Box plots of parameters evaluated in the selected mutant and wild type strains. Specific hydrogen production (mmol hydrogen/g CDW, YH2/X) (a), specific ethanol production (mmol ethanol/g CDW, YE/X) (b) and specific glycerol consumption (mmol glycerol consumed/g CDW, YG/X) (c). In each graph the white and black boxes represent the 22 and 46 h interquartile range values respectively and bars the SD. The dashed lines in each graph indicate the wild type averages for each parameter at 22 and 46 h. In the X-axis, the strains whose average values are higher with statistical significance in comparison to that of the wild type using a P < 0.05 were framed. The wild type data was obtained from at least 75 replicates and the coefficient of variation (CV) was <11% for all parameters, except for ethanol concentration, which was lower than 21%. These results were considered to be suitable to establish a reference for comparison of the mutant strain average values with respect to those obtained for the wild type.