Biocontrol of Aspergillus and Fusarium Mycotoxins in Africa : benefits and limitations

Fungal contamination and the consequent mycotoxin production is a hindrance to food and feed safety, international trade and human and animal health. In Africa, fungal contamination by Fusarium and Aspergillus is heightened by tropical climatic conditions that create a suitable environment for pre- and postharvest mycotoxin production. The biocontrol of Fusarium and its associated fusariotoxins has stagnated at laboratory and experimental levels with species of Trichoderma, Bacillus and atoxigenic Fusarium being tested as the most promising candidates. Hitherto, there is no impetus to upscale for field use owing to the inconsistent results of these agents. Non-aflatoxigenic strains of Aspergillus have been developed to create biocontrol formulations by outcompeting the aflatoxigenic strains, thus thwarting aflatoxins on the target produce by 70% to 90%. Questions have been raised on their ability to produce other mycotoxins like cyclopiazonic acid, to potentially exchange genetic material and to become aflatoxigenic with consequent deleterious effects on other organisms and environments. Other biocontrol approaches to mitigate aflatoxins include the use of lactic acid bacteria and yeast species which have demonstrated the ability to prevent the growth of Aspergillus flavus and consequent toxin production under laboratory conditions. Nevertheless, these strategies seem to be ineffective under field conditions. The efficacy of biological agents is normally dependent on environmental factors, formulations' safety to non-target hosts and the ecological impact. Biocontrol agents can only be effectively evaluated after long-term use, causing a never-ending debate on the use of live organisms as a remedy to pests and diseases over the use of chemicals. Biocontrol should be used in conjunction with good agricultural practices coupled with good postharvest management to significantly reduce mycotoxins in the African continent

Parallel validation of a green-solvent extraction method and quantitative estimation of multi-mycotoxins in staple cereals using LC-MS/MS

In this study, 15 different mycotoxins were estimated in three staple cereals from selected agro-ecological regions in Nigeria using a 'novel' green extraction method, pressurized hot water extraction (PHWE) in comparison to a conventional solvent extraction method. Discrimination of the results of PHWE and solvent extraction using principal component analysis (PCA) and orthogonal projection to latent structures discriminate analysis (OPLS-DA) did not yield any differential clustering patterns. All maize samples (n=16), 32% (n=38) of sorghum and 35% (n=37) of millet samples were positive for at least one of the 15 tested mycotoxins. Contamination levels for the cereals were higher in the warm humid rain forest region and gradually decreased towards the hot and arid region in the north of the country. The results demonstrate the applicability of PHWE as a possible alternative extraction method to conventional methods of extraction, which are solvent based

Beyond aflatoxins : unravelling the hidden mycotoxins in Kenyan maize

Mycotoxins are secondary metabolites of some filamentous fungi. When consumed in large quantities they cause death and in small quantities overtime, they can be carcinogenic, nephrotoxic, genotoxic, hepatotoxic and immunosuppressive. In Kenya, loss of life has been documented repeatedly from consumption of aflatoxin contaminated maize. These aflatoxicosis outbreaks have attracted attention from stakeholders in the maize value chain in attempts to finding lasting solutions to the aflatoxin problem. The registration and commercialization of a biocontrol formulation (Aflasafe KE01®) as an aflatoxins pre-harvest control technology and promotion of hermetic storage devices as a post-harvest control technology are commendable efforts in the fight against aflatoxins. However, beyond aflatoxins, there are numerous other mycotoxins currently neglected and are not regulated in Kenya. Without regulation, the public risks being exposed to these mycotoxins. This PhD generates data necessary to support legislative decisions for mycotoxins control by, (i) Unraveling mycotoxins present in Kenyan maize. (ii) Determining the source of these mycotoxins by evaluating the incidence of toxigenic Aspergillus and Fusarium occurring on maize kernels. (iii) As a mitigation strategy, local open pollinated maize varieties are compared with commercial hybrids maize varieties to evaluate which variety is less susceptible to mycotoxin contamination. (iv) Evaluating the toxicity of selected emerging mycotoxins to vertebrates using larval zebrafish. The findings of this PhD reveal that Kenyan maize is laden with multiple mycotoxins, local open pollinated maize varieties are less susceptible to mycotoxin contamination compared to commercial hybrids. Emerging mycotoxins have deleterious health effects on zebrafish extrapolatable to vertebrates. In conclusion, a robust mycotoxin regulatory framework should be enacted and research on mycotoxins mitigation and food safety should be intensified

AI to automate brain tumor classification using visual geometric group (VGG) 16

A brain is the most important part of our body, which authorize the center capacities which attributes inside actual body and predictable with the National mind tumor Society, around 700,000 individuals acknowledge a cerebrum tumor, and in this manner, the figure will ascend to 787,000 by the peak point of 2020. Clinical imaging for medical diagnosis of a variety of disorders has benefited from ongoing advancements in the field of deep understanding. Task CNN is the most common and widely used AI computation for visual learning and image identification. Essentially, we show the Convolutional Neural Network (CNN) strategy, together with Data Augmentation and Image Processing, to sort cerebrum MRI examination images into carcinogenic and non-harmful categories in our hypothesis. A programmable mind tumour layout based on deep learning-based Visual Geometric Group (VGG) 16 is shown in this study. The model (VGG-16) has a 96 percent and 96 percent accuracy for both training and testing photos respectively

Comprehensive analysis of multiple mycotoxins and Aspergillus flavus metabolites in maize from Kenyan households

This study assessed the levels of mycotoxins in maize from Kenyan households. Further, local open pollinated maize varieties were compared with commercial hybrids to evaluate which variety is less susceptible to myco-toxin contamination. Four hundred and eighty (n = 480) maize samples were collected in the years 2018-2020 from households in Eastern, Western, Coastal and Lake Victoria regions of Kenya. Liquid chromatography coupled to tandem mass spectrometry was used to detect and quantify 22 mycotoxins, along with 31 Aspergillus flavus metabolites in the samples. Eastern Kenya had the highest aflatoxin (AF) contamination with 75% of samples having AF levels above the Kenyan regulatory limits (10 mu g/kg), the highest concentration was 558.1 mu g/kg. In Western Kenya, only 18% of samples had concentration levels above the Kenyan regulatory limits for AF with highest sample having 73.3 mu g/kg. The Lake Victoria region had the most fumonisins (F) contamination, with 53% of the samples having fumonisin B1 (FB1) < 1000 mu g/kg. However, only 20% of the samples surpassed the Kenyan regulatory limit for total fumonisins (2000 mu g/kg) with the highest concentration being 13,022 mu g/ kg. In addition, 21.6% of samples from the Lake Victoria region had zearalenone (ZEN) and deoxynivalenol (DON) above regulatory limits for European countries (1000 mu g/kg). Western region had the least A. flavus metabolites contamination (18%) while the Eastern region had the highest incidence of A. flavus metabolites (81%). Among the A. flavus metabolites, cyclopiazonic acid (CPA), beta-cyclopiazonic acid (13 CPA), flavacol (FLV) and methylcitreo-isocoumarin (MIC) positively correlated with each other but negatively correlated with the other metabolites. Significant positive co-occurrence was also noted among Fusarium mycotoxins: nivalenol (NIV) positively correlated with DON (r = 0.81), fusarenon-X (FX) (r = 0.81) and ZEN (r = 0.70). Negative correlations were observed between Aspergillus and Fusarium mycotoxins: aflatoxin B1 (AFB1) negatively corre-lated with FB1 (r =-0.11), FX (r =-0.17) and ZEN (r =-0.20). Local open-pollinated maize varieties (L-opv) were less susceptible to mycotoxin contamination compared to the commercial hybrids (C-hy). This study reveals that Kenyan maize is contaminated with multiple mycotoxins most of which are not regulated in Kenya despite being regulated in other parts of the world. A comprehensive legislation should therefore be put in place to protect the Kenyan public against chronic exposure to these mycotoxins. In addition to high yield, there is a need for commercial hybrid maize breeders to incorporate mycotoxin resistance as an important trait in germplasm improvement in seeds production

Incidence of toxigenic Aspergillus and Fusarium species occurring in maize kernels from Kenyan households

Aspergillus and Fusarium are fungal genera that include toxigenic and pathogenic species, able to suffuse farmers' crops and secrete an array of small molecular weight secondary metabolites which can cause health complications to humans and animals when ingested. In sub-Sahara Africa, contamination and persistence of these fungi is increased by the tropical climatic conditions which are ideal for the fungi to thrive. This study evaluated the incidence, regional distribution and toxigenic potential of Aspergillus and Fusarium species occurring in maize kernels from Eastern, Western, Coastal and the Lake Victoria agro-ecological zones of Kenya. Maize kernels were collected from 16 households in each agro-ecological zone. Single spore technique was used to isolate pure cultures of Aspergillus and Fusarium which were identified morphologically. Further, molecular analysis was done using the internal transcribed spacer 1 (ITS 1) region of the ribosomal DNA for Aspergillus and the translation elongation factor-1 alpha (TEF-1 alpha) for Fusarium. The potential of the isolated fungi to produce mycotoxins was probed by polymerase chain reaction (PCR) based on the aflatoxin regulatory aflaR gene in Aspergillus, and the fumonisin backbone structure gene FUM1 in Fusarium. Among the potentially aflatoxigenic A. flavus species isolated, 55% were from Eastern, 27% from the Coastal zone, 13% from Lake Victoria zone and 5% from Western Kenya. Among the potentially fumonisin producing F. verticillioides isolated, 45% were from the Lake Victoria agro-ecological zone, 30% were from Western, 15% from Eastern Kenya and 10% from the Coastal agro-ecological zone. This study adds data on potential mycotoxin hotspots in Kenya useful in employing targeted and regional mycotoxin mitigation strategies in efforts to avert future mycotoxicoses outbreaks in Kenya