BIOLEAP

BIOTECHNOLOGICAL OPTIMIZATION OF LIGHT USE EFFICIENCY IN ALGAE PHOTOBIOREACTORS

Reference: 309485

Call: ERC-2012-StG_20111109

Theme: frontier research

ERC Grantee: Tomas Morosinotto

Department: Biology

UNIPD: host institution

Eu Funding: 1,257,600 €

Email: tomas.morosinotto@unipd.it

Project Description

New renewable energy source are highly needed to compensate exhausting fossil fuels reserves and reduce greenhouse gases emissions. Some species of algae have an interesting potential as feedstock for the production of biodiesel thanks to their ability to accumulate large amount of lipids. Strong research efforts are however needed to fulfil this potential and address many issues involving optimization of cultivation systems, biomass harvesting and algae genetic improvement. This proposal aims to address one of these issues, the optimization of algae light use efficiency. Light, in fact, provides the energy supporting algae growth and must be exploited with the highest possible efficiency to achieve sufficient productivity and make their cultivation competitive. In a photobioreactor algae are highly concentrated and this cause a inhomogeneous light distribution with a large fraction of the cells exposed to very low light or even in the dark. Algae are also actively mixed and they can abruptly move from dark to full illumination and vice versa. Depending on the mixing speed such an alternation of strong light and dark can be beneficial, reducing the damages due to excess irradiation, or harmful, not allowing the time for the activation of photoprotection mechanisms. This proposal aims to assess how these peculiar conditions affect algae growth and functionality of photosynthetic apparatus, analysing the influence of the intensity, duration and frequencies of the light pulses both in batch and continuous cultures. In collaboration with the Chemical Engineering department, experimental data will be exploited to build a model describing the photobioreactor, a fundamental tool to design a system where cells mixing is optimized to have the best photosynthetic efficiency. Conditions found in a photobioreactor are different from the ones cells are evolutionary adapted to and the other main scope of this proposal is the isolation of genetically improved strains. This work will focus on algae of the genus Nannochloropsis, which are highly interesting for biofuels. A first part of the work of setting up protocols for transformation will be followed by a second phase for generation and selection of mutants. Analysis of transcriptome in different light conditions will also be instrumental to identify genes to be targeted by genetic engineering. In order for both previous parts to be effective there is also the need to investigate at the molecular level the composition of Nannochloropsis photosynthetic apparatus composition and regulation which is still poorly investigated. Finally data on light use efficiency obtained in laboratory conditions will be compared with the ones coming from an outdoor pilot scale photobioreactor.