Microbial fermentation to produce

Some steroid drugs are produced by total synthesis, but, in general, the ability of microorganisms to biotransform steroid substrates has proved invaluable in exploiting inexpensive natural steroids as sources of drug materials. It is now possible via microbial fermentation to hydroxylate the steroid nucleus at virtually any position and with defined stereochemistry. These... 

Solichien MS, O Brien D, Hammond EG, and Glatz CE. Membrane-based extractive fermentation to produce propionic and acetic acids Toxicity and mass transfer considerations. Enzyme Microbial Technol, 1995 17(1) 23-31. 

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). 

Lactic acid [50-21-5] (2-hydroxypropanoic acid), CH CHOHCOOH, is the most widely occurring hydroxycarboxylic acid and thus is the principal topic of this article. It was first discovered ia 1780 by the Swedish chemist Scheele. Lactic acid is a naturally occurring organic acid that can be produced by fermentation or chemical synthesis. It is present ia many foods both naturally or as a product of in situ microbial fermentation, as ia sauerkraut, yogurt, buttermilk, sourdough breads, and many other fermented foods. Lactic acid is also a principal metaboHc iatermediate ia most living organisms, from anaerobic prokaryotes to humans. 

It was originally thought that microbial fermentation by Aspergillus terreus followed a similar pattern in that dtric add - produced by glycolysis plus the bridging reaction and two Dathwavs rst reaction of the TCA cyde - was converted to aconitic add. This compound was... 

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. 

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