The experimental
approach applied some modern analytical techniques including
high-performance liquid chromatography equipped
with a UV detector and a diode array and multiple wavelength
detector (HPLC-UV-DAD) for analysis of phenols,
fluorescence staining for analysis of cell viability, and
enzyme technology for analysis of sugar consumption.
Furthermore, potential biotransformation of the inhibitory
phenolics during cultivation was also studied. The four
phenolic model compounds (Figure 1A-D) included two
aldehydes, coniferyl aldehyde and vanillin, and two carboxylic
acids, ferulic acid and 4-hydroxybenzoic acid.
Coniferyl aldehyde has been identified in spruce hydrolysates
and has been used extensively as a model compound
to study the effect of inhibition of production of cellulosic
ethanol by the yeast Saccharomyces cerevisiae [19-21].