25]. For example, the study [26] states that Fusarium Head Blight and Gibberella Ear Rot decrease the yield of the corn crop and may present a risk of contamination with type B toxins. Studying the risk of mycotoxin contamination of raw materials helps to make the most relevant decisions when it comes to storing cereals, fruits, animal feed and food manufacturing [27]. This study has been undertaken to evaluate the factors that promote the risk caused by Fusarium in the food chain and how the occurrence of mycotoxins in food can be controlled. Food safety is ensured not in the manufacture of food, but throughout the food chain.

There are currently many studies [28] [29] [30] where the production of special secondary metabolites and mycotoxins specific to significant models of fungal pathogens-host plants has been analyzed. Serios problems created by Fusarium sp. and their mycotoxins can be found in the works [31] [32] [33]. The authors of the studies [22] [27] [34] note the conditions that influence the development of fungi in Fusarium sp. are pH, temperature, moisture content and nitrogen source. Many authors note that spores and hyphae of the fungi Fusarium sp. in different climatic conditions produce toxins including trichothechenes such as deoxynivalenol (DON) [35] [36] [37] [38], nivalenol (NIV) and T-2 and HT-2 Toxins, as well as zearalenone (ZEN) [39] [40] [41] [42] and fumonisins (FUM): maize [11] [42] [43] [44] [45]; corn [46] [47], nuts [48]; grape-wine chain [49], wine [50] [51], and asparagus [44]. The microbiological and chemical risk posed by fungi and their metabolites is a cumulative process throughout the food chain [52]. Figure 1 shows the factors that favor the risk caused by fungi.

Biological factors

Fungi from different species of Aspergillus, Fusarium, Penicillium and Alternaria produce secondary metabolites presenting a major risk, have been isolated from: cereals [35] [36] [37] [38], corn [60], peas [63], seeds oilseeds [64], fruits (nuts [42] [48], grapes [49] ), and wine [50] [51]. Table 1 presents reported results on the influence of biological factors on the growth of fungal biomass and mycotoxin production.

Environmental factors

Temperature and high relative humidity favor the development of fungi, respectively the production of mycotoxins [57] [67]. Fusarium toxins, usually found in the soil, is caused by relative humidity, temperature for storage and diverse handling that can contaminate different types of cereals, crops, which cand lead to major economic losses [57]. Most fungal species have an optimal growth temperature of 25˚C - 30˚C but can also grow in a range of 5˚C - 30˚C [34] [68]. Optimal temperature for mycotoxin production is 24˚C - 26˚C. The influence of temperature on the growth of fungi, including the FUM1 gene has been studied in fungi Fusarium verticillioides and Fusarium proliferatum isolated from corn [56]. Fumonisins are mainly produced by Fusarium verticillioides [69] [70]. In the study conducted by Sandra N. Jimenez-Garcia et al. [57] the authors mentioned that the drought caused a major contamination of maize with Fusarium verticillioides.

Storage conditions

The accumulation of Fusarium toxins depends on the composition of the substrate (the presence of simple sugars), pH and temperature [53] [71]. The authors of the studies [52] [54] reported data attesting that pH influences the metabolic processes of plants, the risk of fungal development and the interaction between water activity (a_w) and temperature are the major factors on which the accumulation of mycotoxins depends.

Harvesting factors

Harvesting period, harvesting and storage methods have a significant correlation with fungal plant infestation and the amount of mycotoxins produced. There are studies that have investigated this addiction: the influence of wheat variety and different harvest periods [62], late crop harvesting [53], storage conditions [53], stress sores [57] [61].

In other studies by Liu et al. [72] and Uppala et al. [73] it is reported that the production of mycotoxins depends on the sugar content of the substrate. The authors argue this interdependence. The accumulation of Fusarium toxins depends on the composition of the substrate (the presence of simple sugars), pH and temperature [53] [71].

It is necessary to detect fungi and their metabolites in the initial stage of development [74]. For this purpose, various classical and advanced methods have been developed and tested. Mycological methods involve common culturing techniques performed through multiple steps including culture, isolation, and identification [34].

From the advanced methods we can mention utilizing infrared spectroscopy, Raman spectroscopy, capillary electrophoresis, multispectral imaging system, chromatographic technique, radioimmunoassay and enzyme-linked immunosorbent and others found in the work of many world-class researchers [74] [75] [76] [77] [78]. Currently, the Fourier-transform infrared spectroscopy methods (FTIR) [79] [80] [81] [82], near-infrared analysis (NIR) [83] [84] [85], the electronic nose [86] [87] are increasingly used to detect mycotoxins in food, FTIR–photoacoustic spectroscopy (FTIR PAS) [88], color imaging [89] [90], neutron tomography [87] and others, which give exact results even in the presence of very low doses. At the current stage, the study of the problem of fungi and mycotoxins is quite advanced and is done at the level of chromosomes [91] [92]. Adriaan Vanheule et al. [92] have shown that the different biology of the fungal cell, rather than its origin, is responsible for the properties of genomes. The authors of the study [61] López-Errasquín E. et al. reported a positive correlation between FUM1 and the amount of fumonisins biosynthesized by Fusarium fungi (Fusarium verticillioides and Fusarium proliferatum).

To control the risk of fungi and their mycotoxins it is necessary to take certain measures, which is studied and implemented internationally. These approaches include: appropriate planting method [93] [94]; post-planting land and crop management (proper use of fertilizers, irrigation methods, phytosanitary control, etc.) [95] [96]; use of various techniques to reduce contamination of plants and food [97] [98]; implementation of management systems in agriculture and food industry hazard analysis and critical control points (HACCP), good agricultural practice (GAP), good manufacturing practices (GMP), threat assessment critical control points (TACCP), and vulnerability critical control points (VACCP) [99] [100].

Information on the toxicology of purified fumonisins from the FB series can be found in papers published in different years, e.g.: Nelson, P. E. et al. (1993) [101], Gary Munkvold (2017) [102], Claudia Salazar-González et al. (2020) [103]. Other toxic fumonisin analogues are being investigated. Research is being carried out on maize [67] because these grains may show major sources of contamination with FB1, FB2, and FB3.

Current management strategies to reduce the risk of Fusarium sp. and its metabolites consist in crop rotations [104]; fumigation [97] [105]; fungicide treatments [46] [96]; avoiding plant stress [104]; selection of varieties resistant to Fusarium infestation [106]; sanitation [104].

Fusarium poses a major risk to the food chain. Only by having certain knowledge in this field, this risk can be kept under control. In this context, at the Technical University of Moldova, research is being done to detect by rapid methods the outbreak of the formation of the risk produced by fungi and to take prompt measures to prevent its spread. Research is carried out at the genome level of the fungal cell.

Ensuring food safety can only be guaranteed when monitoring the collection of raw materials, transport, processing, storage, manufacture of food and its transportation to consumers [107].

Fusarium sp. poses a risk to plants and food when there are favorable conditions for the development of these fungi and the production of toxins. The use of proper management can control this risk. The negative impact of Fusarium sp. and mycotoxins in the food chain must be monitored simultaneously in two directions: protecting plants by various methods and reducing the risk of infestation by creating the right conditions. The implementation of proper methods from the beginning of the food chain until the end including all stages of production like planting, harvest, drying, storage, processing, packaging, transport helps to decrease the level of contamination and maintain it below the tolerable levels assigned by different countries. In order to ensure food safety, fast and reliable methods of analyzing contamination with fungi and mycotoxins must be implemented.

This reviewed research was funded through Moldova State Project No. 20.80009.5107.09 “Improvement of food quality and safety by biotechnology and food engineering” running at the Technical University of Moldova.

The authors declare no conflicts of interest regarding the publication of this paper.

Sandulachi, E., Ghendov-Mosanu, A., Cojocari, D. and Sturza, R. (2021) The Risk of Fusarium and Their Mycotoxins in the Food Chain. Advances in Microbiology, 11, 541-553. https://doi.org/10.4236/aim.2021.1110040