These types of carbohydrate fermentation tubes are therefore called Phenol red (sugar) broths. The pH of the medium is adjusted to approximately 7.5, so it appears orange/red when using phenol red pH indicator. The medium used to test carbohydrate fermentation is a nutrient broth that contains a fermentable carbohydrate (usually a monosaccharide or a disaccharide), peptone (amino acids) as well as a pH indicator. Therefore bacteria can be differentiated both based on their ability to ferment various carbohydrates, as well as the end products that result from the fermentation process. Figure 1: Carbohydrate fermentationĪlthough the ultimate substrate molecule for fermentation is always glucose, some bacteria use additional chemical reactions to convert other monosaccharides as well as disaccharides into glucose. Microbes such as yeast and bacteria are genetically engineered to produce valuable fermentation products. We use many fermentation products-as diverse as antibiotics, alcohols, and a variety of foods. There can be numerous end products from fermentation, many of which is useful for us, but not necessarily the microbes. By contrast, the waste left over after ATP production by aerobic respiration are limited to CO 2 and H 2O. Fermentation also tends to produce waste products that can accumulate in the extracellular environment. Note that fermentation is mainly a mechanism for regenerating NAD+ when respiratory process do not occur. For example, one fermentation waste product is ethanol, its got so much stored energy it can be used in gasoline solutions to be combusted/burned to release that energy stored in its chemical bonds. Much of the original energy in the substrate remains tin the chemical bonds of organic end products, like lactic acid or ethanol. Keep in mind, microbes are very versatile, the fermentation substrate does not have to be sugars, it can include even unusual compounds like aromatics (benzoate), glycerol (sugar-alcohol), and acetylene (hydrocarbons)! The end products are characteristic of individual bacterial species. Fermentation includes the reactions of glycolysis (where a single molecule of glucose is broken down into 2 molecules of pyruvate), as well as additional reactions that produce a variety of end products (acids, alcohols, gases). \)įermentation is a metabolic process that some microorganisms use to break down substrates such as glucose and other sugars when O 2 is not available or could not be used by the microorganism.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |