AbstractThe effect of the cotton storage trisaccharide raffinose and cottonseed storage protein (CSP) in combination on aflatoxin production by Aspergillus flavus was investigated. The ability of ground whole cottonseed and water‐extracted cottonseed meal to support fungal biosynthesis of aflatoxin also was assessed in vitro. Dose response data showed that utilization of raffinose as a sole carbon source supported growth and aflatoxin production by A. flavus. When raffinose was a carbon source and CSP was the sole nitrogen source, aflatoxin levels were stimulated up to fourfold above those in raffinose reference media. Results with ground whole cottonseed as a sole carbon/nitrogen source demonstrated the capacity for aflatoxin production in A. flavus cultures. Lipid extraction of ground whole seed severely reduced aflatoxigenesis potential; however, lipid extraction followed by water extraction of ground whole seed restored much of the aflatoxin biosynthetic potential, suggesting the presence of a water soluble inhibitory factor. Accessible carbon appeared to be the limiting resource in water‐extracted meal, as a raffinose supplement stimulated aflatoxin production. Either cottonseed storage lipid or raffinose was capable of providing accessible carbon to A. flavus. Raffinose and CSP in developing and mature cottonseed may predispose seed to potentially high levels of aflatoxin contamination by A. flavus upon seed infection.
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