Raffinose content may influence cottonseed susceptibility to aflatoxin contamination

Abstract

ABSTRACT:The 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.Paper no. J8913 in JAOCS 76, 883-886 (July 1999).

Effects of Nutrients in Substrates of Different Grains on Aflatoxin B1Production byAspergillus flavus

“…Compared to the seven nutrients mentioned above, other nutrients did not significantly stimulate AFB 1 production by A. flavus NRRL 3357 (fructose, raffinose, stachyose, alanine, and glycine) and may even inhibit AFB 1 production (iron, copper, manganese, and starch). Raffinose and fructose do not clearly stimulate AFB 1 production, which is in contrast to findings obtained by Mellon and Cotty [ 44 ] and Manda et al [ 37 ], most likely because of the different strains and medium used. In addition, Tiwari et al [ 45 ] found that iron, copper, and manganese sulfate decreased the aflatoxin production to different levels, consistent with our results.…”

Substrate Utilization by Aspergillus flavus in Inoculated Whole Corn Kernels and Isolated Tissues

“…Presence of zein as a supplement in chemically defined culture media stimulates aflatoxin production up to 10-fold and its presence as a sole nitrogen source, together with a rapidly accessible carbon source, stimulates aflatoxin production by 8-fold over reference cultures grown on a chemically defined medium (3). Similarly, the presence of raffinose as a carbon source and cottonseed storage protein as a sole nitrogen source stimulates aflatoxin production 4-fold over chemically defined growth media (4). A hexose transport gene is associated with the aflatoxin biosynthesis cluster (5).…”

Time Course Study of Substrate Utilization by Aspergillus flavus in Medium Simulating Corn (Zea mays) Kernels

“…The presence of zein as a supplement in chemically defined culture media stimulates aflatoxin production up to 10-fold, and its presence as a sole nitrogen source together with a rapidly accessible carbon source stimulates aflatoxin production by 8-fold over chemically defined medium reference cultures (2). Similarly, the presence of raffinose as a carbon source and cottonseed storage protein as a sole nitrogen source stimulates aflatoxin production 4-fold over chemically defined growth media (3). Furthermore, in a study utilizing media that contained the major reserve materials in ratios similar to those found in mature cottonseed, A. flaVus selectively used raffinose for initial biomass and aflatoxin production (4).…”