Photosynthetic bacteria can be useful biotechnological tools – they
produce a variety of valuable products, including high purity hydrogen,
and can simultaneously treat recalcitrant wastewaters. However, while
photobioreactors have been designed and modelled for photosynthetic
algae and cyanobacteria, there has been less work on understanding the
effect of light in photosynthetic bacterial fermentations. In order to
design photobioreactors, and processes using these organisms, robust
models of light penetration, utilisation and conversion are needed. This
article uses experimental data from a tubular photobioreactor designed
to focus in on light intensity effects, to model the effect of light
intensity on the growth of Rhodopseudomonas palustris, a model
photosynthetic bacterium. The work demonstrates that growth is
controlled by light intensity, and that this organism does experience
photoinhibition above 600 W/m2, which has implications for outdoor
applications. Further, the work presents a model for light penetration
in circular photobioreactors, which tends to be the most common
geometry. The work extends the modelling tools for these organisms, and
will allow for better photobioreactor design, and the integration of
modelling tools in designing processes which use photosynthetic
bacteria.
Investigating and modelling the effect of light intensity on Rhodopseudomonas palustris growth
