MICROBIAL-METABOLISM AND BIOTRANSFORMATIONS OF STYRENE

Styrene is an important industrial chemical and it is also produced na turally, mainly by the decarboxylation of cinnamic acid. It possesses both an aromatic ring and a vinyl side-chain and so there are many pos sible routes for its metabolism. Mammalian liver oxidizes styrene, att acking its side-chain to give styrene oxide, followed by hydration to yield phenylethanediol. A strain of Pseudomonas putida has been report ed to use the same route. Initial dioxygenase ring attack followed by meta-cleavage of the ring occurs in a strain of Rhodococcus rhodochrou s, and it has been suggested that initial ring attack occurs in other organisms. Many isolates degrade styrene through phenylacetic acid, an d in one of these bacteria certain of the enzymes have been shown to b e plasmid-encoded. Styrene can be degraded anaerobically by both conso rtia and pure cultures. Bacteria are able to metabolize alpha- and bet a-styrene as well as styrene dimers and tetramers, although higher oli gomers of styrene are recalcitrant. Styrene-degrading organisms have b een used in experimental gas filters, and chiral synthetic precursors based on styrene can be produced using microbial enzymes.