Novel silica forming peptide, RSGH, from Equus caballus: Its unique biosilica formation under acidic conditions

A novel silica forming peptide (SFP), RSGH was designated on the basis of the peptide found from Equus caballus and investigated for its ability to precipitate biosilica under acidic conditions, where biosilica is not easily formed. At pH values of 4, 5 and 6, RSGH showed better performance in the generation of silica particles than the most well-known SFP, silaffin R5, and the amount of the produced biosilica particles increased with the concentration of the peptide. We also demonstrated that RSGH could induce biosilica formation for the processes requiring a low pH, such as silica shell-coating of yeast cells. The RSGH peptide could adsorb to the yeast wall and generate a biosilica shell on the cell surface at a pH of 5, an optimal condition for culturing yeast. These results indicate that RSGH performs well biosilica formation, even in acidic conditions, and can be efficiently applied for mediating biosilica in systems requiring a low pH.