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Category: Applied and Industrial Microbiology; Environmental Microbiology
Physiological Processes: Enzymes, Emulsification, Uptake, and Chemotaxis, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555818036/9781555811792_Chap06-1.gif /docserver/preview/fulltext/10.1128/9781555818036/9781555811792_Chap06-2.gifAbstract:
This chapter focuses on single-enzyme-catalyzed biodegradation reactions and other physiological processes that microbes use to compete successfully for scarce nutritional resources in soil and water. It is likely that a lot of reactions that fall under the general heading of biodegradation are fortuitous. There are numerous examples of this with insects or fungi that biosynthesize broad-specificity enzymes, such as cytochrome P450 monooxygenases, for detoxifying biological toxins. For example, plant-pathogenic fungi are sometimes warded off with toxic chemicals manufactured in the leaves of the plant being attacked. Fungal cytochrome P450 monooxygenases oxidize an enormous array of compounds, some of which are unlikely to prove toxic, and thus these reactions may well fall into the fortuitous category. Catabolic enzymes are so useful in large part because many have been found. In fact, catabolic enzymes may be the major group of enzymes catalyzing unique reactions found on the Earth. Additionally, there are the known catabolic enzymes which catabolize industrial chemicals. The role of biosurfactants in microbial metabolism has been investigated primarily with petroleum or with purified alkanes. Surfactants are compounds which are amphipathic; that is, they contain hydrophilic and hydrophobic chemical groups linked together in the same molecule. People use surfactants as soaps and detergents and as emulsifying agents in food. The sensing of chemical compounds starts with binding at the cell membrane to a methyl-accepting chemotaxis protein (MCP). The extracellular sensing is transmitted through the MCP, which spans the membrane, to its cytoplasmic domain.
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Metabolism of alkylbenzenes showing the commonality in processing reactions with release of correspondingly larger organic acids with larger alkyl side chains.
Metabolism of alkylbenzenes showing the commonality in processing reactions with release of correspondingly larger organic acids with larger alkyl side chains.
Space-filling model of the active site of naphthalene dioxygenase from P. putida. The redox active groups, the iron-sulfur cluster and the mononuclear- iron center, are shown in green. (Courtesy of R. E. Parales and D. T. Gibson.)
Space-filling model of the active site of naphthalene dioxygenase from P. putida. The redox active groups, the iron-sulfur cluster and the mononuclear- iron center, are shown in green. (Courtesy of R. E. Parales and D. T. Gibson.)
Permeation rates across a lipid membrane bilayer by different compounds. Those compounds further to the right transfer across a membrane correspondingly faster.
Permeation rates across a lipid membrane bilayer by different compounds. Those compounds further to the right transfer across a membrane correspondingly faster.
Stereo view of bacterial cells adhering to an oil droplet. (From reference 63 with permission.)
Stereo view of bacterial cells adhering to an oil droplet. (From reference 63 with permission.)
Bacterial sensing and chemotaxis (top) are comparable to the human sense of smell (bottom)
Bacterial sensing and chemotaxis (top) are comparable to the human sense of smell (bottom)
EC major divisions and distribution of enzymes in the UM-BBD as of 1 September 1999
EC major divisions and distribution of enzymes in the UM-BBD as of 1 September 1999
Reactions catalyzed by naphthalene 1,2-dioxygenase a
Reactions catalyzed by naphthalene 1,2-dioxygenase a
Examples of biosurfactant-producing microbes a
Examples of biosurfactant-producing microbes a