Sustainable utilization of feather waste to produce alkaline serine protease by genetically engineered Bacillus amyloliquefaciens

In this study, the efficient production of alkaline serine protease from engineered Bacillus amyloliquefaciens was achieved using feather meal as nitrogen sources. By screening of signal peptides library, a recombinant strain HZ12/SP2 with alkaline protease activity of 399.00 U/mL was constructed, which was 357% higher than the control strain HZ12/SP0. Furthermore, the alkaline protease activity was increased by 47%, up to 586.73 U/mL by deletion of the genes pssA, clsA, and sigF. Finally, the feather meal was used as nitrogen sources, and the strain ΔFCP/SP2 produced a maximum protease activity of 688.42 U/mL, which was 580% higher than the strain HZ12/SP0. In conclusion, an efficient alkaline serine protease-expression strain was constructed, which realized the valuable reuse of feather waste as nitrogen sources.