• Ethanol Production
    Through Fermentation

Background to Bioethanol Production

Bioethanol production for the renewable fuels sector largely has historically used starch as the feedstock, however work is undergoing to commercialise the prouction of ethanol from cellulose. However yeast can not ferment starch or cellulose directly, so these polysaccharides are broken down to monomers using enzymes. Enzymes are one of the major costs involved in fermentation and hence consolidated bioprocessing is being researched.

Saccharomyces cerevisiae and its recombinant forms are used for ethanol fermentation. S. cerevisiae are genetically modified for amylolytic activity, ethanol tolerance, high gravity fermentations, inhibitors tolerance (generated during pre-treatment of lignocellulosic biomass), pentose fermentation, and co-fermentation.

Though yeast fermentation has been known for centuries, there are still challenges and process conditions that need to be optimised from feedstock to feedstock and from plant to plant. There is more heterogeneity in beer than in biofuel, brewers keep isolating the natural yeast strains for better flavors and high alcohol concentration, whereas most of the biofuel plants restrict themselves to industrially-available strains. Exploring yeasts beyond S. cerevisiae is required to obtain natural yeasts that have high potential to ferment different types of sugars to ethanol and if necessary, use recombinant technology to further improve growth and fermentation potential.

How Celignis Can Help

There are 3 main types of processes for the fermentation of sugars to bioethanol: 1. Separate hydrolysis and fermentation (SHF); 2. Simultaneous saccharification and fermentation (SSF); 3. Simultaneous saccharification and co-fermentation (SSCF). SHF allows both enzymes and yeast operate at their optimum conditions, but is limited with product inhibition to enzymes and feed inhibition to yeast. This is overcome in SSF and SSFC fermentation where the enzymatic product glucose is consumed by yeast as it is produced. High solids loading fermentation with ethanol-tolerant yeast strains allows production of high concentrations of ethanol. High-solids fermentation causes viscosity issues and hence suitable fermentation regimes and mixers should be designed in order to obtain maximum ethanol concentrations, yields and productivity.

At Celignis we can use a variety of yeast types to produce bioethanol and can undertake and optimise each of these three main fermentation processes.


Bio-glycerol is gaining attention due to the consumer demand for non-petroleum derived products and also because of its potential to be a feedstock for microbial chemicals production (e.g. 1,3 PDO).

We can design processes to produce glycerol in high glucose concentrations using osmo-tolerant yeasts.

Get more info...Glycerol Production

Single Cell Oils (SCOs)

Some yeast and fungal strains are capable of producing lipids in a variety of substrates such as different types of sugars, glycerol, etc. and have wide pH ranges. SCOs are edible oils if they are produced in clean substrates and can be converted to biofuel if industrial by-product streams are used for their production.

Get in touch with us if you would like to learn more about how we can produce SCOs from your biomass and process liquids.

Get more info...Single Cell Oils


The type, quality and quantity of emulsifier depends on microbial strain, carbon source, media components such as major and minor elements, temperature, pH etc. It is important to optimise the process for product quality and quantity. This is only possible with the through understanding of microbial strain, its metabolism and needs. Our experts can guide you through and optimise the process.

Get in touch with us if you would like further information.

Get more info...Emulsifiers Production

Bacterial Fermentation

Bacteria are mainly used to produce organic acids and alcohols by anaerobic fermentation and enzymes by aerobic fermentation processes. Very well-known natural fermenters are lactic acid bacteria (LAB) for lactic acid production and Bacillus species such as B. subtilis, B. amyloliquefaciens, B. licheniformis, B. megaterium etc. for the production of enzymes, antibiotics, surfactins, and biopolymers.

Get more info...Bacterial Fermentation

Microalgal Fermentation

Algal cultivation is complicated and requires optimisation to achieve high biomass yields. Algal biomass production depends on nutrient uptake and other environmental conditions such as temperature, pH, salt concentration etc. It is important to select the strain based on the type of production (open ponds, photobioreactors), feedstock and application. We have particular expertise in the evaluation and optimisation of algae thorugh our Chief Innovation Officer, Lalitha, who is currently undertaking a Marie-Curie funded project at Celignis on this topic.

Get more info...Microalgae Fermentation

Contact Us For Further Details

We are available to answer any questions you may have on how to get high value chemicals and biofuels from biomass through fermentation processes. Just get in touch with us by sending us an email info@celignis.com, giving us a call at (+353) 61 371 725, or through our contact form.

Get more info...Get in Touch