[Isolation and analysis of protease-deficient mutants of Bacillus amyloliquefaciens].

Four types of protease negative mutants of Bacillus amyloliquefaciens A50 were selected after four stages of step-by-step UV light mutagenesis. EDTA, and PMSF were used as inhibitors of protease activity to characterize the protease negative mutants with regard to the protease type. The electrophoretic patterns of proteases from culture medium of B. amyloliquefaciens protease deficient mutants were studied. The proinsulin stability in the culture medium of different mutants was analysed. Protease deficient B. amyloliquefaciens strain A50-32 may be used as a recipient for cloning and expression of a foreign proteins genes.