RESUMEN
The possibility of obtaining mutant yeasts Yarrowia lipolytica VKM Y-2373 with increased ability to synthesize citric acid from glucose by using UV irradiation and N-methyl-NT-nitro-N-nitrosoguanidine was studied. Of 1500 colonies of the Y. lipolytica treated with either UV or N-methyl-NT-nitro-N-nitrosoguanidine, three mutants were selected that displayed higher (by 23%) biosynthetic ability as compared with the initial strain. Additionally, three mutants were selected from 1000 colonies of the Y. lipolytica exposed to a combined action of UV and N-methyl-NT-nitro-N-nitrosoguanidine; their biosynthetic activity exceeded that of the initial strain by 43.9%. The selective media with citrate and acetate were developed for a rapid selection of mutants as well as the express methods for the detection of active citric acid producers on the solid media with chalk and bromocresol containing a limiting concentration of amine nitrogen and an excess of glucose.