Mutations and protoplast fusion technique as tools for improving propor. to-amylase production in aspergillus ofetidus

摘要

Aspergillus foetidus NRRL 337 was irradiated with UV light at 20 cm distance from the lamp for 4, 8 and 12 minutes. Thirty nine stable mutants were isolated as auxotrophs or/and morphological variants. Upon testing these mutants along with their parental strain for propor. to-amylase production capacity, it was found that most of them overyielded their original strain in the production of the enzyme, whereas some mutants produced the enzyme with capacity like their parent, still others produced itwith capacitites less than the original strain. Three isolates were chosen from these mutants (designated A, B and C) for protoplast fusion to obtain fusants from the three possible combinations (AXB, AXC and BXC). Eighteen stable fusants were obtained and regenerated. Upon testing these fusants for propor. to-amylase production, few ones overyielded the higher parent, some was similar to it, still others were either intermediate within their parental range or less than the lower parent in the capacityof enzyme production.