Fig. 3

Verification of the lchAC disruption and the characterization of the mutant. a Screening process of the mutants. a-1 was the verification of the single-crossover recombinant with a band of 1200 bp and a-2 was the verification of the double-crossover mutant with a band of 1300 bp (M marker, NC negative control); b Alkaline protease enzyme activity assay and the viable cell count of the lchAC mutant and wild-type strain. The left Y axis indicated the viable cell count ( BL Δupp, BL ΔS) and the right Y axis indicated the alkaline protease enzyme activity ( BL Δupp, BL ΔS)