Synthetic ecology: Journal Club with Dr Jagroop Pandhal

Journal Club is often an opportunity for the Grantham Scholars to learn about new concepts. In this post, Grantham Scholar Emanga Alobwede covers the session where her lead supervisor, Dr Jagroop Pandhal, introduced the concept of ‘synthetic ecology’.

This week’s paper

Synthetic ecology – A way forward for sustainable algal biofuel production?’ by E. Kazamiaa, D. C. Aldridgeb and A. G. Smitha

emanga-alobwedeLast week’s Journal club was hosted by my lead supervisor Dr Jags Pandhal, a lecturer in bioengineering based in the Department of Chemical and Biological Engineering. The chosen paper was on the topic of algal cultivation using synthetic ecology, titled ‘Synthetic ecology – A way forward for sustainable algal biofuel production?

Before discussing the paper, the Journal Club started with the Scholars identifying the important aspects one must look at with every journal article. These included the university and department in which the article was written, the journal in which the article was published, and the authors. All these factors, rightly or wrongly, may influence our opinion of the evidence and conclusions presented in the paper, but the important thing is to focus on the merits of the work itself.

This scientific review discussed 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, as bio-fertiliser in the agricultural industry (which my PhD thesis focuses on), but one of their more common uses is in the production of biofuel.

The use of algae in producing biofuel stems from the fact that they are able to produce large quantities of lipids (essentially, oils) and their carbohydrates can also be fermented into ethanol. To carry out this process on an industrial scale is particularly costly due to several factors including the requirement of huge quantities of algae, which need large amounts of nutrients to grow, while also tackling the risk of contamination in the algal cultures grown in raceway ponds – an aspect which the paper focused 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 (so to speak), hence the idea of synthetic ecology.

Our discussion began by analysing the term ‘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 (Tilman, 1982). Basically, this means algal cultures should not be axenic (free of other organisms) but should consist of symbiotic bacteria that are not in direct competition, where 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, as they feed on algae, causing them to bunch together and form colonies, making the lipid-producing algae easier to harvest. However, 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 as stated by the article title, how sustainable is it really?

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 widely topical issue which has been debated amongst many environmentalists who raise concerns over the potential rise in food prices as a result of the use of agricultural land to grow crops for biofuels – concerns echoed by the Grantham Scholars too.

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 simply for growing algae for biofuel production would not be sustainable in the least. However alternatives were highlighted for obtaining nutrients in a sustainable way, 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.

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 (ie, cost effectively, less environmentally demanding in terms of nutrients and using minimal amounts of resources and land to avoid borrowing land from other sectors) would be interesting and exciting to see.

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

References

Tilman, D. (1982) Resource competition and community structure. Princeton press, Princeton, USA

Woertz, I. Feffer, A. Lundquist, T. & Nelson, Y. (2009) Algae grown on dairy and municipal wastewater for simultaneous nutrient removal and lipid production for biofuel feedstock. Journal of Environmental Engineering. 135(11).p.115-1122.