Investigation of increased production of Citric acid by Aspergillus Niger mutant isolates

Background and Aim : Citric acid is one of the most important organic acids that its consumption is very important in the world and its demand is increasing every year. The aim of this study was to induce mutations in normal isolates and compare the ability to produce citric acid between normal isolates and mutant isolates.Methods : Isolation of fungi used in this study from different environments (air, soil, water) was used. After successive cultures on PDA medium, the isolates were identified and purified. The main isolates as well as mutant isolates were cultured in the center of CZapek Dax Agar specific medium by inoculation in the center Acid production was observed every ۲۴ hours by measuring the diameter of the halo. Aspergillus Niger (PTCC ۵۰۱۰) was used as a control. Finally, the isolates were inoculated into liquid culture medium and the amount of citric acid production was investigated.Results : ۵ different isolates obtained ۵ new mutant isolates by inducing mutation in each. The highest amount of citric acid production was related to mutant isolate No. ۵ called AMR and the lowest amount was related to isolate without mutant No. ۱.Conclusion : In isolates without mutation, the maximum production of citric acid was ۱۵ g / l and in isolates after induction of mutation, a maximum of ۲۱ g / l was observed.

Keywords:

Aspergillus Niger , CZapek Dax Agar , Citric acid , Mutant isolates