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Cellobiose uptake and metabolism by Ruminococcus flavefaciens
1Department of Animal Sciences, University of Illinois, Urbana-Champaign 61801.
Applied and Environmental Microbiology
|January 1, 1991
Summary
Ruminococcus flavefaciens FD-1 actively transports cellobiose using a specialized system, not glucose. This bacterium utilizes cellobiose phosphorylase for energy, not a phosphoenolpyruvate-dependent pathway.
Area of Science:
- Microbiology
- Bacterial Physiology
- Biochemistry
Background:
- Ruminococcus flavefaciens FD-1, a ruminal bacterium, grows on cellobiose but not glucose.
- Understanding nutrient uptake mechanisms is crucial for rumen function.
Purpose of the Study:
- To investigate the mechanism of cellobiose uptake in Ruminococcus flavefaciens FD-1.
- To determine if cellobiose is transported via an active system and identify its phosphorylation pathway.
Main Methods:
- Anaerobic measurement of [G-3H]cellobiose uptake in R. flavefaciens FD-1.
- Assessing the effect of various inhibitors on cellobiose transport.
- Enzyme assays for cellobiose phosphorylation (cellobiose phosphorylase and phosphoenolpyruvate-dependent systems).
Main Results:
- Cellobiose uptake occurred at 9 nmol/min per mg protein and was inhibited by electron transport inhibitors, ionophores, and other compounds, indicating active transport.
- Glucose transport was not detected.
- Cellobiose phosphorylation was not phosphoenolpyruvate-dependent; cellobiose phosphorylase activity was constitutive (329 nmol/min per mg protein).
Conclusions:
- R. flavefaciens FD-1 possesses an active transport system for cellobiose.
- Cellobiose is phosphorylated by cellobiose phosphorylase, not a phosphoenolpyruvate-dependent system, supporting its growth on cellobiose.