Proteomic Characterization of Bacillus Subtilis on Bio-degumming of Ramie Bast

Ramie bast is a kind of multipurpose biological material. Selective bio-degradation of ramie bast compounds is an important step to partial utilization of complex polysaccharides. Bacillus subtilis is a kind of dominant species with its ability to degrade ramie bast. In order to understand how polysaccharides were catalyzed and utilized in the metabolism of the bacteria, the proteome of B. subtilis strain 168 was analyzed in the presence of ramie bast as sole carbon source, and the cells were grown in glucose as a reference proteome. In total, 2129 proteins are identified, 1871 proteins were used for quantification between different growth conditions, and 363 proteins were differentially expressed under ramie bast and glucose culturing environment. The carbon source affected the abundance of proteins related to carbohydrate transporters via cell membrane, specific reducing sugars degradation pathway, and central carbon metabolism. qRT-PCR analysis revealed that the mRNA levels of four extracellular enzymes participated in polysaccharides degradation were upregulated under ramie bast condition. This study is the first time to uncover comprehensive information on the proteome response of B. subtilis to ramie bast degradation, and may provide important scientific basis for constructing engineering strains in selective extraction of polysaccharide components in ramie bast.