Industrial fermentation

Technology
Technology details
Name:	Industrial fermentation
Category:	Biochemical processes and technologies
Feedstock:	Garden and park waste, food waste
Product:	Biomass, bioproducts (e.g., enzymes, biopolymers, organic acids, alcohols)

Industrial fermentation is a biotechnological process which uses microorganisms (genetically modified or not), in particular bacteria, yeasts, fungi or algae, to make useful products. The cells are real "cell factories" for the industrial conversion of a wide range of renewable feedstocks into bulk chemicals, fine chemicals, platform chemicals, pharmaceutical ingredients, bio-fuels, bio-plastics, etc. It is a multidisciplinary technology and includes the integrated application of disciplines such as biochemistry, microbiology, molecular genetics and process technology to develop useful processes and products.

Feedstock

Composition and origin

Depending on the type of microorganisms and its genetic modifications, a various range of feedstocks can be used. The most commonly used feedstocks are listed below:

Lignocellulose and cellulose

Lignocellulose is present in garden and park waste. Cellulose is present in food waste such as fruit and vegetable waste. Via hydrolysis, which is usually performed through enzymatic or thermal treatment, fermentable sugars can be obtained from lignocellulose and cellulose.

Starch

Starch is present in food waste such as potatoes, corn, wheat or cassava. Starch can directly be utilized by amylase-producing microorganisms, particularly filamentous fungi. However, to allow its use in a wider range of fermentations, starch is usually converted into glucose or dextrins by enzymatic hydrolysis.

Oils and Fat

Oils and fats are present in food waste such as gravy, used cooking oil and grease. They can directly be used as fermentation substrate. As they are not water soluble, extensive mixing is required to allow a good contact between the liquid droplets and the fermentation water phase.

Dairy waste

Whey, the liquid by-product of cheese manufacturing, is used as a source of fermentable carbohydrate and nitrogen.

Sugars

Sugar-rich waste streams can be derived from food industry waste, e.g., from the candy industry.

Pre-treatment

Depending on the type of feedstock and its purity, specific pre-treatment technologies are required to provide fermentable substrates to the microorganisms. Generally, this involves a size reduction step, after which the milled biomass can be processed to separate the desired substrate by e.g., centrifugation, filtration, evaporation or crystallization.

In addition, it should be taken into account that some of the above mentioned feedstocks only provide the carbon source (which compose about 50% of the weight of most microorganisms), in that case also other nutrients such as nitrogen, phosphate and potassium need to be added.

Process and technologies

Microorganisms

Microorganisms used in industrial fermentations include: bacteria, yeast, fungi or algae. In practice, these are well-known, productive and harmless (GRAS - Generally Regarded As Safe) production organisms, equipped with the new genetic information, that are used to produce the desired products in high yield and efficiency. A major advantage is that these often genetically modified microorganisms do their work under controlled conditions in a fermenter or bio-reactor, carefully contained and separated from the outside world (contained environment). They cannot escape from the factory so that ecological problems or concerns regarding the release of genetically modified organisms in the environment are avoided.

Schematic representation of an industrial fermentation bioreactor

Equipment

A typical industrial fermenter consists of an CSTR equipped with:

• an aeration and agitation system: to provide good mixing and availability of oxygen for the cell culture
• a temperature and pH control system: to assure optimal conditions for growth or production
• a foam control system: to avoid excessive foam formation
• sampling ports
• addition ports
• a cleaning and sterilization system: to avoid contamination with other, undesired microorganism

Operating conditions

As it involves living organisms, a fermentation process is typically conducted under mild conditions (pH and temperature). As a result, the energy consumption is relatively low as well as the capital and operating costs. However, fermentation technologies are complex and sensitive requiring careful control of quality and safety of the raw materials, process parameters, contamination, etc.

Industrial fermentations may be carried out as batch, fed-batch, or continuous culture systems. Batch and fed-batch operations are quite common, continuous fermentations being relatively rare .

Scale-up of industrial fermentations

Typically, a pure starter culture (or seed), maintained under carefully controlled conditions, is used to inoculate sterile petri dishes or liquid medium in the shake flasks. After sufficient growth, the preculture is used to inoculate the seed fermenter. Because industrial fermentations tend to be large (typically 1–250 m³), the inoculum is built up through several successively larger stages, to 5–10% of the working volume of the production fermenter. However, scale-up of a fermentation process is not straightforward as an increase in fermenter size affects the various process parameters in different ways. Therefore, ample expertise is required to find a compromise between all process parameters.

Products

Depending on the type of microorganisms and its genetic modifications, a range of products can be synthesized. The most common products are listed and divided over two categories: (1) biomass, (2) bioproducts. In case of the latter, some products require complex genetic modifications.

Biomass

• Single Cell Protein
• Single Cell Oil
• Baker's yeast
• Lactic acid bacteria

Bioproducts

Enzymes

• Proteases
• Lipases
• Amylases
• Cellulases
• Peroxidases

Biopolymers

• Poly-hydroxyalkanoates (PHA)
• Polysaccharides: xanthan gum, dextran

Organic acids

• Acetic acid
• Lactic acid

• Citric acid
• Tartaric acid
• Fumaric acid

Alcohols

• Ethanol
• Butanol
• Glycerol
• Butanediol

Solvents

• Acetone

Pharmaceuticals

• Vitamins: vitamin C, B2, B12 ...
• Antibiotics: aminoglycosides, penicillins, cephalosporins, tetracyclines ...
• Hormones

Biocolorants

• cartenoids
• astaxanthins

Biosurfactants and bioemulsifiers

• glycolipids
• rhamnolipids

Amino-acids

• monosodium glutamate (MSG)
• Lysine
• Tryptophan
• Phenylalanine

Post-treatment

The first step in the post-treatment of fermentation broth cultures, also known as downstream processing (DSP), is to remove the cells from the medium. This is typically performed by a solid-liquid separation technology, such, as centrifugation or membrane filtration. Each fraction can then undergo further processing, depending on whether the product is the biomass itself or an intra- or extracellular product. While intracellular products require cell disruption to release the products, extracellular products are solubilized in the depleted fermentation medium. Cell disruption techniques can be divided into mechanical methods (f.e. homogenisation, grinding, sonication, microwave treatment, steam explosion) and non-mechanical methods (f.e. osmotic or temperature shock, enzymatic destruction). To further purify and concentrate the products several methods can be used including chromatography, solvent extraction, crystallization, distillation, drying etc. The choice of purification technology is depending on the characteristics of the desired products.

Technology providers

Amphi-Star

Industrial fermentation provider

General information
Company:	AmphiStar
Country:	Belgium
Contact:	info@amphistar.be
Webpage:	www.amphi-star.be
Technology and process details
Technology name:	BioSurf Biosurfactant Technology Platform	Technology category:	Conversion (Biochemical processes and technologies)
TRL:	1-7	Capacity:	Lab-scale kg·h-1
Aeration:	Yes	Agitator:
Biosafety level:	1	Controlled parameters:	Temperature, pH, Oxygen, Stirring speed, feed rates, etc.
Microorganism:	Starmerella bombicola, Candida kuoi, Rhodotorula bogoriensis, etc. Open for collaboration on any BSL-1 biosurfactant producing strain	Reactor material:	Glass or stainless steel
		Other:	Biofuels and bio-based chemicals, proteins, specialty sugars, specialty chemicals
Feedstock and product details
Feedstock:	Vegetable oils and sugars from biomass	Product:	Biosurfactants e.g. glycolipids such as sophorolipids

AmphiStar has developed a proprietary technology platform for the cost-efficient and ecological production of biosurfactants. We are a founders-led spin-off company established in July 2021 that is the result of 15 years joint development between Ghent University (Inbio.be) and the Bio Base Europe Pilot Plant. We derisk the early development stage for biosurfactant production, guide and support technology transfer to industrial manufacturers and collaborate intensely for further development and improvement of the licensed technology.

Our technology platform is initially based on the fermentative production with the yeast Starmerella bombicola, producing many different biosurfactants at a high volumetric productivity. Our biosurfactants are made from sustainable, renewable feedstocks and waste streams. Microbial fermentation is a clean production technology that is safe for people and the environment. Our biosurfactants are environmentally friendly, palm oil-free, sulfate-free, mild, non-toxic and non-irritant.

NovelYeast bv

Industrial fermentation provider

General information
Company:	NovelYeast bv
Country:	Belgium
Contact:	johan.thevelein@novelyeast.com
Webpage:	https://www.linkedin.com/in/johan-thevelein-aab60a10/
Technology and process details
Technology name:	Yeast fermentation to biofuels and bio-based chemicals. Protein production	Technology category:	Conversion (Biochemical processes and technologies)
TRL:	3-5	Capacity:	Lab-scale kg·h-1
Aeration:	Aerobic, semi-anaerobic	Agitator:
Biosafety level:	BSL-1	Controlled parameters:	Standard parameters
Microorganism:	Saccharomyces cerevisiae, other yeast species, Trichoderma	Reactor material:	Glass
		Other:	Construction of cell factories with recombinant DNA technology
Feedstock and product details
Feedstock:	1G and 2G feedstocks	Product:	Biofuels and bio-based chemicals, proteins, specialty sugars, specialty chemicals

NovelYeast bv was founded in 2019 by Prof. Johan Thevelein (KU Leuven and VIB) to continue his R&D activities after his retirement in 2020 as emeritus. The company focusses on the development and industrial implementation of yeast cell factories for the production of biofuels, bio-based chemicals as well as specialty sugars and ingredients with first- and second-generation feedstocks. It also develops cell factories for the production of specific proteins for food applications and enzymes for saccharification of lignocellulosic biomass. In addition, it uses yeast as a tool for biomedical and agroindustrial applications, including yeast probiotics and anti-cancer drugs selected by screening in yeast. NovelYeast has several R&D service collaborations with companies world-wide.

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