Plant Pathway Discovery and Bioengineering of the Most Popular Flavor, Vanillin

Nethaji J Gallage and Birger Lindberg Møller

Plant Biochemistry Laboratory, Department of Plant and Environmental Sciences, University of Copenhagen

Vanilla and its key flavour component vanillin, is a universally appreciated flavour and probably the most popular plant natural product, being derived from the seedpods of the orchid Vanilla planifolia and other related Vanilla species. Vanillin (3-methoxy-4-hydroxybenzaldehyde) is the main flavor compound in the vanilla extract and is the basis and an additive of sweets, ice creams, soft drinks and many more products in the food, beverage and pharmaceutical industry. Our studies during last 4 years reveal how the vanilla orchid produces the most popular aroma compound in the world. In the vanilla pod, vanillin synthesize via ferulic acid and its glucoside. A single hydratase/lyase type enzyme designated vanillin synthase (VpVAN) catalyzes direct conversion of ferulic acid and its glucoside into vanillin and its glucoside, respectively¹.

In 2010, the annual global sales of vanillin reached more than 15,000 tons. Nowadays, it is less than 1% of the global production of vanillin is derived from vanilla pods while the majority is produced synthetically using e.g. lignin and eugenol as starting materials. Production of 1 kilogram (kg) of vanillin requires approximately 500 kg of vanilla pods corresponding to the hand pollination of approximately 40,000 vanilla orchid flowers. This is why; a huge surge in the exploration of more environmentally friendly biosynthetic procedures to make natural flavours has risen². Moreover, Industrial application of bioengineered microorganisms for vanillin production has gained quite a lot of attention not only from the flavour and fragrance industries, but also from environmental groups and the general public^{3, 4}. The recent identification of VpVAN from the vanilla orchid can contribute to an entirely new opportunity for biotechnology based production of natural vanillin². We currently in the process of constructing an exclusive vanilla orchid vanillin production in engineered yeast encompassing vanilla orchid vanillin biosynthetic genes.

Furthermore we have initiated and involved in a project aims at unlocking the potential in Vanilla farming in Africa. Despite being the World’s favorite flavor, Vanilla and vanilla production faces many challenges. Out of 110 Vanilla species, only three have been cultivated for farming, all of South-American origin, but grown in non-native environments primarily in Madagascar and regions of Africa. Apart from reducing the species gene-pool markedly and thus leaving the cultivated species and production reliability highly vulnerable to pests and diseases, the current production is highly labor demanding requiring intensive care and hand pollination as there are no natural pollinators in these non-native environments. However, in the African continent several native Vanilla species are found, but none have been elucidated for cultivability due to lack of resources. This project is the first comprehensive scientific study ever initiated on characterizing metabolite profile of 100 vanilla species with the final goal of discovering a vanilla species with African origin that has high quality vanilla pods and is better adapted to the African continent with possible natural pollinators in Uganda.

1. Gallage, N.J. et al. Vanillin formation from ferulic acid in Vanilla planifolia is catalysed by a single enzyme. Nat Commun 5 (2014).

2. Gallage, N.J. & Møller, B.L. Vanillin–Bioconversion and Bioengineering of the Most Popular Plant Flavor and Its De Novo Biosynthesis in the Vanilla Orchid. Molecular Plant 8, 40-57 (2015).

3. Waltz, E. Engineers of scent. Nature biotechnology 33, 329–332 (2015).

4. Bomgardner, M.M. The problem with vanilla, After vowing to go natural, food brands face a shortage of the favored flavor. Chemical and engineering news 94, 38-42 (2016).