BIOTECHNOLOGY - V. H. Gerasymenko - 2006

Part II. Special Biotechnologies

Chapter 21. BIOTECHNOLOGY OF PROTEIN PRODUCTION

21.3. BASIC PROCESS FLOW DIAGRAM FOR MICROBIAL PROTEIN PRODUCTION

Regardless of the type of raw material used, the technology for protein production through the accumulation of microorganism biomass (Yeasts, Bacteria, microscopic Fungi) follows a general process flow diagram (Fig. 21.1). The core technological stage is Fermentation, and the main apparatus is the fermenter, where the GROWTH AND DEVELOPMENT of producer microorganisms take place. Fermentation refers to the entire sequence of operations, starting from the Introduction of the producer into a pre-prepared nutrient medium until the completion of growth, Biosynthesis, or biotransformation processes due to the depletion of medium nutrients, cessation of biosynthesis, loss of culture activity, or other reasons.

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Fig. 21.1. Basic process flow diagram for fodder biomass production

(after V. A. Bykov et al., 1987).

Organic raw Materials (carbon source), mineral salt solutions, ammonia, and air are continuously fed into the fermenter containing the microorganism culture, while a Cell suspension in an aqueous medium is withdrawn from it. The Cells are separated from the aqueous solution by centrifugation, heat-treated, and dried. The product can be supplied in powder or granulated form. The protein content in the product ranges from 50-66%. The Nutritional Value of the produced microbial protein is determined by its Lysine (an essential amino acid) content. Yeasts contain about 10% of it relative to total protein (for comparison, the lysine content in soybeans is slightly more than 6%).

An obligatory stage in the technological scheme for producing protein substances is the purification of gaseous emissions containing viable microbial cells, protein dust, and other products of Protein Synthesis.