Caprolactam is most often synthesized from the benzene component of the BTEX production stream in petroleum processing. It is a precursor in the synthesis of Nylon-6 and as such, among the most highly used chemical intermediates in manufacturing worldwide. More than 9.5 billion pounds of Caprolactam is produced each year with a market value exceeding 4.5 billion dollars.
The manufacture and use of Caprolactam in such large quantities makes environmental contamination inevitable. This is of concern, because it is known to have some toxic affects. Prolonged, heavy exposure in humans can lead to dermatitis, fever and seizures. In several tests, Caprolactam had a mutagenic affect, introducing DNA damage and chromosomal aberrations.
In some studies it has been observed that strains of Pseudomonas sp. capable of degrading Caprolactam could be isolated from enriched sources. In 36.8% of these strains the degradative capability was linked to plasmids contained therein (Esikova et al., 1990). In recent reports, strains of Pseudomonas aeruginosa capable of utilizing Caprolactam as the sole source of carbon and nitrogen were readily isolated following enrichment of pond water, or activated sludge (Steffensen and Alexander, 1995; Kulkarni and Kanekar, 1998). Furthermore, there are numerous reports showing the removal of Caprolactam with normal waste water treatment. Thus the ability to utilize Caprolactam seems to be widespread.
The following is a text-format Caprolactam pathway map. Organisms which can initiate the pathway are given, but other organisms may also carry out later steps. Follow the links for more information on compounds or reactions. This map is also available in graphic (8k) format.
epsilon-Caprolactam Pseudomonas aeruginosa Pseudomonas sp. plasmid pBS1001 and others | | | epsilon-caprolactam | lactamase | | v 6-Aminohexanoate <------- from the Nylon Oligomer Pathway | | | 6-aminohexanoate | transaminase | | v 6-Oxohexanoate | | | | | | v to the Cyclohexane Pathway
Page Author(s): Doug Hershberger
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