Abstract

Shindia A.A, Ammar H, Ismail A.E.A and Abdel-Khalik A

Ochratoxin A represents an important problem in fungal food poisoning in some countries. It has toxic effect on human and animals. So far the potentiality of thirty four fungal species belonging to 12 genera isolated from Egyptian legume seeds to release ochratoxin A in their culture filtrates and some ecophysiological factors affecting its production were tested. It was found that nearly 56% of the tested fungi showed positive results as the production of ochratoxin A. Aspergilli particularly Aspergillus ochraceus was distinguished by its capacity to produce ochratoxin A when grown on a selected medium. The maximum ochratoxin A yield was achieved were showed after 9 days incubation at 25???C. An initial pH value of 6.0 was found to be optimum for ochratoxin production and growth of A. ochraceus. The influence of water activity (aw) upon biosynthesis of ochratoxin A and biomass yields were also discussed briefly. The present study gives an account of observations made on the production of ochratoxin A and biomass in relation to the carbon substrate and mitogen compounds supplied in the bioprocess. Sucrose followed by glucose and maltose were more initiative for the growth and ochratoxin A production than cellulosic substrate. Peanut seeds represent the most favorable natural substrate than other substrates investigated. Yeast extract followed by ammonium nitrate were the best nitrogen compounds for biomass and ochratoxin A production by test fungus. In addition the impact of the level of selected carbon and nitrogen ratio on both experimental parameters were also elucidated.