Study On The Mutation Breeding Of Aspergillus Niger Fermented Production Citric Acid

Citric acid is a kind of natural composition and intermediate product of physiological metabolism in the bodies of animals and plants. It has a pleasant sour, safe and nonpoisonous.Furtheremore, it has no remains of sour once enters the mouth. It is an important organic acid which is produced by microorganisms fermented.Its salts, fats and derivatives have their own characteristics especially.There are extremely extensive uses and good development prospects. This research further developes the breeding research of the Citric acid production strains of aspergillus niger on the basis of existing job from the view of application, combining the ⁶⁰Co -γ ray,Ion implantation and metal salt compound - chlorine lithium mainly (LiCl) together to mutagenesis citric acid production strains of aspergillus niger. Four different methods of mutation were used in our experiment, and we got 11 strains which produced high yield acid after primary screening, generation and cultivating alternativly. The basic target of the experiment was achieved. We analyzed the results of the experiment and discussed some problems that we met in the experiment too. Meanwhile, we pointed out the methods to solve it. In the end, the mechanism of the mutation was analyzed and discussed according to the result of experiment.