Mutagenesis of Aspergillus oryzae IPT-301 to improve the production of -fructofuranosidase
Maresma, Beatriz GuilarteCastillo, Boris GutarraFernández, Rubén CuervoSilva, Elda Sabino daMaiorano, Alfredo EduardoRodrigues, Maria Filomena de Andrade
Aspergillus oryzae IPT-301, previously reported as a -fructofuranosidase producing microorganism, was successfully mutated using UV irradiation at 253.7 nm followed by the screening of survivors resistant to certain stress conditions. Strains were first subjected to the -fructofuranosidase activity assay using a portion from the colony grown in Petri dish as the enzyme source. Seven mutants with fructofuranosidase activity values relative to the parent culture between 140 -190% were selected from survivors grown at temperature of 40ºC or 0.018% (w/v) sodium dodecyl sulfate concentration. They were cultivated on a rotary shaker to characterize mycelium and extracellular fructosyltransferase activities. Three mutants named IPT-745, IPT-746 and IPT-748 showed the highest amount of mycelium activity whose values increased 1.5 -1.8 fold, compared with the parent strain. It was found that more than 55% of total enzyme activity (mycelium- plus extracellular- activity) from these strains was detected in the mycelium fraction. Only one mutant, IPT-747, exceeded the amount of extracellular enzyme exhibited by the parent strain (1.5 times). This mutant also showed the highest value of total fructosyltransferase activity.
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