Gelhaye E, Petitdemange H, Gay R
Laboratoire de Chimie Biologique I, Université de Nancy, France.
J Bacteriol. 1993 Jun;175(11):3452-8. doi: 10.1128/jb.175.11.3452-3458.1993.
The rate of tritiated-thymidine incorporation into DNA was used to estimate Clostridium cellulolyticum H10 growth rates on Avicel cellulose, taking into consideration both the unattached cells and the cells adhered to the substrate. The generation time on cellobiose calculated from the data on cell density (4.5 h) agreed well with the generation time calculated by tritiated-thymidine incorporation (3.8 h). Growth on Avicel cellulose occurred when bacteria were adhered to their substrate; 80% of the biomass was detected on the cellulose. Taking into consideration attached and free bacteria, the generation time as determined by thymidine incorporation was about 8 h, whereas by bacterial-protein 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 found during the exponential phase. Under the conditions used, the end of growth was characterized by an acute release of biomass and cellulase activity from the cellulose. An exhaustion of the accessible cellulose could be responsible for this release.
考虑到未附着细胞和附着在底物上的细胞，用氚化胸腺嘧啶核苷掺入DNA的速率来估计解纤维梭菌H10在微晶纤维素上的生长速率。根据细胞密度数据计算出的纤维二糖上的世代时间（4.5小时）与通过氚化胸腺嘧啶核苷掺入计算出的世代时间（3.8小时）非常吻合。当细菌附着在其底物上时，在微晶纤维素上生长；在纤维素上检测到80%的生物量。考虑到附着和游离的细菌，通过胸腺嘧啶核苷掺入确定的世代时间约为8小时，而通过细菌蛋白估计则约为13小时。除了细菌在纤维素上的生长速率外，附着细胞的释放是纤维素分解效率的一个重要因素。生长阶段影响解纤维梭菌的附着；在指数期发现最大附着。在所使用的条件下，生长结束的特征是生物量和纤维素酶活性从纤维素上急剧释放。可利用纤维素的耗尽可能是这种释放的原因。
