Chi18A, the endochitinase in the cellulosome of the thermophilic, cellulolytic bacterium Clostridium thermocellum.

The chitinase gene chiA was identified on the Clostridium thermocellum genome downstream of the endoglucanase gene celA. It contains a catalytic module of glycosyl hydrolase family 18 and a cellulosomal dockerin module. Chi18A hydrolyzes aryl-acetyl-chito-oligosaccharides preferentially. In denaturing electrophoresis of purified cellulosomes, a single chitinase activity band was identified in zymograms and Western blots, indicating that Chi18A is the only chitinase in the cellulosome.