extraction, the extraction procedures are often time-consuming,
and may vary in reliability [4,7].
A recent study using Chlorella vulgaris and exogenous quinone,
as an electrochemical mediator, detected an amperometric signal
from a photoelectrochemical cell in the presence of illumination;
the amperometric signal was generated by the reducing action of
algae on the mediator resulting from photosynthesis [3]. Therefore,
it can be deduced that these amperometric signals resulting
from the coupling between the photobiochemical metabolic activity
and a redox mediator could be used for growth monitoring
of multicellular photosynthetic microorganisms during cultivation.
In this article, we compared amperometric signals from the
photoelectrochemical cell with the DCW and chlorophyll a concentration
in order to elucidate the relationship between sensor signal
and cyanobacterial metabolic activity. Although numerous applications
using electrochemical techniques for biomass and metabolic
activity measurements have been proposed in recent years, the
comparison of amperometric signals withmetabolic activities offilamentous,
multicellular cyanobacteria, such as Spirulina sp., during
a whole batch cultivation period has not been reported [