The feather is a valuable by-product with a huge annual yield produced by the poultry industry. Degradation of feathers by microorganisms is a prerequisite to utilize this insoluble protein resource. To improve the degrading efficiency of feathers, mutagenesis of the bacterium Bacillus subtilis S1-4 was performed. By combining ultraviolet irradiation and N-methyl-N’-nitro-N-nitrosoguanidine treatment for mutagenesis, a high protease-producing mutant (UMU4) of B.
The Arabidopsis thaliana genome encodes 56 subtilisin-like serine proteases (subtilases). In order to evaluate the protease activity of a previously uncharacterized subtilase, designated as AtSBT1.9, we cloned its full-length cDNA from A. thaliana seedlings. An AtSBT1.9 mature peptide coding sequence was inserted into the bacterial expression vector, pMAL-c2x, and the recombinant vector was transformed into Escherichia coli BL21 (DE3).