Fermentation process, microbial

Hosobuchi, M., Kurosawa, K. and Yoshikawa, H. (1993) Application of computer on monitoring and control of fermentation process microbial conversion of ML-236B sodium to pravastatin. Biotechnology and Bioengineering, 42, 815-820. 

Hosobuchi M. Kurosawa K, Yoshikawa H. Application of computer to monitoring and control of fermentation process Microbial conversion of ML-236B Na to pravastatin. Biotech Bioeng 1993 42 815. 

Lactic acid-producing bacteria associated with fermented dairy products have been found to produce antibiotic-like compounds caUed bacteriocins. Concentrations of these natural antibiotics can be added to refrigerated foods in the form of an extract of the fermentation process to help prevent microbial spoilage. Other natural antibiotics are produced by Penicillium wqueforti the mold associated with Roquefort and blue cheese, and by Propionibacterium sp., which produce propionic acid and are associated with Swiss-type cheeses (3). 

Fermentation. The microbial production of citric acid on a commercial scale was begun in 1923 utilizing certain strains yispergillus nigerio produce citric acid on the surface of a sucrose and salt solution. This tray fermentation technique is still used today, although it is being replaced by a submerged process known as deep tank fermentation (14—22). 

FIG. 18-28 Usually, the gas-liquid mass-transfer coefficient, K, is reduced with increased viscosity. This shows the effect of increased concentration of microbial cells in a fermentation process. 

Microorganisms have been identified and exploited for more than a century. The Babylonians and Sumerians used yeast to prepare alcohol. There is a great history beyond fermentation processes, which explains the applications of microbial processes that resulted in the production of food and beverages. In the mid-nineteenth century, Louis Pasteur understood the role of microorganisms in fermented food, wine, alcohols, beverages, cheese, milk, yoghurt and other dairy products, fuels, and fine chemical industries. He identified many microbial processes and discovered the first principal role of fermentation, which was that microbes required substrate to produce primary and secondary metabolites, and end products. 

Use of biofilm reactors for ethanol production has been investigated to improve the economics and performance of fermentation processes.8 Immobilisation of microbial cells for fermentation has been developed to eliminate inhibition caused by high concentrations of substrate and product, also to enhance productivity and yield of ethanol. Recent work on ethanol production in an immobilised cell reactor (ICR) showed that production of ethanol using Zymomonas mobilis was doubled.9 The immobilised recombinant Z. mobilis was also successfully used with high concentrations of sugar (12%-15%).10... 

The potential use of immobilised cells in fermentation processes for fuel production has been described previously. If intact microbial cells are directly immobilised, the removal of microorganisms from downstream product can be omitted and the loss of intracellular enzyme activity can be kept to a minimum level.11... 

Normally, fermentation processes can be classified depending on the objective of study. For example, in terms of products fermentation is divided into 4 types, namely, microbial cell, microbial enzyme, microbial metabolite and transformation process. If considering due to its contaminating conditions, it will be classified into 3 types septic, semi-septic and aseptic fermentation. However, in general, the fermentation processed are classified into 3 types as follows. 

Improvement of microbial strains for the overproduction of natural metabolites has been the hallmark of all commercial fermentation processes. Therefore, the aim of this chapter is to highlight several aspects of process improvement to yield natural products for industry at the laboratory, pilot plant and factory scales. 

Parekh S, Vinci VA, Strobel RJ. (2000) Improvement of microbial strains and fermentation processes. Appl Microbiol Biotechnol 54 287-301. 

Han L, Parekh S. (2004) Development of improved strains and optimization of fermentation processes. In Barredo JL (ed). Microbial Processes and Products, (Humana, Totowa, New Jersey), pp. 1-23. 

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