A proteomic analysis of secreted proteins from xylan-induced Bacillus sp. strain K-1

The expression level of extracellular proteins in an alkaliphilic bacterium, Bacillus sp. strain K-1, grown in a xylan-containing medium, is significantly increased when compared with that grown in the nonxylan culture medium. A proteomic approach has been efficiently applied to separate and characterize these differentially expressed secretory proteins. Eight prominent protein spots were identified and subjected to N-terminal amino acid sequencing. The results show that three spots share considerable similarity with the xylanolytic enzymes and that two spots share considerable similarity with the GltC regulatory protein and 3-dehydroquinate dehydratase, respectively. In addition, the three other proteins show little similarity with the known proteins in the database. In conclusion, our results demonstrate that the proteomic approach is a highly efficient method to rapidly study the differential expression of the secreted proteins by Bacillus sp. strain K-1 grown under xylan-induced condition.