objective(s): the enzymatic activity of fungi has recently inspired the scientists with re-explore the fungi as potential biofactories rather than the causing agents of humans and plants infections. in very recent years, fungi are considered as worthy, applicable and available candidates for synthesis of smaller gold, silver and other nano-sized particles.  materials and methods: a standard str...

objective: aflatoxin is important in the food industry, in animal husbandry and the medical area; there are enormous negative economic impacts due to this toxin. numerous studies have researched extracts and plant compounds with the intent to reduce the growth of aflatoxin-producing organisms, inhibit toxin production and suppress the major toxin encoded genes (i.e., aflr) in these organisms. l...

Levels of aflatoxin produced in peanuts differed with the genetic variety of plant and with the species and strain of invading fungus. Possibilities for identifying groundnut varieties partially resistant to aflatoxin production are discussed.

Soil is a source of primary inoculum for Aspergillus flavus and A. parasiticus, fungi that produce highly carcinogenic aflatoxins in peanuts. Aflatoxigenic fungi commonly invade peanut seeds during maturation, and the highest concentrations of aflatoxins are found in damaged seeds. A laboratory procedure was developed in which viable peanut seeds were wounded and inoculated with field soil cont...

The origin of aflatoxin G1 was studied using mutant strains of Aspergillus parasiticus blocked early in the pathway and by tracing 14C-labelled aflatoxin B1 (AFB1) in wild-type A. flavus and A. parasiticus strains. Sterigmatocystin (ST) was a precursor of AFB1, AFG1 and AFG2 in the four mutants examined. The identity of AFG1 was confirmed by mass spectrometry. No evidence for conversion of AFB1...

The conversion of O-methylsterigmatocystin (OMST) and dihydro-O-methylsterigmatocystin to aflatoxins B1, G1, B2, and G2 requires a cytochrome P-450 type of oxidoreductase activity. ordA, a gene adjacent to the omtA gene, was identified in the aflatoxin-biosynthetic pathway gene cluster by chromosomal walking in Aspergillus parasiticus. The ordA gene was a homolog of the Aspergillus flavus ord1 ...

Functional disruption of the gene encoding nitrate reductase (niaD) in Aspergillus parasiticus was conducted by two strategies, one-step gene replacement and the integrative disruption. Plasmid pPN-1, in which an internal DNA fragment of the niaD gene was replaced by a functional gene encoding orotidine monophosphate decarboxylase (pyrG), was constructed. Plasmid pPN-1 was introduced in linear ...