Microbial synthesis of coniferyl alcohol by the fungus Byssochlamys fulva V107

Vanillin-bioconversion and bioengineering of the most popular plant flavor and its de novo biosynthesis in the vanilla orchid

In recent years, biotechnology-derived production of flavors and fragrances has expanded rapidly. The world's most popular flavor, vanillin, is no exception. This review outlines the current state of biotechnology-based vanillin synthesis with the use of ferulic acid, eugenol, and glucose as substrates and bacteria, fungi, and yeasts as microbial production hosts. The de novo biosynthetic pathway of vanillin in the vanilla orchid and the possible applied uses of this new knowledge in the biotechnology-derived and pod-based vanillin industries are also highlighted.

Harnessing eugenol as a substrate for production of aromatic compounds with recombinant strains of Amycolatopsis sp. HR167

To harness eugenol as cheap substrate for the biotechnological production of aromatic compounds, the vanillyl alcohol oxidase gene (vaoA) from Penicillium simplicissimum CBS 170.90 was cloned in an expression vector suitable for Gram-positive bacteria and expressed in the vanillin-tolerant Gram-positive strain Amycolatopsis sp. HR167. Recombinant strains harboring hybrid plasmid pRLE6SKvaom exhibited a specific vanillyl alcohol oxidase activity of 1.1U/g protein. Moreover, this strain had gained the ability to grow on eugenol as sole carbon source. The intermediates coniferyl alcohol, coniferyl aldehyde, ferulic acid, guajacol, and vanillic acid were detected as excreted compounds during growth on eugenol, whereas vanillin could only be detected in trace amounts. Resting cells of Amycolatopsis sp. HR167 (pRLE6SKvaom) produced coniferyl alcohol from eugenol with a maximum conversion rate of about 2.3 mmol/h/l of culture, and a maximum coniferyl alcohol concentration of 4.7 g/1 was obtained after 16 h biotransformation without further optimization. Beside coniferyl alcohol, traces of coniferyl aldehyde and ferulic acid were also detected.

Ferulic acid production from clove oil byPseudomonas fluorescens E118

For the production of the useful antioxidant ferulic acid from clove oil containing abundant eugenol, the growth of eugenol-degrading microorganisms in the presence of clove oil was examined. Pseudomonas fluorescens E118, a clove-oil-tolerant strain, accumulated 6.1 g/l ferulic acid under optimized culture conditions with the intermittent addition of eugenol. When the bacterium was applied to ferulic acid production from clove oil, 5.8 g/l ferulic acid was produced with the intermittent addition of clove oil. Since clove oil is much cheaper than eugenol, ferulic acid production from clove oil by the bacterium is promising for the industrial production of ferulic acid.