ADHESION AND GROWTH-RATE OF CLOSTRIDIUM-CELLULOLYTICUM ATCC-35319 ON CRYSTALLINE CELLULOSE

The rate of tritiated-thymidine incorporation into DNA was used to est imate Clostridium cellulolyticum H10 growth rates on Avicel cellulose, taking into consideration both the unattached cells and the cells adh ered to the substrate. The generation time on cellobiose calculated fr om the data on cell density (4.5 h) agreed well with the generation ti me calculated by tritiated-thymidine incorporation (3.8 h). Growth on Avicel cellulose occurred when bacteria were adhered to their substrat e; 80% of the biomass was detected on the cellulose. Taking into consi deration attached and free bacteria, the generation time as determined by thymidine incorporation was about 8 h, whereas by bacterial-protei n estimation it was about 13 h. In addition to the growth rate of the bacteria on the cellulose, the release of adhered cells constituted an important factor in the efficiency of the cellulolysis. The stage of growth influenced adhesion of C cellulolyticum; maximum adhesion was f ound during the exponential phase. Under the conditions used, the end of growth was characterized by an acute release of biomass and cellula se activity from the cellulose. An exhaustion of the accessible cellul ose could be responsible for this release.