Reisolation and characterization of Clostridium longisporum, a ruminal sporeforming cellulolytic anaerobe.

Two strictly anaerobic strains of ruminal cellulolytic bacteria were isolated which are very similar to the original description given for Clostridium longisporum. Vegetative cells were 1 micron wide by 5 to 15 microns long. Subterminal spores were observed only when an insoluble carbon source was provided for growth. Besides cellulose, the organisms fermented cellobiose, glucose, galactose, fructose, mannose, pectin, salicin and sucrose. Xylan and xylose were not fermented. Fermentation products from glucose or alfalfa cell walls included formate, acetate, butyrate, ethanol, H2 and CO2. The GC content was 23% for one strain and 33% for the other. These isolates hydrolyzed cell wall fractions of alfalfa, in particular, hemicellulose, more rapidly and extensively than other ruminal cellulolytic species examined.