1 research outputs found
Photoelectrochemistry of Photosystem II <i>in Vitro</i> vs <i>in Vivo</i>
Factors
governing the photoelectrochemical output of photosynthetic
microorganisms are poorly understood, and energy loss may occur due
to inefficient electron transfer (ET) processes. Here, we systematically
compare the photoelectrochemistry of photosystem II (PSII) protein-films
to cyanobacteria biofilms to derive: (i) the losses in light-to-charge
conversion efficiencies, (ii) gains in photocatalytic longevity, and
(iii) insights into the ET mechanism at the biofilm interface. This
study was enabled by the use of hierarchically structured electrodes,
which could be tailored for high/stable loadings of PSII core complexes
and Synechocystis sp. PCC 6803 cells.
The mediated photocurrent densities generated by the biofilm were
2 orders of magnitude lower than those of the protein-film. This was
partly attributed to a lower photocatalyst loading as the rate of
mediated electron extraction from PSII <i>in vitro</i> is
only double that of PSII <i>in vivo</i>. On the other hand,
the biofilm exhibited much greater longevity (>5 days) than the
protein-film
(<6 h), with turnover numbers surpassing those of the protein-film
after 2 days. The mechanism of biofilm electrogenesis is suggested
to involve an intracellular redox mediator, which is released during
light irradiation