Fluorescence measurements under aerobic and anaerobic conditions on Pichia stipitis, Pachysolen tannophilus and Candida utilis grown on D-xylose

Abstract

Batch growth of the yeasts Candida utilis, Pachysolen tannophilus and Pichia stipitis on 1% D-xylose was monitored using a commercial fluorosensor with an excitation wavelength of 340 nm and a detection wavelength of 460 nm. Step changes in oxygen concentration were made and in the presence of 0.3 g/l of xylose, step changes from aerobic to anaerobic conditions resulted in an increase of the fluorescence level by about 40% for the non-fermentative yeast C. utilis. However, the increases of the fluorescence levels for P. tannophilus and P. stipitis stayed below 10%. These measurements indicate better control of (or better redox balance for) intracellular NADH concentration in P. tannophilus and P. stipitis than in C. utilis.