In recent years there has been a significant interest in the potential for using seaweed (or macroalgal biomass) for the production of energy, biofuels, and chemicals
through a biorefining approach. This is for a number of reasons.
Firstly, since seaweed is an aquatic biomass, its utilisation does not cause food-vs-fuel
or land-use conflicts,
both of which can occur when land or biomass which could be used for food production is instead used for energy. Also, since seaweed is a fast growing feedstock that does not
an existing resource that can be potentially harvested over several harvest cycles over the year in numerous locations around the world, it is an abundant existing biomass resource
that can make a significant contribution to the bioeconomy and targets regarding bioenergy, biofuels, and bio-products.
Additionally, the chemistry of seaweed constituents offer the
potential to extract numerous high value chemicals many of which could not be sourced from lignocellulosic biomass.
Seaweed Composition
Seaweed composition differs greatly from that of lignocellulosic biomass. For instance, while lignin forms a significant proportion of
lignocellulose, it is absent in seaweed. The other two constituents of lignocellulose are cellulose and hemicellulose, however seaweed hemicelluloses differ substantially from
those in terrestrial biomass and cellulose is typically present in
much smaller amounts in seaweed. There are also a number of polysaccharides that are unique to seaweeds.
In many of these polysaccharides, sugars that are not present in lignocellulose, or are only present in small amounts,
are present in significant quantities. For example, uronic acids are much more prevalent in seaweed, including
mannuronic acid and guluronic acid which are absent from most lignocellulosic biomasss. The deoxy sugars
fucose and rhamnose are also much more prevalent in seaweed, as is the sugar alcohol
mannitol.
In addition to being significantly different from lignocellulose, the chemistry of seaweeds can also vary greatly between different species. Seaweeds are classed
into three main groups (brown (Phaeophyceae), red (Rhodophyceae), and green (Chlorophyceae)) and there are characteristic differences between each type.
Analysis of Brown Seaweed
Brown seaweeds have been particularly focussed on in recent years as potential biorefinery feedstocks. Laminaria digitata and Saccharina latissima
are examples of brown seaweeds.
Laminarin is one of the polysaccharides found in brown seaweeds. It functions
primarily as a carbohydrate reserve and consists of
a mainchain of glucose with some side chains, also of glucose. The degree of polymerisation of this polysaccharide is around 25, with either mannitol
or glucose as the terminal sugar. Mannitol is also another important cabrohydrate reserve in brown seaweeds.
Fucoidans are another major polysaccharide in brown seaweed. They consist of a backbone of sulphated fucose with additional substitutions
involving galactose and acetate.
Alginic acid is a brown seaweed polysaccharide that contain boths guluronic acid and mannuronic acid
in linear chains with the relative proportions of
mannuronic acid to guluronic acid varying from ratios of 1.2 to 2.1 or greater. Within this linear chain
these hexuronic acids tend to be arranged in C5 epimer blocks of one or the other, although less crystalline blocks involving both sugars can also be present.
Cellulose is only present in minor amounds in brown seaweeds.
Other Constituents and Seasonality in Brown Seaweed
Ash can be a major constituent in brown seaweeds, reaching levels of over 35% in some cases. Protein can also be an important mass component.
It is important to note that the composition of brown seaweed can vary substantially according to species and season. For instance, laminarin can be in concentrations of less than 1%
or over 30%, depending on the season. Similarly, the amount of mannitol can vary by an order of magnitude, whilst alginate can be less than 20% or more than 40%, depending on the
season. Due to this great variation in composition we strongly recommend that samples are analysed directly, for instance with one of our seaweed analysis packages, rather than
using data from the literature.
Analysis of Red Seaweed
Examples of red seaweeds include Kapphaphycus alvarezii, Gracilaria salicornia, and Gelidium amansii.
In red seaweeds the main polysaccharides are agar, carrageenan, cellulose, and mannan. Agar is a mixture of agarose, the major component, and agaropectin. Agarose is a linear
polysaccharide that consists of a backbone of galactose and 3,6-anhydro-galactose, with these two sugars existing as a repeating disaccharide unit. Carrgeenan
also contains these two sugars but they can exist in sulphated and non-sulphated forms. There are different classes of carrageenans and these differ according to the
number and position of the sulphate groups. Mannan is a polysaccharide of mannose and can be sulphated in some cases.
Analysis of Green Seaweed
Examples of green seaweeds include Ulva lactuca and Ulva pertusa.
In green seaweeds the main polysaccharides are cellulose, ulvan, and mannan. The main constituents of ulvan are rhamnose,
xylose, and
glucuronic acid.
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Analysis of Seaweed at Celignis
Our expertise with ion chromatography has allowed us to develop protocols for determining the carbohydrate
and amino acids composition of brown seaweeds.
Analysis package P72 - Seaweed Amino Acids will give the amounts of 12 different amino acids present in seaweed samples.
While these analyses packages are tailored towards the analysis of brown seaweeds we can also analyse red and green seaweeds. Please get in touch if you would like
to find the value of these types of macroalgae.
Celignis will be presenting their outputs from the first 12-months of the project
Celignis's Oscar and Fernando are today attending the 12-month review meeting of our CBE-JU research project MANUREFINERY. The event is taking place at the facility of project partner ENCO in Naples, Italy.
MANUREFINERY, entitled "Smart modular mobile biorefining of manure to zero-waste maximising resource recovery for feed and fertiliser bioingredients in rural areas" is one of the 7 ongoing CBE-JU projects that Celignis is currently involved in. Click here to read more about these projects.
Today we welcomed our partners from the EnXylaScope project to Limerick for the final in-person meeting of the project. The event is being held at the Limerick Strand Hotel and will include a tour of Celignis's Bioprocess and Analytical facilities.
EnXylaScope has been a hugely successful project, leading to multiple innovations in enzyme discovery and biomass processing, with Celignis making impactful developments in technologies for xylan extraction and modification. The project's success has led to a number of follow-on projects (BIONEER and PROMOFER) that involve demonstration of these technologies at higher TRL levels.
Lalitha Presents our EnXylaScope Work at EUBCE 2025
Event takes place in Valencia Spain
Lalitha is today presenting the outputs of our EnXylaScope project at the 34th European Biomass Conference & Exhibition (EUBCE) which is being held in Valencia, Spain.
The presentation, entitled "EnXylaScope: Unleashing xylan's potential with enzymes for a scope of consumer products", will provide a wide-ranging overview of the project which is now in its 4th year.
Today we registered sample number 50,000 on our internal LIMS system. Over the years we have analysed every kind of biomass sample imagineable and we look forward to achieving further milestones in the future as we continue to grow and expand our operations.
Will play a key role as our "Mechanical Engineer for Scaled-up Bioprocesses"
Today the Celignis family welcomed Dileep Raveendran-Nair to the fold. Dileep is a Mechanical Engineer with over 11 years of hands-on experience in biofuel, biochar, and bioproduct process engineering. His career has focused on the operation, maintenance, and optimization of large-scale bioprocess and bioenergy systems, integrating engineering precision with biotechnological innovation to advance sustainable industrial application.
At Celignis he will play a key-role ("Mechanical Engineer for Scaled-up Bioprocesses") in the development of our bioprocessing capabilities as we increase the Technology Readiness Levels (TRL) of our bioprocessing facility to TRL7 and cubic-metre reactors.
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