methods for improving binding of a proteinaceous substance to cell - wall material of a gram - positive bacterium are disclosed . the proteinaceous substance includes an acma cell - wall binding domain , homolog or functional derivative thereof . the method includes treating the cell - wall material with a solution capable of removing a cell - wall component such as a protein , lipoteichoic acid or carbohydrate from the cell - wall material and contacting the proteinaceous substance with the cell - wall material .