Production of polysaccharide and accumulation of cell mass during the initial 3 days of adsorption of cells of C. acetobutylicum onto bonechar for the production of butanol from whey permeate in a packed bed reactor. 1. Initiation of excessive production of polysaccharide; 2. Maximum growth and attachment starts; 3. Biofilms become visible and polysaccharide production continues.