<p>Maize is a major calorie source for people living
in Sub-Sahara Africa. In this region, <i>Aspergillus
flavus</i> causes ear rot diseases in maize, contributing to food insecurity
due to aflatoxin contamination. The biological control principle of competitive
exclusion has been applied in both the United States and Africa to effectively
reduce aflatoxin levels in maize at harvest by introducing atoxigenic strains
that out-compete toxigenic strains. The goal of this study was to determine if
the efficacy of preharvest biocontrol treatments carry over into the drying
period, which is often delayed in Sub-Sahara Africa by the complexities of
postharvest drying practices and lack of modern drying machinery. Maize was
collected from fields in Texas and North Carolina that were treated with
commercial biocontrol, and control fields that were untreated. To simulate
moisture conditions similar to those experienced by farmers during drying in
Sub-Sahara Africa, we adjusted the grain to 20% moisture content and incubated
it at 28 ℃ for 6 days. Although the
initial number of infected kernels in most samples were high, less than 24% of
kernels were infected with <i>Aspergillus
flavus</i> and aflatoxin levels were low (<4ppb). Both toxigenic and
atoxigenic strains increased and spread through the grain over the incubation
period, and aflatoxin levels increased, even in samples from biocontrol-treated
fields. Our molecular analysis suggests that applied biocontrol strains from
treated fields migrate to untreated fields. The results also indicate that the
population of toxigenic <i>A. flavus</i> in
the harvested grain will grow and produce aflatoxin during the drying period
when moisture is high. Therefore, any potential postharvest reduction in
aflatoxin accumulation will depend on how effective the biocontrol strain was
at displacing the toxigenic populations prior to harvest.</p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/9104831 |
| Date | 14 August 2019 |
| Creators | Sharon Wanjiru Kinyungu (7041278) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/Efficacy_of_pre-harvest_Aspergillus_flavus_biocontrol_treatment_on_reducing_aflatoxin_accumulation_during_drying/9104831 |
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