High capacity xylose transport in Candida intermedia PYCC4715.

• 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 (small mu, Greekmax=0.5 h−1, 30°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.

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TEKNIK OCH TEKNOLOGIER  -- Industriell bioteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Industrial Biotechnology (hsv//eng)

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