Biotechnological Production of Vanillin

To cater for the large demand for vanillin, besides different synthetic methods also biotechnological processes have been developed. Synthetic vanillin has a major drawback that products containing this compound cannot be labelled as containing a natural flavour. On the other hand, biotechnological products can be labelled as natural. 

For the synthesis several processes have been described using different natural starting materials, such as coniferin, eugenol, guaiacol and lignin (for reviews, see [22, 44, 48, 60, 61]. 

To produce natural vanillin at a lower price, various biotechnological approaches have been explored, such as plant cell cultures and bioconversion of natural compounds by means of microorganisms or isolated enzymes. 

The HCHL encoding gene (see above) has been overexpressed in various plant cells and plants by Walton and co-workers (tobacco. Datura stramonium). In none of these systems could vanillin be detected however, various benzoic 

Whether genetically engineered organisms will be successful for the production of vanillin not only depends on the economic feasibility of the process, but also on the acceptance by the public of GMO-produced vanillin. 

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Priefert H, Rabenhorst J, Steinbuechel (2001) Biotechnological production of vanillin. Appl Microbiol Biotechnol 56 296-314... 

Benz, I. and Muheim, A. Biotechnological Production of Vanillin. In Flavour Science. Recent Developments (Taylor, A.J. and Mottram, D.S., eds.). The Royal Society of Chemistry Information Services, pp. 111-117 (1996)... 

Priefert, H., J. Rabenhorst, A. Steinbuchel, Biotechnological production of vanillin, Appl. Microbiol. Biotechnol., 56, 3-4, p. 296, 2001. 

Scheme 9.1 Principal biochemical pathways involved in the biotechnological production of vanillin.

Labuda IM, Goers KA, Keon KA (1993) Microbial bioconversion process for the production of vanillin. In Schreier P, Winterthaler P (eds) Progress in flavour precursor studies analysis, generation, biotechnology. Proceedings of the international conference, Wuerzburg. Allured, Carol Stream, pp 477-482... 

The VAO-catalyzed production of vanillin is of special synthetic interest. In particular, a route starting from capsaicin that is readily available from red hot pepper has some biotechnological potential. Here, vanillylamine is obtained by hydrolysis of capsaicin using rat liver microsomes and further oxidized by VAO (Fig. 16.3-3). Furthermore, a one-pot synthesis using carboxylesterase for capsaicin hydrolysis is proposed1121. 

Here we will review the current knowledge about the vanilla curing process, the biosynthesis of vanillin and alternative biotechnological production methods. 

Besides the disadvantage of the slow growth process, plant tissue cultures are not ideal for vanillin production because the vanillin biosynthetic pathway is not very actively expressed [32]. In order to provide a realistic alternative to natural vanillin, which is expensive and in limited supply, several iimovative approaches to the biotechnological production ofvanillin from readily available starting materials were developed, especially after the 1990s. The main biochemical reactions involved [33] are summarized in Scheme 9.1. 

A. J., Steinbuchel, A., and Priefert, H. (2006) Potential of Rhodococcus strains for biotechnological vanillin production from ferulic acid and eugenol. Appl. Microbiol. Biotechnol, 72, 745—755. 

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