**11. Discussion**

The experiment was conducted at Plant Bacteriology and Biotechnology Laboratory of Department of Plant Pathology, Bangladesh Agricultural University, Mymensingh during the period of 2019–2020. The purpose of the experiment were to detect the levels of fumonisins and aflatoxins and to identify the aflatoxin and fumonisins producing *Aspergillus* and *Fusarium* in maize associated with maize by PCR using nor, omtA, apa-2 and *FUM1*. Genes involving *afl R*, *ver-1*, *omt-1* and *apa-2* associated with biosynthetic pathway regarding aflatoxins production [73–76]. *Apa-1*, *Nor-1*, *Omt-1* and *Ver-1* gens belong to four primers were applied to detect aflatoxins contamination [77, 78]. *A. flavus* was quantified by *nor-1* gene in several contaminated food samples and cereals using PCR assay [77]. Besides, [56] mentioned that *FUM1* gene with an expected amplicon size of 183 bp can easily detect the fumonisin and non-fumonisin producing *Fusarium,* moreover other researchers also identified the fumonisin by using *FUM1* gene which is in accordance with our study [79–81]. We gathered samples from 15 maize growing areas to measure the aflatoxins and fumonisins level but not all the *Aspergillus* strains are capable of engendering mycotoxins, thus screening is crucial and we detected by Agra Quant Total Aflatoxin and Fumonisin Test Kit following ELISA approach for detection and this method also used by [82–87] for detecting aflatoxins and fumonisin. In our experiment, we detected the aflatoxins contamination Agra Quant Total Aflatoxins 96 well microtiter plate ELISA test kit produced in Romer Labs, Packers and Stockyards Administration (GIPSA) in US Department of Agriculture (USDA) which ability to detect individual aflatoxins very precisely and accurately with a range of 0–320 ppb in accrodance with an experiment conducted by [82]. A number of approaches have been widely used to detect mycotxin naming high-performance liquid chromatography (HPLC), enzyme-linked immunosorbent assay (ELISA), and thin layer chromatography (TLC) [83, 84] and served as a reliable method for detecting aflatoxins and fumonisins [85, 88, 89]. In Gaibandha and Cumilla region fumonisin contamination were highest and lowest compared to other areas revealing moderate amount of fumonisins. In this study, all of the 15 samples were found positive with fumonisins producing *Fusarium* and aflatoxin producing fungi *Aspergillus* which in accordance with the findings of [90, 91]. We found positive correlation for both aflatoxins and fumonisins contamination between their toxin percentages which were matched with the findings of [92] who found apositive correlation has been identified between the proportion of *FUM1* transcripts and the proportion of fumonisins biosynthesized by the *F. verticillioides* and *F. proliferatum* species.

In case of Percent total Fumonisins concentration over standard limit, five regions were under the regulatory limit and other ten regions were exposed higher limit than the regulatory limit exhibiting 65 % followed by 53.5 %, 47.5 %, 47 %, 46.5 %, 45 %, 28.5 %, 27 %, 27 %, 18 % over the standard limit (1 ppm) in the area of Rangpur, Kishoreganj, Gaibandha, Manikganj, Panchagarh, Kustia, Bogura, Nilphamari, Thakurgaon, Lalmonirhat respectively. On the other hand, highest and lowest aflatoxin concentration was recorded in Chuadanga and Dinajpur regions and in terms of percent aflatoxin concentration over standard limit, eight regions were below the permissible limit of aflatoxins, conversely, five regions exposing 915.7 % followed by 587.3 %, 214.8 %, 208.85 %, 19.5 % aflatoxin concentration beyond permissible limit of 10 μg in the region of Chuadanga, Gaibandha, Kustia, Kishoreganj and Cumilla respectively. Refs. [15, 93] recorded that surges of aflatoxin contamination levels beyond regulatory limit due to increased droughts, pest damages, temperatures, host susceptibility.

As we observed that both aflatoxin and fumonisin concentration were fluctuate one region to another region which have been also monitored that due to association of several significant factors like temperature, water activity, storage conditions, drought, humidity, insect damage, flowering stage, plant characteristics [94–98]. Ref. [48] revealed that aflatoxin production comprised of several factor including existence of certain genes and in intact that means deletions or insertions within the gene regions, crop stress [99] and in fumonisins two factors temperatures and water potential are fundamental to produce fumonisins [99] along with rainfall patterns, longer durations of drought which has been prominent in Mediterranean regions [100–103]. These all conditions significantly impact on the variation of the population of mycotoxin producing fungi both *Fusarium* and *Aspergillus* [103]. In our experiment, we recorded over all three regions (Chuadanga, Kishoreganj, Gaibandha) were engendering higher amount of aflatoxins and fumonisins production respectively, thus we speculated in Chuadanga, temperature fluctuation influences the mycotoxin production, in Kishoreganj which exposed with flood and severe water stress and the region Gaibandha with drought problems, these might have the feasible factor for *Aspergillus* and *Fumonisins* to produce gigantic amount of mycotoxins compared to other areas. Aflatoxin levels rise as a result of drought, insect damage, and heat during fungal growth [25]. Marasas [104] found that, the presence of fumonisins is linked to weather conditions, with larger instances occurring during hot and dry conditions. Abbas et al. [105] revealed that *A. flavus* grows supreme around 28–37° C with a humidity level of at least 80 %.

Post-harvest factors are also exacerbate mycotoxin production and generate a favorable condition for fungus related to their growth and mycotoxin production and those include storage fungus, insect infestation, contaminant mold respiration, insects and mites, water availability and temperature ultimately deteriorate grain quality [106–108]. As [109] also observed that interaction between these factors triggered the mycotoxigenic species growth, mycotoxin production, niche occupation and competitiveness, [110] also revealed the moisture and surrounding air conditions also influenced mycotoxin production by initiating biological and biochemical activity. Maize is a hygroscopic crop which easily absorbs or release moisture and humidity in the surrounding ambience until getting the adjustment with equilibrium conditions which led to swift degradation in storage. *Fusarium* species can damage stored grain by causing seedling illnesses, root rots, stalk rots, and ear rots in maize which ultimately hazardous to plants and animal [111–116]. Due to all correlating factors with aflatoxin production, high amount of aflatoxins were found in Bangladeshi markets [23] and 82 % contamination in South Asia [49]. Decomposing potentiality of AFs are very slow several approaches including

*Aflatoxins and Fumonisins Contamination of Maize in Bangladesh: An Emerging Threat… DOI: http://dx.doi.org/10.5772/intechopen.101647*

physical, chemical have been investigated [19] and monitored changing in sensory property and nutrient diminishment which led to mount food safety problems ultimately. A number of microorganisms have been identified fruitfully working as a biocontrol agents to control mycotoxins such as *Bacillus subtilis*, *Pseudomonas*, *Trichoderma*, atoxigenic strains of *A. flavus* and *A. parasiticus* [117–119]*.* Thus, suppressing mycotoxins by biocontrol agent would be a fruitful approach though several experiments need to be conducted precisely in future.
