Fig. 2

Confirmation of the eps cluster disruption and difference comparison of phenotype. a Screening process of the mutants. a-1 was the verification of the single-crossover recombinant with a band of 1750 bp and a-2 was the verification of the double-crossover mutant with a band of 1900 bp. M-marker, 250, 500, 750, 1000, 1500, 2000, 2500, 3000, 4000, 5000, 6000, 8000, 10,000 bp; NC-negative control; b Comparation of cell growth in 250 mL flask with LB medium of different strains. b-1 was the thallus of the wild-strain and b-2 was the thallus of the eps cluster mutant; c Fermentation broth of the eps cluster mutant and the wild-type strain. c-1 was the fermentation broth with granulated thallus of wild-type strain and c-2 was the exquisite fermentation broth of eps cluster mutant; d Alkaline protease enzyme activity assay and the viable cell count of the eps cluster mutant and wild-type strain. The left Y axis indicated the viable cell count ( BL Δupp, BL ΔEP) and the right Y axis indicated the alkaline protease enzyme activity ( BL Δupp, BL ΔEP)