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Three types of media and a multiplex PCR procedure with a set of four primers were used to differentiate between aflatoxinogenic and non-aflatoxinogenic strains of Aspergillus flavus and Aspergillus parasiticus. Four sets of primers were the aflR, nor-1, ver-1, and omt-A genes of the aflatoxin biosynthetic pathway. Multiplex PCR showed that the four aflatoxinogenic strains gave a quadruplet pattern, indicating the presence of all the genes involved in the aflatoxin biosynthetic pathway which encode for the products. Non-aflatoxinogenic strains gave varying results with two, three, or four banding patterns. A banding pattern in seven non-aflatoxinogenic strains resulted in non-differentiation between these and aflatoxinogenic strains. [ABSTRACT FROM AUTHOR]

The conditions for the sulfhydryl oxidase (SOX) production and activity from an Egyptian isolate of Aspergillus niger were optimized. Purification and determination of the kinetic properties ( K and V) of the purified enzyme have been done. The possibility for the SOX induction using L-Cys (as a natural substrate) was studied to determine whether SOX could be produced as an inducible enzyme in addition to being a constitutive one (i.e. whether induction leads to increase SOX production and activity or not). The optimum temperature and pH for its activity were found to be 60°C and 5.5, respectively. The activity of the induced intracellular SOX, was measured according to Ellman's method using the standard GSH oxidation where it reached 94% while that of non-induced one reached only 27.6%. This wide difference in activity between the induced and non-induced SOX indicates the successful L-Cys-induction of the SOX production (i.e. SOX from A. niger AUMC 4947 is an inducible enzyme). Molecular characterization of the pure SOX revealed that it is constituted of two 50-55 KDa subunits. K and V were found to be 6.0 mM and 100 μM/min/mg respectively. [ABSTRACT FROM AUTHOR]