title: Cellobiose uptake and metabolism by Ruminococcus flavefaciens.
abstract: The cellulolytic ruminal bacterium Ruminococcus flavefaciens FD-1 utilizes cellobiose but not glucose as a substrate for growth. Cellobiose uptake by R. flavefaciens FD-1 was measured under anaerobic conditions (N2), using [G-3H]cellobiose. The rate of cellobiose uptake for early- or late-log-phase cellobiose-grown cells was 9 nmol/min per mg of whole-cell protein. Cellobiose uptake was inhibited by electron transport inhibitors, iron-reactive compounds, proton ionophores, sulfhydryl inhibitors, N,N-dicyclohexylcarbodiimide, and NaF, as well as lasalocid and monensin. The results support the existence of an active transport system for cellobiose. Transport of [U-14C]glucose was not detected with this system. Phosphorylation of cellobiose was not by a phosphoenolpyruvate-dependent system. Cellobiose phosphorylase activity was detected by both a coupled spectrophotometric assay and a discontinuous assay. The enzyme was produced constitutively in cellobiose-grown cells at a specific activity of 329 nmol/min per mg of cell-free extract protein.
authors.affiliation: Department of Animal Sciences, University of Illinois, Urbana-Champaign 61801.
authors.forename: C T
authors.initials: CT
authors.lastname: Helaszek
authors.forename: B A
authors.initials: BA
authors.lastname: White
mesh_terms: D000963:Antimetabolites / Q000494:pharmacology; D001693:Biological Transport, Active; D002475:Cellobiose / Q000378:metabolism / Q000493:pharmacokinetics*; D010459:Peptococcaceae / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*
chemical_list: D000963:Antimetabolites; D002475:Cellobiose