Enzyme formation by a yeast cell wall lytic Arthrobacter species: formation of amylase

Abstract

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 (0.507o) proceeded quite rapidly (~t = 0.31 h -l ) 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) 1-1] the formation of a relatively high level of c~-glucosidase (90 U 1 -1) was detected, the latter almost exclusively bound to bacterial cells. Growth on 0.5°70 trehalose occurred at a reduced rate (~t = 0.22 h -1) with post-logarithmic enzyme synthesis in the stationary phase. Amylase activity attained a level of 1200 U 1-1, whereas c~-glucosidase was very low at 7.7 U 1-1. Continuous culture experiments in the chemostat showed maximal volumetric productivity of amylase (105 U1-1 h -1) at a dilution rate of 0.15h -1. Growth on various carbohydrates revealed low levels of amylolytic activity (< 100U l-I), which were increased by c~-l,4glucans and oligosaccharides such as starch, dextrin, maltotriose and maltose. On 0.5°70 maltose, growth-associated enzyme synthesis (230 U l-l) was detected at a reduced growth rate (~t = 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.

Proteolytic activity of a yeast cell wall lytic Arthrobacter species

“…All cultivations were performed at 30°C and pH 7·5. Shake flask cultivations were carried out on an orbital shaker (250 rev min −1 , 25 mm throw) for 48 h in Erlenmeyer flasks containing 200 ml medium as described elsewhere (John and Hampel 1992) with 5 g l −1 complex substrate. The crude culture supernatant was used for the experiments reported here.…”