Acenaphthylene and acenaphthalene, polyaromatic hydrocarbons (PAHs), are constituents of coal tar and tobacco smoke. Their degradation serves as a model for bridged PAH metabolism. Rhizobium sp. CU-A1 and Stenotrophomonas sp. RMSK can use acenaphthylene as their sole source of carbon and energy. The pathway involves dioxygenation at the bridge double bond to form 1,2-dihydroxyacenaphthalene, a tautomer of 1-hydroxy-2-ketoacenaphthene. Naphthalene 1,2-dioxygenase, the enzyme which can initiate this route of bacterial acenaphthylene metabolism ([http://www.ncbi.nlm.nih.gov/pubmed/16535238|Selifonov et al., 1996]), has many other catalytic abilities, which are documented in a table of Reactions of Naphthalene 1,2-Dioxygenase. 1-Hydroxy-2-ketoacenaphthene is oxidized to acenaphthenequinone, which is oxidatively cleaved to form naphthalene-1,8-dicarboxylate. This is decarboxylated to 1-naphthoic acid, which is further metabolized to salicylate, which can be transformed to gentisate or catechol ([http://www.ncbi.nlm.nih.gov/pubmed/16957226|Poonthrigpun et al., 2006] and [http://www.ncbi.nlm.nih.gov/pubmed/19543983|Nayak et al., 2009]). A Beijerinckia sp. can metabolize acenaphthylene to acenaphthenequinone by a similar pathway, but no further ([http://www.ncbi.nlm.nih.gov/pubmed/6089663|Schocken & Gibson, 1984]). Acenaphthalene is also degraded through acenaphthenequinone, though the inital metabolites are different. Beijerinchia sp., Pseudomonas sp. BR, BC and A2279, and Sphingomonas sp. A4 can transform acenaphthalene to 1-acenaphthalenol. This compound is either hydroxylated to form 1,2-dihydro-1,2-acenaphthylenediol, or the hydroxyl group is oxidized to form 1-ketoacenaphthene. Both of these compounds are oxidized to 1-hydroxy-2-ketoacenaphthene and from there to acenaphthenequinone ([http://www.ncbi.nlm.nih.gov/pubmed/6089663|Schocken & Gibson, 1984], [http://www.ncbi.nlm.nih.gov/pubmed/9546181|Selifonov et al., 1998], and [http://www.ncbi.nlm.nih.gov/pubmed/16849808|Kouzuma et al., 2006]).