title: L-Arabinose metabolism in Candida arabinofermentans PYCC 5603T and Pichia guilliermondii PYCC 3012: influence of sugar and oxygen on product formation.
abstract: L-Arabinose utilization by the yeasts Candida arabinofermentans PYCC 5603(T) and Pichia guilliermondii PYCC 3012 was investigated in aerobic batch cultures and compared, under similar conditions, to D-glucose and D-xylose metabolism. At high aeration levels, only biomass was formed from all the three sugars. When oxygen became limited, ethanol was produced from D-glucose, demonstrating a fermentative pathway in these yeasts. However, pentoses were essentially respired and, under oxygen limitation, the respective polyols accumulated--arabitol from L-arabinose and xylitol from D-xylose. Different L-arabinose concentrations and oxygen conditions were tested to better understand L-arabinose metabolism. P. guilliermondii PYCC 3012 excreted considerably more arabitol from L-arabinose (and also xylitol from D-xylose) than C. arabinofermentans PYCC 5603(T). In contrast to the latter, P. guilliermondii PYCC 3012 did not produce any traces of ethanol in complex L-arabinose (80 g/l) medium under oxygen-limited conditions. Neither sustained growth nor active metabolism was observed under anaerobiosis. This study demonstrates, for the first time, the oxygen dependence of metabolite and product formation in L-arabinose-assimilating yeasts.
authors.affiliation: Centro de Recursos Microbiológicos (CREM), Faculty of Sciences and Technology, New University of Lisbon, 2829-516, Caparica, Portugal.
authors.forename: César
authors.initials: C
authors.lastname: Fonseca
authors.forename: Isabel
authors.initials: I
authors.lastname: Spencer-Martins
authors.forename: Bärbel
authors.initials: B
authors.lastname: Hahn-Hägerdal
mesh_terms: D000332:Aerobiosis; D001089:Arabinose / Q000378:metabolism*; D018533:Biomass; D001709:Biotechnology / Q000379:methods; D002175:Candida / Q000254:growth & development / Q000378:metabolism*; D003470:Culture Media; D005285:Fermentation; D005947:Glucose / Q000378:metabolism / Q000494:pharmacology*; D010100:Oxygen / Q000494:pharmacology*; D010843:Pichia / Q000254:growth & development / Q000378:metabolism*; D014994:Xylose / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D003470:Culture Media; D014994:Xylose; D001089:Arabinose; D005947:Glucose; D010100:Oxygen