Assessment of Biochemical Factors Involved in Selection of Isolates for Biocontrol of Aflatoxin Contamination of Corn
Food and Feed Safety Research
2013 Annual Report
1a.Objectives (from AD-416):
Determine why certain strains of Aspergillus flavus used for biocontrol of aflatoxin production in corn are more effective than other strains.
1b.Approach (from AD-416):
Use fluorescent-tagged Aspergillus flavus biocontrol strain to determine distribution and spread of introduced strains compared to the natural populations and assess whether differences in mating type genes affect corn invasion.
Six fluorescent-tagged Aspergillus flavus strains were obtained from Southern Regional Reseasrch Center (SRRC). Small field plots of maize in Texas are being treated with these strains under typical conditions for biocontrol. Field studies of competitor potential in corn in Texas have just been initiated using the fluorescent-tagged mutants. Results are not available yet. Other studies have been done that challenge the hypothesis that biocontrol occurs by displacement. These studies found that the preferred biocontrol strain with mating type Mat1-2 (the equivalent in lower organisms of the sexes in higher organisms) competitively inhibits aflatoxin production by a type of thigmotropic (touch) sensing. These in vitro observations are being followed up by field studies. The thigmotropic sensor may be a secondary metabolite produced by a polyketide or non-ribosomal peptide biosynthesis pathway (types of chemical processes ocurring within a cell). This work is in progress at SRRC.