Microbial Autotrophy via Direct Uptake of Extracellular Electrons from Liquid–Solid Triboelectrification

Energy is fundamental to all terrestrial life, including
microorganisms,
which currently rely primarily on chemical and light energy. The triboelectric
effect, a ubiquitous phenomenon resulting from interfacial charge
transfer during contact-separation of materials, is hypothesized to
efficiently convert mechanical energy into electricity. Here, we demonstrate
that liquid–solid friction can convert mechanical energy into
electrical energy, thereby supporting autotrophic microbial growth
and metabolism without relying on conventional sunlight or chemical
energy inputs. Using electroactive Rhodopseudomonas
palustris and dielectric poly(vinylidene fluoride)
(PVDF) as a model biohybrid system, we found that mechanical vibration
primarily induces triboelectric charge transfer at the water-PVDF
interface, leading to free electron accumulation on the PVDF surface.
These electrons are subsequently taken up by R. palustris for carbon fixation and denitrification, resulting in an increase
in biomass from ca. 2.79 ± 0.25 to 6.27 ± 0.31 mg of protein/L
over 30 days. This phenomenon was further observed across various
dielectric materials and electroactive bacterial strains, suggesting
a potentially universal mechanical-force-driven process for microbial
communities. Our findings reveal a novel role of mechanical force
via the triboelectric effect as an energy source for driving microbial
growth and metabolism, which enhances our understanding of the interactions
between mechanical forces and biological systems.