The effect of salinity and osmotic pressure of the medium on the growth, sporulation and changes in the total organic acid content of Aspergillus flavus and Penicillium chrysogenum

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Abstract
Extreme conditions of a medium effects the growth of microorganisms. The effect of salinity (NaCl) and osmotic pressure on the vegetative and reproductive growth as well as on changes in the amount of total organic acid of Aspergillus flavus and Penicillium chrysogenum; isolated from the soil; have been studied in this investigation. The vegetative growth of both species increased with an increase in the NaCl content of the nutrient medium. The maximum increase was observed in A. flavus in the nutrient medium containing 9% NaCl, as compared to the control. On the other hand the salinity and the osmotic pressure values, depending on the changes in the salinity; had inhibitive effects on the production of conidia of A. flavus and stimulative effects on those of Penicillium chrysogenum. P. chrysogenum for maximum production of conidia was observed in the nutrient medium containing 1% NaCl whereas maximum vegetative growth was recorded in the nutrient medium containing 9% NaCl. However, no definite results were obtained concerning a parallelity between the increase in vegetative and reproductive growth. In view of these observations, for a production of total organic acid incubation medium of the fungal species, each species must reach a particular conidia production, and salinity and osmotic pressure of the medium effects their production differently depending on the species.