• Lactic Acid Fermentation
    Bioprocess Development Services at Celignis

Background to Lactic Acid Fermentation

Lactic acid bacteria (LAB) are industrially-recognised microorganisms for their lactic acid applications and for their probiotic benefits. Although the process is a well-known fermentation that has been followed for a number of years, lactic acid bacteria suffer from substrate-inhibition and product-inhibition. Product inhibition is considered to be a key reason for not achieving biomass yield and maximum theoretical conversion efficiency.

Conventionally, lime is used to reduce the product inhibition, but this process results in very high amounts of solid and liquid wastes that are high in salts and need to be treated before disposal. Extractive lactic acid fermentation by using liquid-liquid extraction systems, membranes, adsorption resins in fed-batch fermentation mode is gaining attention as it takes care of the product and substrate inhibition.

Lactic acid bacteria are hetero- and homo-fermentative. However, this is not straightforward as, under slow growth rates, mixed acids will be formed even with homofermentative bacteria. It is important to select the strains that are homo-fermentative, have no racemase activity, and are tolerant to inhibitors that are present in industrial by-product streams that have significant amounts of: starch e.g. starch production and processing plants (potato, cassava, sweet potatoes etc); sugars (e.g. lactose whey permeate); and cellulose (e.g. paper industry streams).

How Celignis Can Help

At Celignis we have expertise and experience in screening lactic acid bacteria for the selection of substrate- and product-tolerant strains.. We can also develop: fed-batch strategies to achieve high cell mass, and in situ product recovery techniques to separate lactic acid from the fermentation broth. Our experts will work with you and develop bespoke lactic acid fermentation methods for your feedstock or industrial waste streams.

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Propionic Acid Fermentation

Propionic acid can be produced from a variety of substrates such as glucose, ethanol, lactose, glycerol, and pectin. So, several industrial streams will be suitable to produce propionic acid, if the bacteria are adapted to the inhibitors present in the waste streams and fermentation is optimised to achieve high cell densities and high product concentration.

We can perform anaerobic fermentations and develop fermentation strategies to achieve high cell mass and in-situ product recovery techniques. We can screen your feedstock for propionic acid production, adapt the strain to any inhibitors present in the feed, and develop bespoke fermentation and product recovery processes.

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Butyric Acid Fermentation

Butyric acid is biologically produced by Clostridium species and like other acids (acetic acid, lactic acid, propionic acid), it is toxic to the bacteria after a certain concentration. Hence, the product titres are generally low which makes downstream expensive. In order to reduce these costs, in situ removal of butyric acid can be developed. In situ removal strategies are not yet industrially applied for butyric acid, but it is a key area where progress has to be made to make the process economically sustainable.

At Celignis, we have strong expertise in Clostridial fermentation. We can isolate and or adapt the strains that are suitable for your feedstock and can develop fermentation strategies to reduce substrate and product inhibition. We will innovate with you for you.

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Butanol Fermentation

Butanol fermentation is also one of the difficult fermentation pathways due to substrate and product inhibition. However, this can be avoided by fed-batch fermentation and in-situ stripping of butanol. Also, reducing the feedstock and enzyme costs will make the process more economically viable. Through using industrial waste streams (negative costs), enzymatic cocktails tailored for the feedstock (allowing low-enzyme dosages), and with high sugar yields, the right choice of microbial strain, and an effective in-situ removal technology, it is possible to develop an economically-viable butanol process.

At Celignis, we have considerable expertise in Clostridial fermentation and especially butanol fermentation. Our Chief Innovation Officer Dr Lalitha Gottumukkala has extensively worked in this area and has isolated novel strains and developed novel methods for non-acetogenic butanol fermentation as part of her PhD.

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1,3-Propanediol Fermentation

Natural microbes that produce 1,3-Propanediol are Klebsiella, Clostridia, Citrobacter, Enterobacter and Lactobacilli. They all use glycerol as a carbon source and produce 1,3-PDO through 3-hydroxypropionaldehyde route using glycerol dehydratase enzymes and 1,3-propanediol oxidoreductase enzymes.

At Celignis, we have expertise and experience in performing anaerobic fermentations and developing fermentation strategies to achieve high cell mass and in situ product recovery techniques. We can screen your feedstock for 1,3-Propanediol production, adapt the strain to any inhibitors present in the feed, and develop bespoke fermentation and product recovery process.

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Polyhydroxy Alkanoates (PHAs) Production

PHA is one of the most complicated fermentation processes, but the possibility to use mixed microbial cultures and the avoidance of sterilisation costs makes it an interesting process to produce bioplastics. Also, PHA blends are becoming more and more popular to increase the tensile strength and flexibility of the polymer, possible by using mixed culture substrates.

At Celignis, we have experience in enrichment of desired microorganisms, fed-batch and continuous fermentations with cell-recycling. We can design and develop the most suitable process for your feedstock by using mixed or mono-culture fermentations. We can also develop cost-efficient downstream processing steps for efficient PHA extraction by using non-toxic and environmentally friendly techniques.

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Yeast and Fungal Fermentation

Yeast fermentation is one of the oldest fermentations and is used in everyday life to produce a variety of commodity products including bread, beer, wine, cheese, and soy sauce. A few decades ago, yeast gained popularity as an industrial strain for biorefinery and biofuel applications.

At Celignis, we can use yeast and fungi for the production of: bioethanol, glycerol, single cell oils (SCOs), and emulsifiers, among other products.

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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.

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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.

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