. We could observe slight xylitol accumulation when growth had ceased, reaching 1.24 g/L Additionally, in these conditions and similarly to the wild type in glucose medium, the excess carbon flux was also redirected towards citric acid, a preferred metabolic sink in this yeast . However, in S. cerevisiae the XR/XDH pathway impairs both growth and product formation in anaerobic conditions, and the xylose isomerase (XI) pathway has been required to permit efficient ethanol production in anaerobiosis from xylose . Recent publication in Y. lipolytica suggests a positive effect in lipid production when 02 is limited in the productive phase due to a favored metabolic flux towards fatty acid synthesis rather than citric acid. More studies are required to evaluate the efficiency of the XR/XDH pathway in limited aeration in Y. lipolytica, and in case of deleterious effect due to cofactor imbalance, XI pathway might be considered. Furthermore, we investigated xylose consumption in media that also contained glucose. Similarly to what had been found with engineered S. cerevisiae , our mutant strain only consumed xylose when glucose in the media had dropped .