Plant Microbial Fuel Cells in a botanical perspective: Nomenclatural constraints and new insights on plant traits potentially affecting bioelectrical perfomance

Plant microbial fuel cells represent an innovative type of microbial fuel cell technology, utilizing plant rhizodeposition to fuel electrochemically active bacteria on the anode surface, thereby generating bioelectricity. This study delves into some botanical aspects of plant species employed in PMFCs and Constructed Wetland PMFCs, aiming to investigate whether their bioelectrical performance is influenced by Raunkiær life forms and root architecture. Our study involved 40 plant species described in 38 documents. In some cases, nomenclature issues prevented the interpretation of actual species used in the experiments. The bioelectrical performance of PMFCs appeared to be significantly affected by both life forms and root architecture. Therophytes and Hemicriptophytes exhibited higher median values than the other life forms, while the Geophyte group showed very high power density values despite a lower median value. In contrast, CW-PMFCs do not appeared to be significantly affected by the botanical traits considered, likely due to the limited data collected on this experimental configuration. The plant species that performed the best in PMFCs include Carex hirta, Alisma plantago-aquatica, Glyceria maxima and Canna indica, all of which have an adventitious root system. C. hirta, G. maxima and C. indica are geophytes, while A. plantago-aquatica is a hydrophyte. Consequently, epiphytes, chamaephytes and nanophanerophytes, as well as plants with fibrous root systems, appeared to be not recommended for PMFCs. Nevertheless, the results of our study may have certain limitation due to nomenclature issues that prevented the accurate identification of species used in the PMFCs, the absence of a standardized benchmark for electrical measurement, and the lack of clear match between each species and its bioelectrical performance, reducing the data pool.