The diversion of lactose carbon through the tagatose pathway reduces the intracellular fructose 1,6-bisphosphate and growth rate of Streptococcus bovis |
| |
Authors: | D R Bond B M Tsai J B Russell |
| |
Institution: | (1) Section of Microbiology, Cornell University and Agricultural Research Service, U.S. Department of Agriculture, Ithaca, New York, 14853, USA, US |
| |
Abstract: | Twenty strains of Streptococcus bovis grew more slowly on lactose (1.21 ± 0.12 h−1) than on glucose (1.67 ± 0.12 h−1), and repeated transfers or prolonged growth in continuous culture (more than 200 generations each) did not enhance the growth
rate on lactose. Lactose transport activity was poorly correlated with growth rate, and slow growth could not be explained
by the ATP production rate (catabolic rate). Batch cultures growing on lactose always had less␣intracellular fructose 1,6-bisphosphate
(Fru1,6P
2) than cells growing on glucose (6.6 mM compared to 16.7 mM), and this difference could be explained by the pathway of carbon
metabolism. Glucose and the glucose moiety of lactose were metabolized by the Embden-Meyerhoff-Parnas (EMP) pathway, but the
galactose moiety of lactose was catabolized by the tagatose pathway, a scheme that by-passed Fru1,6P
2. A mutant capable of co-metabolizing lactose and glucose grew more rapidly when glucose was added, even though the total
rate of hexose fermentation did not change. Wild-type S. bovis grew rapidly with galactose and melibiose, but these galactose-containing sugars were activated by galactokinase and catabolized
via EMP. On the basis of these results, rapid glycolytic flux through the EMP pathway is needed for the rapid growth (more
than 1.2 h−1) of S.␣bovis.
Received: 3 June 1997 / Received revision: 10 September 1997 / Accepted: 6 January 1998 |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|