Purification, biochemical characterization, and molecular elucidation of a new biotechnologically compatible serine peptidase from Virgibacillus natechei strain FarDT

A new peptidase designated as SAPV produced from a moderately halophilic Virgibacillus natechei sp. nov., strain FarDT was investigated by purification to homogeneity followed by biochemical and molecular characterization purposes. Through optimization, it was determined that the optimum peptidase activity to be 16,000 U/mL in the optimized liquid medium that contains only white shrimp shell by-product as sole energy and carbon sources. The SAPV enzyme is a monomer protein with a molecular mass of 31 kDa. The sequence of its NH2-terminal amino-acid residues showed homology with those of Bacillus peptidases S8/S53 superfamily. The SAPV showed optimal activity at pH 9 and 60 °C. The sapV gene was cloned, sequenced, and heterologously over expressed in the extracellular fraction of E. coli BL21(DE3)pLysS. The biochemical properties of the recombinant peptidase (rSAPV) were similar to those of native one. The highest sequence identity value (97.66%) of SAPV was obtained with peptidase S8 from Virgibacillus massiliensis DSM 28587, with 9 amino-acid residues of difference. Interestingly, rSAPV exhibited an excellent detergent stability and compatibility than Alcalase 2.4 L FG and Bioprotease N100L