Submitted to: Conference on Rumen Function
Publication Type: Abstract Only
Publication Acceptance Date: 10/31/1997
Publication Date: N/A
Interpretive Summary: Not required.
Technical Abstract: Fibrobacter succinogenes S85 cultures that were cellobiose-limited, converted cellobiose to succinate and acetate, produced little glucose or cellotriose, maintained an intracellular ATP of 4.1 mM and a membrane potential of 140 mV for 24h, did not lyse at a rapid rate once they had reached stationary phase, and had a most probable number (mpn) of viable cells that was greater than 106 per ml. When the cellobiose concentration was increased 6-fold (5 to 30 mM), ammonia was exhausted, and the cultures left 10 mM cellobiose. The cellobiose-excess cultures produced succinate and acetate while they were growing, but there was little increase in fermentation acids after the ammonia was depleted and growth ceased. The stationary phase, cellobiose-excess cultures had a lysis rate that was 7-fold faster than the sellobiose-limited cultures, and the MPN was only 3.3 X 103 cell per ml. The stationary phase, cellobiose-excess cultures had d2.5 times as much cellular polysaccharide as the cellobiose-limited cultures, but the intracellular ATP and membrane potential were very low (0.1 mM and 40 mV, respectively). Methyglyoxal, a potentially toxic end- product of carbohydrate fermentation, could not be detected, and fresh inocula grew rapidly in spent medium that was supplemented with additional ammonia. Stationary phase, cellobiose-excess cultures converted cellobiose to glucose and cellotriose, but the apparent Km of cellotriose formation was 15-fold lower than Km of glucose production (0.7 versus 10 mM.