Recombinant maltodextrin-phosphorylase from Escherichia coli was produced in under control of its native promotor in E. coli JM 109 and used for glucose-1-phosphate (G-1-P) production from different alpha-glucans such as maltodextrins or soluble starch. A phosphorylase preparation free of comtaminating phosphatase activity was recovered from crude cell extracts in approximately 75% yield by hydrophobic interaction followed by affinity chromatography. The conditions partially optimized for phosphorolytic a-glucan degradation were established at a pH of 7.5 and an inorganic phosphate concentration of 300 to 500 mM. Two factors clearly limit the attainable maximum product yield : A) the equilibrium constant of G-1-P to inorganic phosphate at 30 degrees C and pH 7.5 (K-eq = 0.22-0.24), and B) the maximum degree of conversion, sion of a particular cu-glucan by phosphorylase, i.e., 45 and 38% for starch and maltodextrins . These latter values were shown to be increased to 70 and 65% for the cases of starch and maltodextrins, respectively, by the synergistic, simultaneous, or subsequent action of pullulanase (50-200 IUg(-1) substrate) and phosphorylase. Continuous, enzymatic conversion of maltodextrins in an ultrafiltration membrane reactor has been performed using limiting concentrations of either phosphate or pretreated maltodextrin. On a laboratory scale, productivities of 2.6 g (10 mmol) G-1-P per 1 h(-1) with a phosphorylase loading of 1 IU ml(-1) reactor volume were reached and could be maintained for reaction rimes up to 600 h.