29 October 2019

A bloody good algae

Why does 'Blood Algae' make salmon pink and how could it be a super antioxidant? PhD student Tom Butler explains why he's working with this algae.

PhD Student Tom Butler

Thomas Butler a PhD student in the Department tells us about his previous work with 'Haematococcus' also know as 'Blood Algae'. 

What is Haematococcus?

The green alga (Chlorophyte) Haematococcus lacustris is a predominantly freshwater species and is regarded as the ‘bird bath’ alga (as this is typically where it is found).  It is distinct from other species of Haematococcus due to its ability to produce a vegetative resting stage and is known to accumulate high amounts of the carotenoid astaxanthin (which is the beautiful/spooky vivid red colour).  From this one species there are greater than 60 strains which all have different growth rates and astaxanthin contents. 

Why is Haematococcus and astaxanthin important?

The global astaxanthin market in 2014 was $447 million but has grown considerably since and is envisioned to reach $1.5 billion in 2020. In 2014 280 tonnes of astaxanthin was produced but <10 tonnes is from H. lacustris.  Astaxanthin is commercially sold as a pigment for animal feed, most notably as a pigment for salmon and that is why they are red, without astaxanthin they would be grey and would not be as appealing for the consumer.  Astaxanthin is also sold in a capsule as an antioxidant for the nutraceutical sector. Dr Joseph Mercola, one of the world’s most followed physicians had declared that astaxanthin was ‘the #1 supplement you’ve never heard of that you should be taking’.  Astaxanthin is predominantly manufactured synthetically from petrochemicals (>95 % of the market) but is also obtained naturally from H. lacustris.  Only the natural form from H. lacustris has been used as a nutraceutical but in future the aim is to incorporate the natural form in more everyday products and to replace the synthetic additive in aquaculture but this is a matter of economics!  

What are the problems to address?

The H. lacustris derived astaxanthin industry has been a commercial success, but several constraints have arisen including contamination issues, relatively low biomass and astaxanthin productivities, high downstream processing costs, and photo-bleaching issues in the red stage (die-off from exposure to high light).  These constraints need to be addressed for the production of astaxanthin from H. lacustris for the aquaculture sector. 

What have you been working on?

H. lacustris has a complex life cycle and normally produces astaxanthin in the encysted form but at the Scottish Association for Marine Science (SAMS) during my masters I was focusing on producing astaxanthin in an alternative life cycle stage, red motile macrozooids, lacking the thick walls of aplanospores.  It is believed that the red motile macrozooids could be harvested and fed as a whole-cell product directly to the aquaculture sector as they are rich in astaxanthin and polyunsaturated fatty acids, and could bypass the cell disruption and extraction steps to deliver bioavailable astaxanthin as a biobased feed.  However, as usual in research further testing is required before this becomes a commercial reality.

If you are interested in a more detailed account I have been working with a company in writing a chapter of a book on astaxanthin from H. lacustris which should be published in February 2020:

Microalgae Biotechnology for Food, Health and High Value Products’ Md. Asraful et al., 2020. 


Thomas Butler is part of the Algal Biotechnology Sheffield and the Pandhal Research Group. 

Find a PhD

Search for PhD opportunities at Sheffield and be part of our world-leading research.