Electricity generation and microbial communities in microbial fuel cell powered by macroalgal biomass

The potential of macroalgae Laminaria digitata as substrate for bioelectricity production was examined in a microbial fuel cell (MFC). A maximum voltage of 0.5 V was achieved without any lag time due to the high concentration of glucose and mannitol in the hydrolysate. Total chemical oxygen demand removal efficiency reached over 95% at the end of batch run.

Glucose and mannitol were degraded through isobutryrate as intermediate. The 16S rRNA gene high throughout sequencing analysis of anodic biofilm revealed complex microbial composition dominated by Bacteroidetes (39.4%), Firmicutes (20.1%), Proteobacteria (11.5%), Euryarchaeota (3.1%), Deferribacteres (1.3%), Spirochaetes (1.0%), Chloroflexi (0.7%), Actinobacteria (0.5%), and others (22.4%).

The predominance of Bacteroidetes, Firmicutes and Proteobacteria demonstrated their importance for substrate degradation and simultaneous power generation. These results demonstrate that macroalgae hydrolysate can be used as a renewable carbon source of microbial electrochemical systems for various environmental applications.