Growth dependence of alpha-glucan phosphorylase activity in Thermus thermophilus

Glycogen from the thermophilic eubacterium Thermus thermophilus has been characterized by enzymatic, chemical and spectroscopic analysis. With an average chain length of seven glucose units, the glycogen from T. thermophilus is one of the most highly branched glycogens known. In contrast to other bacterial species, in T. thermophilus, accumulation of glycogen appears not be affected by low nitrogen concentration. For the first time, alpha-glucan phosphorylase activity and glycogen content were measured throughout the growth cycle of T. thermophilus in order to gain insight into glycogen metabolism. In contrast to the situation that prevails in Escherichia coli, additional carbon sources had no effect on alpha-glucan phosphorylase activity in T. thermophilus. Maximal activity of the thermophilic enzyme was found in the early logarithmic phase of growth, suggesting a function of the alpha-glucan phosphorylase in T. thermophilus as an outgrowth-specific enzyme.