Vanillin biosynthesis

Scheme 9.1 Proposed pathway for vanillin biosynthesis in Vanilla planifolia beans according to Kanisawa et al. [26]. The thick arrows represent the most likely pathway...

For the biosynthesis of vanillin, several other enzymes are of interest. First of all, phenylalanine ammonia lyase (PAL) this enzyme converts phenylalanine into the cinnamic acid type of compounds, the first intermediates in the vanillin biosynthesis after the primary metabolism. PAL activity could be detected in green beans, but after scalding this activity is lost. The chain shortening enzyme (CSE), responsible for the conversion of a C Cs compound into a C6Ci compound, was found to be localised in the cytosol of cells of the placental tri-chomes in the green beans [23]. 

Ranadive, A.S., Szkutnica, K., Guerrera, J.G. and Frenkel, C. (1983) Vanillin biosynthesis in vanilla beans. In Proceedings of the IX International Congress of Essential Oils, Singapore, pp. 147-154. 

Vanillin, biosynthesis of, 268 Vi Antigen, 335 Viscose process, 95 Viscosity, of dextran solutions, 350 effects of structure on, 350... 

Recently, an unusual cysteine protease named 4-hydroxybenzaldehyde synthase (HBS) was shown to catalyze the eonversion of p-eoiunaric acid to p-hydroxybenzaldehyde. However, the role of HBS in 3-4-DHBA and vanillin biosynthesis remains under... 

Capsaicinoids are synthesized by the condensation of vanillylamine with a short chain branched fatty acyl CoA. A schematic of this pathway is presented in Fig. 8.4. Evidence to support this pathway includes radiotracer studies, determination of enzyme activities, and the abundance of intermediates as a function of fruit development [51, 52, 57-63], Differential expression approaches have been used to isolate cDNA forms of biosynthetic genes [64-66], As this approach worked to corroborate several steps on the pathway, Mazourek et al. [67] used Arabidopsis sequences to design primers to clone the missing steps from a cDNA library. They have expanded the schema to include the biosynthesis of the key precursors phenylalanine and leucine, valine and isoleucine. Prior to this study it was not clear how the vanillin was produced, and thus the identification of candidate transcripts on the lignin pathway for the conversion of coumarate to feruloyl-CoA and the subsequent conversion to vanillin provide key tools to further test this proposed pathway. 

Validation of the role of femloyl-CoA in the synthesis of the vanillin precursor will be detection of the appropriate intermediates and/or enzyme activities in placental extracts that could account for the production of the predicted levels of capsaicinoids. The presence of low levels of monolignol intermediates could be explained by lignin biosynthesis. An alternate route from phenylalanine to vanillin has been considered by some investigators Orlova et al. [68] demonstrated the role of the benzenoid pathway in petunia flowers for the biosynthesis of phenylpropanoid/benzenoid volatiles. 

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

The biosynthesis of vanillin has been extensively studied both in the plant and in plant cell cultures (Scheme 9.1). There are some contradictions between the results of these studies, and consequently several questions about the biosynthetic... 

Funk C, Brodelius P (1992) Phenylpropanoid metabolism in suspension cultures of Vanilla planifolia Andr. IV Induction of vanillinic acid formation. Plant Physiol 99 256-262 Funk C, Brodelius P (1994) Vanilla planifolia Andrews in vitro biosynthesis of vanillin and other phenylpropanoids derivatives. In Bajaj YPS (ed) Biotechnology in agriculture and forestry. Medicinal and aromatic plants VI, vol 26. Springer, Berlin Heidelberg New York, pp 377-402... 

Walton NJ, Narbad A, Faulds CB, Williamson G (2000) Novel approaches to the biosynthesis of vanillin. Curr Opin Biotechnol 11 490-496... 

Zenk MFl (1965) Biosynthesis von Vanillin in Vanilla planifolia Andr. Z Pflanzenphysiol 53 404-414... 

Biosynthesis of vanillin has been attempted by various workers, as reviewed by Walton etal. (2003). 

Benzaldehyde is the second most important material after vanillin. It is used as an ingredient in cherry and other natural fruit flavors in the flavor industry. Natural benzaldehyde is generally extracted from fruit kernels such as apricots. Nowadays, the fermentation of natural substrates such as phenylalanine offers an alternative route for the biosynthesis of natural benzaldehyde (Moller et al., 1998). However, production via the fermentation process will become commercially acceptable only if sufficient yields can be obtained, which has been difficult until now. 

Effect of Furfural, Vanillin and Syringaldehyde on Candida guilliermoiuBi Growth and Xylitol Biosynthesis... 

To investigate the effect of furfural, syringaldehyde, and vanillin on xylitol biosynthesis, as opposed to C. guilliermondii growth rate, the cells were grown to about 10 O.D in batch... 

Fig. 9 Effect of inhibitors on xylitol biosynthesis in high cell density bioreactor cultivation during the resuspension phase. Time 0 is the start of resuspension. Cell density in the bioreactors was constant during the entire resuspension phase in all experiments at 8 OD oo nm-Filled diamond, no inhibitor filled triangle, furfural / //ed square, syringaldebyde filled circle, vanillin...

Natural vanilla flavours have a much more aromatic and delicate character than pure vanillin because more than 250 components contribute to the flavour. However, because of high demand, vanillin is manufactured by biosynthesis, using micro-organisms to imitate the formation of vanillin during the curing process. Vanillin can also be... 

Negishi, 0., K. Sugiura, and Y. Negishi, Biosynthesis of vanillin via ferulic acid in Vanilla planifolia. J. Agric. Food Chem., 2009. 57(21) p. 9956-61. 

As in vitro regeneration of SAM 1 is currently not feasible, MT reactions were often performed with live whole-cell biocatalysts to avoid the need of cofactor supply (i.e., microbial hosts expressing recombinant MTs, see next section). However, a drawback of this strategy is the relatively low intracellular concentration of endogenous SAM 1, which limits methylation capacity and, thus, leads to low product yield. Even in the biosynthesis of natural products in microorganisms, such as methylated antibiotics [69] and triterpenoids [70] or fatty acid methyl esters [71], or in the biotransformation of phenolic compounds by plant cell cultures, for example, of protocatechuic aldehyde to vanillin 28 [72], availability of SAM 1 is rate-limiting. 

G. R., Biinner, K.M., Kristensen, C., Jensen, O.R., Okkels, F.T., Olsen, C.E., Motawia, M.S., and Hansen, J. (2009) De novo biosynthesis of vanillin in fission yeast (Schizosaccharomyces pombe) and baker s yeast (Saccharomyces cere-visiae). Appl. Environ. Microbiol., 75, 2765-2774. 

Dehydroshikimic acid from the aromatic amino acid biosynthesis pathway of yeasts serves as a precursor for the production of the vanillin (Figure 14.4). 

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