Algae – a novel solution to the climate crisis?

The global population is estimated to grow from around 7.8 to 9.8 billion people in the next 30 years, and we will need extra food, fuel and water to survive. Algae are a diverse group of aquatic organisms that are increasingly being used to provide sustainable solutions to global problems. Many species of algae can be grown in saltwater, on non-arable land, and they also absorb sunlight and CO₂. This opens up a huge opportunity to expand large scale solar biotechnologies onto areas of land that would otherwise be non-productive, as well as into the oceans, using the Sun’s energy to fuel the world’s future needs.

Advancing algae technologies

The Centre for Solar Biotechnology has thirty research teams across Australia, New Zealand, Europe, Asia and the USA, all working on different aspects of algae, including the collection and characterisation of new species, the development of novel strains and products using synthetic biology and gene editing technologies, the optimisation of production and downstream processes, and techno-economic feasibility studies that are essential for successful scale-up and commercialisation of algal products. We are working on advanced algae technologies for the production of fuels, food, livestock feeds and therapeutic proteins, and have connected with numerous industries and research institutes to further those projects. This ensures that we are well informed of what’s required, and how we can advance the underpinning science to deliver what the industry needs.

Adapting automation to algae screening

We have two Tecan laboratory automation systems to help us develop the high throughput screening approaches necessary to select for certain characteristics, as well as to optimise the production of specific microalgae. We’ve developed these instruments to meet our exact needs with assistance from the manufacturer. One system has been adapted for the growth of photosynthetic microalgae by adding three shaker modules, each holding six multi-well plates, and sealing the chamber to control atmospheric conditions.¹ We then integrated LEDs for every well of a 96-well plate to enable independently controlled light conditions, allowing us to simulate weather patterns or conditions inside an algae culture.²

This platform has a robotic manipulator arm that transfers the plates from the shakers to the onboard spectrophotometer for optical density and fluorescence measurements. It allows us to check the responses of the microalgae to different illumination settings to determine the best conditions for growth.³ One of the great things about this automated set-up is that it allows us to measure the density for each of the 1,728 algae cultures every three hours, day and night, for three days – the throughput is excellent, and we can gather an amazing amount of data this way. As well as optimising the light conditions, different nutrients also need to be tested in order to provide the best synthetic efficiency.

Exploring media composition

The second instrument has a liquid handling arm that we use to explore media compositions and screen different growth conditions to optimise the nutrients for every strain individually. There can be up to 20 different nutrients for each species and, if you decided to test every combination at only three concentrations, you quickly end up with a large number of individual conditions that you need to investigate, making the design of statistically compressed and automated screens essential. We developed a statistical approach to identify high performance production conditions for 100 microalgae cell lines, which meant conducting more than 25,000 individual experiments.⁴ The power of the instruments is that they allow us to investigate and analyse these complicated data sets and find something close to the optimum. This would be impossible using manual screens.

Collaboration for scale-up

We have been using the platforms for a while now, and are very happy with the work that they have enabled; they have really contributed to the robustness of our experiments and have increased our throughput immensely. The local system engineers have been fantastic in helping us to adapt the systems for our workflow, and we are now involved in building a large, collaborative research project within the industry to assist with system scale-up. These kinds of projects are driven forward by everyone working together, and we look forward to seeing what we can achieve.

References

1 Radzun, K.A et al. Automated nutrient screening system enables high-throughput optimisation of microalgae production conditions. Biotechnology for Biofuels, 2015, 8(65). 

2 Yarnold, J et al. Photoacclimation and productivity of Chlamydomonas reinhardtii grown in fluctuating light regimes which simulate outdoor algal culture conditions. Algal Research, 2016, 13, 182-194.

3 Sivakaminathan, S et al. High-throughput optimisation of light driven microalgae biotechnologies. Scientific Reports, 2018, 8(11687).

4 Wolf, J et al. High-throughput screen for high performance microalgae strain selection and integrated media design. Algal Research, 2015, 11, 313-325. 

Authors: 

Professor Ben Hankamer is Director of the University of Queensland’s Centre for Solar Biotechnology

Juliane Wolf is Researcher and Manager of the Centre for Solar Biotechnology pilot plant