Phenylacetate is derived from the metabolism of phenylalanine, Z-phenylacetaldoxime, styrene, and many other compounds. Phenylacetate aerobic metabolism in fungi usually proceeds by oxidation to homogentisate ([http://www.ncbi.nlm.nih.gov/pubmed/8919815|Cox et al., 1996]), as shown in the left branch below. In bacteria, this rarely occurs, rather the initial step is ligation with CoA. Pseudomonas putida U uses both pathways; 4-hydroxyphenylacetate is metabolised via oxidation and phenylacetate via ligation with CoA ([http://www.ncbi.nlm.nih.gov/pubmed/8168524|Olivera et al., 1994]). Ligation is followed by epoxide formation, isomerization of the epoxide to an oxepin, and hydrolytic ring cleavage, to eventually produce acetyl-CoA and succinyl-CoA, as shown in the right branch. This pathway is found in 16% of 640 bacteria whose genomes have been sequenced, including Pseudomonas putida and Escherichia coli ([http://www.ncbi.nlm.nih.gov/pubmed/20660314|Teufel et al., 2010]). Under anaerobic conditions, the denitrifying bacterium Thauera aromatica oxidizes phenylacetate to benzoyl-CoA via the intermediates phenylacetyl-CoA and phenylglyoxylate (benzoylformate) ([http://www.ncbi.nlm.nih.gov/pubmed/10336636|Rhee and Fuchs, 1999]). This pathway is shown in the KEGG database.