Emanga Alobwede who researches algae biofertilisers agriculture

Synthetic ecology for algal cultivation by Emanga Alobwede

Grantham Scholar Emanga Alobwede discusses synthetic ecology, which may be a more sustainable way to grow algae for biofuels.

Journal club was hosted by Dr Jags Pandhal a lecturer in bioengineering and my supervisor. Jags chose a paper on algal cultivation using synthetic ecology, Synthetic ecology – A way forward for sustainable algal biofuel production?

Synthetic ecology – A way forward for sustainable algal biofuel production?

This paper discusses the question of how to increase the cultivation of algae for the production of biofuels on a commercial scale to meet realistic fuel demands of a growing population.

Algae are a diverse group of photosynthesising organisms capable of forming blooms as a result of nutrient pollution. Particularly an overabundance of nitrogen (N) and phosphorus (P). They have been used as feed, food supplements in the nutraceutical industry and as bio-fertiliser in the agricultural industry (which my project focuses on).

But one of algae’s more common uses is in the production of biofuel.

Algae as biofuels

The use of algae in producing biofuel stems from the fact that they are able to produce large quantities of lipids (essentially, oils).

Also, their carbohydrates can be fermented into ethanol.

To carry out this process on an industrial scale is costly due to several factors, such as the need for huge quantities of algae, which in turn need large amounts of nutrients to grow. Also there is a risk of contamination in the algal cultures grown in raceway ponds – an aspect which the paper focuses on. Algal cultures are usually at risk of contamination by bacteria and other organisms which occupy different niches, compete for the same resources as algae and eventually wipe them out, hence the idea of synthetic ecology.

What is synthetic ecology?

Synthetic ecology is the practice of producing artificial environments by merging ecological and engineering principles to create new biological functions and systems.

Simply put, in this case it involves putting together different combinations of building blocks – nutrients, algal species, symbiotic bacteria (that form mutualistic associations with algae) and grazers (which feed on algae or bacteria) – to form a synthetic, or unnatural community.

This is based on the competitive exclusion principle whereby diverse communities are more robust and productive than species-poor communities living in the same environment. For more on this look at Resource competition and community structure by Tilman.

Basically, this means algal cultures should not be axenic (free of other organisms). Instead they should consist of symbiotic bacteria that are not in direct competition. So the algae can feed on nutrients provided by the bacteria and vice versa, allowing them both to reach stable population densities.

Grazers such as daphnia (water fleas) are another example. They they feed on algae, causing them to bunch together and form colonies, making the lipid-producing algae easier to harvest.

It was pointed out that the term ‘synthetic ecology’ is an oxymoron that attempts to apply unnatural principles in a natural world. Nevertheless is represents a promising idea in terms of enhancing algal production, and reducing production costs by eliminating the problem of contamination which typically occurs in large scale algal cultures. However how sustainable is it really?

How sustainable is synthetic ecology?

Comparisons were drawn between sugar cane cultivation for ethanol fuel production and algal cultivation for biofuels, both of which represent a more sustainable alternative to the drilling and production of crude oil.

Sugar cane cultivation for ethanol fuel is a topical issue which has been debated amongst many environmentalists. Concerns have been raised over the potential increase in food prices as a result of the use of agricultural land to grow crops for biofuels.

Does algal cultivation using synthetic ecology face similar issues?

Algal cultivation is a nutrient intensive process as previously mentioned, deriving nutrients such as nitrogen and phosphorus from inorganic sources. Nitrogen, for example, is generally derived from the atmosphere or through the Haber-Bosch process, which is energy intensive and costly. Phosphorus is a finite resource used in agricultural fertiliser. Therefore using large quantities of this mineral for growing algae for biofuel production would not be sustainable.

However, alternatives were highlighted for obtaining nutrients in a sustainable way. For example, by growing algae on wastewater, where the algae are able to recycle nutrients from waste (Woertz et al, 2009). However – as pointed out by one of the Scholars – because it is also a water intensive process, it would be difficult for this technology to be carried out in water stressed regions.

What next for algae and biofuels?

Overall, the creation of a well-designed community of various algal species growing in consortium has the potential to increase algal yields and therefore lipid production for the conversion into biofuel.

Whether this can be attained and, moreover, in a sustainable manner would be interesting and exciting to see. To be sustainable it would need to be cost effective, less environmentally demanding in terms of nutrients, and use minimal amounts of resources and land.

The discussion and paper yielded positive reviews from the Scholars. Particularly as it introduced synthetic ecology, which could be a useful concept in several of our projects.

More from Emanga on algae

The advantages of algae as biofertilisers in agriculture by Emanga Alobwede. In this blog, Emanga introduces the benefits to sustainability of using algae as biofertilisers in agriculture.

Journal Club is meet up of Grantham Scholars to discuss publications from a multidisciplinary perspective. It is part of the Grantham Scholar training programme.

Edited by Claire Moran. Main image shows Emanga in the lab.