Water-soluble glucans from Streptococcus mutans strain Ing-Britt as an energy source for bacterial growth

Two fractions of water-soluble glucans with different molecular weight were produced by Streptococcus mutans IB. The larger glucan had a molecular weight of about 40,000. The molecular weight of the small glucan was estimated to be 4,100 by gel filtration chromatography and by biochemical methods. These glucans were tested for their ability to initiate and support growth of S. mutans IB and Streptococcus sanguis 903. S. sanguis 903 could grow with the low molecular weight glucan at a reduced rate compared with glucose. S. mutans IB could not utilize any of the glucans. No endo- or exo-glucanase activities could be detected in culture supernatants of any of the strains. In addition to maltose S. sanguis 903 could also utilize maltotriose, maltopentaose and maltoheptaose for growth while S. mutans IB could not grow with maltopentaose or maltoheptaose.