PURPOSE:To provide tunicamycin-resistant Bacillus subtilis TU strain having improved productivity of a pullulanase-like enzyme. CONSTITUTION:The mother strain of Bacillus subtilis is suspended in distilled water, and irradiated with ultraviolet radiation. A part of the cell suspension is inoculated in a tunicamycin-containing medium and cultured under aerobic condition. The proliferated cell is sprayed on the same plate medium containing agar, and incubated. The produced colony is stored in a slant medium having the same composition. A strain having improved productivity of a pullulanase- like enzyme was found frequently in the mutant strain exhibiting tunicamycin- resistance and prepared by the above process. The tunicamycin-resistant mutant strain can be proliferated relatively smoothly in a medium containing 25-100mug/ml of tunicamycin in contrast to the mother strain which cannot be proliferated under the same condition. Accordingly, the strain prepared by the present process is supposed as a novel mutant of Bacillus subtilis from the tunicamycin-resistance and the high productivity of the pullulanase-like enzyme.
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