Interaction of strains of non-toxigenic Aspergillus flavus with Aspergillus parasiticus on aflatoxin production
Aflatoxins production is affected by abiotic, biotic and genetic parameters. Eugenesic and dysgenetic condition for aflatoxinogenesis are relatively well studied, such as: the influence of temperature, pH, Aw, Oxigen tension, osmotic pression, organic and inorganic nutrients, substance with fungistatic effects: however there are relatively few knowledge about endogenous regulator mechanisms, the kinetic of the anabolism and the interaction between the productive moulds and remaining microflora holding in eutrophying substrates. The main objective of this study is to evaluate biotic interaction between five indigenous strains of A. flavus, confirmed non-toxigenic, and a productive strain (A. parasiticus ATCC 15 517), cultured simultaneously on two substrates: one natural (cracked corn) and a synthetic one, modified Czapeck-Dox broth. Aflatoxins quantifications were performed by HPLC at 8th and 12th days. Results of those interactive cultures showed that all strains were synergic, increasing aflatoxins production in a range between 5.6 and 106.5% over the control values, with an exception registered on one of the strains cultured in cracked corn at the 12th day, where the production decreased (-7.6%).
Epidemiology of Aflatoxin Formation by Aspergillus Flavus
The epidemiology of aflatoxin contamination in groundnuts, maize and cottonseed, the life cycle of the fungus from sources of primary and secondary inoculum, the mode of entry of A. flavus into the plant, seed infection and, finally, aflatoxin formation in the seed is reviewed.
A new stochastic factor model: General explicit solutions
We present a new stochastic factor model. In doing so, we provide general, explicit solutions to the portfolio optimization problem.