Absorption and utilization of oligosaccharides by Cellvibrio gilvus

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Virginia Polytechnic Institute

The ability of a cellulolytic bacterium Cellvibrio gilvus, to absorb and utilize members of the cellulose oligosaccharide series was investigated.

Resting cell suspensions prepared from 24-hour cultures were incubated with the cellulodextrins. At various times samples were removed from the incubation flasks and filtered. The filtrates were analyzed for sugar concentration by a modified phenol-sulfuric acid procedure and degree of polymerization (D.P.) by a borohydride reduction phenol-sulfuric acid method. The rate of disappearance of the oligosaccharides from the supernatant of the resting cell suspensions was linear with respect to time indicating an active absorption mechanism. The conclusion that the rate of absorption was controlled by the respiration of the cell was based on the observation that independent of the D.P. of the cellulodextrin, the number of glucose molecules removed per cell per minute was approximately the same. The D.P. of the substrates remained constant over the experimental period with the cells suggesting that the molecules were removed intact. No effect on sugar concentration or D.P. was observed when the oligosaccharides were incubated with the filtrates which confirm these data. It was not possible from these results to determine if the oligosaccharides entered the cell or were metabolized at the cell wall.