The kinetics of the release of chitinolytic activity (endochitinase EC 3.2.1.14, beta-Ar-acetylglucosaminidase 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 (mu(max)) of 0.23 h(-1) and yielded 2700 mU l(-1) chitinase. Yeast cell wall and mycelium of T. reesei supported more rapid growth (mu(max) = 0.30 h(-1) and 0.25 h(-1) respectively) but yielded reduced chitinase activity (565 mU l(-1) and 700 mU l(-)1). The growth rate on glucosamine (mu(max) = 0.24 h(-1)) was reduced when this was mixed with acetate (mu(max) = 0.12. h(-1)), whereas the enzyme yield was increased from 720 mU l(-1) to 960 mU l(-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.