Engineered Microbes Make ‘Essence Of Grape’

By optimizing the levels of an enzyme in bacteria strains, researchers in South Korea have found a way to produce grape flavoring without requiring toxic acid catalysts.

A team of scientists in South Korea has found a method to engineer bacteria to produce grape flavoring. Their findings are published in the Proceedings of the National Academy of Sciences.

Flavor compounds are abundant in nature, but synthesizing them in the lab can be tricky. Rather than rely on chemical synthesis methods to produce methyl anthranilate (MANT)—the molecule that gives grape its characteristic flavor—researchers led by Professor Lee Sang-Yup at the Korea Advanced Institute of Science and Technology have used metabolically engineered bacteria.

Image Credit: Asian Scientist
Image Credit: Asian Scientist

The researchers first optimized the levels of an enzyme called AAMT1 in strains of Escherichia coli and Corynebacetrium glutamicum. AAMT1 is responsible for transferring a methyl group onto a MANT precursor molecule.

To maximize production of MANT, the authors tested six strategies, including increasing the supply of the precursor compound to the engineered microbes, as well as enhancing the availability of a co-substrate. The most productive strategy proved to be a two-phase extractive culture, in which MANT was extracted into a solvent.

Using their strategy, the researchers produced 4.47-5.74 grams of MANT per liter, a significant amount, considering that engineered microbes produce most natural products at a scale of milligrams or micrograms per liter.

According to the authors, the results suggest that MANT and other related molecules typically obtained through industrial processes can be produced at scale by engineered microbes in a manner that would allow those flavor compounds to be marketed as natural products instead of artificial ones.

 

Originally published in Asian Scientist. Read original article here.

For more information on the study: Luo et al. (2019) Microbial Production of Methyl Anthranilate, a Grape Flavor Compound.