Wolffia globosa as a biocatalyst in plant-based biofuel cells

Abstract

The rootless duckweed Wolffia globosa, not explored toward electrogenicity till now, is investigated as a putative biocatalyst in Plant-based Biofuel Cells (P-BFC) for the electrical current generation and its basic metabolic changes during the polarization are depicted. After a short adaptation period, the open-circuit voltage of P-BFC, utilizing W. globosa as an anodic biocatalyst, reaches values of 630 mV. At a connected external resistor of 1 kΩ in the electric circuit, stable current densities of 170±10 mA m-2 are achieved. The electrical outputs depend on the anodic potential, reaching negative values of ca. -200 mV (vs. SHE). W. globosa produces an electrochemically active compound, acting as an electron shuttle. The polarization intensifies the W. globosa metabolism, expressed in a double increased glucose and starch content along with 1.82 times higher specific amylase activity of 70.0±2.8 U g-1 wet biomass in the organelle-enriched fractions of the explored as biocatalysts plants compared to the control. The results reveal that Wolffia globosa can be utilized as a biocatalyst in P-BFC for simultaneous electricity generation and increased carbohydrate and protein content.