Enzyme formation by a yeast cell wall lytic Arthrobacter species: chitinolytic activity

Abstract

The kinetics of the release of chitinolytic activity (endochitinase EC 3.2.1.14, \-N-acetyglucosaminidase EC 3.2.1.30) by a yeast cell wall lytic Arthrobacter species was studied. The organism was cultivated on yeast cell wall, mycelium of Trichoderma reesei, colloidal chitin, N-acetylglucosamine, glucosamine and mixtures with acetate. With the exception of yeast cell wall, these substrates were used as the sole source of carbon and nitrogen. The growth on colloidal chitin (0.5%) proceeded at a maximum specific growth rate (μumax) of 0.23 h−1 and yielded 2700 mU1−1 chitinase. Yeast cell wall and mycelium of T. reesei supported more rapid growth (μmax = 0.30 h−1 and 0.25 h−1 respectively) but yielded reduced chitinase activity (565 mUl−1 and 700 mUl−1). The growth rate on glucosamine (μmax = 0.24 h−1) was reduced when this was mixed with acetate (μmax = 0.12 h−1), whereas the enzyme yield was increased from 720 mUl−1 to 960 mUl−1. The same effect on growth rate was observed with glucose and equimolar mixtures of glucose and acetate, indicating a strong impact of the organic acid on carbohydrate transport or metabolism. The growth of adapted cells on N-acetylglucosamine was comparable to that observed on an equimolar mixture of glucosamine and acetate, indicating that N-acetylglucosamine is rapidly hydrolysed by adapted cells.