Abstract
In this article, we report the results of electrochemical monitoring regarding a multicellular photosynthetic cyanobacterial species using a photoelectrochemical sensor. The sensor utilizes the photosynthesis-based reducing action of the cyanobacteria (Spirulina maxima) on an electrochemical mediator (2-hydroxyl-1,4-naphthoquinone) and reoxidation of the mediator at an electrode. When the amperometric signals from the cyanobacteria are compared with dry cell weight, chlorophyll a concentration, and pH, the amperometric signals from the system show a considerable relationship with the chlorophyll a concentration in the cyanobacteria during the cultivation over 54 days.