Algae Research & Biotechnology
Single-celled, or microalgae, are a very diverse group of species with many potential applications including the production of biofuels, pigments, protein for animal feed and industrial feedstocks. Their mass culture could also help capture harmful CO2 to combat climate change and to clean wastewater to reduce environmental damage.
Before algae can realize this potential a number of technical challenges must be overcome, such as thermo-tolerance, increased photosynthetic efficiency and reduced harvesting and product recovery costs. These challenges are the focus of several projects in the lab.
1- Thermo-tolerance – Roman algae
The large-scale culture of algae is likely to take place in regions with high light intensities in order to
maximize photosynthetic yield. With light comes heat. However, most algae species have relatively low temperature optima for growth and are therefore likely to perform poorly in such production systems. Our ‘Roman algae’ project is attempting to identify thermo-tolerant species that synthesize useful products, including the precursors of biodiesel. The water within the Roman baths in Bath city centre is green due to the presence of microalgae. There are two different baths: the ‘King’s Bath’ is at 39oC and the ‘Great Bath’ is at 39oC; both have remained constant for many years. Bioprospecting coupled to rDNA bar-coding has identified seven different species of algae. The next steps in the project include: evaluating the ability of the Roman algae species to synthesize biodiesel precursors at elevated temperatures; searching for other valuable chemical compounds using analytical chemistry techniques, such as GC-MS and determining which most suits potential future mass growth for biodiesel production.
2- Increased photosynthetic efficiency and reduced product recovery costs
The Denso Corporation of Japan is attempting to use a particular species of microalgae (Pseudochoricystis ellipsoidea) to capture CO2 emissions from its factories and to recover biodiesel from the resulting algal biomass. In common with most wild algae species, the photosynthetic apparatus of P. ellipsoidea is optimized for operation across a range of light intensities. Consequently, these unmodified strains have more chlorophyll than is required for optimum performance in commercial culture systems, such as shallow raceway ponds or photobioreactors (PBRs), where light is not limiting. This reduces the overall photosynthetic efficiency of the culture due to mutual shading, where algal cells close to the surface intercept more light that they can use, and thereby shade algae deeper in the culture. On objective of this project is to develop strains with reduced chlorophyll content using mutation breeding. These will be evaluated for improved productivity in both raceway ponds and PBRs in facilities located within the Biology and Biochemistry Department. Mutation breeding is also being applied to improve the recovery of oil from the algae by generating strains with reduced cell wall strength.
3- Cleaning wastewater and reducing the cost of algae biomass production
Water utility companies are under intense and growing pressure to reduce the environmental impacts of wastewater treatment, caused principally by excess nitrates and phosphates. At the same time there is demand for sustainable production of biomass for diverse uses, including feed, chemicals and liquid fuels. This project which is part funded by Aragreen (UK) Ltd and the EPSRC addresses both issues by developing methods to cultivate algal biomass in wastewater, supplemented with other waste streams, and utilizing LEDs to provide energy efficient light for growth. The removal of nitates and phosphates from wastewater in sewage works is often an energy intensive process, which relies on chemical inputs and produces CO2 and other wastes. Since nitrates and phosphates (together with CO2and light) are key feedstocks for algal
biomass production, the system we are developing aims to reduce both water treatment costs and the cost of products extracted from algal biomass.
The project has established a pilot scale facility based at Stowfield in South Gloucestershire featuring a
large PBR, state-of-the-art lighting and harvesting equipment and a link to a near-by wastewater treatment works operated by Welsh water. The objective is to demonstrate the feasibility of wastewater treatment using algae by transferring knowledge gained in lab scale experiments conducted at Bath to this much larger and more challenging scale.