Bioconversion of resveratrol using resting cells of non-genetically modified Alternaria sp.

Bioconversion of resveratrol is mainly achieved using plant cells and genetically modified microorganisms. We proposed a reaction system for resveratrol production using resting cells of a non-genetically modified strain, Alternaria sp. MG1, a resveratrol-producing endophytic fungus isolated from the grape. Effects of phenylalanine concentration, inoculum size, resting time, bioconversion medium, cell age, and pH on resveratrol production in the bioconversion process were investigated and their levels were optimized. The resulting optimal bioconversion medium was 0.2 mM phosphate buffer (pH 6.5), 0.1 g/L MgSO₄, 0.2 g/L CaSO₄, and 4.66 mM phenylalanine. Resting cells obtained from cultures of liquid potato-glucose medium after 4 days proved to be at the most suitable cell age for the bioconversion process with high resveratrol production and nonobvious cell growth. Highest resveratrol production (1.376 μg/L) was observed under the obtained optimal conditions of inoculum size, 12.16% (wet cell weight in 100 mL medium), and resting time, 21.3 H. The study provides a new way to produce resveratrol and establishes an essential reaction system for further study of the biosynthesis pathway of resveratrol in microorganisms, especially fungi.