Riboflavin–Vitamin B2

Production

MAHYAR M AGHEGH

UNIVERSITY OF TEHRAN – FACULTY OF CHEMICAL ENGINEERING

Introduction• Riboflavin was first isolated by Blyth in 1879 from whey, and

the water-soluble, yellow, fluorescent material was named lactochrome.

• According to IUPAC rules, riboflavin [83-88-5] is called 7,8-dimethyl-10-(d-1’-ribityl)isoalloxazine, also known as vitamin B2 or lactoflavin.

• The daily human demand for riboflavin is around 1.7 mg, and deficiencies lead to various symptoms such as, e.g., versions of dermatitis.

• The vitamin cannot be stored in the body and a constant intake is required.

A solution of riboflavin.

Introduction• Chemical synthesis was the first production method to be

established and is still dominating, but in recent years the production is shifting more and more to fermentation.

• Green plants, most bacteria, and moulds, however, can produce their own riboflavin.

• At present, three organisms are used for the industrial production of riboflavin by fermentation: • The filamentous fungus Ashbya gossypii (BASF, Germany)• The yeast Candida famata (ADM, USA)• A genetically engineered strain of Bacillus subtilis (DSM,

Germany)

Upstream

Downstream

Production Process• In this case study, a batch process using E. Ashbyii with a capacity

of around 1000 tons/year is analyzed.• Upstream processing consists of preparation of medium and

associated continuous counter-current sterilization.• Feed components are: 70% glucose syrup, yeast and malt extract,

sunflower oil, sulfuric acid, and concentrated salt solution at room temperature.

• Fermentation is operated batch-wise with 10% inoculum ratios.• Downstream processing starts with harvesting followed by

crystallization, centrifugation (decanter), and final drying (spray dryer) .

• The requested purity of riboflavin is 70%. The residual 30% consists of salts and biomass. The product is obtained as dry powder or as granulate.

Upstream• The upstream processes include preparation and sterilization of the

medium.• The medium’s composition does not allow sterilization of all

components mixed together and using classical batch conditions (121◦C, 20 minutes). Therefore, the medium would be divided into several groups:I. glucose and sunflower oil, II. peptone, yeast and malt extracts, III. salts in waterIV. methionine. The latter is sterilized by filtration. Sulfuric acid does not require sterilization.

• Only two separate solutions have to be prepared:1. 70% glucose (P-1)2. other nutrients (Nutrients Tank / P-4)

Fermentation• In several steps the necessary seed cultures are prepared in

different seed fermenters.• The last seed culture is the start inoculum for the main

fermentation.• The duration of a seed-fermentation is around 50 hours, while

the main fermentation lasts about 500 hours.• During this time the strain produces 27 g/L riboflavin.• Fermentation requires aeration accomplished by a gas

compressor (P-7) and a sterile filter (P-8).• Exhaust gases are filtered by a second filter (P-10).• A small fraction of the harvested broth is put into another tank

and is used as inoculum for the next batch (P-13).

Downstream• After fermentation the broth is harvested into the harvest tank

(P-15).• Part of the product crystallizes in the fermenter and also in the

harvesting tank. Crystallization is completed in the crystallizer (P-16) by evaporation of some of the water.

• Afterwards the suspension is stored in tank P-17.• From the decanter three streams are harvested, two liquid

phases and the cell/crystal suspension (P-18). To achieve higher purity, a washing step is used with a second separation.

• The last step is drying, either using a spray dryer to obtain a powdered product or applying a spray granulation to obtain granulate. Granulate can be dosed more precisely(P-20)

Inventory Analysis• Air is used for aeration but only a little oxygen is actually

consumed (<1%).• Nitrogen is inert in this process and passes through the system

unchanged.• Water is used in the fermentation and in downstream

processing.• Major organic materials used are sunflower oil, glucose, malt

and yeast extracts, and peptone.• The major products of the fermentation are riboflavin,

biomass, carbon dioxide, and water.• Roughly 50% of the carbon used is converted into product,

25% to biomass, and 25% to carbon dioxide.

A handful of malted barley, the white sprouts visible Viscous yeast extract.

Refrences• Heinzle, Elmar, Arno P. Biwer, and Charles L. Cooney.

Development of sustainable bioprocesses: modeling and assessment. John Wiley & Sons, 2007.

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