The isolation and characterization of a rumen chitinolytic bacterium.

Chitinolytic bacteria were detected in faeces and digesta of wild and domesticated herbivores. The presence of chitinolytic bacteria in two cows was verified following enrichment culture of rumen fluid on colloidal chitin. In three other cows, direct counts on chitin agar showed that the numbers of these bacteria in the rumen fluid ranged from 5 x 10(4) to 2 x 10(8) ml-1. Most of these bacteria were Clostridium-like spore producers. The most typical strain, Clostridium sp. ChK5, was characterized further. This bacterium degraded colloidal chitin and produced mainly acetate, butyrate and lactate. Endochitinase and chitobiase were produced when chitin was the growth substrate. Endochitinase was also detected in cultures grown on N-acetylglucosamine and glucose. Optimal conditions for endochitinase activity were 37 degrees C and pH 4.5-6.1. The Michaelis constant (Km) for this enzyme was 19.3 mg ml-1. Strain ChK5 shows strong phenotypic similarity to Clostridium tertium.