A study was undertaken to isolate new strains of bacteria that produce keratan sulfate-hydrolyzing endoglycosidase (keratanase) at reasonable high rate in usual culture medium. Firstly, screening was made on all the bacteria capable of growing on the synthetic medium containing keratan sulfate as the sole carbon source, and 658 isolates were thus obtained from marine, freshwater and land environments in Japan. These isolates were cultured in keratan sulfate-containing peptone medium, and the cultures obtained were assayed for keratanase activity. Out of 658 isolates, only 22 isolates were found to produce appreciable amounts of keratanase in the presence of keratan sulfate. The chosen bacteria were transferred to the peptone medium without any supply of keratan sulfate, and the cultures obtained were then assayed for keratanase activity. It was found that in the absence of keratan sulfate some bacteria produced more whereas others produced less keratanase. Strain no. F-179 from Flavobacterium sp. possessed the highest productivity of keratanase among all the isolates. Finally, the keratanase from strain no. F-179 was purified, and its enzymatic properties were examined. It was concluded that this organism may be a good source of keratanase.
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