In common parlance, "sugar" is used to mean any substance that tastes sweet. In chemical terms, sugars are chemical units that make up carbohydrates, whether they're sweet or starchy tasting. The sugar glucose is one of the most ubiquitous chemicals on the planet, and is a source of energy for many living organisms.
Significance
Bacteria, like humans, other animals, and plants, digest glucose for energy. The glucose molecule is made up of six carbon atoms, 12 hydrogen atoms, and six oxygen atoms. Because most of the carbon atoms are in what is called a "reduced" state, the molecule contains lots of energy. By reacting the carbon in such a way that it becomes oxidized rather than reduced, bacteria can liberate energy from glucose and use it for cellular processes, explain Drs. Reginald Garrett and Charles Grisham in their book, "Biochemistry."
Function
As bacteria digest glucose, they produce either carbon dioxide and water or one of a number of other products, depending upon the metabolic strategy they use. They also liberate energy, which they then use to make adenosine triphosphate, or ATP. Drs. Mary Campbell and Shawn Farrell, in their book, "Biochemistry," explain that ATP is a universal "chemical currency" molecule that enzymes and other components of cells can use to run processes. Bacterial motion, for instance, requires ATP.
Considerations
Some bacteria digest glucose under aerobic conditions, meaning that they require oxygen in order to metabolize the sugar. Other types of bacteria use strictly anaerobic strategies, and don't use oxygen. Still others use a combination of the two metabolic types. Note Drs. Garrett and Grisham, bacteria that use aerobic metabolic strategies produce far more energy--approximately 15 times more--per glucose molecule that they digest as compared to bacteria that use strictly anaerobic strategies.
Effects
Glucose digestion does more than simply provide energy to bacteria. In many cases, it also prevents other reactions from taking place. For instance, the bacterial species Escherichia coli has a portion of its genetic code called the "lac operon" that codes for enzymes capable of digesting lactose. The bacteria only use this portion of the genome, and only digest lactose, if glucose is absent, note Drs. Thomas Pollard and William Earnshaw in their book, "Cell Biology." As such, glucose prevents the bacteria from using lactose.
Expert Insight
Since so many bacteria can digest glucose, and since many of the byproducts of glucose digestion by bacteria are acidic, glucose in the human mouth presents an ideal breeding ground for bacteria, with consequences for dental health. As bacteria feed on glucose between human teeth, they secrete acids that can eat away at dental enamel, leading to gum disease and cavities. Regular brushing helps maintain dental health, notes the American Dental Association.
References
- "Biochemistry;" Reginald Garrett, Ph.D. and Charles Grisham, Ph.D.; 2007
- "Biochemistry;" Mary Campbell, Ph.D. and Shawn Farrell, Ph.D.; 2005
- "Cell Biology;" Thomas Pollard, M.D. and William Earnshaw, Ph.D.; 2007
- American Dental Association: Dental Hygiene
