In the process of the fermentation of steroid C_(11)α-hydroxylgenation strain As-pergillus flavus AF-ANo208,a red pigment is derived,which will affect the isolation and pu-rification of the target product.Low energy ion beam implantation is a new tool for breedingexcellent mutant strains.In this study,the ion beam implantation experiments were performedby infusing two different ions:argon ion(Ar^+)and nitrogen ion(N^+).The results showed thatthe optimal ion implantation was N^+ with an optimum dose of 2.08×10^(15)ions/cm^2,with whichthe mutant strain AF-ANm16 that produced no red pigment was obtained.The strain had highgenetic stability and kept the strong capacity of C_(11)α-hydroxylgenation,which could be utilizedin industrial fermentation.The differences between the original strain and the mutant strain ata molecular level were analyzed by randomly amplified polymorphic DNA(RAPD).The resultsindicated that the frequency of variation was 7.00%,which would establish the basis of applicationinvestigation into the breeding of pigment mutant strains by low energy ion implantation.
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