Action of chitinase on spines of the diatom Thalassiosira fluviatilis

An electron microscopic study of the degradation of the chitin spines of the diatom Thalassiosira fluviatilis by Streptomyces chitinase revealed that only the apices of fibrils are broken down. The result suggests that the enzymolysis of crystalline chitinous structures may be rate-limited by the area of microfibril apices available, which varies with chitin source. A suspension of spines can be used as an assay for chitinase activity by monitoring the rate of loss of turbidity, and although this is not a sensitive assay, it does allow assessment of activity on a crystalline substrate.