Photosynthetic bio-fuel cells using immobilized cyanobacterium Anabaena variabilis M-3

A photosynthetic reaction begins with charge separation in the reaction centers producing reduced equivalents. In a photosynthetic bio-fuel cell, such reductants in micro-algae are captiu*ed by electron transfer mediators and the electrons are transferred to an electrode to produce electricity as shown in Fig. 1. Similarly, the reducing power generated from oxidative degradation of reserved carbohydrate is also converted into current in the bio-fuel cells running in the dark. We have studied two bio-fuel cells using the marine cyanobacterium Synechococcus sp. (UTEX2380) and the freshwater cyanobacterium Anaftaena variabilis M-2 with 2-hydroxy-l,4-naphthoquinone (HNQ) as a mediator [1, 2]. In a previous study [1], we found that endogenous glycogen in algal cells decreased during discharge not only in the dark but also imder illumination and that these outputs were higher for larger glycogen contents. Therefore, the recovery of the