Fig. 2
a NADH/NAD+ ratios and b NADH and NAD+ concentrations of KMK-12, KMK-21, KMK-22 and KMK-23 strains grown in 55 g L−1 glycerol medium. c NADH/NAD+ ratios and d NADH and NAD+ concentrations of KMK-23 grown in the medium containing 40 g L−1 glycerol and 20 g L−1 various co-substrates; mannitol (Man), glucose (Glc), xylose (Xyl) and galactose (Gal)