Principles of Fermentation Technology

Peter F Stanbury, Allan Whitaker, Stephen J Hall

• Editore: Butterworth-Heinemann
• Anno: 2016
• ISBN:
  9780444634085
• Edizione: 3
• Argomento: Technology & Engineering
• Categoria: Chemical & Biochemical Engineering

The successful structure of the previous edition of Principles of Fermentation Technology has been retained in this third edition, which covers the key component parts of a fermentation process including growth kinetics, strain isolation and improvement, inocula development, fermentation media, fermenter design and operation, product recovery, and the environmental impact of processes. This accurate and accessible third edition recognizes the increased importance of animal cell culture, the impact of the post-genomics era on applied science and the huge contribution that heterologous protein production now makes to the success of the pharmaceutical industry.

This title is ideally suited for both newcomers to the industry and established workers as it provides essential and fundamental information on fermentation in a methodical, logical fashion. Stanbury, Whitaker and Hall have integrated the biological and engineering aspects of fermentation to make the content accessible to members of both disciplines with a focus on the practical application of theory. This text collates all the fermentation fundamentals into one concise reference, making it a valuable resource for fermentation scientists, as well as those studying in the field.

• Retains its successful structure and covers all components of the fermentation process
• Integrates the biological and engineering aspects of fermentation to discuss the most recent developments and advancements in the field
• Written in a style accessible to readers from either a biological or engineering background with each chapter supported by an extensive bibliography

Chapter 1

An introduction to fermentation processes

Abstract

This chapter introduces the reader to the fermentation industry and lays the foundation for the rest of the book. The range of products manufactured by fermentation is discussed followed by an explanation of the chronological development of the industry and the six key steps in its evolution, from the production of organic solvents to recombinant proteins and animal cell processes. A “typical” fermentation is then described in terms of its component parts, or unit operations, enabling the reader to place the content of the subsequent chapters in the context of the whole process. Finally, the rationale adopted by the authors is explained and the reader is guided through the contents of the book.

Keywords

fermentation

biomass

primary metabolite

secondary metabolite

recombinant products

transformation processes

batch culture

continuous culture

fed-batch culture

The term “fermentation” is derived from the Latin verb fervere, to boil, thus describing the appearance of the action of yeast on the extracts of fruit or malted grain. The boiling appearance is due to the production of carbon dioxide bubbles caused by the anaerobic catabolism of the sugar present in the extract. However, fermentation has come to have with different meanings to biochemists and to industrial microbiologists. Its biochemical meaning relates to the generation of energy by the catabolism of organic compounds, whereas its meaning in industrial microbiology tends to be much broader.

The catabolism of sugar is an oxidative process, which results in the production of reduced pyridine nucleotides, which must be reoxidized for the process to continue. Under aerobic conditions, reoxidation of reduced pyridine nucleotide occurs by electron transfer, via the cytochrome system, with oxygen acting as the terminal electron acceptor. However, under anaerobic condition, reduced pyridine nucleotide oxidation is coupled with the reduction of an organic compound, which is often a subsequent product of the catabolic pathway. In the case of the action of yeast on fruit or grain extracts, NADH is regenerated by the reduction of pyruvic acid to ethanol. Different microbial taxa are capable of reducing pyruvate to a wide range of end products, as illustrated in Fig. 1.1. Thus, the term fermentation has been used in a strict biochemical sense to mean an energy-generation process in which organic compounds act as both electron donors and terminal electron acceptors.

Figure 1.1 Bacterial Fermentation Products of Pyruvate
Pyruvate formed by the catabolism of glucose is further metabolized by pathways which are characteristic of particular organisms and which serve as a biochemical aid to identification. End products of fermentations are italicized (Dawes & Large, 1982).
A, Lactic acid bacteria (Streptococcus, Lactobacillus); B, Clostridium propionicum; C, Yeast, Acetobacter, Zymomonas, Sarcina ventriculi, Erwinia amylovora; D, Enterobacteriaceae (coli-aerogenes); E, Clostridia; F, Klebsiella; G, Yeast; H, Clostridia (butyric, butylic organisms); I, Propionic acid bacteria.

The production of ethanol by the action of yeast on malt or fruit extracts has been carried out on a large scale for many years and was the first “industrial” process for the production of a microbial metabolite. Thus, industrial microbiologists have extended the term fermentation to describe any process for the production of product by the mass culture of a microorganism. Brewing and the production of organic solvents may be described as fermentation in both senses of the word but the description of an aerobic process as a fermentation is obviously using the term in the broader, microbiological, context and it is in this sense that the term is used in this book.

The range of fermentation processes

There are five major groups of commercially important fermentations:

1. Those that produce microbial cells (or biomass) as the product.

2. Those that produce microbial enzymes.

3. Those that produce microbial metabolites.

4. Those that produce recombinant products.

5. Those that modify a compound that is added to the fermentation—the transformation process.

The historical development of these processes will be considered in a lat...