Background: The purpose of this work was to find a rapid method for
glycerol detection during microbial fermentations. The method
requirements were, first, to avoid sample pretreatment, and second, to
measure glycerol precisely especially out of fermentation broth.
Results: This was achieved by combining two reaction principles \u2014
the Malaprade reaction and the Hantzsch reaction. In the Malaprade
reaction, glycerol is converted into formaldehyde. This forms a dye in
the Hantzsch reaction after which adsorption is than detected. The
subsequent assay was investigated with two different fermentation
media, a chemically undefined and a chemically defined media, used for
Pichia pastoris fermentation. In both media, as well as in real
fermentation samples, glycerol content could be reproducibly detected
with the method. Moreover, measurements were more precise than using a
standard glycerol detection kit. Conclusions: With this rapid assay,
glycerol could be detected easily in microbial fermentation broth. It
is reliable over a wide concentration range including advantages such
as an easy assay set-up, a short assay time and no sample pretreatment