LAUSR

Bovine lactoferrin N-lobe plays an important role in the nonimmunological defense system. In this work, the most suitable promoter Pveg was selected and the fragment coding bovine lactoferrin N-lobe was optimized according to codon bias of Bacillus. The recombinant plasmid pMA0911-Pveg-mBLF-N was introduced into Baicillus subtilis 168 to create B. subtilis/pMA0911-Pveg-mBLF-N. The bovine lactoferrin N-lobe was highly expressed at 28 oC for 15 h. Its purified protein was obtained with 16.5 mg/L and a purity of 93.6% using ammonium sulfate precipitation, Ni-NTA and molecular exclusion. About 200 ng/mL purified bovine lactoferrin N-lobe completely inhibited cell-growth of Escherichia coli JM109 (DE3), 70.3% of Pseudomonas aeruginosa CGMCC 1.6740 and 41.5% of Staphylococcus aureus CGMCC 1.282. To our knowledge, this is the first report about active expression, purification and characterization of bovine lactoferrin N-lobe in safe bacterium B. subtilis, which opens an available application way in the biomedical and food industries.