IMPROVEMENT OF AUREOBASIDIUM PULLULANS A.P.-3 FOR PULLULAN BIOSYNTHESIS BY ASSOCIATED MUTAGENESIS.
 
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Pol. J. Food Nutr. Sci. 1999;49(2):235–243
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ABSTRACT
The strain Aureobasidium pullulans A.p.-3 was subjected to mutagenesis to improve its ability to pullulan biosynthesis. The mutagenesis of 18-h old culture was carried out in two variants using ethylen imine (EI) and ultraviolet (UV) radiation at the EI concentration and UV exposure times of 2.0 mg/mL and 1.5 min (variant I), and 2.0 mg/mL and 2.0 min (variant II). Among 240 cultures examined, the positive mutants made 26% for variant I and 13% for variant II. Two best black mutants Dy-17 and Dx-30 synthesized the polysaccharide with the yields greater than those of parent strain by 24 and 21%, respectively. White mutant was also obtained, the pullulan yield for which was on the level as for strain A.p.-3, but free from melanin contaminants. Acquired characteristic of black mutants was found stable when re-examined after 3- and 6-month storage at 4oC. The kinetics of pullulan biosynthesis by black mutants indicated that the pullulan production was intensified beginning from the second day of culturing, as compared to strain A.p.-3.
ISSN:1230-0322