title: High capacity xylose transport in Candida intermedia PYCC 4715.
abstract: Xylose-utilising yeasts were screened to identify strains with high xylose transport capacity. Among the fastest-growing strains in xylose medium, Candida intermedia PYCC 4715 showed the highest xylose transport capacity. Maximal specific growth rate was the same in glucose and xylose media (mu(max)=0.5 h-1, 30 degrees C). Xylose transport showed biphasic kinetics when cells were grown in either xylose- or glucose-limited culture. The high-affinity xylose/proton symport system (Km = 0.2 mM, Vmax = 7.5 mmol h-1 g-1) was more repressed by glucose than by xylose. The less specific low-affinity transport system (K = 50 mM, Vmax = 11 mmol h-1 g-1) appeared to operate through a facilitated-diffusion mechanism and was expressed constitutively. Inhibition experiments showed that glucose is a substrate of both xylose transport systems.
authors.affiliation: Centro de Recursos Microbiológicos (CREM), Faculty of Sciences and Technology, New University of Lisbon, 2829-516, Caparica, Portugal.
authors.forename: Márk
authors.initials: M
authors.lastname: Gárdonyi
authors.forename: Måns
authors.initials: M
authors.lastname: Osterberg
authors.forename: Carla
authors.initials: C
authors.lastname: Rodrigues
authors.forename: Isabel
authors.initials: I
authors.lastname: Spencer-Martins
authors.forename: Bärbel
authors.initials: B
authors.lastname: Hahn-Hägerdal
mesh_terms: D001693:Biological Transport, Active; D002175:Candida / Q000378:metabolism*; D003470:Culture Media; D005285:Fermentation; D005947:Glucose / Q000378:metabolism; D007700:Kinetics; D014994:Xylose / Q000378:metabolism*
chemical_list: D003470:Culture Media; D014994:Xylose; D005947:Glucose