The fission yeast Schizosaccharomyces pombe CBS 356 exhibits extracellular
maltase activity. This activity may be of commercial interest as it exhibited a low pH optimum (3.5) and a high affinity for
maltose (Km of 7.0+/-1.8 mM). N-terminal sequencing of the
protein indicates that it is the product of the AGL1 gene. Regulation of this gene occurs via a derepression/repression mechanism. In
sugar- or
nitrogen-limited chemostat cultures, the specific rate of
enzyme production (q(p)) was independent of the nature of the
carbon source (i.e.
glucose or
maltose), but synthesis was partially repressed by high
sugar concentrations. Furthermore, q(p) increased linearly with specific growth rate (mu) between 0.04 and 0.10 h(-1). The
enzyme is easily mass-produced in aerobic
glucose-limited fed-batch cultures, in which the specific growth rate is controlled to prevent alcoholic fermentation. In fed-batch cultures in which biomass concentrations of 83 g L(-1) were attained, the
enzyme concentration reached 58,000 Units per liter culture supernatant. Extracellular
maltase may be used as a dough additive in order to prevent mechanisms such as
maltose-induced
glucose efflux and
maltose-
hypersensitivity that occur in
maltose-consuming Saccharomyces cerevisiae.