Secondary metabolites (idiolites) are structurally diverse and unusual, generally are produced in mixtures with other members of the same chemical family, and usually are formed at low specific growth rates. In batch cultures, processes leading to the production of idiolites are often sequential; the cultures exhibit a distinct growth phase (trophophase) followed by a production phase (idiophas...

Aflatoxins are a group of mycotoxins that have major adverse effects on human health. Aflatoxin B1 (AFB1) is the most important aflatoxin and potent carcinogen once converted into DNA-reactive form by cytochrome P450 enzymes (CYP450). AFB1 biosynthesis involves formation Versicolorin A (VerA) which shares structural similarities with can be found in contaminated commodities, often co-occurring ...

Small RNAs in Penicillium digitatum were identified and analyzed via transcriptome sequencing on the BGISEQ-500 platform. A total of 15 predicted miRNAs 10718 novel siRNAs found. Their length distribution, sequence, construction, base bias, expression levels potential targets determined as well. Through pathway KEGG enrichment analysis, miRNA target genes mostly involved carbohydrate metabolism...

Contamination of crops with aflatoxin is a serious global threat to food safety. Aflatoxin production by Aspergillus flavus is exacerbated by drought stress in the field and by oxidative stress in vitro. We examined transcriptomes of three toxigenic and three atoxigenic isolates of A. flavus in aflatoxin conducive and non-conducive media with varying levels of H2O2 to investigate the relationsh...

Two genes involved in aflatoxin B1 (AFB1) biosynthesis in Aspergillus parasiticus, nor-1 and ver-1, were localized to a 35-kb region on one A. parasiticus chromosome and to the genomic DNA fragment carried on a single cosmid, NorA. A physical and transcriptional map of the 35-kb genomic DNA insert in cosmid NorA was prepared to help determine whether other genes located in the nor-1-ver-1 regio...

Pseudomonas fluorescens strain 3JW1, which has a broad-spectrum antimicrobial activity, was studied to investigate whether it affects the amounts of aflatoxin B1 (AFB1) produced by Aspergillus flavus. It was found that the bacterium reduced the amounts of AFB1 in potato dextrose broth (PDB) and peanut medium by 97.8% and 99.4%, respectively. It also reduced AFB1 by ~183 μg/kg (55.8%) when appli...

The pathway oxoaverantin (OAVN) --> averufin (AVR) --> hydroxyversicolorone (HVN) --> versiconal hemiacetal acetate (VHA) is involved in aflatoxin biosynthesis, and the cypX and moxY genes, which are present in the aflatoxin gene cluster, have been previously suggested to be involved in this pathway. To clarify the function of these two genes in more detail, we disrupted the genes in aflatoxige...

An Aspergillus parasiticus gene, designated apa-2, was identified as a regulatory gene associated with aflatoxin biosynthesis. The apa-2 gene was cloned on the basis of overproduction of pathway intermediates following transformation of fungal strains with cosmid DNA containing the aflatoxin biosynthetic genes nor-1 and ver-1. Transformation of an O-methylsterigmatocystin-accumulating strain, A...

An inhibitor of aflatoxin biosynthesis localized in the seed coats of developing cotton was partially purified and characterized. Aqueous extracts from 25-day postanthesis seed coat tissue inhibited aflatoxin (B(inf1)) production in liquid cultures of Aspergillus flavus AF13. Inhibition was concentration dependent, with a 50% effective dose of 173 (mu)g of crude extract per ml of medium. The in...