Fusarium verticillioides of maize plant: Potentials of propitious phytomicrobiome as biocontrol agents

Abstract

Oluwadara Pelumi Omotayo, Olubukola Oluranti Babalola

Disease outbreaks have been recorded due to exposure to Fusarium verticillioides and fumonisin, a mycotoxin produced by this fungus. F. verticillioides is a fungal pathogen of maize that causes infections, such as wilting and rotting, while contact with its fumonisin derivative manifests in the form of mild to severe illnesses in humans and animals. Maize infection by F. verticillioides causes loss or reduction in expected crop yield, thereby influencing households and nations’ economies. While several efforts have been made to control the pathogenic fungus and its occurrence in the environment, it remains a challenge in agriculture, particularly in maize production. Several microorganisms which are plant-associated, especially those associated with the rhizosphere niche have been noted to possess antagonistic effects against F. verticillioides. They can inhibit the pathogen and tackle its debilitating effects on plants. Hence this study reviews the use of rhizosphere-associated biocontrol agents, such as Bacillus spp., Pseudomonas, Enterobacter, and Microbacterium oleivorans which forms part of the phytomicrobiome in other to prevent and control this toxicogenic fungus. These microorganisms were found to not only be effective in controlling its occurrence on maize plants but are environmentally safe and promote crop yield.

https://www.frontiersin.org/articles/10.3389/ffunb.2023.1095765/full

Comparative study of aflatoxin contamination of winter and summer ginger from the North West Province of South Africa

Abstract

Oluwadara Pelumi Omotayo, Abiodun Olusola Omotayo, Olubukola Oluranti Babalola, Mulunda Mwanza

The presence of mycotoxins in staple food can have adverse effects that result in ill health and associated socio-economic losses. Mycotoxins are naturally occurring toxins produced by certain fungi and can be found in staple food plants such as ginger. Ginger is a renowned medicinal plant that is extensively used for cooking and healing. However, this medicinal plant is with little information about its possible mycotoxins contamination. This study determined the occurrence and prevalence of Aflatoxin B1, B2, G1 and G2 and Ochratoxin A contamination in raw ginger sold around Mahikeng, North West Province, South Africa. Samples were collected purposively from various retailers over winter and summer. The analytical procedure optimized was based on immunoaffinity column cleanup (IAC), followed by High-performance liquid chromatography with fluorescence (HPLC-FLC) detection. ELISA was also used for mycotoxin screening. On HPLC, the limits of detection and quantification for the four Aflatoxins were 3.9 × 10−7-1.4 × 10 -3 and 1.3 × 10-6 - 4.7 × 10-3 for samples collected in winter, and 3.7 × 10−7- 1.4 × 10-3, LOQ 1.2 × 10-6 – 4.6 × 10-3 for the summer samples. The average recoveries at three spiking levels ranged from 62 to 91% for the summer samples and 70–93% for those collected in winter. A linearity was observed for the analytes whose correlation coefficients were within the range of 0.9995 and 1.000 for the winter samples and 0.9995 and 1.000 for those collected in summer. The results showed that the contamination levels, especially for samples collected in summer were greater than the legally permissible limits. The t-test analysis shows that the mean and standard deviation of the four types of Aflatoxins considered were higher in summer than in winter. The findings of the study indicated that ginger, as for all agricultural commodities, are prone to mycotoxin contamination.

https://www.sciencedirect.com/science/article/pii/S2214750018307315

Microbial Genes of Agricultural Importance in Maize Rhizosphere Unveiled Through Shotgun Metagenomics

Oluwadara Pelumi Omotayo, Ozede Nicholas Igiehon, Olubukola Oluranti Babalola 

Genes possessed by microbes in the rhizosphere influence the metabolic activities that occur in this zone. Although the maize rhizosphere has been reported to be a hotspot of genes, these genes remain under-investigated. Hence, this study aimed at identifying putative microbial genes with plant beneficial functions in the underexplored maize rhizosphere microbiome using a shotgun metagenomics approach. Sampling was done at the flowering stage of the maize plants and both the rhizosphere and bulk soils were collected in triplicates. The metagenomes of the examined rhizosphere and bulk soils revealed genes involved in carbon fixation, nitrogen fixation, iron acquisition, heat and cold shock, phosphorus solubilization and utilization, sulfur cycling, and siderophore production. The beta diversity analysis showed significant variations (p < 0.05) in these genes across the examined rhizosphere and bulk soils which was further confirmed by the distinct separations between the samples as seen on the principal coordinate analysis (PCoA) plot. Contrarily, no significant difference was observed in diversity within the habitats (p = 0.99). The predominance of significant genes of agricultural importance such as the nifH, nifA, groES, and cspA in the rhizosphere metagenomes signifies that this region is endowed with beneficial organisms with potential for improving plant growth, mitigating stress, and reducing the effect of extreme temperatures, which can be optimized in developing biofertilizers. Therefore, the development of strategies that will help in cultivating these organisms, which are mostly unculturable, is encouraged. This would make them readily available for use as bio-inoculants and in other biotechnological applications.

http://journal.frontierspartnerships.org/article/10.3389/sjss.2022.10427/full?&utm_source=Email_to_authors_&utm_medium=Email&utm_content=T1_11.5e1_author&utm_campaign=Email_publication&field=&journalName=Spanish_Journal_of_Soil_Science&id=10427

 Resident rhizosphere microbiome’s ecological dynamics and conservation: Towards achieving the envisioned Sustainable Development Goals, a review

Oluwadara Pelumi Omotayo and Olubukola Oluranti Babalola

The role of the rhizosphere microbiome remain crucial to human existence and can therefore not be over-looked, particularly with respect to plant growth, development and yield. The rhizosphere is the ‘home’ for several genes, some of which are responsible for the various trait and features exhibited by plants. Numerous microbes have been identified to inhabit the rhizosphere, some of which are the proteobacteria, nitrogen fixing bacteria, plant growth promoting rhizobacteria, mycorrhizal and mycoparasitic fungi. Likewise, chemical compounds such as amino acids (crystathionine and homoserine), which inhibits nematodes, carbohydrates (fructose), which enhance the growth of microorganisms, and sterols (sitosterol), which regulate plant growth, reside in the plant rhizosphere. Several factors contributes to the existence and survival of these microbes, one being good agricultural practices, as some farming techniques negatively affects the soil microbial content. This study therefore focused on the agricultural and health importance of the soil organisms, as well as the various techniques that can be employed to maintain the rhizosphere microbiome, despite the rise and intensification of various harmful land use activities. This will enable a better understanding of the soil rhizosphere conservation, restoration and sustainable use, specifically of degraded land. This will avoid depleting or alternating the soil microbial content while aiming to ensure a healthy ecosystem, biodiversity, maximal crop productivity, food security and all round sustainability, as targeted by the United Nation’s Sustainable Developments Goals.

https://www.sciencedirect.com/science/article/pii/S209563392030054X

Prevalence of mycotoxins and their consequences on human health

 Oluwadara Pelumi Omotayo, Abiodun Olusola Omotayo, Mulunda Mwanza, Olubukola                                                         Oluranti Babalola

Abstract

Mycotoxin contamination is a global phenomenon and causes a wide array of negative effects and other complications. This study focused on commonly found mycotoxins in Africa and the possible means of prevention or reduction of their contaminating effects. Mycotoxins are secondary metabolites of mold and fungi; they are generally toxic to living organisms. Hundreds of mycotoxins have been identified thus far, with some, such as aflatoxins, ochratoxins, trichothecenes, zearalenone, fumonisins, and patulin, considered agro-economically important. Several factors contribute to the presence of mycotoxins in food, such as climatic conditions, pest infestation, and poor harvest and storage practices. Exposure to mycotoxins, which occurs mostly by ingestion, leads to various diseases, such as mycotoxicoses and mycoses that may eventually result in death. In light of this, this review of relevant literature focuses on mycotoxin contamination, as well as various methods for the prevention and control of their prevalence, to avert its debilitating consequences on human health. Clear evidence of mycotoxin contamination is present in Africa, and it was therefore recommended that adequate prevention and control of these toxic substances in our food system should be encouraged and that appropriate measures must be taken to ensure food safety as well as the enhanced or long-lifespan of the African populace. Governments, research institutions, and non-governmental organizations should tailor the limited resources available to tackle mycotoxin prevalence, as these will offer the best prospects for the successful development of a sustainable food system in Africa.

Keywords: Mycotoxin, Contamination, Prevalence, Toxic, Food safety

https://link.springer.com/article/10.5487/TR.2019.35.1.001