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 collo
idal 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-lik
e spore producers. The most typical strain, Clostridium sp. ChK5, was
characterized further. This bacterium degraded colloidal chitin and pr
oduced mainly acetate, butyrate and lactate. Endochitinase and chitobi
ase 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 (K-m) for this enzyme was 19.3 mg m
l(-1). Strain ChK5 shows strong phenotypic similarity to Clostridium t
ertium.