Article Abstract:
The transport of arginine and lysine in a monensin-sensitive ruminal bacterium was characterized. Transport assays showed that arginine could be transported either through facilitated diffusion or through an energy requiring mechanism. The latter had an absolute requirement for sodium. Experiments showed that arginine is converted to ornithine, and its efflux creates a sodium gradient which drives arginine transport. The arginine carrier also transports lysine, but in this case the mechanism is through facilitated diffusion. The active transport of arginine accounts for approximately 40% of the total ATP.
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Article Abstract:
Fibrobacter succinogenes cells utilize glucose via a pH-sensitive, sodium symport that requires either an electrical or a chemical sodium gradient. However, a pH of less than 5.5 can inhibit glucose uptake despite the presence of a gradient. These conclusions were based on studies using cells of F. succinogenes strain S85 which revealed inhibition of the glucose carrier at a low pH. The ionophores monesin and lasalocid also prevent glucose transport by decreasing intracellular ATP resulting in dissipation of both the electrical and chemical gradients of sodium.
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Article Abstract:
Prevotella bryantii is a ruminal amylolytic bacteria that produces glycogen via uridine diphosphate (UDP) glucose. P. bryantii has a UDP-glucose phosphorylase that converts glucose-1-phosphate to UDP-glucose which is a precursor for glycogen synthesis. The enzyme is induced in the presence of fructose-1,6-bis phosphate and in P. bryantii grown on maltose, cellobiose, glucose or sucrose. The glycogen synthase activity is affected by the culture medium.
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