Bioconversion of toluene

Another interesting speculation on the initial anaerobic bioconversion of toluene is that of Tschech Fuchs (1989)- They note that toluene might be carboxylated to form a toluic acid isomer (Figure 3 -1). To date, there is no evidence to support this contention. 

Bioconversion of Toluene to p-Hydroxybenzoate Using a Recombinant Pseudomonas putida... 

Chua JW, Hsieh J. (1990).Oxidative bioconversion of toluene to 1,3-butadiene-1,4-dicarboxylie acid (cis, ci -muconic acid). World J Microb Biot, 6, 127-143. 

B. C. Buckiand, and C. Lee, Directed evolution of toluene dioxygenase from Pseudomonas putida for improved selectivity towards cis-(lS,2R)-indanediol during indane bioconversion, Melah. Eng. 2000, 2, 339-348. 

Figure 7, HPLC spectra of toluene bioconversion to HBA, HBA retention time, 8,24 min, salicylate retention time, 17,71 min, and m-cresol retention time, 16,78 min. All other peaks detected in the chromatogram are associated with cell growth and glutamate metabolism, (Reproduced with permission from reference 26, Copyright 1999 The Royal Society of Chemistry,)...

Of the C-2-substituted toluenes tested, p-xylene and 2-chlorotoluene, only o-xylene was found to undergo bioconversion, giving 4-hydroxy-2-methylbenzoate as a major product. Less than 1% of the initial 100 ppm o-xylene was found to undergo bioconversion, whereas 6% conversion of toluene, and 86% conversion of 3,4-dimethylphenol, the predicted product of o-xylene conversion by T4MO, were... 

A wide variety of organic solvents has been used to conduct bioconversions including nonpolar solvents such as isooctane, n-hexane, and toluene, in addition to methanol, acetone, and other water-miscible solvents. Dipolar aprotic solvents dimethylformamide (DMF) and dimethylsulfoxide (DMSO) are also compatible with many enzymes and are often used to enhance the solubility of substrates in combination with a nonpolar solvent. Tertiary alcohols such as f-butanol and t-amyl alcohol have been used for many lipase-mediated esterifications as the hindered tertiary alcohol is not typically a good substrate for most enzymes. It should be noted that the presence of small amounts of water is essential for the effective use of most biocatalysts in organic solvents. In some cases an enzyme may only require a monolayer of water molecules on its surface in order to operate. In other cases there may need to be enough water to form reverse micelles where the biocatalyst is contained within a predominantly aqueous... 

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