Public Release: 

'Tricking' bacteria into hydroxylating benzene

Nagoya University



Credit: Osami Shoji and Masayuki Karasawa

Nagoya, Japan - Breaking carbon-hydrogen bonds is notoriously difficult in lab chemistry, yet nature does it effortlessly. Now, scientists have used E.coli bacteria to oxidize the C-H bonds in benzene to generate phenol, with a genetically inserted enzyme (cytochrome P450BM3), that originally evolved to target other molecules, long-chain fatty acids.

Getting enzymes to do novel reactions - effectively hijacking the biochemistry of living cells for our own purposes - is generally tricky, involving harsh conditions or genetic modification of the enzymes themselves.


As reported in Angewandte Chemie International Edition, the research team created a compound - dubbed C7-Pro-Phe - based on amino acids. This decoy molecule resembles the fatty acids that E.coli metabolizes. Insert the decoy into an E.coli cell, and it will be mis-recognized as a fatty acid, triggering activation of the inserted P450 enzyme. Now supply benzene (C6H6), and the bacteria get busy, oxidizing C6H6 to C6H6O (phenol). No need for the usual lab kit - living cells can do complex chemistry quietly and efficiently.


All that is needed is a ready supply of glucose - which can be recycled from waste products - to feed the E.coli.

Because a naturally occurring - rather than genetically modified - variant of the enzyme is expressed by the E.coli, it is likely that other bacteria could also be modified with the same gene to perform this job. Moreover, different decoys might be suitable for different substrates or bacteria. "A combined program of decoy-screening and mutagenesis could create a versatile toolkit for whole-cell reactions using bacteria," co-author Osami Shoji says.


The article, "Whole-Cell Biotransformation of Benzene to Phenol Catalysed by Intracellular Cytochrome P450BM3 Activated by External Additives," was published in Angewandte Chemie International Edition at DOI:10.1002/anie.201804924.
