Enzymes fermentation

The term fermentation can be used in its original strict meaning (to produce alcohol from sugar—nothing else) or it can be used more or less broadly. We will use the modern broad definition  

This whole classification is shown in Fig. 27.1. Enzyme fermentations can be represented by 

The key distinction between these two types of fermentation is that in enzyme fermentation the catalytic agent, the enzyme, does not reproduce itself, but acts as an ordinary chemical, while in microbial fermentation the catalytic agent, the 

Catalysed by ENZYMES - high molecular weight compounds, which are very specific, and usually only act on one compound 

In this chapter we introduce enzyme fermentations, in the following chapters we take up microbial fermentations. 

---

Next let us see how to evaluate the two rate constants of this important enzyme fermentation equation. 

Arthur Harden and Hans A. S. von Euler-Chelpin Chemistry Fermenting enzymes, fermentation of sugars... 

In many enzyme fermentations, the limiting component, usually the C-source, has to be added semi-continuously to keep its concentration at a predetermined, usually low, value. This measure makes it possible either to influence selectivity between different pathways or to uncouple predominantly cell growth during the first phase of the fermentation from predominantly product (i.e., enzyme) formation in the later stages of the fermentation cycle. Often, protein formation is induced by adding an inducer (see Chapter 4). During the fed-batch phase, the broth volume increases. Either the broth is harvested when the maximum volume is reached, or broth is withdrawn from time to time. The product is present in high concentrations. 

We have discussed how each step in the bioconversion process (e.g., the ECB and ECB deacylase fermentations and the bioconversion) can be improved. The overall improvement in the process is shown in Figure 5. However, with limited resources and time, it is important to focus development efforts on steps that will have the greatest effect on the overall productivity of the process. An excellent way to achieve this is to develop an economic model of the overall process and to use this as shown schematically in Fig. 6. For example, it may be wasteful to focus efforts on improving the yield of the enzyme fermentation if the major cost was due to the ECB fermentation. 

The majority of dextrans in nature are produced extracellularly via dextran-sucrase from sucrose by several lactic acid bacteria, principally Leuconostoc and Streptococcus species [13]. Dextran is also synthesised by dextrinase of different Gluconobacter species [56]. Referring to this enzyme, fermentation of maltodextrins leads to a- —4) branched dextrans with comparatively lower Mw. However, dextransucrase from Leuconostoc mesenteroid.es NRRL B-512F has attracted most interest because of commercial use. 

Takata, H., Takaha, T., Nakamura, H., Fujii, K., Okada, S., Takagi, M., and Imanaka, T. 1997. Production and some properties of a dextrin with a narrow size distribution by the cyclization reaction of branching enzyme./. Ferment. Bioeng.,84,119-123. 

K. Kubota, K. Yakozeki, and H, Ozaki, Effects of L-serine dehydratase activity of L-serine production by Corymbacterium glycinojdiilum and an examination of the properties of the enzyme, /. Ferment. Bioeng, 67 341 (1989). 

Neuberg s studies of the enzymic fermentation of lactic acid resulted in the introduction of its salts as brake fluids in German artillery pieces during World War I. 

K. Brocklehurst, B. S. Baines, and M. P. J. Kierstan. Papain and other constituents of Carica papaya L. In Topics Enzymes Fermentation Biotechnology 5 (A. Wiseman, ed.). Ellis Horwood, Chichester, 1981, p. 264. 

A bioreactor is a reactor in which enzymes or living cells catalyze the biochemical transformations. It is frequently called a fermenter whether the transformation is carried out by living cells or in vivo cellular components (enzymes). Fermentation originally referred to the metabolism of an organic compound under anaerobic conditions. However, modem industrial fermentation includes both aerobic and anaerobic cultures of organisms. Currently, bioreactor and fermenter can be regarded as synonyms. 

Explain the distinction between enzyme fermentations and microbial fermentations. 

Olympia, M., Fukuda, H., Ono, H., Kaneko, Y. et al (1995) Characterization of starch-hydrolyzing lactic acid bacteria isolated from a fermented fish and rice food, Burong Isda , and its amylolytic enzyme. /. Ferment. Bioeng., 80, 124-130. 

---