ENZYME FORMATION BY A YEAST-CELL WALL LYTIC ARTHROBACTER SPECIES - FORMATION OF AMYLASE

The kinetics of amylolytic enzyme formation by a yeast cell wall lytic Arthrobacter species were studied. Cultivation on autoclaved cells of baker's yeast showed that amylase formation was closely related to trehalose and glycogen dissimilation. Growth on yeast glycogen (0.5%) proceeded quite rapidly (mu = 0.31 h-1) with extensive amylase formation during exponential cell multiplication and a further low increase in activity during the stationary phase. Beside amylolytic activity [450 units (U) l-1] the formation of a relatively high level of alpha-glucosidase (90 U l-1) was detected, the latter almost exclusively bound to bacterial cells. Growth on 0.5% trehalose occurred at a reduced rate (mu = 0.22 h-1) with post-logarithmic enzyme synthesis in the stationary phase. Amylase activity attained a level of 1200 U l-1, whereas alpha-glucosidase was very low at 7.7 U l-1. Continuous culture experiments in the chemostat showed maximal volumetric productivity of amylase (105 U l-1 h-1) at a dilution rate of 0.15 h-1. Growth on various carbohydrates revealed low levels of amylolytic activity (< 100 U l-1), which were increased by alpha-1,4-glucans and oligosaccharides such as starch, dextrin, maltotriose and maltose. On 0.5% maltose, growth-associated enzyme synthesis (230 U l-1) was detected at a reduced growth rate (mu = 0.14 h-1). Amylolytic enzyme preparations from the culture fluid showed an unusual cleavage pattern; acting on starch, the polymer was almost completely hydrolysed to maltotriose and maltose in a molar ratio of 3:1.