Toluene bioconversion

Figure 5. Determination of carbon flux bottlenecks in the toluene bioconversion pathway using resting cells of P. putida EM2878, (a) Identification of T4MO rate limiting step. Arrow denotes time at which p-cresol was added to culture. Curves indicate amount of p-cresol added (A), 0 ppm (B), 10 ppm (C), 50 ppm (D), 150 ppm. (b) Transient accumulation of p-hydroxybenzyl alcohol in conversion of p-cresol to HBA. (k) p-cresol ( ) HBA HBZ IWi) p-hydroxybenzyl alcohol. Lines drawn to indicate trends. (Reproduced with permission from reference 26. Copyright 1999 The Royal Society of Chemistry.)...

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. 

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. 

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... 

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

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... 

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. 

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